WorldWideScience

Sample records for supercell lightning simulations

  1. Numerical Simulation of a Tornado Generating Supercell

    Science.gov (United States)

    Proctor, Fred H.; Ahmad, Nashat N.; LimonDuparcmeur, Fanny M.

    2012-01-01

    The development of tornadoes from a tornado generating supercell is investigated with a large eddy simulation weather model. Numerical simulations are initialized with a sounding representing the environment of a tornado producing supercell that affected North Carolina and Virginia during the Spring of 2011. The structure of the simulated storm was very similar to that of a classic supercell, and compared favorably to the storm that affected the vicinity of Raleigh, North Carolina. The presence of mid-level moisture was found to be important in determining whether a supercell would generate tornadoes. The simulations generated multiple tornadoes, including cyclonic-anticyclonic pairs. The structure and the evolution of these tornadoes are examined during their lifecycle.

  2. Spatial and temporal characteristics of VHF radiation source produced by lightning in supercell thunderstorms

    Institute of Scientific and Technical Information of China (English)

    ZHANG Yijun; MENG Qing; P. R. Krehbiel; LIU Xinsheng; ZHOU Xiuji

    2004-01-01

    The three-dimensional temporal and spatial characteristics of VHF radiation events produced by lightning discharges in three supercell thunderstorms have been analyzed based on the data measured by the lightning mapping array system with high time and space resolution. The results indicate that lightning hole (lighting free region) with about 5-6 km in diameter or lighting ring (annular lighting free region) is associated with the strong updraft in thunderstorm. The lasting time of lightning holes is either short or long, being about 20 min in a tornado-producing thunderstorm. The lightning holes appear before the occurrence of tornado. The lightning hole is the most obvious during the occurrence of tornado and some self-existent lighting radiation events appear at a height of 15-16 km. The lightning channels of inter-cloud (IC) lightning discharge exhibit clockwise rotary structures and do not have clear bilevel structures in the vicinity of the tornado. The lightning holes are corresponding to the strong updraft region. The temporal and spatial distribution of lightning radiation events reveals the structure of strong updraft in supercell thunderstorms.Positive cloud-to-ground (CG) lightning discharges dominate in these thunderstorms and the peak of positive CG lightning flash rate appears, with the maximum of 6 per minute, after or before the occurrence of tornado.

  3. Lightning and Radar Observations of the 29 May 2004 Tornadic HP Supercell during TELEX

    Science.gov (United States)

    Macgorman, D. R.; Kuhlman, K. M.

    2006-12-01

    On 29 May 2004, a tornadic heavy-precipitation (HP) supercell storm moved through central Oklahoma and through the Thunderstorm Electrification and Lightning Experiment (TELEX) domain. Three dimensional lightning location data from the Oklahoma Lightning Mapping Array (OK-LMA) depict the evolution of the storm, including convective surges, overshooting tops, and the formation and dissipation of lightning weak holes. In addition to the OK-LMA, the storm was also observed by two C-band mobile radars (SMART-R radars) providing three-minute volume scans and by the KOUN polarimetric S-band radar. Analysis of a lightning weak hole showed that it was co-located horizontally with a core of strong updrafts and with a bounded weak echo region. The majority of the cloud-to-ground lightning detected in the storm by the National Lightning Detection Network lowered negative charge to ground. However, during genesis of the strongest tornado, the dominant polarity of ground flashes near the reflectivity core of the storm evolved to positive. Also at approximately this time, negative ground strikes began occurring under the anvil, tens of kilometers from the reflectivity core, as lightning activity surged roughly 100 km into the anvil. Observations from these platforms provide insight into HP supercell evolution and structure and into relationships of lightning with other properties of the storm.

  4. Charge structures and cloud-to-ground lightning discharges characteristics in two supercell thunderstorms

    Institute of Scientific and Technical Information of China (English)

    ZHANG Yijun; MENG Qing; LU Weitao; Paul Krehbiel; LIU Xinsheng; ZhOU Xiuji

    2006-01-01

    The charge structures and temporal and spatial characteristics of cloud-to-ground (CG) lightning discharges in two supercell thunderstorms have been analyzed based on the data of three-dimen- sional VHF radiation sources with high time and space resolution produced by lightning discharges. The results indicate that the charge structures in main part (convective region) of the thunderstorms were inverted tripole while a number of positive CG lightning discharges were occurring in the two thunderstorms. The positive CG lightning discharges occurred in main part of the thunderstorms and originated from the positive charge region located at the middle part of the thunderstorms. While a number of negative CG lightning discharges were occurring, the negative CG lightning discharges occurred in the anvil of the thunderstorm. The charge structure is inverted dipole in the region due to the slant of charge structure in main region toward anvil region. The negative charge region located at the upper part of anvil produced a lot of negative CG lightning discharges. No or less CG lighting was produced directly by the charge region located at the lower part of the thunderstorm. The charge region in lower part of the thunderstorm plays an important role for the occurrence of CG lightning from charge region above it.

  5. A Total Lightning Perspective of the 20 May 2013 Moore, Oklahoma Supercell

    Science.gov (United States)

    Stano, Geoffrey T.; Schultz, Christopher J.; Carey, Lawrence D.; MacGorman, Don R.; Calhoun, Kristin M.

    2014-01-01

    In the early afternoon of 20 May 2013, a storm initiated to the west-southwest of Newcastle, Oklahoma. This storm would rapidly intensify into the parent supercell of the tornado that struck the city of Moore, Oklahoma. This article describes what contributions total lightning observations from the Oklahoma Lightning Mapping Array could provide to operational forecasters had these observations been available in real-time. This effort includes a focus on the GOES-R pseudo-geostationary lightning mapper demonstration product as well as the NASA SPoRT / Meteorological Development Laboratory's total lightning tracking tool. These observations and tools identified several contributions. Two distinct lightning jumps at 1908 and 1928 UTC provided a lead time of 19 minutes ahead of severe hail and 26 minutes ahead of the Moore, Oklahoma tornado's touchdown. These observations provide strong situational awareness to forecasters, as the lightning jumps are related to the rapid strengthening of the storm's updraft and mesocyclone and serve as a precursor to the stretching of the storm vortex ahead severe weather.

  6. Lightning characteristics relative to radar, altitude and temperature for a multicell, MCS and supercell over northern Alabama

    Science.gov (United States)

    Mecikalski, Retha M.; Carey, Lawrence D.

    2017-07-01

    Cloud electrification leads to the production of nitrogen oxides (NOx), which has an effect on ozone concentrations. Currently large uncertainties exist regarding the contribution of lightning to the global and local NOx budget, even on a per flash basis. Most lightning NOx (LNOx) models distribute the LNOx at reflectivities (Z) ≥ 20 dBZ in the horizontal, while vertically, a Gaussian distribution function with a peak at - 15 °C is used for cloud-to-ground (CG) flashes and a bimodal distribution function with peaks at - 15 °C and - 45 °C is used for inter- and intra-cloud (IC) flashes. This research aims to improve our basic understanding of lightning location relative to radar Z as a function of storm and flash type. Using data from the North Alabama Lightning Mapping Array (NALMA) and the Multi-Radar Multi-Sensor data suite, the results from analyzing a multicell storm, mesoscale convective system and supercell storm showed that 29.7%, 15.9% and 6.9% of all flashes initiated in regions where Z lightning initiation distribution for IC flashes was also not observed for any of the three storms. In addition, it is shown that when incorporating the propagation of the flash, the percentage of NALMA lightning sources located in regions where Z < 20 dBZ increases. Finally, when comparing flash types, the results show that Hybrid flashes have consistently larger sizes than IC and CG flashes, while IC and Hybrid flashes tend to have more sources located at Z < 20 dBZ than CG flashes.

  7. Supercell design for first-principles simulations of solids and application to diamond, silica, and superionic water

    Science.gov (United States)

    Militzer, B.

    2016-12-01

    For efficient first-principles computation of crystalline materials at high density and temperature, an optimal choice of the supercell is important to minimize finite size errors. An algorithm is presented to construct compact supercells for arbitrary crystal structures. Rather than constructing standard supercells by replicating the conventional unit cell, we employ the full flexibility that we gain by using arbitrary combinations of the primitive cell vectors in order to construct a series of cubic and nearly cubic supercells. In cases where different polymorphs of a material needed to be compared, we are able construct supercells of consistent size. Our approach also allows us to efficiently study the finite size effects in systems like superionic water where they would otherwise difficult to obtain because a standard replication of the unit cells leads to supercells that are too expensive to be used for first-principles simulations. We apply our method to simple, body-centered, and face-centered cubic as well as hexagonal close packed cells. We present simulation results for diamond, silica in the pyrite structure, and superionic water with an face-centered cubic oxygen sub-lattice. The effects of the finite simulation cell size and Brillouin zone sampling on the computed pressure and internal energy are analyzed.

  8. Simulation of modulated protein crystal structure and diffraction data in a supercell and in superspace

    Energy Technology Data Exchange (ETDEWEB)

    Lovelace, Jeffrey J.; Simone, Peter D. [Eppley Institute for Research in Cancer and Allied Diseases, 987696 Nebraska Medical, Omaha, NE 68198-7696 (United States); Petříček, Václav [Academy of Sciences of the Czech Republic, Na Slovance 10, 182 21 Praha (Czech Republic); Borgstahl, Gloria E. O., E-mail: gborgstahl@unmc.edu [Eppley Institute for Research in Cancer and Allied Diseases, 987696 Nebraska Medical, Omaha, NE 68198-7696 (United States)

    2013-06-01

    A computer simulation was created for a modulated protein structure along with structure factors in a periodic supercell and in superspace for the purpose of developing and validating software modifications that will be used to solve and refine modulated protein crystals. The toolbox for computational protein crystallography is full of easy-to-use applications for the routine solution and refinement of periodic diffraction data sets and protein structures. There is a gap in the available software when it comes to aperiodic crystallographic data. Current protein crystallography software cannot handle modulated data, and small-molecule software for aperiodic crystallography cannot work with protein structures. To adapt software for modulated protein data requires training data to test and debug the changed software. Thus, a comprehensive training data set consisting of atomic positions with associated modulation functions and the modulated structure factors packaged as both a three-dimensional supercell and as a modulated structure in (3+1)D superspace has been created. The (3+1)D data were imported into Jana2006; this is the first time that this has been performed for protein data.

  9. Simulation of modulated protein crystal structure and diffraction data in a supercell and in superspace.

    Science.gov (United States)

    Lovelace, Jeffrey J; Simone, Peter D; Petříček, Václav; Borgstahl, Gloria E O

    2013-06-01

    The toolbox for computational protein crystallography is full of easy-to-use applications for the routine solution and refinement of periodic diffraction data sets and protein structures. There is a gap in the available software when it comes to aperiodic crystallographic data. Current protein crystallography software cannot handle modulated data, and small-molecule software for aperiodic crystallography cannot work with protein structures. To adapt software for modulated protein data requires training data to test and debug the changed software. Thus, a comprehensive training data set consisting of atomic positions with associated modulation functions and the modulated structure factors packaged as both a three-dimensional supercell and as a modulated structure in (3+1)D superspace has been created. The (3+1)D data were imported into Jana2006; this is the first time that this has been performed for protein data.

  10. Time domain simulations of preliminary breakdown pulses in natural lightning

    CERN Document Server

    Carlson, B E; Bitzer, P; Christian, H

    2016-01-01

    Lightning discharge is a complicated process with relevant physical scales spanning many orders of magnitude. In an effort to understand the electrodynamics of lightning and connect physical properties of the channel to observed behavior, we construct a simulation of charge and current flow on a narrow conducting channel embedded in three-dimensional space with the time domain electric field integral equation, the method of moments, and the thin-wire approximation. The method includes approximate treatment of resistance evolution due to lightning channel heating and the corona sheath of charge surrounding the lightning channel. Focusing our attention on preliminary breakdown in natural lightning by simulating stepwise channel extension with a simplified geometry, our simulation reproduces the broad features observed in data collected with the Huntsville Alabama Marx Meter Array. Some deviations in pulse shape details are evident, suggesting future work focusing on the detailed properties of the stepping mecha...

  11. Simulating lightning into the RAMS model: implementation and preliminary results

    Directory of Open Access Journals (Sweden)

    S. Federico

    2014-05-01

    Full Text Available This paper shows the results of a tailored version of a previously published methodology, designed to simulate lightning activity, implemented into the Regional Atmospheric Modeling System (RAMS. The method gives the flash density at the resolution of the RAMS grid-scale allowing for a detailed analysis of the evolution of simulated lightning activity. The system is applied in detail to two case studies occurred over the Lazio Region, in Central Italy. Simulations are compared with the lightning activity detected by the LINET network. The cases refer to two thunderstorms of different intensity. Results show that the model predicts reasonably well both cases and that the lightning activity is well reproduced especially for the most intense case. However, there are errors in timing and positioning of the convection, whose magnitude depends on the case study, which mirrors in timing and positioning errors of the lightning distribution. To assess objectively the performance of the methodology, standard scores are presented for four additional case studies. Scores show the ability of the methodology to simulate the daily lightning activity for different spatial scales and for two different minimum thresholds of flash number density. The performance decreases at finer spatial scales and for higher thresholds. The comparison of simulated and observed lighting activity is an immediate and powerful tool to assess the model ability to reproduce the intensity and the evolution of the convection. This shows the importance of the use of computationally efficient lightning schemes, such as the one described in this paper, in forecast models.

  12. Simulating High Lightning Flash Rates at Upper Levels in Strong and Severe Thunderstorms

    Science.gov (United States)

    Mansell, E.

    2015-12-01

    Lightning mapping systems have detected high lightning flash rates at the top of convective cores above the environmental -30°C level, particularly in severe storms. Previous 3-D model simulations have reproduced similarly high flash rates using bulk (one or two moment) microphysics, but the details of the charge separation were not closely examined. Recent work has raised questions as to whether the charging processes have been adequately simulated, both in terms of grid resolution and microphysical processes. New simulations of a severe supercell storm with Takahashi spectral bin microphysics and 4x better grid resolution (250m horizontal and 125 vertical spacing) are better able to capture the steep vertical temperature gradients (on the order of 8°C per km) and the process of freezing of larger liquid particles. The results suggest that high charge separation rates can occur as larger drops freeze homogeneously while smaller droplets remain liquid. This process far outstrips other small ice particle production processes like vapor nucleation or ice multiplication. This intense and vertically narrow charging zone then leads to sufficiently fast electric field growth that favors smaller flashes. These results form the hypothesis that high rates of spatially small lightning flashes result from a high density charging current in a relatively small volume, such that initiation electric field thresholds are met quickly before larger net charge regions have time to form. Results will also be presented for bulk microphysics with an updated droplet freezing scheme that emulates the freezing of droplets based on diameter and ambient temperature. An important consideration in both schemes is how to handle newly-freezing droplets in the calculation of riming rate (or cloud water content) in the charge separation rate equations.

  13. Fractal model of lightning channel for simulating lightning strikes to transmission lines

    Institute of Scientific and Technical Information of China (English)

    HE JinLiang; ZHANG XueWei; DONG Lin; ZENG Rong; LIU ZeHong

    2009-01-01

    How to accurately evaluate the direct-strike lightning protection is one of the key issues in the design of transmission lines.In this paper, three important issues in applying the fractal simulation to the lightning protection of transmission lines were discussed, including the criteria and implementation of upward leader inception, the connection with the magnitude of lightning current, and the calculation and control of fractal dimensions.Then we conducted the simulation iterately, leading to statistical results, which indicate that even if the transmission line satisfies the perfect shielding condition, shielding failure fault remains possible.Furthermore, we calculated the shielding failure fault rates of an EHV line with different ground obliquities and distribution of strike points over the interval between two neighboring towers along a UHV-DC line to find out the weak point of transmission-line lightning protection.This work provides a promising approach for improving the lightning protection property of transmission lines by optimizing the configuration of shielding wires and phase or pole conductors.

  14. Fractal model of lightning channel for simulating lightning strikes to transmission lines

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    How to accurately evaluate the direct-strike lightning protection is one of the key issues in the design of transmission lines. In this paper, three important issues in applying the fractal simulation to the lightning protection of transmission lines were discussed, including the criteria and implementation of upward leader inception, the connection with the magnitude of lightning current, and the calculation and control of fractal dimensions. Then we conducted the simulation iterately, leading to statistical results, which indicate that even if the transmission line satisfies the perfect shielding condition, shielding failure fault remains possible. Furthermore, we calculated the shielding failure fault rates of an EHV line with different ground obliquities and distribution of strike points over the interval between two neighboring towers along a UHV-DC line to find out the weak point of transmission-line lightning protection. This work provides a promising approach for improving the lightning protection property of transmission lines by optimizing the configuration of shielding wires and phase or pole conductors.

  15. An Optical Lightning Simulator in an Electrified Cloud-Resolving Model to Prepare the Future Space Lightning Missions

    Science.gov (United States)

    Bovalo, Christophe; Defer, Eric; Pinty, Jean-Pierre

    2016-04-01

    The future decade will see the launch of several space missions designed to monitor the total lightning activity. Among these missions, the American (Geostationary Lightning Mapper - GLM) and European (Lightning Imager - LI) optical detectors will be onboard geostationary satellites (GOES-R and MTG, respectively). For the first time, the total lightning activity will be monitored over the full Earth disk and at a very high temporal resolution (2 and 1 ms, respectively). Missions like the French Tool for the Analysis of Radiation from lightNIng and Sprites (TARANIS) and ISS-LIS will bring complementary information in order to better understand the lightning physics and to improve the weather prediction (nowcasting and forecasting). Such missions will generate a huge volume of new and original observations for the scientific community and weather prediction centers that have to be prepared. Moreover, before the launch of these missions, fundamental questions regarding the interpretation of the optical signal property and its relation to cloud optical thickness and lightning discharge processes need to be further investigated. An innovative approach proposed here is to use the synergy existing in the French MesoNH Cloud-Resolving Model (CRM). Indeed, MesoNH is one of the only CRM able to simulate the lifecycle of electrical charges generated within clouds through non-inductive charging process (dependent of the 1-moment microphysical scheme). The lightning flash geometry is based on a fractal law while the electrical field is diagnosed thanks to the Gauss' law. The lightning optical simulator is linked to the electrical scheme as the lightning radiance at 777.4 nm is a function of the lightning current, approximated by the charges neutralized along the lightning path. Another important part is the scattering of this signal by the hydrometeors (mainly ice particles) that is taken into account. Simulations at 1-km resolution are done over the Langmuir Laboratory (New

  16. Time domain simulations of preliminary breakdown pulses in natural lightning

    Science.gov (United States)

    Carlson, B E; Liang, C; Bitzer, P; Christian, H

    2015-01-01

    Lightning discharge is a complicated process with relevant physical scales spanning many orders of magnitude. In an effort to understand the electrodynamics of lightning and connect physical properties of the channel to observed behavior, we construct a simulation of charge and current flow on a narrow conducting channel embedded in three-dimensional space with the time domain electric field integral equation, the method of moments, and the thin-wire approximation. The method includes approximate treatment of resistance evolution due to lightning channel heating and the corona sheath of charge surrounding the lightning channel. Focusing our attention on preliminary breakdown in natural lightning by simulating stepwise channel extension with a simplified geometry, our simulation reproduces the broad features observed in data collected with the Huntsville Alabama Marx Meter Array. Some deviations in pulse shape details are evident, suggesting future work focusing on the detailed properties of the stepping mechanism. Key Points Preliminary breakdown pulses can be reproduced by simulated channel extension Channel heating and corona sheath formation are crucial to proper pulse shape Extension processes and channel orientation significantly affect observations PMID:26664815

  17. Time domain simulations of preliminary breakdown pulses in natural lightning.

    Science.gov (United States)

    Carlson, B E; Liang, C; Bitzer, P; Christian, H

    2015-06-16

    Lightning discharge is a complicated process with relevant physical scales spanning many orders of magnitude. In an effort to understand the electrodynamics of lightning and connect physical properties of the channel to observed behavior, we construct a simulation of charge and current flow on a narrow conducting channel embedded in three-dimensional space with the time domain electric field integral equation, the method of moments, and the thin-wire approximation. The method includes approximate treatment of resistance evolution due to lightning channel heating and the corona sheath of charge surrounding the lightning channel. Focusing our attention on preliminary breakdown in natural lightning by simulating stepwise channel extension with a simplified geometry, our simulation reproduces the broad features observed in data collected with the Huntsville Alabama Marx Meter Array. Some deviations in pulse shape details are evident, suggesting future work focusing on the detailed properties of the stepping mechanism. Preliminary breakdown pulses can be reproduced by simulated channel extension Channel heating and corona sheath formation are crucial to proper pulse shape Extension processes and channel orientation significantly affect observations.

  18. Simulation of Meteosat Third Generation-Lightning Imager through tropical rainfall measuring mission: Lightning Imaging Sensor data

    Science.gov (United States)

    Biron, Daniele; De Leonibus, Luigi; Laquale, Paolo; Labate, Demetrio; Zauli, Francesco; Melfi, Davide

    2008-08-01

    The Centro Nazionale di Meteorologia e Climatologia Aeronautica recently hosted a fellowship sponsored by Galileo Avionica, with the intent to study and perform a simulation of Meteosat Third Generation - Lightning Imager (MTG-LI) sensor behavior through Tropical Rainfall Measuring Mission - Lightning Imaging Sensor data (TRMM-LIS). For the next generation of earth observation geostationary satellite, major operating agencies are planning to insert an optical imaging mission, that continuously observes lightning pulses in the atmosphere; EUMETSAT has decided in recent years that one of the three candidate mission to be flown on MTG is LI, a Lightning Imager. MTG-LI mission has no Meteosat Second Generation heritage, but users need to evaluate the possible real time data output of the instrument to agree in inserting it on MTG payload. Authors took the expected LI design from MTG Mission Requirement Document, and reprocess real lightning dataset, acquired from space by TRMM-LIS instrument, to produce a simulated MTG-LI lightning dataset. The simulation is performed in several run, varying Minimum Detectable Energy, taking into account processing steps from event detection to final lightning information. A definition of the specific meteorological requirements is given from the potential use in meteorology of lightning final information for convection estimation and numerical cloud modeling. Study results show the range of instrument requirements relaxation which lead to minimal reduction in the final lightning information.

  19. Lightning

    Science.gov (United States)

    Pampe, William R.

    1970-01-01

    Presents basic physical theory for movement of electric charges in clouds, earth, and air during production of lightning and thunder. Amount of electrical energy produced and heating effects during typical thunderstorms is described. Generalized safety practices are given. (JM)

  20. RSRM top hat cover simulator lightning test, volume 2. Appendix A: Resistance measurements. Appendix B: Lightning test data plots

    Science.gov (United States)

    1990-01-01

    Resistance measurements are given in graphical for when a simulated lightning discharge strikes on an exposed top hat cover simulator. The test sequence was to measure the electric and magnetic fields induced inside a redesigned solid rocket motor case.

  1. On the robustness of aerosol effects on an idealized supercell storm simulated with a cloud system-resolving model

    Directory of Open Access Journals (Sweden)

    H. Morrison

    2012-08-01

    Full Text Available A cloud system-resolving model (the Weather Research and Forecasting model with 1 km horizontal grid spacing is used to investigate the response of an idealized supercell storm to increased cloud droplet concentrations associated with polluted conditions. The primary focus is on exploring robustness of simulated aerosol effects in the face of complex process interactions and feedbacks between the cloud microphysics and dynamics. Simulations are run using sixteen different model configurations with various microphysical or thermodynamic processes modified or turned off. Robustness of the storm response to polluted conditions is also explored for each configuration by performing additional simulations with small perturbations to the initial conditions. Differences in the domain-mean accumulated surface precipitation and convective mass flux between polluted and pristine conditions are small for almost all model configurations, with relative differences in each quantity generally less than 15%. Configurations that produce a decrease (increase in cold pool strength in polluted conditions also tend to simulate a decrease (increase in surface precipitation and convective mass flux. Combined with an analysis of the dynamical and thermodynamic fields, these results indicate the importance of interactions between microphysics, cold pool evolution, and dynamics along outflow boundaries in explaining the system response. Several model configurations, including the baseline, produce an overall similar storm response (weakening in polluted conditions despite having different microphysical or thermodynamic processes turned off. With hail initiation turned off or the hail fallspeed-size relation set to that of snow, the model produces an invigoration instead of weakening of the storm in polluted conditions. These results highlight the difficulty of foreseeing impacts of changes to model parameterizations and isolating process interactions that drive the system

  2. Numerical Simulation of the Lightning Return Stroke.

    Science.gov (United States)

    da Frota Mattos, Marcos Andre

    Available from UMI in association with The British Library. Requires signed TDF. Several lightning return stroke models were developed in this work. Initially very simple models were developed, and subsequently many of the main features of the channel were added. The corona effect, the geometrical parameters, non-linear losses and the cloud losses are these features. To solve the RLC network model of the channel the numerical technique known as TLM was used. A numerical sensitivity study was made to analyse the influence of the filtering and the Gibbs effects on the results. A sensitivity study of the channel's parameters was also made. For the first time three of the main measured lightning channel quantities were calculated showing good agreement with observations. These quantities are the electromagnetic field, current waveshape at ground and the velocity of propagation. The surge impedence and the current rise-time were also calculated at all heights.

  3. Simulation of quasi-linear mesoscale convective systems in northern China: Lightning activities and storm structure

    Science.gov (United States)

    Li, Wanli; Qie, Xiushu; Fu, Shenming; Su, Debin; Shen, Yonghai

    2016-01-01

    Two intense quasi-linear mesoscale convective systems (QLMCSs) in northern China were simulated using the WRF (Weather Research and Forecasting) model and the 3D-Var (three-dimensional variational) analysis system of the ARPS (Advanced Regional Prediction System) model. A new method in which the lightning density is calculated using both the precipitation and non-precipitation ice mass was developed to reveal the relationship between the lightning activities and QLMCS structures. Results indicate that, compared with calculating the results using two previous methods, the lightning density calculated using the new method presented in this study is in better accordance with observations. Based on the calculated lightning densities using the new method, it was found that most lightning activity was initiated on the right side and at the front of the QLMCSs, where the surface wind field converged intensely. The CAPE was much stronger ahead of the southeastward progressing QLMCS than to the back it, and their lightning events mainly occurred in regions with a large gradient of CAPE. Comparisons between lightning and non-lightning regions indicated that lightning regions featured more intense ascending motion than non-lightning regions; the vertical ranges of maximum reflectivity between lightning and non-lightning regions were very different; and the ice mixing ratio featured no significant differences between the lightning and non-lightning regions.

  4. Simulation of lightning attachment to open ground, tall towers and aircraft

    Energy Technology Data Exchange (ETDEWEB)

    Ratnamahilan, P.; Hoole, P. (Univ. of Technology, Lae (Papua New Guinea). Dept. of Electrical and Telecommunications Engineering); Ratnajeevan, S.; Hoole, H. (Harvey Mudd College, Claremont, CA (United States). Dept. of Engineering)

    1993-04-01

    The characteristics of lightning waveforms are important in taking protective measures against it. However, many of these characteristics cannot be measured. This paper employs a mathematical model of lightning currents to write a software package to simulate all manner of lightning flashes. The capabilities available to us through this are demonstrated by extracting the behavior of lightning waveforms following attachment to open ground, tall towers and aircraft.

  5. Simulating statistics of lightning-induced and man made fires

    Science.gov (United States)

    Krenn, R.; Hergarten, S.

    2009-04-01

    The frequency-area distributions of forest fires show power-law behavior with scaling exponents α in a quite narrow range, relating wildfire research to the theoretical framework of self-organized criticality. Examples of self-organized critical behavior can be found in computer simulations of simple cellular automata. The established self-organized critical Drossel-Schwabl forest fire model (DS-FFM) is one of the most widespread models in this context. Despite its qualitative agreement with event-size statistics from nature, its applicability is still questioned. Apart from general concerns that the DS-FFM apparently oversimplifies the complex nature of forest dynamics, it significantly overestimates the frequency of large fires. We present a straightforward modification of the model rules that increases the scaling exponent α by approximately 1•3 and brings the simulated event-size statistics close to those observed in nature. In addition, combined simulations of both the original and the modified model predict a dependence of the overall distribution on the ratio of lightning induced and man made fires as well as a difference between their respective event-size statistics. The increase of the scaling exponent with decreasing lightning probability as well as the splitting of the partial distributions are confirmed by the analysis of the Canadian Large Fire Database. As a consequence, lightning induced and man made forest fires cannot be treated separately in wildfire modeling, hazard assessment and forest management.

  6. Pulse generator with intermediate inductive storage as a lightning simulator

    Science.gov (United States)

    Kovalchuk, B. M.; Kharlov, A. V.; Zherlytsyn, A. A.; Kumpyak, E. V.; Tsoy, N. V.

    2016-06-01

    Compact transportable generators are required for simulating a lightning current pulse for electrical apparatus testing. A bi-exponential current pulse has to be formed by such a generator (with a current rise time of about two orders of magnitude faster than the damping time). The objective of this study was to develop and investigate a compact pulse generator with intermediate inductive storage and a fuse opening switch as a simulator of lightning discharge. A Marx generator (six stages) with a capacitance of 1 μF and an output voltage of 240 kV was employed as primary storage. In each of the stages, two IK-50/3 (50 kV, 3 μF) capacitors are connected in parallel. The generator inductance is 2 μH. A test bed for the investigations was assembled with this generator. The generator operates without SF6 and without oil in atmospheric air, which is very important in practice. Straight copper wires with adjustable lengths and diameters were used for the electro-explosive opening switch. Tests were made with active-inductive loads (up to 0.1 Ω and up to 6.3 μH). The current rise time is lower than 1200 ns, and the damping time can be varied from 35 to 125 μs, following the definition of standard lightning current pulse in the IEC standard. Moreover, 1D MHD calculations of the fuse explosion were carried out self-consistently with the electric circuit equations, in order to calculate more accurately the load pulse parameters. The calculations agree fairly well with the tests. On the basis of the obtained results, the design of a transportable generator was developed for a lightning simulator with current of 50 kA and a pulse shape corresponding to the IEEE standard.

  7. Pulse generator with intermediate inductive storage as a lightning simulator.

    Science.gov (United States)

    Kovalchuk, B M; Kharlov, A V; Zherlytsyn, A A; Kumpyak, E V; Tsoy, N V

    2016-06-01

    Compact transportable generators are required for simulating a lightning current pulse for electrical apparatus testing. A bi-exponential current pulse has to be formed by such a generator (with a current rise time of about two orders of magnitude faster than the damping time). The objective of this study was to develop and investigate a compact pulse generator with intermediate inductive storage and a fuse opening switch as a simulator of lightning discharge. A Marx generator (six stages) with a capacitance of 1 μF and an output voltage of 240 kV was employed as primary storage. In each of the stages, two IK-50/3 (50 kV, 3 μF) capacitors are connected in parallel. The generator inductance is 2 μH. A test bed for the investigations was assembled with this generator. The generator operates without SF6 and without oil in atmospheric air, which is very important in practice. Straight copper wires with adjustable lengths and diameters were used for the electro-explosive opening switch. Tests were made with active-inductive loads (up to 0.1 Ω and up to 6.3 μH). The current rise time is lower than 1200 ns, and the damping time can be varied from 35 to 125 μs, following the definition of standard lightning current pulse in the IEC standard. Moreover, 1D MHD calculations of the fuse explosion were carried out self-consistently with the electric circuit equations, in order to calculate more accurately the load pulse parameters. The calculations agree fairly well with the tests. On the basis of the obtained results, the design of a transportable generator was developed for a lightning simulator with current of 50 kA and a pulse shape corresponding to the IEEE standard.

  8. Transient Simulation of Wind Turbine Towers under Lightning Stroke

    Directory of Open Access Journals (Sweden)

    Xiaoqing Zhang

    2013-01-01

    Full Text Available A simulation algorithm is proposed in this paper for lightning transient analysis of the wind turbine (WT towers. In the proposed algorithm, the tower body is first subdivided into a discrete multiconductor system. A set of formulas are given to calculate the electrical parameters of the branches in the multiconductor system. By means of the electrical parameters, each branch unit in the multiconductor system is replaced as a coupled π-type circuit and the multiconductor system is converted into a circuit model. Then, the lightning transient responses can be obtained in different parts on the tower body by solving the circuit equations of the equivalent discretization network. The laboratory measurement is also made by a reduced-scale tower for checking the validity of the proposed algorithm.

  9. Energy Conversion Efficiency of Mcg-Based Lightning Simulators

    Science.gov (United States)

    Chernykh, E. V.; Fortov, V. E.; Gorbachev, K. V.; Kujekin, I. P.; Nesterov, E. V.; Stroganov, V. A.; Karpoushin, Yu. A.; Shourupov, A. V.

    2004-11-01

    The problem of HE mass gain minimization is extremely important due to environmental and safety considerations of MCG application to mobile simulators of lightning current (MSLC). There are several methods of increasing the efficiency of MSLC with an electrical explosive opening switch (EEOS) in the circuit of the secondary winding of a conventional transformer (CT) with inductance L2. One may use the battery of fast-run MCGs of a small diameter, or increase both the magnitude of L2 and the energy of power supply bank of capacitors, or use larger diameter wires with solid insulation. Results of experiments using spiral-coaxial MCG, 36 mm in diameter, have produced an acceptable efficiency of 12%. When the wires were insulated with polyethylene, energy absorption was high. Analysis of alternatives to open switches (OS) in the MCG circuit has shown their competitiveness. They allow reduction of the optimum L2 magnitude, use of a modular device design, and shaping of the waveform and of the lightning current pulse duration during its droop by introducing one additional MCG module into the circuit.

  10. Sandia Lightning Simulation Facility Building 888. Hazards assessment document

    Energy Technology Data Exchange (ETDEWEB)

    Banda, Z.; Barnett, B.

    1994-10-01

    The Department of Energy Order 5500.3A requires facility-specific hazards assessments be prepared, maintained, and used for emergency planning purposes. This hazards assessment document describes the chemical and radiological hazards associated with the Sandia Lightning Simulation Facility, Building 888. The entire inventory was screened according to the potential airborne impact to onsite and offsite individuals. The air dispersion model, ALOHA, estimated pollutant concentrations downwind from the source of a release, taking into consideration the toxicological and physical characteristics of the release site, the atmospheric conditions, and the circumstances of the release. The greatest distance at which a postulated facility event will produce consequences exceeding the Early Severe Health Effects threshold is 23 meters. The highest emergency classification is a Site Area Emergency. The Emergency Planning Zone is 65 meters.

  11. Modeling and Simulation Research on Lightning Over-voltage of 500kV Hydroelectric Station

    Directory of Open Access Journals (Sweden)

    Huang Wang-jun

    2012-08-01

    Full Text Available Lightning over-voltage amplitude of equipments on different branch nodes of the arterials has been obtained after the modeling and simulation analysis based on the EMTP (electromagnetic transients program were done on the lightning over-voltage of a 500kV hydroelectric station was with the system’s worst working condition (single-line, single-transforming, and the line tower on the near side of 500kv hydroelectric station’s GIS was struck by lightning. Thus, precise data have been acquired to select suitable equipments and verify the resisting lightning performance of the station. Finally, reasonable measures (such as reducing pulse resistance of line tower are proposed to improve the comprehensive lightning resisting level of hydroelectric stations.

  12. A Simulation Study of Lightning Surge Characteristics of a Distribution Line Using the FDTD Method

    Science.gov (United States)

    Matsuura, Susumu; Tatematsu, Akiyoshi; Noda, Taku; Yokoyama, Shigeru

    Recently, numerical electromagnetic field computation methods, which solve Maxwell's equations, have become a practical choice for the lightning surge analysis of power systems. Studies of lightning surge response of a transmission tower and lightning-induced voltages on a distribution line have already been carried out using the numerical electromagnetic field computation methods. However, a direct lightning stroke to a distribution line has not yet been studied. The authors have previously carried out pulse tests using a reduced-scale distribution line model which simulate the direct lightning stroke to a distribution line. In this paper, first, the pulse test results are simulated using the FDTD (Finite Difference Time Domain) method which is one of the numerical electromagnetic field computation methods, and comparisons are shown to validate the application of the FDTD method. Secondly, we present lightning surge characteristics of an actual-scale distribution line obtained by the FDTD method. The FDTD simulation takes into account the following items: (i) detailed structure of the distribution line; (ii) resistivity of the ground soil; (iii) propagation speed of the lightning return stroke.

  13. Potential of convective rainfall estimation from lightning data in the context of the "Simulation of Meteosat Third Generation - Lightning Imager through Tropical Rainfall Measuring Mission - Lightning Imaging Sensor data

    Science.gov (United States)

    Biron, D.; de Leonibus, L.; Zauli, F.; Melfi, D.; Laquale, P.; Labate, D.

    2009-04-01

    The Centro Nazionale di Meteorologia e Climatologia Aeronautica recently hosted a fellowship sponsored by Selex Galileo, with the intent to study and perform a simulation of Meteosat Third Generation - Lightning Imager (MTG-LI) sensor behavior through Tropical Rainfall Measuring Mission - Lightning Imaging Sensor data (TRMM-LIS). For the next generation of earth observation geostationary satellite, major operating agencies are planning to insert an optical imaging mission, that continuously observes lightning pulses in the atmosphere; EUMETSAT has decided in recent years that one of the candidate mission to be flown on MTG is LI, a Lightning Imager. MTG-LI mission has no Meteosat Second Generation heritage, but users need to evaluate the possible real time data output of the instrument to agree in inserting it on MTG payload. Authors took the expected LI design from MTG Mission Requirement Document, and reprocess real lightning dataset, acquired from space by TRMM-LIS instrument, to produce a simulated MTG-LI lightning dataset. The simulation is performed in several run, varying Minimum Detectable Energy, taking into account processing steps from event detection to final lightning information. A definition of the specific meteorological requirements is given from the potential use in meteorology of lightning final information for convection estimation and numerical cloud modeling. Study results show the range of instrument requirements relaxation which lead to minimal reduction in the final lightning information. Potential in convective rainfall estimation over ocean from space lightning observation is addressed and a retrieval example making use of lightning ground network data is reported both with validation by radar observation.

  14. A Simple Lightning Assimilation Technique For Improving Retrospective WRF Simulations

    Science.gov (United States)

    Convective rainfall is often a large source of error in retrospective modeling applications. In particular, positive rainfall biases commonly exist during summer months due to overactive convective parameterizations. In this study, lightning assimilation was applied in the Kain...

  15. A simple lightning assimilation technique for improving retrospective WRF simulations.

    Science.gov (United States)

    Convective rainfall is often a large source of error in retrospective modeling applications. In particular, positive rainfall biases commonly exist during summer months due to overactive convective parameterizations. In this study, lightning assimilation was applied in the Kain-F...

  16. An isolated tornadic supercell of 14 July 2012 in Poland - A prediction technique within the use of coarse-grid WRF simulation

    Science.gov (United States)

    Taszarek, Mateusz; Czernecki, Bartosz; Walczakiewicz, Szymon; Mazur, Andrzej; Kolendowicz, Leszek

    2016-09-01

    On 14 July 2012 a shortwave trough with a cold front passed through Poland. A few tornadoes were reported in the north central part of the country within an isolated cyclic supercell. The cell moved along the thermal and moisture horizontal gradients and the support of a synoptic scale lift. An analysis allowed for setting up four tornado damage tracks in a distance of 100 km and with a total length of 60 km. Tornadoes damaged 105 buildings with predominant intensity of F1-F2/T3-T4 (maximum F3/T6) in Fujita/TORRO scale, caused 1 fatality, 10 injures and felled 500 hectares of Bory Tucholskie forest. The main aim of this article was to analyze this event and assess the possibilities of its short-term prediction. In order to achieve this, a model forecast data derived from WRF-ARW simulation with a spatial resolution of 15 km and initial conditions extracted from 0000 UTC GFS was used. An analysis yielded that the cell moved in the environment of a low lifting condensation level, rich boundary layer's moisture content and a steepening vertical lapse rates that provided the presence of a thermodynamic instability. A wind vectors tilting with height and an increased vertical wind shear occurred as well. A forecasting method that combined a Universal Tornadic Index composite parameter with a convective precipitation filter showed that convective cells at 1500 UTC in the north central Poland had a potential to become tornadic. Within the use of a proposed methodology, it was possible to issue a tornado forecast for the areas where an index pointed the risk.

  17. Simulation of Lightning Overvoltage Distribution on Stator Windings of Wind Turbine Generators

    Institute of Scientific and Technical Information of China (English)

    LIU Rong; LIU Xue-zhong; WANG Ying; LI Dan-dan

    2011-01-01

    This paper analyzes lightning surge on the stator windings of wind turbine generators. The path of lightning in the wind turbines was analyzed. An equivalent circuit model for megawatt direct-driven wind turbine system was developed, in which high-frequency distributed parameters of the blade conducts, tower, power cables and stator windings of generator were calculated based on finite element method, and the models of converter, grounding, loads, surge protection devices and power grid were established. The voltage distribution along stator windings, when struck by lightning with 10/350 ~ts wave form and different amplitude current between 50 kA and 200 kA, was simulated u- sing electro-magnetic transient analysis method. The simulated results show that the highest coil-to-core voltage peak appears on the last coil or near the neutral of stator windings, and the voltage distribution along the windings is non- uniform initially. The voltage drops of each coil fall from first to last coil, and the highest voltage drop appears on the first coil. The insulation damage may occur on the windings under lightning overvoltage. The surge arresters can re- strain the lightning surge in effect and protect the insulation. The coil-to-core voltage in the end of windings is nearly 19.5 kV under the 200 kA lightning current without surge arresters on the terminal of generator, but is only 2.7 kV with arresters.

  18. Natural Lightning Parameters and their Simulation in Laboratory Tests

    Science.gov (United States)

    1976-02-01

    of the order of hundreds of amperes for hundreds of milliseconds. (4) Electromagnetic coupling from flashes that are " near misses ." Both intracloud...follows that ’.he vulnerability to the fields produced by a lightning " near miss " is increasing. The calculation of these fields is quite involved...because the linear dimensions of the radiating channels are comparable with, or greater than, the distance involved in a near miss . Hiere Is also a

  19. Laboratory simulations of volcanic ash charging and conditions for volcanic lightning on Venus

    Science.gov (United States)

    Airey, Martin; Warriner-Bacon, Elliot; Aplin, Karen

    2017-04-01

    Lightning may be important in the emergence of life on Earth and elsewhere, as significant chemical reactions occur in the superheated region around the lightning channel. This, combined with the availability of phosphates in volcanic clouds, suggests that volcanic lightning could have been the catalyst for the formation of biological compounds on the early Earth [1]. In addition to meteorological lightning, volcanic activity also generates electrical discharges within charged ash plumes, which can be a significant contributor to atmospheric electricity on geologically active planets. The physical properties of other planetary atmospheres, such as that of Venus, have an effect on the processes that lead to the generation of volcanic lightning. Volcanism is known to have occurred on Venus in the past, and recent observations made by ESA's Venus Express satellite have provided evidence for currently active volcanism [2-4], and lightning discharges [e.g. 5]. Venusian lightning could potentially be volcanic in origin, since no meteorological mechanisms are known to separate charge effectively in its clouds [6]. The hunt for further evidence for lightning at Venus is ongoing, for example by means of the Lightning and Airglow Camera (LAC) [7] on Akatsuki, the current JAXA mission at Venus. Our laboratory experiments simulate ash generation and measure electrical charging of the ash under typical atmospheric conditions on Earth and Venus. The study uses a 1 litre chamber, which, when pressurised and heated, can simulate the high-pressure, high-temperature, carbon dioxide-dominated atmosphere of Venus at 10 km altitude ( 5 MPa, 650 K). A key finding of previous work [8] is that ash plume-forming eruptions are more likely to occur at higher altitudes such as these on Venus. The chamber contains temperature/pressure monitoring and logging equipment, a rock collision apparatus (based on [9]) to generate the charged rock fragments, and charge measurement electrodes connected

  20. The Effects of Orographic Geometry on Supercell Thunderstorms

    CERN Document Server

    Smith, Galen M

    2016-01-01

    The effect of elongated bell-shaped mountain orientation on supercell thunderstorms is numerically investigated using the Bryan Cloud Model 1 (CM1). The orography is varied by three mountain heights and is varied in four different positions, effectively producing 12 different terrain configurations. It is found that the different orientations produce variations in the supercell life cycle with shorter cycles for higher inflow rates. Furthermore, these cycles are associated with the storm reaching its minimum intensity just after a peak rain period. Moreover, the effect of stronger inflow was seen before direct storm-terrain interactions started. The higher inflow also played a significant role in increasing rainfall rate and areal extent, to the point that further convection, associated with the cold pool, was triggered adding to rainfall amount. Using a stricter form of the National Weather Service Tornado Detection Algorithm to investigate the tornadic nature of simulated supercells; it is found that terrai...

  1. A Tower Model for Lightning Overvoltage Studies Based on the Result of an FDTD Simulation

    Science.gov (United States)

    Noda, Taku

    This paper describes a method for deriving a transmission tower model for EMTP lightning overvoltage studies from a numerical electromagnetic simulation result obtained by the FDTD (Finite Difference Time Domain) method. The FDTD simulation carried out in this paper takes into account the following items which have been ignored or over-simplified in previously-presented simulations: (i) resistivity of the ground soil; (ii) arms, major slant elements, and foundations of the tower; (iii) development speed of the lightning return stroke. For validation purpose a pulse test of a 500-kV transmission tower is simulated, and a comparison with the measured result shows that the present FDTD simulation gives a sufficiently accurate result. Using this validated FDTD-based simulation method the insulator-string voltages of a tower for a lightning stroke are calculated, and based on the simulation result the parameter values of the proposed tower model for EMTP studies are determined in a systematic way. Since previously-presented models include trial-and-error process in the parameter determination, it can be said that the proposed model is more general in this regard. As an illustrative example, the 500-kV transmission tower mentioned above is modeled, and it is shown that the derived model closely reproduces the FDTD simulation result.

  2. Simulation Study About the Influence of Atmospheric Stratification on Lightning Activities

    Institute of Scientific and Technical Information of China (English)

    ZHENG Dong; ZHANG Yijun; LU Weitao; MA Ming; MENG Qingi

    2008-01-01

    A 2D model about charging and discharging processes in thundercloud is used to simulate three differential atmospheric stratifications resulting in discrepant thunderstorm processes in Beijing region. The dynamic and microphysical processes in thunderstorm and their influence on lightning activities are also discussed.The results indicate that ascending velocity and water vapor axe the most important factors to influence lightning activities. At the same time, they affect each other and are together controlled by atmospheric stratification. The magnitude of the ascending velocity determines the intensity of storm and the time when the thunderstorm matured. The thunderstorm with strong updrafts can reach a large height in a short time. Strong persistent updrafts and sufficient water vapor which help to generate more ice phase hydrometeors that directly influence charging and discharging process will prolong the mature stage of the thunderstorm and thereby enhance lightning activities. Though the big density of ice phase hydrometeors can be formed, it is difficult to sustain a long time in the condition of strong updrafts and scant water vapor. Under the condition of weak updrafts and suffcient water vapor in the whole levels, it is easy to form warm cloud process in which the ice phase process and lightning activities are weak. The favorable stratification conditions for strong lightning activities are the sufficient vapor in the lower atmosphere,moderate humidity in the mid troposphere, big instability energy and some suitable convective inhibition.Through calculating some atmospheric instability parameters, it is indicated that convective instability index smaller than -10℃ (negative means instable), convective available potential energy larger than 1000 J kg-1,convective inhibition larger than 40 J kg-1, the 700-hPa potential equivalent temperature larger than 340 K and the 35%-85% humidity in the mid troposphere (700-400 hPa) are the advantageous conditions

  3. Lightning simulation of a combined overhead line/cable connected GIS

    DEFF Research Database (Denmark)

    Kessel, Jakob; Atlason, Vioir; Bak, Claus Leth;

    2008-01-01

    at the surge arrester grounding in the overhead line/cable transition and different length of the connection cable between the transformer and the GIS busbar with a SA implemented. Those simulations are conducted for different positions of the circuit breaker present at the GIS busbar. The lightning current...... required to cause inadmissible voltages at the transformer is evaluated and the MTBF is found for different cases. With the circuit breaker at the GIS busbar in closed position results indicate that SF does not cause inadmissible voltages to appear at the trasformer. However, BFO caused by a lightning...... stroke of extremely high magnitude can cause inadmissible voltages to appear at the transformer. With the circuit breaker at the GIS busbar in open position results indicate that both SF and BFO can cause inadmissible voltages to appear at the tranformer. A risk assessment based on the simulation results...

  4. Modeling and Simulation of the Current Quenching Behavior of a Line Lightning Protection Device

    CERN Document Server

    Mürmann, Mario; Fuchs, Roman; Nefedov, Alexander; Nordborg, Henrik

    2016-01-01

    We develop a consistent model for a Line Lightning Protection Device and demonstrate that this model can explain the two modes of current quenching -- impulse quenching and current zero quenching -- observed in such devices. A dimensional analysis shows that impulse quenching can always be obtained if the power loss from the electric arcs is large enough as compared to $U_0 I_f$, where $U_0$ is the grid voltage and $I_f$ is the maximum follow current after a lightning strike. We further show that the two modes of quenching can be reproduced in a full 3D arc simulations coupled to the appropriate circuit model. This means the arc simulations can be used for optimization and development of future LLPDs.

  5. Three dimensional simulation of a DC free burning arc. Application to lightning physics

    Science.gov (United States)

    Chemartin, L.; Lalande, P.; Montreuil, E.; Delalondre, C.; Chéron, B. G.; Lago, F.

    2009-02-01

    One of the mechanisms assumed to be involved in the ignition channel cut off is associated with the development of instability. Like any other electric arc, lightning channels become unstable if the provided power is insufficient. In order to study this phenomenon, ONERA in collaboration with EDF has performed 3D simulations of a part of a lightning channel in order to compute the main characteristics of the arc and understand in the future the physical conditions for the ignition of instability. The model, based on the resistive magneto hydro dynamic equations, was adapted to the lightning channel context. In a first step, the results were compared to the experiment of Tanaka et al. [Tanaka, S., Sunabe, K., and Goda, Y., 2000. Three dimensional behaviour analysis of D.C. free arc column by image processing technique, XIII Int'l Conf on Gas Discharges and their applications, Glasgow.] on long electric arcs subjected to continuing current at mean sea level. A good agreement between computations and measurements was found for times greater than tens of millisecond. Results also showed that the internal resistance continuously decreases with time. Finally, this model was adapted to investigate the effects of altitude on the characteristics of the arc column. Results showed that the effects of altitudes are negligible for altitudes lower than 4 km.

  6. Impacts of WRF lightning assimilation on offline CMAQ simulations

    Science.gov (United States)

    Deep convective clouds vertically redistribute trace gases and aerosols and also provide a source for scavenging, aqueous phase chemistry, and wet deposition, making them important to air quality.? Regional air quality simulations are typically driven by meteorological models tha...

  7. MSFC shuttle lightning research

    Science.gov (United States)

    Vaughan, Otha H., Jr.

    1993-01-01

    The shuttle mesoscale lightning experiment (MLE), flown on earlier shuttle flights, and most recently flown on the following space transportation systems (STS's), STS-31, -32, -35, -37, -38, -40, -41, and -48, has continued to focus on obtaining additional quantitative measurements of lightning characteristics and to create a data base for use in demonstrating observation simulations for future spaceborne lightning mapping systems. These flights are also providing design criteria data for the design of a proposed shuttle MLE-type lightning research instrument called mesoscale lightning observational sensors (MELOS), which are currently under development here at MSFC.

  8. The simulation of TGF origin in lightning leader electric fields by cosmic ray shower electrons

    Science.gov (United States)

    Connell, P. H.; Atri, D.

    2015-12-01

    With the TGF simulation package LEPTRACK we can easily create all kinds of electric field geometries and electron flux fields to simulate Relativistic Runaway Electron Avalanches - it is script driven, with the details of high energy scattering physics hidden from the user, and an easily accessible output database for each particle created or scattered. We will show the results of simulating a realistic scenario of TGF origin based on cosmic ray shower electron flux fields in the neighbourhood of electric field geometries expected around lightning leader tips. Electron fluxes are derived from simulations using the CORSIKA cosmic ray simulation package and leader electric field geometry from current models. Presuming a TGF observed at orbital altitudes must come from a lightning leader pointing "upwards", and that cosmic rays enter at angles pointing "downwards" to "horizontal", we will show which combinations allow the electron flux to curve into the compact electric field of the leader and gain sufficient acceleration to create a TGF photon flux observable in orbit.

  9. Lightning path simulation based on the stepped leader: Electrical conductivity effects

    Science.gov (United States)

    Mendes, Odim; Domingues, Margarete Oliveira

    2005-09-01

    A numerical simulation for the stepped leader path in the earth atmosphere has been developed to study the influence of the tropospheric electric conductivity on the lightning behaviour. This model is based on the assumption that the leader path follows the gradient of the electric potential. In the model, the charge configuration (amount of charge and location), the variation of the atmospheric conductivity, the charge deposited along the leader channel and the charge at the leader tip are considered. A perfectly conducting ground surface and a curl-free electric field assumption are considered too. The result of the simulation is that the inclusion of an atmospheric conductivity of exponentially increasing value with height alters the percentage of positive cloud-to-ground flashes compared to that percentage obtained assuming a constant conductivity profile. A higher amount of positive flashes occur for high altitude (low latitude) clouds even in the case of little horizontal displacement between the positive and the negative dipole charges in the cloud, that is, with no significant wind shear in the horizontal wind. The simulation has shown that positive lightning, the most dangerous kind, can occur in clear air at great distances from the thundercloud, with safety risk implications.

  10. Numerical Investigation on the Growth of Large Hail in a Simulated Supercell Thunderstorm%超级单体风暴中大冰雹增长机制的模拟研究

    Institute of Scientific and Technical Information of China (English)

    陈宝君; 郑凯琳; 郭学良

    2012-01-01

    A three-dimensional convective cloud model with a hail-bin microphysics scheme and a hail growth model were used to further investigate the growth mechanism of large hail in supercell storms. The observed supercell features such as quasi-steady mesocyclone, a pronounced bounded weak echo region and a forward overhang were reproduced well by the simulation. During the storm developing stage, hail embryos were produced mainly by the freezing process of raindrops and occurred at the top of the main updraft region and the mid- to upper-portion of the storm from the northwest flank of the main updraft region. Approximately 7%-8% of hail embryos forming at the developing stage continued to grow into hail larger than 10 mm in diameter; only 1% of hail embryos ultimately achieved diameters of 20 mm. Most of the largest hailstones grew from millimeter-size embryos that originated in the upper-level region around the north flank of the updraft and thereafter entered the main updraft cyclonically and grew into large hailstones in a single up-down path. Other embryos originated in the upper-level region of the northwest flank around the main updraft and grew into large hailstones in a down-up-down path along the updraft edge cyclonically. These results suggest that there are two growth paths for large hailstones in supercell storms.%为调查超级单体中大冰雹的运行增长机制,使用三维冰雹分档对流云模式结合三维粒子运行增长模式,对一例超级单体风暴进行了数值模拟.实测风暴的结构如中气旋、弱回波区、前悬回波等被很好地模拟再现,显示了模式对超级单体具有良好的模拟能力.雹胚在风暴发展阶段由过冷雨滴冻结产生,主要分布在主上升气流区上部,在主上升气流区西北侧中高层也有相当数量的雹胚粒子,冰雹主要分布在主上升气流区东侧.风暴发展阶段产生的雹胚有7%~8%增长到1 cm以上,1%左右增长到2 cm以上,这些大冰雹

  11. Simulation of radiation from lightning return strokes - The effects of tortuosity

    Science.gov (United States)

    Levine, D. M.; Meneghini, R.

    1978-01-01

    A Monte Carlo simulation has been developed for the electromagnetic fields radiated from a tortuous lightning channel. This was done using a piecewise linear model for the channel and employing for each element the field radiated by a traveling wave on an arbitrarily oriented filament over a conducting plane. The simulation reproduces experimental data reasonably well and has been used to study the effects of tortuosity on the fields radiated by return strokes. Tortuosity can significantly modify the radiated waveform, tending to render it less representative of the current pulse and more nearly unipolar than one would expect based on the theory for a long straight channel. In the frequency domain the effect of tortuosity is an increase in high frequency energy as compared with an equivalent straight channel. The extent of this increase depends on the mean length of the elements comprising the channel and can be significant.

  12. Simulation of radiation from lightning return strokes: The effects of tortuosity

    Science.gov (United States)

    Levine, D. M.; Meneghini, R.

    1977-01-01

    A Monte Carlo simulation has been developed for the electromagnetic fields radiated from a tortuous lightning channel. This was done using a piecewise linear model for the channel and employing for each element the field radiated by a traveling wave on an arbitrarily oriented filament over a conducting plane. The simulation reproduces experimental data reasonably well and had been used to study the effects of tortuousity on the fields radiated by return strokes. Tortuosity can significantly modify the radiated waveform, tending to render it less representative of the current pulse and more nearly unipolar than one would expect based on the theory for a long straight channel. In the frequency domain the effect of tortuosity is an increase in high frequency energy as compared with an equivalent straight channel. The extent of this increase depends on the mean length of the elements comprising the channel and can be significant.

  13. Physical mechanism and numerical simulation of the inception of the lightning upward leader

    Energy Technology Data Exchange (ETDEWEB)

    Li Qingmin [Beijing Key Lab of High Voltage and EMC, School of Electric and Electronic Engineering, North China Electric Power University, Beijing 102206 (China) and State Key Lab of Alternate Electrical Power System with Renewable Energy Sources, North China Electric Power University, Beijing 102206 (China); Lu Xinchang; Shi Wei; Zhang Li; Zou Liang; Lou Jie [Shandong Provincial Key Lab of UHV Technology and Gas Discharge, School of Electrical Engineering, Shandong University, Jinan 250061 (China)

    2012-12-15

    The upward leader is a key physical process of the leader progression model of lightning shielding. The inception mechanism and criterion of the upward leader need further understanding and clarification. Based on leader discharge theory, this paper proposes the critical electric field intensity of the stable upward leader (CEFISUL) and characterizes it by the valve electric field intensity on the conductor surface, E{sub L}, which is the basis of a new inception criterion for the upward leader. Through numerical simulation under various physical conditions, we verified that E{sub L} is mainly related to the conductor radius, and data fitting yields the mathematical expression of E{sub L}. We further establish a computational model for lightning shielding performance of the transmission lines based on the proposed CEFISUL criterion, which reproduces the shielding failure rate of typical UHV transmission lines. The model-based calculation results agree well with the statistical data from on-site operations, which show the effectiveness and validity of the CEFISUL criterion.

  14. Lightning Strike Ablation Damage Influence Factors Analysis of Carbon Fiber/Epoxy Composite Based on Coupled Electrical-Thermal Simulation

    Science.gov (United States)

    Yin, J. J.; Chang, F.; Li, S. L.; Yao, X. L.; Sun, J. R.; Xiao, Y.

    2016-12-01

    According to the mathematical analysis model constructed on the basis of energy-balance relationship in lightning strike, and accompany with the simplified calculation strategy of composite resin pyrolysis degree dependent electrical conductivity, an effective three dimensional thermal-electrical coupling analysis finite element model of composite laminate suffered from lightning current was established based on ABAQUS, to elucidate the effects of lighting current waveform parameters and thermal/electrical properties of composite laminate on the extent of ablation damage. Simulated predictions agree well with the composite lightning strike directed effect experimental data, illustrating the potential accuracy of the constructed model. The analytical results revealed that extent of composite lightning strike ablation damage can be characterized by action integral validly, there exist remarkable power function relationships between action integral and visual damage area, projected damage area, maximum damage depth and damage volume of ablation damage, and enhancing the electrical conductivity and specific heat of composite, ablation damage will be descended obviously, power function relationships also exist between electrical conductivity, specific heat and ablation damage, however, the impact of thermal conductivity on the extent of ablation damage is not notable. The conclusions obtained provide some guidance for composite anti-lightning strike structure-function integration design.

  15. Spectrum of infrasound radiation from supercell storms

    CERN Document Server

    Akhalkatsi, Mariam

    2010-01-01

    We consider the generation of acoustic waves by turbulent convection and perform spectral analysis of a monopole source of sound related to the heat production by condensation of moisture. A quantitative explanation of the correlation between intensity of infrasound generated by supercell storms and later tornado formation is given. It is shown that low lifting condensation level (LCL) and high values of convective available potential energy (CAPE), which are known to favor significant tornadoes, also lead to a strong enhancement of supercell's low frequency acoustic radiation.

  16. Numerical simulations of the bi-level and branched structure of intracloud lightning flashes

    Institute of Scientific and Technical Information of China (English)

    TAN Yongbo; TAO Shanchang; ZHU Baoyou; MA Ming; LU Weitao

    2006-01-01

    Intracloud (IC) lightning flashes have been simulated in fine resolution (12.5 m) by using a bidirectional stochastic lightning parameterization scheme within 2-dimensional domain. The simulated results show that the IC flashes have a bilevel channel structure and the altitudes of the horizontal channels are at the same heights of potential wells, which are supported by the previous VHF source observations and balloon soundings of electric field profile in the thundercloud. Further conclusions are: (1) After an IC flash is initiated near the boundary between positve and nagetive charge zone, the negative (or positive) leader tends to propagate into the positive (or negative) charge zone.Both types of positive and negative IC flashes have been reproduced and their polarity depends on the up and down disposition of the positive and negative charge regions. (2) The extension range of leaders is correlative with the cloud charge distribution. The leader is possible to extend through the inverted charge region all over where it is extending, but keeps away from the isolated charge area of the same polarity. (3) The channel structures also depend on the electric potential distributions in the thundercloud. Before propagating into the central area of potential wells, the leader tends to extend along the direction with the maximum of potential gradient. Once extending away from the center of potential wells, the leader tends to extend along the direction with the slowest potential change. (4)The IC flash channels have the fractal feature with fractal dimension 1.45 before leaders pass through the central area of charge regions. The exponent decreases rapidly once leaders extend into the low-density charge regions. (5) The induced charges of opposite polarity are deposited in the leader channels within preexisting positive and negative charge regions during IC flash discharges. This causes a new and complicated charge distribution in the thundercloud, and the potential

  17. Production of lightning NOx and its vertical distribution calculated from three-dimensional cloud-scale chemical transport model simulations

    KAUST Repository

    Ott, Lesley E.

    2010-02-18

    A three-dimensional (3-D) cloud-scale chemical transport model that includes a parameterized source of lightning NOx on the basis of observed flash rates has been used to simulate six midlatitude and subtropical thunderstorms observed during four field projects. Production per intracloud (PIC) and cloud-to-ground (PCG) flash is estimated by assuming various values of PIC and PCG for each storm and determining which production scenario yields NOx mixing ratios that compare most favorably with in-cloud aircraft observations. We obtain a mean PCG value of 500 moles NO (7 kg N) per flash. The results of this analysis also suggest that on average, PIC may be nearly equal to PCG, which is contrary to the common assumption that intracloud flashes are significantly less productive of NO than are cloud-to-ground flashes. This study also presents vertical profiles of the mass of lightning NOx after convection based on 3-D cloud-scale model simulations. The results suggest that following convection, a large percentage of lightning NOx remains in the middle and upper troposphere where it originated, while only a small percentage is found near the surface. The results of this work differ from profiles calculated from 2-D cloud-scale model simulations with a simpler lightning parameterization that were peaked near the surface and in the upper troposphere (referred to as a “C-shaped” profile). The new model results (a backward C-shaped profile) suggest that chemical transport models that assume a C-shaped vertical profile of lightning NOx mass may place too much mass near the surface and too little in the middle troposphere.

  18. Development of a Technique for Representing Lightning Arresters in the Surge Simulations based on the FDTD Method and its Application to the Calculation of Lightning-Induced Voltages on a Distribution Line

    Science.gov (United States)

    Tatematsu, Akiyoshi; Noda, Taku

    Recently, the FDTD (Finite Difference Time Domain) method, which directly solves Maxwell's equations, has been applied to lightning surge problems involving electrical wires in three-dimensional arrangements, such as power and telecommunication circuits. Lightning arresters are installed to protect the circuits from abnormal voltages due to lightning, for example. We have already proposed a technique for representing a lightning arrester in the FDTD method. However, this technique simply represents the V-I characteristics of the arrester using just three parameters and requires a method for avoiding the numerical oscillation due to the nonlinear characteristics of the arrester. In this paper, we propose a new technique for representing the V-I characteristics of the arrester in detail using the piecewise linear function defined by several points and for improving the numerical stability without the method for avoiding the numerical oscillation. Using a test circuit, the proposed technique is validated by comparing the results calculated by the FDTD method with those by the EMTP (ElectroMagnetic Transients Program) which is a circuit-theory-based simulation program. Finally, as an example of applying the proposed technique, we calculate lightning-induced voltages on a distribution line with a lightning arrester. The calculated results by the FDTD method agree well with those by a conventional method based on circuit theroy.

  19. Modeling of Nonlinear Elements During Lightning Overvoltage Simulations%雷电过电压仿真中非线性元件的建模

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The paper presents some problems of lightning overvoltage modeling in transmission lines with nonlinear elements. The presented results were obtained mostly for fast front transients of subsequent lightning return stroke currents. The effectiveness of numerical algorithms of nonlinear models and possibilities of their development for such transients are analyzed. Computer simulations carried out by application of EMTP show that nonlinear models of back-flashover and ZnO arresters work properly, while the implemented corona model can not be used for relatively large peak values of subsequent lightning return-stroke currents.

  20. Numerical Simulations of Lightning Surge Responses in a Seismic Isolated Building by FDTD and EMTP

    Science.gov (United States)

    Nagaoka, Naoto; Morita, Hiroshi; Baba, Yoshihiro; Ametani, Akihiro

    Current distribution and overvoltages in a structure of a seismic isolated building struck by lightning are analyzed by a Finite-Difference Time-Domain (FDTD) method and by the Electromagnetic Transients Program (EMTP). The simulated results by the FDTD method show that the voltage at the first floor, which is an important factor of a design of building installation, shows a damped oscillatory wave. The transient overvoltage is caused by the multiple reflections within the structures and the resonance between a stray capacitance of the structure and an equivalent inductance of the bonding wire, which electrically shunts a rubber insulator installed for dumping earthquake tremor. The investigation shows that the transient response can be expressed by a lumped-parameter equivalent circuit. Two numerical models for circuit analysis method are proposed in this paper. A multiphase model reproduces a distribution of currents flowing through vertical pillars by mutual couplings between the pillars. A single phase model is obtained by a simplification of the multiphase model and gives the voltage at the first floor. The calculation time is remarkably reduced compared to that by the FDTD method. The accuracy of the models is discussed in comparison with the results obtained by the FDTD method.

  1. Lightning Potential Index performances in multimicrophysical cloud-resolving simulations of a back-building mesoscale convective system: The Genoa 2014 event

    Science.gov (United States)

    Lagasio, M.; Parodi, A.; Procopio, R.; Rachidi, F.; Fiori, E.

    2017-04-01

    Severe weather events are responsible for hundreds of fatalities and millions of euros of damage every year on the Mediterranean basin. Lightning activity is a characteristic phenomenon of severe weather and often accompanies torrential rainfall, which, under certain conditions like terrain type, slope, drainage, and soil saturation, may turn into flash flood. Building on the existing relationship between significant lightning activity and deep convection and precipitation, the performance of the Lightning Potential Index, as a measure of the potential for charge generation and separation that leads to lightning occurrence in clouds, is here evaluated for the V-shape back-building Mesoscale Convective System which hit Genoa city (Italy) in 2014. An ensemble of Weather Research and Forecasting simulations at cloud-permitting grid spacing (1 km) with different microphysical parameterizations is performed and compared to the available observational radar and lightning data. The results allow gaining a deeper understanding of the role of lightning phenomena in the predictability of V-shape back-building Mesoscale Convective Systems often producing flash flood over western Mediterranean complex topography areas. Moreover, they support the relevance of accurate lightning forecasting for the predictive ability of these severe events.

  2. Lightning Injuries

    Science.gov (United States)

    ... to electrical equipment or telephone lines inside a house. Lightning can injure a person several ways: Lightning ... a feathering, branching pattern, consist of clusters of tiny pinpoint spots like a cigarette burn, or consist ...

  3. The 3-dimensional numerical simulation of artificially altitude-triggered negative lightning

    Science.gov (United States)

    Zhang, Bo; Chen, Bin; Shi, Lihua; Chen, Qiang

    2013-03-01

    A 3-dimensional numerical model for artificially altitude-triggered negative lightning is developed based on an analytic thunderstorm model and the Dielectric Breakdown Model (DBM). Two major parameters are concerned, they are the thundercloud electric field and the length of the nylon wire which isolates the triggering wire from the ground. A few groups of contrast numerical experiments are done to study their effects on the success rates of altitude-triggered lightning. It is found that the success rates of altitude-triggered lightning increase when the thundercloud electric field enhances or the length of the nylon wire increases. Another interesting phenomenon is that the upward positive leader is always initiated earlier than the downward negative leader in either case.

  4. Impact of updraft on neutralized charge rate by lightning in thunderstorms: A simulation case study

    Science.gov (United States)

    Wang, Fei; Zhang, Yijun; Zheng, Dong

    2015-12-01

    The rate of neutralized charge by lightning (RNCL) is an important parameter indicating the intensity of lightning activity. The total charging rate (CR), the CR of one kind of polarity (e.g., negative) charge (CROP), and the outflow rate of charge on precipitation (ORCP) are proposed as key factors impacting RNCL, based on the principle of conservation of one kind of polarity charge in a thunderstorm. In this paper, the impacts of updraft on CR and CROP are analyzed by using a 3D cloud resolution model for a strong storm that occurred in Beijing on 6 september 2008. The results show that updraft both promotes and inhibits RNCL at the same time. (1) Updraft always has a positive influence on CR. The correlation coefficient between the updraft volume and CR can reach 0.96. Strengthening of the updraft facilitates strengthening of RNCL through this positive influence. (2) Strengthening of the updraft also promotes reinforcement of CROP. The correlation coefficient between the updraft volume and CROP is high (about 0.9), but this promotion restrains the strengthening of RNCL because the strengthening of CROP will, most of the time, inhibit the increasing of RNCL. (3) Additionally, increasing of ORCP depresses the strengthening of RNCL. In terms of magnitude, the peak of ORCP is equal to the peak of CR. Because precipitation mainly appears after the lightning activity finishes, the depression effect of ORCP on RNCL can be ignored during the active lightning period.

  5. Mathematical Constraints on the Use of Transmission Line Models for Simulating Initial Breakdown Pulses in Lightning Discharges

    Science.gov (United States)

    da Silva, C. L.; Merrill, R. A.; Pasko, V. P.

    2015-12-01

    A significant portion of the in-cloud lightning development is observed as a series of initial breakdown pulses (IBPs) that are characterized by an abrupt change in the electric field at a remote sensor. Recent experimental and theoretical studies have attributed this process to the stepwise elongation of an initial lightning leader inside the thunderstorm [da Silva and Pasko, JGR, 120, 4989-5009, 2015, and references therein]. Attempts to visually observe these events are hampered due to the fact that clouds are opaque to optical radiation. Due to this reason, throughout the last decade, a number of researchers have used the so-called transmission line models (also commonly referred to as engineering models), widely employed for return stroke simulations, to simulate the waveshapes of IBPs, and also of narrow bipolar events. The transmission line (TL) model approach is to prescribe the source current dynamics in a certain manner to match the measured E-field change waveform, with the purpose of retrieving key information about the source, such as its height, peak current, size, speed of charge motion, etc. Although the TL matching method is not necessarily physics-driven, the estimated source characteristics can give insights on the dominant length- and time-scales, as well as, on the energetics of the source. This contributes to better understanding of the environment where the onset and early stages of lightning development takes place.In the present work, we use numerical modeling to constrain the number of source parameters that can be confidently inferred from the observed far-field IBP waveforms. We compare different modified TL models (i.e., with different attenuation behaviors) to show that they tend to produce similar waveforms in conditions where the channel is short. We also demonstrate that it is impossible to simultaneously retrieve the speed of source current propagation and channel length from an observed IBP waveform, in contrast to what has been

  6. Measuring Method for Lightning Channel Temperature

    Science.gov (United States)

    Li, X.; Zhang, J.; Chen, L.; Xue, Q.; Zhu, R.

    2016-01-01

    In this paper, we demonstrate the temperature of lightning channel utilizing the theory of lightning spectra and the model of local thermodynamic equilibrium (LTE). The impulse current generator platform (ICGS) was used to simulate the lightning discharge channel, and the spectral energy of infrared spectroscopy (930 nm) and the visible spectroscopy (648.2 nm) of the simulated lightning has been calculated. Results indicate that the peaks of luminous intensity of both infrared and visible spectra increase with the lightning current intensity in range of 5–50 kA. Based on the results, the temperature of the lightning channel is derived to be 6140.8–10424 K. Moreover, the temperature of the channel is approximately exponential to the lightning current intensity, which shows good agreement with that of the natural lightning cases. PMID:27665937

  7. Measuring Method for Lightning Channel Temperature

    Science.gov (United States)

    Li, X.; Zhang, J.; Chen, L.; Xue, Q.; Zhu, R.

    2016-09-01

    In this paper, we demonstrate the temperature of lightning channel utilizing the theory of lightning spectra and the model of local thermodynamic equilibrium (LTE). The impulse current generator platform (ICGS) was used to simulate the lightning discharge channel, and the spectral energy of infrared spectroscopy (930 nm) and the visible spectroscopy (648.2 nm) of the simulated lightning has been calculated. Results indicate that the peaks of luminous intensity of both infrared and visible spectra increase with the lightning current intensity in range of 5-50 kA. Based on the results, the temperature of the lightning channel is derived to be 6140.8-10424 K. Moreover, the temperature of the channel is approximately exponential to the lightning current intensity, which shows good agreement with that of the natural lightning cases.

  8. Measuring Method for Lightning Channel Temperature.

    Science.gov (United States)

    Li, X; Zhang, J; Chen, L; Xue, Q; Zhu, R

    2016-09-26

    In this paper, we demonstrate the temperature of lightning channel utilizing the theory of lightning spectra and the model of local thermodynamic equilibrium (LTE). The impulse current generator platform (ICGS) was used to simulate the lightning discharge channel, and the spectral energy of infrared spectroscopy (930 nm) and the visible spectroscopy (648.2 nm) of the simulated lightning has been calculated. Results indicate that the peaks of luminous intensity of both infrared and visible spectra increase with the lightning current intensity in range of 5-50 kA. Based on the results, the temperature of the lightning channel is derived to be 6140.8-10424 K. Moreover, the temperature of the channel is approximately exponential to the lightning current intensity, which shows good agreement with that of the natural lightning cases.

  9. Simulation Analysis of Lightning Protection Characteristics of Photovoltaic System%光伏系统雷电防护特性仿真分析

    Institute of Scientific and Technical Information of China (English)

    陈坤; 谭进; 吉容佩

    2012-01-01

    由于光伏系统具有面积较大、暴露设备较多且需考虑直击雷防护装置阴影对太阳能电池板的遮挡影响等特点,因此其雷电屏蔽与传统电站存在差异.为更深入地了解光伏系统的雷电防护特性,结合光伏系统结构和雷电侵入途径,采用ATPDraw仿真软件,对光伏阵列及其电气设备进行建模,仿真计算了雷击光伏阵列不同位置、不同雷电流幅值及不同接地电阻情况下光伏阵列的损坏程度和对光伏系统内部设备过电压的影响,并根据计算结果提出了光伏系统雷电防护的重点.%photovoltaic system has characteristics, such as large area, many exposed device and the impact of direct lightning protection device shadows on the shelter of solar panels. Therefore, it exist difference between lightning shiel ding for photovoltaic system and conventional power plants. For a better understanding of photovoltaic system lightning protection performance, simulation software ATPDrawiis used to modeling photovoltaic array and electrical equipment by considering photovoltaic system structure and lightning invasion way. Under the conditions of lightning photovoltaic array of different position, different lightning current amplitude and different grounding resistance, it simulates the damaged condition of photovoltaic array and the impact of photovoltaic system internal equipment over-voltage. According to the calculation results, it puts forward the focal point of lightning protection of photovoltaic system.

  10. Lightning flash sizes relative to storm structure and turbulence during the Kinematic Texture and Lightning Experiment

    Science.gov (United States)

    Bruning, E. C.; Salinas, V.; Berkseth, S.; Chmielewski, V.; Brothers, M.

    2016-12-01

    Ongoing work as part of the Kinematic Texture and Lightning Experiment at Texas Tech University has quantified the lightning flash size, rate, and energy alongside the turbulent structure of thunderclouds. 2016 was the final year of observations, which fielded two high-resolution mobile Ka-band radars and mobile environmental soundings. Lightning measurements were made by a VHF Lightning Mapping Array. In order to enhance the detection of the smallest lightning discharges in the turbulent portions of the thundercloud, a rapidly-deployable mobile Lightning Mapping Array (LMA) station augmented a traditional fixed LMA. This capability of targeting particular storm complexes with LMA measurements will be described, and the improved detection capability quantified. The complete set of field measurements from 2014-16 sampled numerous individual cells and storm complexes, ranging in intensity from multicellular convection to supercells and mesoscale convective systems. Flash measurements coincident with radar observations included deep, highly turbulent convective cores and extensive anvil regions. Comparison of flash characteristics across these storm morphologies will be shown, with a focus on the dynamical organization of storms and the turbulent kinematics that drive differences in lightning flash sizes and rates.

  11. Lightning Phenomenology

    Science.gov (United States)

    Kawasaki, Zen

    This paper presents a phenomenological idea about lightning flash to share the back ground understanding for this special issue. Lightning discharges are one of the terrible phenomena, and Benjamin Franklin has led this natural phenomenon to the stage of scientific investigation. Technical aspects like monitoring and location are also summarized in this article.

  12. Lightning NOx and Impacts on Air Quality

    Science.gov (United States)

    Murray, Lee T.

    2016-01-01

    Lightning generates relatively large but uncertain quantities of nitrogen oxides, critical precursors for ozone and hydroxyl radical (OH), the primary tropospheric oxidants. Lightning nitrogen oxide strongly influences background ozone and OH due to high ozone production efficiencies in the free troposphere, effecting small but non-negligible contributions to surface pollutant concentrations. Lightning globally contributes 3-4 ppbv of simulated annual-mean policy-relevant background (PRB) surface ozone, comprised of local, regional, and hemispheric components, and up to 18 ppbv during individual events. Feedbacks via methane may counter some of these effects on decadal time scales. Lightning contributes approximately 1 percent to annual-mean surface particulate matter, as a direct precursor and by promoting faster oxidation of other precursors. Lightning also ignites wildfires and contributes to nitrogen deposition. Urban pollution influences lightning itself, with implications for regional lightning-nitrogen oxide production and feedbacks on downwind surface pollution. How lightning emissions will change in a warming world remains uncertain.

  13. New model simulations of the global atmospheric electric circuit driven by thunderstorms and electrified shower clouds: The roles of lightning and sprites

    DEFF Research Database (Denmark)

    Rycroft, Michael J.; Odzimek, Anna; Arnold, Neil F.

    2007-01-01

    Several processes acting below, in and above thunderstorms and in electrified shower clouds drive upward currents which close through the global atmospheric electric circuit, These are all simulated in a novel way using the software package PSpice. A moderate negative cloud-to-ground lightning di...

  14. The North Alabama Lightning Mapping Array: Recent severe storm observations and future prospects

    Science.gov (United States)

    Goodman, S. J.; Blakeslee, R.; Christian, H.; Koshak, W.; Bailey, J.; Hall, J.; McCaul, E.; Buechler, D.; Darden, C.; Burks, J.; Bradshaw, T.; Gatlin, P.

    2005-07-01

    The North Alabama Lightning Mapping Array became operational in November 2001 as a principal component of a severe weather test bed to infuse new science and technology into the short-term forecasting of severe and hazardous weather, principally within nearby National Weather Service forecast offices. Since the installation of the LMA, it has measured the total lightning activity of a large number of severe weather events, including three supercell tornado outbreaks, two supercell hailstorm events, and numerous microburst-producing storms and ordinary non-severe thunderstorms. The key components of evolving storm morphology examined are the time rate-of-change (temporal trending) of storm convective and precipitation characteristics that can be diagnosed in real-time using NEXRAD WSR-88D Doppler radar (echo growth and decay, precipitation structures and velocity features, outflow boundaries), LMA (total lightning flash rate and its trend) and National Lightning Detection Network (cloud-to-ground lightning, its polarity and trends). For example, in a transitional season supercell tornado outbreak, peak total flash rates for typical supercells in Tennessee reached 70-100 min -1 and increases in the total flash rate occurred during storm intensification as much as 20-25 min prior to at least some of the tornadoes. The most intense total flash rate measured during this outbreak (over 800 flashes min -1) occurred in a storm in Alabama. In the case of a severe summertime pulse thunderstorm in North Alabama, the peak total flash rate reached 300 min -1, with a strong increase in total lightning evident some 9 min before damaging winds were observed at the surface. In this paper, we provide a sampling of LMA observations and products during severe weather events to illustrate the capability of the system, and discuss the prospects for improving the short-term forecasting of convective weather using total lightning data.

  15. Study of irradiation of flash lightning type in a Titan simulated atmosphere; Estudio de irradiaciones tipo relampago en una atmosfera simulada de Titan

    Energy Technology Data Exchange (ETDEWEB)

    Rosa C, J.G. De la

    2001-07-01

    Titan is the greatest satellite of the Saturn planet and the unique moon of the Solar System which presents a dense atmosphere constituted by nitrogen, methane and traces of hydrocarbons and nitriles. Constantly it is bombarded by different energy sources which interacting with the atmosphere cause countless of chemical reactions which have giving origin to the synthesis of organic molecules from its formation since 4.5 thousand millions of years ago. The electric activity was not detected in the satellite when the space probe Voyager I had its nearest match with Titan in November 1980, however, due to the presence of methane clouds rain and of convective activity in the troposphere of the satellite, it is thought in the possible existence of electrical activity in this. In this work it is studied the production of gaseous compounds generated by irradiations type flash lightning in the Titan simulated atmosphere constituted by nitrogen and methane. The lightning are imitated by laser induced plasma (LIP) with similar physical properties to the naturals produced in the Earth. The separation and identification of the organic compounds generated by simulated lightning s were carried out by attached methods of analysis such as the Gas chromatography, Infrared spectroscopy with Fourier transform (FTIR-S) and Mass spectroscopy (MS). The compounds which were identified are: hydrocarbons and nitriles, some of them already have been identified in Titan as well as the hydrogen cyanide (HCN), acetylene, etilene and cyanoacetylene. Moreover we studied the influence that different parameters of irradiation have in the production of organic molecules generated submitting to discharges type lightning the simulated atmosphere of Titan. It was realized an estimation of the available energy in the satellite which could be vanished as discharges type lightning. By means of a model based on conditions of thermodynamic equilibria it was calculated the temperature to which are freeze

  16. Thermal characterization of nanoscale phononic crystals using supercell lattice dynamics

    Science.gov (United States)

    Davis, Bruce L.; Hussein, Mahmoud I.

    2011-12-01

    The concept of a phononic crystal can in principle be realized at the nanoscale whenever the conditions for coherent phonon transport exist. Under such conditions, the dispersion characteristics of both the constitutive material lattice (defined by a primitive cell) and the phononic crystal lattice (defined by a supercell) contribute to the value of the thermal conductivity. It is therefore necessary in this emerging class of phononic materials to treat the lattice dynamics at both periodicity levels. Here we demonstrate the utility of using supercell lattice dynamics to investigate the thermal transport behavior of three-dimensional nanoscale phononic crystals formed from silicon and cubic voids of vacuum. The periodicity of the voids follows a simple cubic arrangement with a lattice constant that is around an order of magnitude larger than that of the bulk crystalline silicon primitive cell. We consider an atomic-scale supercell which incorporates all the details of the silicon atomic locations and the void geometry. For this supercell, we compute the phonon band structure and subsequently predict the thermal conductivity following the Callaway-Holland model. Our findings dictate that for an analysis based on supercell lattice dynamics to be representative of the properties of the underlying lattice model, a minimum supercell size is needed along with a minimum wave vector sampling resolution. Below these minimum values, a thermal conductivity prediction of a bulk material based on a supercell will not adequately recover the value obtained based on a primitive cell. Furthermore, our results show that for the relatively small voids and void spacings we consider (where boundary scattering is dominant), dispersion at the phononic crystal unit cell level plays a noticeable role in determining the thermal conductivity.

  17. Thermal characterization of nanoscale phononic crystals using supercell lattice dynamics

    Directory of Open Access Journals (Sweden)

    Bruce L. Davis

    2011-12-01

    Full Text Available The concept of a phononic crystal can in principle be realized at the nanoscale whenever the conditions for coherent phonon transport exist. Under such conditions, the dispersion characteristics of both the constitutive material lattice (defined by a primitive cell and the phononic crystal lattice (defined by a supercell contribute to the value of the thermal conductivity. It is therefore necessary in this emerging class of phononic materials to treat the lattice dynamics at both periodicity levels. Here we demonstrate the utility of using supercell lattice dynamics to investigate the thermal transport behavior of three-dimensional nanoscale phononic crystals formed from silicon and cubic voids of vacuum. The periodicity of the voids follows a simple cubic arrangement with a lattice constant that is around an order of magnitude larger than that of the bulk crystalline silicon primitive cell. We consider an atomic-scale supercell which incorporates all the details of the silicon atomic locations and the void geometry. For this supercell, we compute the phonon band structure and subsequently predict the thermal conductivity following the Callaway-Holland model. Our findings dictate that for an analysis based on supercell lattice dynamics to be representative of the properties of the underlying lattice model, a minimum supercell size is needed along with a minimum wave vector sampling resolution. Below these minimum values, a thermal conductivity prediction of a bulk material based on a supercell will not adequately recover the value obtained based on a primitive cell. Furthermore, our results show that for the relatively small voids and void spacings we consider (where boundary scattering is dominant, dispersion at the phononic crystal unit cell level plays a noticeable role in determining the thermal conductivity.

  18. Effects of assimilating precipitation zones derived from satellite and lightning data on numerical simulations of tropical-like Mediterranean storms

    Directory of Open Access Journals (Sweden)

    L. Fita

    2009-08-01

    Full Text Available The scarcity of meteorological observations in maritime areas is a well-known problem that can be an important limitation in the study of different phenomena. Tropical-like storms or medicanes developed over the Mediterranean sea are intense storms with some similarities to the tropical ones. Although they do not reach the hurricane intensity, their potential for damage is very high, due to the densely populated Mediterranean coastal regions. In this study, the two notable cases of medicane development which occurred in the western Mediterranean basin in September 1996 and October 2003, are considered. The capability of mesoscale numerical models to simulate general aspects of such a phenomena has been previously shown. With the aim of improving the numerical results, an adjustment of the humidity vertical profiles in MM5 simulations is performed by means of satellite derived precipitation. Convective and stratiform precipitation types obtained from satellite images are used to individually adjust the profiles. Lightning hits are employed to identify convective grid points. The adjustment of the vertical humidity profiles is carried out in the European Centre for Medium-Range Weather Forecasts (ECMWF analyses used as initial conditions for the simulations. Analyses nudging to ECMWF analyses and to the satellite-based humidity-corrected version of these analyses has also been applied using Four Dimensional Data Assimilation (FDDA. An additional adjustment is applied as observation nudging of satellite/lightning information at different time and spatial resolutions. Statistical parameters are proposed and tested as an objective way to intercompare satellite-derived and simulated trajectories. Simulations of medicanes exhibit a strong sensitivity to vertical humidity profiles. Trajectories of the storms are improved or worsened by using FDDA. A case dependence is obtained on the characteristics of the humidity-corrected medicanes. FDDA sensitivity

  19. Effects of assimilating precipitation zones derived from satellite and lightning data on numerical simulations of tropical-like Mediterranean storms

    Energy Technology Data Exchange (ETDEWEB)

    Fita, L.; Romero, R.; Luque, A.; Ramis, C. [Univ. de les Illes Balears, Palma de Mallorca (Spain). Grup de Meteorologia

    2009-07-01

    The scarcity of meteorological observations in maritime areas is a well-known problem that can be an important limitation in the study of different phenomena. Tropical-like storms or medicanes developed over the Mediterranean sea are intense storms with some similarities to the tropical ones. Although they do not reach the hurricane intensity, their potential for damage is very high, due to the densely populated Mediterranean coastal regions. In this study, the two notable cases of medicane development which occurred in the western Mediterranean basin in September 1996 and October 2003, are considered. The capability of mesoscale numerical models to simulate general aspects of such a phenomena has been previously shown. With the aim of improving the numerical results, an adjustment of the humidity vertical profiles in MM5 simulations is performed by means of satellite derived precipitation. Convective and stratiform precipitation types obtained from satellite images are used to individually adjust the profiles. Lightning hits are employed to identify convective grid points. The adjustment of the vertical humidity profiles is carried out in the European Centre for Medium-Range Weather Forecasts (ECMWF) analyses used as initial conditions for the simulations. Analyses nudging to ECMWF analyses and to the satellite-based humidity-corrected version of these analyses has also been applied using Four Dimensional Data Assimilation (FDDA). An additional adjustment is applied as observation nudging of satellite/lightning information at different time and spatial resolutions. Statistical parameters are proposed and tested as an objective way to intercompare satellite-derived and simulated trajectories. Simulations of medicanes exhibit a strong sensitivity to vertical humidity profiles. Trajectories of the storms are improved or worsened by using FDDA. A case dependence is obtained on the characteristics of the humidity-corrected medicanes. FDDA sensitivity on temporal and

  20. Lattice dynamics and electron-phonon coupling calculations using nondiagonal supercells

    Science.gov (United States)

    Lloyd-Williams, Jonathan; Monserrat, Bartomeu

    Quantities derived from electron-phonon coupling matrix elements require a fine sampling of the vibrational Brillouin zone. Converged results are typically not obtainable using the direct method, in which a perturbation is frozen into the system and the total energy derivatives are calculated using a finite difference approach, because the size of simulation cell needed is prohibitively large. We show that it is possible to determine the response of a periodic system to a perturbation characterized by a wave vector with reduced fractional coordinates (m1 /n1 ,m2 /n2 ,m3 /n3) using a supercell containing a number of primitive cells equal to the least common multiple of n1, n2, and n3. This is accomplished by utilizing supercell matrices containing nonzero off-diagonal elements. We present the results of electron-phonon coupling calculations using the direct method to sample the vibrational Brillouin zone with grids of unprecedented size for a range of systems, including the canonical example of diamond. We also demonstrate that the use of nondiagonal supercells reduces by over an order of magnitude the computational cost of obtaining converged vibrational densities of states and phonon dispersion curves. J.L.-W. is supported by the Engineering and Physical Sciences Research Council (EPSRC). B.M. is supported by Robinson College, Cambridge, and the Cambridge Philosophical Society. This work was supported by EPSRC Grants EP/J017639/1 and EP/K013564/1.

  1. Transient electromagnetic simulations of substation earth grid for improving lightning withstand performance of a large power transformer

    DEFF Research Database (Denmark)

    Bak, Claus Leth; Einarsdottir, Kristin E.; Andresson, Einar

    connections are analyzed with respect to lightning overvoltage at the transformer bushings and it is shown clearly that the layout of the grounding system in the vicinity of the surge arrester down conductors plays an important role for the magnitude of the transformer bushing overvoltage during lightnings...

  2. Automated effective band structures for defective and mismatched supercells

    Science.gov (United States)

    Brommer, Peter; Quigley, David

    2014-12-01

    In plane-wave density functional theory codes, defects and incommensurate structures are usually represented in supercells. However, interpretation of E versus k band structures is most effective within the primitive cell, where comparison to ideal structures and spectroscopy experiments are most natural. Popescu and Zunger recently described a method to derive effective band structures (EBS) from supercell calculations in the context of random alloys. In this paper, we present bs_sc2pc, an implementation of this method in the CASTEP code, which generates an EBS using the structural data of the supercell and the underlying primitive cell with symmetry considerations handled automatically. We demonstrate the functionality of our implementation in three test cases illustrating the efficacy of this scheme for capturing the effect of vacancies, substitutions and lattice mismatch on effective primitive cell band structures.

  3. Full scale lightning test technique

    Science.gov (United States)

    Walko, L. C.; Schneider, J. G.

    1980-01-01

    A test technique was developed for applying a full scale mean value (30 kiloampere peak) simulated lightning return stroke current on a complete flight ready aircraft to assess the threat of lightning to aircraft electrical circuits. A computer-aided generator design was used to establish the parameters of the test system. Data from previous work done on development of low inductance current paths determined the basic system configuration.

  4. On the Relationship between Observed NLDN Lightning ...

    Science.gov (United States)

    Lightning-produced nitrogen oxides (NOX=NO+NO2) in the middle and upper troposphere play an essential role in the production of ozone (O3) and influence the oxidizing capacity of the troposphere. Despite much effort in both observing and modeling lightning NOX during the past decade, considerable uncertainties still exist with the quantification of lightning NOX production and distribution in the troposphere. It is even more challenging for regional chemistry and transport models to accurately parameterize lightning NOX production and distribution in time and space. The Community Multiscale Air Quality Model (CMAQ) parameterizes the lightning NO emissions using local scaling factors adjusted by the convective precipitation rate that is predicted by the upstream meteorological model; the adjustment is based on the observed lightning strikes from the National Lightning Detection Network (NLDN). For this parameterization to be valid, the existence of an a priori reasonable relationship between the observed lightning strikes and the modeled convective precipitation rates is needed. In this study, we will present an analysis leveraged on the observed NLDN lightning strikes and CMAQ model simulations over the continental United States for a time period spanning over a decade. Based on the analysis, new parameterization scheme for lightning NOX will be proposed and the results will be evaluated. The proposed scheme will be beneficial to modeling exercises where the obs

  5. Simulation of a two step TGF ignition above cloudtops with MeV electron input fluxes generated in the electric fields of lightning streamers

    Science.gov (United States)

    Connell, P. H.

    2014-12-01

    The origin of high energy electrons which contribute to the Runaway Electron Avalanche of a TGF are not precisely known, or yet observed, though the most obvious source would seem to be the products of cosmic ray showers, or electron avalanches generated in the high electric field near the tips of lightning leaders. With our TGF simulation software package LEPTRACK we can easily create all kinds of electric field geometries and are investigating the second scenario with combinations of lightning leader and streamer micro-fields producing electron avalanches, which may or may not be runaway, which are then input to the macro-fields expected at or above thunderstorm cloudtops.We will present the detailed evolution of photon, electron, neutron/proton and ionization density fields resulting to demonstrate the possibility that TGF origin is not one of the two models currently proposed but may be a combination of both.

  6. Relativistic-microwave theory of ball lightning

    Science.gov (United States)

    Wu, H.-C.

    2016-06-01

    Ball lightning, a fireball sometimes observed during lightnings, has remained unexplained. Here we present a comprehensive theory for the phenomenon: At the tip of a lightning stroke reaching the ground, a relativistic electron bunch can be produced, which in turn excites intense microwave radiation. The latter ionizes the local air and the radiation pressure evacuates the resulting plasma, forming a spherical plasma bubble that stably traps the radiation. This mechanism is verified by particle simulations. The many known properties of ball lightning, such as the occurrence site, relation to the lightning channels, appearance in aircraft, its shape, size, sound, spark, spectrum, motion, as well as the resulting injuries and damages, are also explained. Our theory suggests that ball lighting can be created in the laboratory or triggered during thunderstorms. Our results should be useful for lightning protection and aviation safety, as well as stimulate research interest in the relativistic regime of microwave physics.

  7. Relativistic-microwave theory of ball lightning.

    Science.gov (United States)

    Wu, H-C

    2016-06-22

    Ball lightning, a fireball sometimes observed during lightnings, has remained unexplained. Here we present a comprehensive theory for the phenomenon: At the tip of a lightning stroke reaching the ground, a relativistic electron bunch can be produced, which in turn excites intense microwave radiation. The latter ionizes the local air and the radiation pressure evacuates the resulting plasma, forming a spherical plasma bubble that stably traps the radiation. This mechanism is verified by particle simulations. The many known properties of ball lightning, such as the occurrence site, relation to the lightning channels, appearance in aircraft, its shape, size, sound, spark, spectrum, motion, as well as the resulting injuries and damages, are also explained. Our theory suggests that ball lighting can be created in the laboratory or triggered during thunderstorms. Our results should be useful for lightning protection and aviation safety, as well as stimulate research interest in the relativistic regime of microwave physics.

  8. Improvements of an FDTD-based surge simulation code and its application to the lightning overvoltage calculation of a transmission tower

    Energy Technology Data Exchange (ETDEWEB)

    Noda, Taku; Tatematsu, Akiyoshi; Yokoyama, Shigeru [Electric Power Engineering Research Lab., CRIEPI (Central Research Institute of Electric Power Industry), 2-6-1 Nagasaka, Yokosuka-shi, Kanagawa-pref. 240-0196 (Japan)

    2007-09-15

    This paper presents new features recently added to a general-purpose surge simulation code based on the Finite Difference Time Domain (FDTD) method. The added features include various-shape conductor models, lumped-parameter circuit-element models, a lightning-channel model, and an integrated analysis environment (IAE). For precisely modelling the shapes of various conductors, the following conductor models have been added: inclined thin wire; disc; square plate; cylinder; cone; and quadrangular pyramid. The lumped-parameter circuit-element models allow the user to represent the lumped impedance of an apparatus placed inside the analysis space. The lightning-channel model realizes a return-stroke development at a speed slower than the light speed. The IAE includes a Graphical User Interface (GUI), which allows the user to enter geometrical data in a visual way. It also provides a waveform plotting program for viewing voltage, current, electric-field, and magnetic-field waveforms and a movie program for displaying the animation of a transient electric/magnetic field intensity distribution. For an illustrative example, the lightning overvoltage calculation of a transmission tower is presented. (author)

  9. Constraining lightning channel growth dynamics by comparison of time domain electromagnetic simulations to Huntsville Alabama Marx Meter Array observations

    Science.gov (United States)

    Carlson, B. E.; Bitzer, P. M.; Burchfield, J.

    2015-12-01

    Major unknowns in lightning research include the mechanism and dynamics of lightning channel extension. Such processes are most simple during the initial growth of the channel, when the channel is relatively short and has not yet branched extensively throughout the cloud. During this initial growth phase, impulsive electromagnetic emissions (preliminary breakdown pulses) can be well-described as produced by current pulses generated as the channel extends, but the overall growth rate, channel geometry, and degree of branching are not known. We approach such issues by examining electric field change measurements made with the Huntsville Alabama Marx Meter Array (HAMMA) during the first few milliseconds of growth of a lightning discharge. We compare HAMMA observations of electromagnetic emissions and overall field change to models of lightning channel growth and development and attempt to constrain channel growth rate, degree of branching, channel physical properties, and uniformity of thunderstorm electric field. Preliminary comparisons suggest that the lightning channel branches relatively early in the discharge, though more complete and detailed analysis will be presented.

  10. Lightning Science: Five Ways Lightning Strikes People

    Science.gov (United States)

    ... Hurricanes Lightning Rip Currents Space Thunderstorms, Hail Tornadoes Tsunamis Ultraviolet (UV) Wildland Fires Wind Winter Weather INFORMATION ... affects a much larger area than the other causes of lightning casualties, the ground current causes the ...

  11. Digital system upset. The effects of simulated lightning-induced transients on a general-purpose microprocessor

    Science.gov (United States)

    Belcastro, C. M.

    1983-01-01

    Flight critical computer based control systems designed for advanced aircraft must exhibit ultrareliable performance in lightning charged environments. Digital system upset can occur as a result of lightning induced electrical transients, and a methodology was developed to test specific digital systems for upset susceptibility. Initial upset data indicates that there are several distinct upset modes and that the occurrence of upset is related to the relative synchronization of the transient input with the processing sate of the digital system. A large upset test data base will aid in the formulation and verification of analytical upset reliability modeling techniques which are being developed.

  12. Lightning Technology.

    Science.gov (United States)

    1980-04-01

    33-38, 1975. 6. Schonland, B.F.J., The Lightning Discharge, Handbuch der Physik , 22, 576-628, Springer-Verlag, OHG, Berlin, 1956. 25 (K,z) R GROUND o... Dictionary of Electrical and Electronic Terms, IEEE Std 100-1977, New York, John Wiley & Sons, Inc., 1977. 313 cc C 0J 0J o -4 0$4j 4j)4J 0 1.4 >- ~ o 0 0 .,.C...Electric Power Research Institute) EL-1140, Project 1141 Final Report, Sept. 1979. 8. IEEE Standard Dictionary of Electrical and Electronics Terms, Wiley

  13. METHODS OF MEASURING THE EFFECTS OF LIGHTNING BY SIMULATING ITS STRIKES WITH THE INTERVAL ASSESSMENT OF THE RESULTS OF MEASUREMENTS

    Directory of Open Access Journals (Sweden)

    P. V. Kriksin

    2017-01-01

    Full Text Available The article presents the results of the development of new methods aimed at more accurate interval estimate of the experimental values of voltages on grounding devices of substations and circuits in the control cables, that occur when lightning strikes to lightning rods; the abovementioned estimate made it possible to increase the accuracy of the results of the study of lightning noise by 28 %. A more accurate value of interval estimation were achieved by developing a measurement model that takes into account, along with the measured values, different measurement errors and includes the special processing of the measurement results. As a result, the interval of finding the true value of the sought voltage is determined with an accuracy of 95 %. The methods can be applied to the IK-1 and IKP-1 measurement complexes, consisting in the aperiodic pulse generator, the generator of high-frequency pulses and selective voltmeters, respectively. To evaluate the effectiveness of the developed methods series of experimental voltage assessments of grounding devices of ten active high-voltage substation have been fulfilled in accordance with the developed methods and traditional techniques. The evaluation results confirmed the possibility of finding the true values of voltage over a wide range, that ought to be considered in the process of technical diagnostics of lightning protection of substations when the analysis of the measurement results and the development of measures to reduce the effects of lightning are being fulfilled. Also, a comparative analysis of the results of measurements made in accordance with the developed methods and traditional techniques has demonstrated that the true value of the sought voltage may exceed the measured value at an average of 28 %, that ought to be considered in the further analysis of the parameters of lightning protection at the facility and in the development of corrective actions. The developed methods have been

  14. A Sensitivity Study of Aerosol Effects on an Idealized Supercell Storm

    Science.gov (United States)

    Takeishi, A.; Storelvmo, T.

    2013-12-01

    One of the largest uncertainties in future climate projections lies in the climatic effects of aerosols. It has been shown that the cooling effect of aerosols could partially offset the current global warming induced by increased greenhouse gas concentration. Among the effects of aerosols, the interaction between aerosols and deep convective clouds is especially difficult to quantify, due to the complex interaction and limited measurements available. Although the radiative effect of deep convective clouds on climate is small, they could affect the local, regional, and global climate by altering precipitation and the large-scale circulations. Thus, it is of importance to understand how deep convection changes its development and evolution with aerosol loading. This study aims to understand the effects of varying aerosol number concentrations on deep convective clouds, using the Weather Research and Forecasting (WRF) model. A quarter-circular shear supercell is simulated with three different microphysics schemes in an idealized setting, while mimicking the changes in aerosol concentration by changing either cloud droplet concentration or activated cloud condensation nuclei concentration. We find that the simulated amount of precipitation has quite different sensitivities to aerosol concentration, depending on the microphysics scheme used; one of the simulations shows a drastic decrease in precipitation with increased aerosol loading, whereas simulations with the other two schemes show relatively low sensitivities to aerosol concentration. This fact highlights uncertainties in the complex microphysical interactions in convective clouds. In addition, changes in ice nuclei concentration are mimicked by changing the ice nucleation rate in each scheme. Sensitivity to this variation is also dependent on the microphysics scheme used. Furthermore, radiation is added in the simulations so that both radiative and microphysical effects of aerosol on the supercell storm are

  15. Theory of ball lightning

    CERN Document Server

    Wu, H -C

    2014-01-01

    We present a comprehensive explanation on ball lightning, a luminous sphere occasionally witnessed after ordinary lightning. In the last decade, it has been well established that natural lightning routinely generates relativistic electrons, which account for observed x rays. So we assume that, in a ball lightning event, a well-defined relativistic electron bunch is produced by the stepped leader of lightning. When this electron bunch strikes various media, a powerful microwave pulse is emitted by the coherent transition radiation mechanism. This intense microwave ionizes air, evacuates plasmas by its radiation pressure to form a globular plasma cavity, and then gets trapped inside the cavity. This theory successfully explains all characteristics of ball lightning, especially the appearance of ball lightning in fully-screened aircraft. Moreover, the proposed radiation mechanism fully explains the strongest radio signals from lightning and nanosecond spikes in the signals are direct evidences on the generation ...

  16. The lightning flash

    CERN Document Server

    Cooray, Vernon

    2014-01-01

    With contributions from today's leading lightning engineers and researchers, this updated 2nd edition of Vernon Cooray's classic text, The Lightning Flash provides the reader with an essential introduction to lightning and its impact on electrical and electronic equipment. Providing the reader with a thorough background into almost every aspect of lightning and its impact on electrical and electronic equipment, this new edition is updated throughout and features eight new chapters that bring the science up to date.

  17. Lightning safety of animals.

    Science.gov (United States)

    Gomes, Chandima

    2012-11-01

    This paper addresses a concurrent multidisciplinary problem: animal safety against lightning hazards. In regions where lightning is prevalent, either seasonally or throughout the year, a considerable number of wild, captive and tame animals are injured due to lightning generated effects. The paper discusses all possible injury mechanisms, focusing mainly on animals with commercial value. A large number of cases from several countries have been analyzed. Economically and practically viable engineering solutions are proposed to address the issues related to the lightning threats discussed.

  18. Infrasound from lightning measured in Ivory Coast

    Science.gov (United States)

    Farges, T.; Millet, C.; Matoza, R. S.

    2012-04-01

    . Moreover, numerous infrasound events which have the infrasound from lightning signature could not be correlated when thunderstorms were close to the station. Statistical analyses of all correlated infrasound events show an exponential decrease of the infrasound amplitude with the distance of one order of magnitude per 50 km. These analyses show also that the relative position of lightning is important: the detection limit is higher when lightning occur at the East of the station than when they occur at the West. The dominant wind (the Easterlies) could be responsible of this dissymmetry. It also exists a high variability of detection efficiency with the seasons (better efficiency in fall than in spring). Finally, these statistics show clearly a structure inside the shadow zone (from 70 to 200 km away from the station). These results will be compared with intensive numerical simulations. The simulations are separated into two parts: the simulation of the near-field blast wave generated by a lightning and the simulation of the non-linear propagation of the shock front through a realistic atmosphere. By comparing our numerical results to recorded data over a full 1-year period, we aim to show that dominant features of statistics at the IMS station may be explained by the meteorological variability.

  19. Lightning protection for wind turbines in Vietnam

    Directory of Open Access Journals (Sweden)

    Thuan Nguyen

    2017-01-01

    Full Text Available Wind energy has become increasingly important in the total electrical energy supply mix in Vietnam over the last few years. Small, kW turbines were installed in isolated areas a decade ago, while wind farms of several MW to few hundred MW are now being connected directly to national grid, with many additional projects in planning or under construction to fulfill an objective of 6% of the total installed capacity by 2030 (approximately 6200 MW of wind energy component. The increase in wind farm generation results in increased damage from lightning. In this paper, the annual frequency of lightning strikes to wind turbines in Vietnam is calculated using electrogeometric model. Reported lightning incidents to three major wind farms in Vietnam are summarized. Possible causes of failure are discussed, and an EMTP simulation for each incident was performed accordingly. The simulations suggest the failure mechanisms as well the potential of improved grounding to reduce lightning induced damage in future windfarms.

  20. Lightning in superconductors.

    Science.gov (United States)

    Vestgården, J I; Shantsev, D V; Galperin, Y M; Johansen, T H

    2012-01-01

    Crucially important for application of type-II superconductor films is the stability of the vortex matter--magnetic flux lines penetrating the material. If some vortices get detached from pinning centres, the energy dissipated by their motion will facilitate further depinning, and may trigger a massive electromagnetic breakdown. Up to now, the time-resolved behaviour of these ultra-fast events was essentially unknown. We report numerical simulation results revealing the detailed dynamics during breakdown as within nanoseconds it develops branching structures in the electromagnetic fields and temperature, with striking resemblance of atmospheric lightning. During a dendritic avalanche the superconductor is locally heated above its critical temperature, while electrical fields rise to several kV/m as the front propagates at instant speeds near up to 100 km/s. The numerical approach provides an efficient framework for understanding the ultra-fast coupled non-local dynamics of electromagnetic fields and dissipation in superconductor films.

  1. Large Charge Moment Change Lightning in an Oklahoma Mesoscale Convective System

    Science.gov (United States)

    Lang, Timothy J.; Cummer, Steven; Petersen, Danyal; Flores-Rivera, Lizxandra; Lyons, Walt; MacGorman, Donald; Beasley, William

    2014-01-01

    On 31 May 2013, a line of severe thunderstorms developed during the local afternoon in central Oklahoma, USA. One of the supercells produced the El Reno tornado, which caused significant damage and killed several people. During the 2300 UTC hour (during the mature supercell stage and just after the tornado began), the storm produced several positive cloud-to-ground (+CG) lightning strokes that featured large (> 100 C km) impulse charge moment changes (iCMCs; charge moment during the first 2 ms after the return stroke). These discharges occurred mainly in convection, in contrast to the typical pattern of large-CMC and sprite-parent +CGs occurring mainly in stratiform precipitation regions. After this time, the line of thunderstorms evolved over several hours into a large mesoscale convective system (MCS). By the 0700 UTC hour on 1 June 2013, the large-CMC pattern had changed markedly. Large-CMC negative CGs, which were absent early in the storm's lifetime, occurred frequently within convection. Meanwhile, large-CMC +CGs had switched to occurring mainly within the broad stratiform region that had developed during the intervening period. The evolution of the large-CMC lightning in this case will be examined using a mix of national mosaics of radar reflectivity, the Oklahoma Lightning Mapping Array (OKLMA), the Charge Moment Change Network (CMCN), and the National Lightning Detection Network (NLDN). A major goal of this study is understanding how storm structure and evolution affected the production of large-CMC lightning. It is anticipated that this will lead to further insight into how and why storms produce the powerful lightning that commonly causes sprites in the upper atmosphere.

  2. Analysis on Three-dimensional Structure and Echo Characteristic Quantity of a Supercell Storm

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    [Objective] The research aimed to study three-dimensional structure and echo characteristic quantity of a supercell storm in central Gansu on May 30,2005.[Method] By monitoring data of Lanzhou CINRAD/CC Doppler radar,the three-dimensional structure characteristics of a rare supercell storm which happened in central Gansu on May 30,2005 were analyzed.We tried to reveal three-dimensional structure and echo characteristic index of supercell storm in the northeast of Qinghai-Tibet Plateau,and find reason of rar...

  3. Lightning Injury: A Review

    Science.gov (United States)

    2008-01-01

    bilateral perilymphatic fistulas from a lightning strike have been reported [65,68]. Other neuro-otologic findings have included transient vertigo...Keraunopathology. An analysis of 45 fatalities. Am J Forensic Med Pathol 1996;17(2):89–98. [7] Blumenthal R. Lightning fatalities on the South African...Trauma 1989;29(5):665–71. [65] Sun GH, Simons JP, Mandell DL. Bilateral perilymphatic fistulas from a lightning strike: a case report. Laryngoscope

  4. LES of Langmuir supercells under constant crosswind tidal forcing

    Science.gov (United States)

    Walker, Rachel; Zhang, Jie; Juha, Mario; Gosch, Chester; Tejada-Martinez, Andres

    2015-11-01

    We report on the impact of a crosswind tidal current on Langmuir supercells (LSCs) in shallow water computed via LES. LSCs consist of parallel counter rotating vortices engulfing the water column in unstratified conditions. These cells have been observed in shallow continental shelf regions of ~15 meters depth during the passage of storms. The cells are aligned roughly in the wind direction and are generated by the interaction of the wind-driven shear current with the Stokes drift velocity induced by surface gravity waves. Without tides, LES reveals that the typical crosswind width of a LSC is ~4 times the water column depth (H). Under a relatively weak crosswind tidal current (weaker than the downwind current), the constant crosswind tidal forcing applied causes a merging of cells leading to cells of width ~8H. The opposite occurs under a crosswind tidal current stronger than the downwind current as the constant crosswind tidal force is able to break up the LSCs giving rise to smaller scale cells with different turbulent structure than that associated with LSC. Statistics of the turbulence during strong and weak crosswind tides will be contrasted and implications of an oscillating crosswind tidal force will be discussed. Support from the US National Science Foundation and the Gulf of Mexico Research Initiative is gratefully acknowledged.

  5. Lightning injury: a review.

    Science.gov (United States)

    Ritenour, Amber E; Morton, Melinda J; McManus, John G; Barillo, David J; Cancio, Leopoldo C

    2008-08-01

    Lightning is an uncommon but potentially devastating cause of injury in patients presenting to burn centers. These injuries feature unusual symptoms, high mortality, and significant long-term morbidity. This paper will review the epidemiology, physics, clinical presentation, management principles, and prevention of lightning injuries.

  6. The physics of lightning

    Energy Technology Data Exchange (ETDEWEB)

    Dwyer, Joseph R., E-mail: jdwyer@fit.edu [Department of Physics and Space Sciences, Florida Institute of Technology, Melbourne, FL 32901 (United States); Uman, Martin A. [Department of Electrical and Computer Engineering, University of Florida, Gainesville, FL 32611 (United States)

    2014-01-30

    Despite being one of the most familiar and widely recognized natural phenomena, lightning remains relatively poorly understood. Even the most basic questions of how lightning is initiated inside thunderclouds and how it then propagates for many tens of kilometers have only begun to be addressed. In the past, progress was hampered by the unpredictable and transient nature of lightning and the difficulties in making direct measurements inside thunderstorms, but advances in instrumentation, remote sensing methods, and rocket-triggered lightning experiments are now providing new insights into the physics of lightning. Furthermore, the recent discoveries of intense bursts of X-rays and gamma-rays associated with thunderstorms and lightning illustrate that new and interesting physics is still being discovered in our atmosphere. The study of lightning and related phenomena involves the synthesis of many branches of physics, from atmospheric physics to plasma physics to quantum electrodynamics, and provides a plethora of challenging unsolved problems. In this review, we provide an introduction to the physics of lightning with the goal of providing interested researchers a useful resource for starting work in this fascinating field.

  7. Design of Lightning Arresters for Electrical Power Systems Protection

    Directory of Open Access Journals (Sweden)

    Shehab Abdulwadood

    2013-01-01

    Full Text Available This paper presents an overview of how the lightning strikes and their effects on power distribution systems can be modeled, where the results give a clear picture of how to eliminate the devastating impact, caused by lightning, by using lightning arresters. The program ATP-Draw (Alternative Transient Program was used to simulate the problem and was applied on a part of a power network.The simulation was done once when the lightning strikes a transmission line and a substation with no lightning arresters in use and once more with their use. The source of the lightning was represented by the ATP models (Type-15 surge function and Type-13 ramp function and the surge arrester was represented by the MOV-Type 92 component. The voltage was recorded at the substation 110/22 kV and at all loads in the electric network, and was drawn by the PlotXWin program. The results obtained indicate that the voltages induced by the lightning can reach values of the order of millions over insulation flashover levels for 22 kV equipment, where is clearly seen in Fig. 12 to 16 and Tab.10, which requires the installation of lightning arresters.

  8. Estimates of lightning NOx production from GOME satellite observations

    Directory of Open Access Journals (Sweden)

    K. F. Boersma

    2005-01-01

    Full Text Available Tropospheric NO2 column retrievals from the Global Ozone Monitoring Experiment (GOME satellite spectrometer are used to quantify the source strength and 3-D distribution of lightning produced nitrogen oxides (NOx=NO+NO2. A sharp increase of NO2 is observed at convective cloud tops with increasing cloud top height, consistent with a power-law behaviour with power 5±2. Convective production of clouds with the same cloud height are found to produce NO2 with a ratio 1.6/1 for continents compared to oceans. This relation between cloud properties and NO2 is used to construct a 10:30 local time global lightning NO2 production map for 1997. An extensive statistical comparison is conducted to investigate the capability of the TM3 chemistry transport model to reproduce observed patterns of lightning NO2 in time and space. This comparison uses the averaging kernel to relate modelled profiles of NO2 to observed NO2 columns. It exploits a masking scheme to minimise the interference of other NOx sources on the observed total columns. Simulations are performed with two lightning parameterizations, one relating convective preciptation (CP scheme to lightning flash distributions, and the other relating the fifth power of the cloud top height (H5 scheme to lightning distributions. The satellite-retrieved NO2 fields show significant correlations with the simulated lightning contribution to the NO2 concentrations for both parameterizations. Over tropical continents modelled lightning NO2 shows remarkable quantitative agreement with observations. Over the oceans however, the two model lightning parameterizations overestimate the retrieved NO2 attributed to lightning. Possible explanations for these overestimations are discussed. The ratio between satellite-retrieved NO2 and modelled lightning NO2 is used to rescale the original modelled lightning NOx production. Eight estimates of the lightning NOx production in 1997 are obtained from spatial and temporal

  9. Estimates of lightning NOx production from GOME satellite observations

    Directory of Open Access Journals (Sweden)

    H. M. Kelder

    2005-05-01

    Full Text Available Tropospheric NO2 column retrievals from the Global Ozone Monitoring Experiment (GOME satellite spectrometer are used to quantify the source strength and 3D distribution of lightning produced nitrogen oxides (NOx=NO2+NO2. A sharp increase of NO2 is observed at convective cloud tops with increasing cloud top height, consistent with a power-law behaviour with power 5±2. Convective production of clouds with the same cloud height are found to produce NO2 with a ratio 1.6/1 for continents compared to oceans. This relation between cloud properties and NO2 is used to construct a 10:30 local time global lightning NO2 production map for 1997. An extensive statistical comparison is conducted to investigate the capability of the TM3 chemistry transport model to reproduce observed patterns of lightning NO2 in time and space. This comparison uses the averaging kernel to relate modelled profiles of NO2 to observed NO2 columns. It exploits a masking scheme to minimise the interference of other NOx sources on the observed total columns. Simulations are performed with two lightning parametrisations, one relating convective preciptation (CP scheme to lightning flash distributions, and the other relating the fifth power of the cloud top height (H5 scheme to lightning distributions. The satellite-retrieved NO2 fields show significant correlations with the simulated lightning contribution to the NO2 concentrations for both parametrisations. Over tropical continents modelled lightning NO2 shows remarkable quantitative agreement with observations. Over the oceans however, the two model lightning parametrisations overestimate the retrieved NO2 attributed to lightning. Possible explanations for these overestimations are discussed. The ratio between satellite-retrieved NO2 and modelled lightning NO2 is used to rescale the original modelled lightning NOx production. Eight estimates of the lightning NOx production in 1997 are obtained from spatial and temporal correlation

  10. Infrasound Observations from Lightning

    Science.gov (United States)

    Arechiga, R. O.; Johnson, J. B.; Edens, H. E.; Thomas, R. J.; Jones, K. R.

    2008-12-01

    To provide additional insight into the nature of lightning, we have investigated its infrasound manifestations. An array of three stations in a triangular configuration, with three sensors each, was deployed during the Summer of 2008 (July 24 to July 28) in the Magdalena mountains of New Mexico, to monitor infrasound (below 20 Hz) sources due to lightning. Hyperbolic formulations of time of arrival (TOA) measurements and interferometric techniques were used to locate lightning sources occurring over and outside the network. A comparative analysis of simultaneous Lightning Mapping Array (LMA) data and infrasound measurements operating in the same area was made. The LMA locates the sources of impulsive RF radiation produced by lightning flashes in three spatial dimensions and time, operating in the 60 - 66 MHz television band. The comparison showed strong evidence that lightning does produce infrasound. This work is a continuation of the study of the frequency spectrum of thunder conducted by Holmes et al., who reported measurements of infrasound frequencies. The integration of infrasound measurements with RF source localization by the LMA shows great potential for improved understanding of lightning processes.

  11. Lightning in aeronautics

    Science.gov (United States)

    Lago, F.

    2014-11-01

    It is generally accepted that a civilian aircraft is struck, on average, once or twice per year. This number tends to indicate that a lightning strike risk is far from being marginal and so requires that aircraft manufacturers have to demonstrate that their aircraft is protected against lightning. The first generation of aircrafts, which were manufactured mainly in aluminium alloy and had electromechanical and pneumatic controls, had a natural immunity to the effects of lightning. Nowadays, aircraft structures are made primarily with composite materials and flight controls are mostly electronic. This aspect of the "more composite and more electric" aircraft demands to aircraft manufacturers to pay a particular attention to the lightning protection and to its certification by testing and/or analysis. It is therefore essential to take this risk into account when designing the aircraft. Nevertheless, it is currently impossible to reproduce the entire lightning phenomenon in testing laboratories and the best way to analyse the lightning protection is to reproduce its effects. In this context, a number of standards and guides are produced by standards committees to help laboratories and aircraft manufacturers to perform realistic tests. Although the environment of a laboratory is quite different from those of a storm cloud, the rules of aircraft design, the know-how of aircraft manufacturers, the existence of international work leading to a better understanding of the lightning phenomenon and standards more precise, permit, today, to consider the risk as properly controlled.

  12. Note on lightning temperature

    Energy Technology Data Exchange (ETDEWEB)

    Alanakyan, Yu. R., E-mail: yralanak@mail.ru [Department of General and Applied Physics, Moscow Institute of Physics and Technology (State University), Dolgoprudny, 141700 Moscow Region (Russian Federation)

    2015-10-15

    In this paper, some features of the dynamics of a lightning channel that emerges after the leader-streamer process, are theoretically studied. It is shown that the dynamic pinch effect in the channel becomes possible if a discharge current before the main (quasi-steady) stage of a lightning discharge increases rapidly. The ensuing magnetic compression of the channel increases plasma temperature to several million degrees leading to a soft x-ray flash within the highly ionized plasma. The relation between the plasma temperature and the channel radius during the main stage of a lightning discharge is derived.

  13. Lightning hazards to aircraft

    Science.gov (United States)

    Corn, P. B.

    1978-01-01

    Lightning hazards and, more generally, aircraft static electricity are discussed by a representative for the Air Force Flight Dynamics Laboratory. An overview of these atmospheric electricity hazards to aircraft and their systems is presented with emphasis on electrical and electronic subsystems. The discussion includes reviewing some of the characteristics of lightning and static electrification, trends in weather and lightning-related mishaps, some specific threat mechanisms and susceptible aircraft subsystems and some of the present technology gaps. A roadmap (flow chart) is presented to show the direction needed to address these problems.

  14. Lightning Behavior and its Dependence on Storm Kinematic and Precipitation Processes in Northern Alabama

    Science.gov (United States)

    Johnson, Elsie V.; Petersen, W. A,

    2009-01-01

    Numerous case studies and recent modeling studies have found that various metrics of updraft intensity appear to be reasonably well correlated to lightning production in thunderstorms, particularly severe thunderstorms. Indeed, the relationship between updraft and lightning flash rate is hypothesized to be the physical connection between a lightning "jump" signature and manifestations of severe weather such as tornadic activity. This study further examines this connection using a combination of dual Doppler wind retrievals made with the UAH ARMOR dual polarimetric and KHTX WSR 88D Doppler radar pair, together with northern Alabama Lightning Mapping Array (LMA) data. The dual Doppler data were used to construct three dimensional wind fields and the retrieved vertical velocity fields were subsequently compared to collocated total lightning flash rates observed by the LMA. Particular attention was paid to the timing of updraft pulses relative to changes in the flash rate, with the goal of assessing impacts on warning decision lead time. Results from the analysis of severe and non severe thunderstorms in Northern Alabama will be presented including the EF 4 tornado producing supercell on 6 February 2008.

  15. Lightning and Electric Field Structure of a Squall Line During TELEX

    Science.gov (United States)

    Macgorman, D.; Rust, D.; Bruning, E.; Ramig, N.; Apostolakopoulos, I.; Schuur, T.; Biggerstaff, M.; Straka, J.; Krehbiel, P.; Rison, B.; Hamlin, T.

    2004-12-01

    During the 2004 field program for the Thunderstorm Electrification and Lightning Experiment (TELEX), simultaneous electric field soundings, three-dimensional lightning mapping observations, high-resolution Doppler radar data, polarimetric radar data, and environmental soundings were acquired for several mesoscale convective systems, supercell storms, and non-severe thunderstorms. The overall data set was of particularly high quality for a squall line that produced frequent lightning in southern and central Oklahoma on the morning of 19 June 2004. A total of five balloon-borne electric field soundings were launched into the leading line of convection and into the trailing stratiform region. Two 5-cm wavelength mobile Doppler radars (SMART-R's) provided coordinated volume scans every 3 min throughout the period of operations. Furthermore, all operations were well within range of the 10-cm wavelength polarimetric radar and the three-dimensional lightning mapping array. This presentation will emphasize lightning mapping and electric field observations to characterize the electrical behavior of the convective line and the stratiform region.

  16. Proximity sounding analysis for derechos and supercells: an assessment of similarities and differences

    Science.gov (United States)

    Doswell, Charles A.; Evans, Jeffry S.

    Proximity soundings (within 2 h and 167 km) of derechos (long-lived, widespread damaging convective windstorms) and supercells have been obtained. More than 65 derechos, accompanied by 115 proximity soundings, are identified during the years 1983 to 1993. The derechos have been divided into categories according to the synoptic situation: strong forcing (SF), weak forcing (WF), and "hybrid" cases (which are neither weakly nor strongly forced). Nearly 100 supercell proximity soundings have been found for the period 1998 to 2001, subdivided into nontornadic and tornadic supercells; tornadic supercells were further subdivided into those producing significant (>F1 rating) tornadoes and weak tornadoes (F0-F1 rating). WF derecho situations typically are characterized by warm, moist soundings with large convective available potential instability (CAPE) and relatively weak vertical wind shear. SF derechos usually have stronger wind shears, and cooler and less moist soundings with lower CAPE than the weakly forced cases. Most derechos exhibit strong storm-relative inflow at low levels. In WF derechos, this is usually the result of rapid convective system movement, whereas in SF derechos, storm-relative inflow at low levels is heavily influenced by relatively strong low-level windspeeds. "Hybrid" cases collectively are similar to an average of the SF and WF cases. Supercells occur in environments that are not all that dissimilar from those that produce SF derechos. It appears that some parameter combining instability and deep layer shear, such as the Energy-Helicity Index (EHI), can help discriminate between tornadic and nontornadic supercell situations. Soundings with significant tornadoes (F2 and greater) typically show high 0-1 km relative humidities, and strong 0-1 km shear. Results suggest it may not be easy to forecast the mode of severe thunderstorm activity (i.e., derecho versus supercell) on any particular day, given conditions that favor severe thunderstorm activity

  17. Numerical simulation of initial lightning attachment points on helicopter based on stream-leader discharge theory%基于先导放电理论的直升机初始雷击附着位置

    Institute of Scientific and Technical Information of China (English)

    黄立洋; 陈晓宁; 郭飞; 赵金龙

    2016-01-01

    The first step to the design of aircrafts is to determinate the initial lightning attachment points.In this paper,a fast numerical simulation method based on the stream-leader discharge theory is presented to simulate the initial lighting attach-ment point on the helicopter.Firstly,the size of the electrode,the distance between the helicopter and the boundary and other pa-rameters are determined according to the test methods of the lightning attachment points in the SAE-ARP 5416A standard.Then, upward leader inception based on Beccera-Cooray criterion is used to analyze the tip of the main rotor and tail rotor ,the head,and the horizontal tail of the UH-60 helicopter.Finally,finding the minimum electric field sustains the positive leader inception by continuously changing the potential of the electrode,which can provide basis to the analysis of the initial lightning attachment points.The simulation results show that the main rotor is most likely to be the lightning initial attachment point and the head is hard to be the lightning initial attachment point.%提出了一种基于流注-先导放电理论的数值模拟方法来快速判断直升机初始雷击附着点。首先,根据标准 SAE-ARP 5416A 中规定的相关试验方法,确定平板电极大小、直升机离边界距离等参数。然后,利用 Becerra-Cooray 正极性先导起始和发展判据对 UH-60“黑鹰”直升机的主旋翼翼尖、尾旋翼翼尖、水平尾翼以及机头部位进行分析比较。最后,通过不断改变平板电极电势的方法,找到各个关键位置产生稳定正极性先导所需的最小背景电场值,以此为依据来对其初始雷击附着位置进行分析。结果表明,主旋翼翼尖最易成为初始雷击附着位置,而机头则较难成为初始雷击附着位置。

  18. Do cosmic ray air showers initiate lightning?: A statistical analysis of cosmic ray air showers and lightning mapping array data

    Science.gov (United States)

    Hare, B. M.; Dwyer, J. R.; Winner, L. H.; Uman, M. A.; Jordan, D. M.; Kotovsky, D. A.; Caicedo, J. A.; Wilkes, R. A.; Carvalho, F. L.; Pilkey, J. T.; Ngin, T. K.; Gamerota, W. R.; Rassoul, H. K.

    2017-08-01

    It has been argued in the technical literature, and widely reported in the popular press, that cosmic ray air showers (CRASs) can initiate lightning via a mechanism known as relativistic runaway electron avalanche (RREA), where large numbers of high-energy and low-energy electrons can, somehow, cause the local atmosphere in a thundercloud to transition to a conducting state. In response to this claim, other researchers have published simulations showing that the electron density produced by RREA is far too small to be able to affect the conductivity in the cloud sufficiently to initiate lightning. In this paper, we compare 74 days of cosmic ray air shower data collected in north central Florida during 2013-2015, the recorded CRASs having primary energies on the order of 1016 eV to 1018 eV and zenith angles less than 38°, with Lightning Mapping Array (LMA) data, and we show that there is no evidence that the detected cosmic ray air showers initiated lightning. Furthermore, we show that the average probability of any of our detected cosmic ray air showers to initiate a lightning flash can be no more than 5%. If all lightning flashes were initiated by cosmic ray air showers, then about 1.6% of detected CRASs would initiate lightning; therefore, we do not have enough data to exclude the possibility that lightning flashes could be initiated by cosmic ray air showers.

  19. Simulation Study on the Development Process of the Upward Leader Incepted From Lightning Rod%避雷针迎面先导发展物理过程仿真研究

    Institute of Scientific and Technical Information of China (English)

    何俊佳; 陈维江; 陈家宏; 贺恒鑫; 谷山强; 钱冠军; 向念文

    2012-01-01

    Researches on the simulation of the inception and development process of upward leaders incepted from lightning rods are beneficial for improving the accuracy of the lightning shielding analysis model. Based on the mechanism of the long air gap discharge, a kind of upward leader model including the process of corona inception, leader inception and leader development was proposed, Observation results of upward leaders under laboratory conditions and natural lightning were used to verify the model. Simulation results agree with the observation results. Characteristics of upward leaders were studied by using the model proposed in this paper. The inception of the upward leader is in advance as the lightning current and the height of the lightning rod increasing. The development process of the upward leader is influenced mainly by the lighting current and the height of the lightning rod. The velocity of the upward leader increases as the approaching of the downward leader. The characteristics of upward leader inception obtained from the rod to plane gap discharge under laboratory conditions should not be used to compute the inception of the upward leader under natural lightning. The hypothesis that the velocity of the upward leader is in proportion to the velocity of the downward leader is improper.%开展避雷针迎面先导起始及发展过程的仿真研究对建立正确的雷电屏蔽分析模型具有重要意义。基于长间隙放电的物理机制,建立了包括正极性电晕起始与流注发展、先导起始、先导一流注体系发展等物理过程的迎面先导发展物理过程仿真模型,并使用实验室和自然雷电条件下的迎面先导发展过程观测结果对其进行了验证,最后采用该模型对避雷针迎面先导特性进行了分析讨论。结果表明:该模型的计算结果与实验室条件下和一次自然雷电条件下获得的正极性迎面先导发展过程观测结果相吻合;迎面先导起始时

  20. Lightning detection in planetary atmospheres

    CERN Document Server

    Aplin, Karen L

    2016-01-01

    Lightning in planetary atmospheres is now a well-established concept. Here we discuss the available detection techniques for, and observations of, planetary lightning by spacecraft, planetary landers and, increasingly, sophisticated terrestrial radio telescopes. Future space missions carrying lightning-related instrumentation are also summarised, specifically the European ExoMars mission and Japanese Akatsuki mission to Venus, which could both yield lightning observations in 2016.

  1. Lightning medicine in South Africa.

    Science.gov (United States)

    Blumenthal, Ryan; Trengrove, Estelle; Jandrell, Ian R; Saayman, Gert

    2012-06-06

    South Africa has a rich history of lightning research; however, research on the clinical and pathological effects and features of lightning-related injury (keraunomedicine or lightning medicine) remains neglected locally. By providing an overview of keraunomedicine and focussing on South African perspectives, we hope to raise awareness and propose that a concerted and co-ordinated attempt be made to report and collate data regarding lightning strike victims in South Africa.

  2. The impact of lightning on tropospheric ozone chemistry using a new global lightning parametrisation

    Science.gov (United States)

    Finney, D. L.; Doherty, R. M.; Wild, O.; Abraham, N. L.

    2016-06-01

    A lightning parametrisation based on upward cloud ice flux is implemented in a chemistry-climate model (CCM) for the first time. The UK Chemistry and Aerosols model is used to study the impact of these lightning nitric oxide (NO) emissions on ozone. Comparisons are then made between the new ice flux parametrisation and the commonly used, cloud-top height parametrisation. The ice flux approach improves the simulation of lightning and the temporal correlations with ozone sonde measurements in the middle and upper troposphere. Peak values of ozone in these regions are attributed to high lightning NO emissions. The ice flux approach reduces the overestimation of tropical lightning apparent in this CCM when using the cloud-top approach. This results in less NO emission in the tropical upper troposphere and more in the extratropics when using the ice flux scheme. In the tropical upper troposphere the reduction in ozone concentration is around 5-10 %. Surprisingly, there is only a small reduction in tropospheric ozone burden when using the ice flux approach. The greatest absolute change in ozone burden is found in the lower stratosphere, suggesting that much of the ozone produced in the upper troposphere is transported to higher altitudes. Major differences in the frequency distribution of flash rates for the two approaches are found. The cloud-top height scheme has lower maximum flash rates and more mid-range flash rates than the ice flux scheme. The initial Ox (odd oxygen species) production associated with the frequency distribution of continental lightning is analysed to show that higher flash rates are less efficient at producing Ox; low flash rates initially produce around 10 times more Ox per flash than high-end flash rates. We find that the newly implemented lightning scheme performs favourably compared to the cloud-top scheme with respect to simulation of lightning and tropospheric ozone. This alternative lightning scheme shows spatial and temporal differences in

  3. Faraday Cage Protects Against Lightning

    Science.gov (United States)

    Jafferis, W.; Hasbrouck, R. T.; Johnson, J. P.

    1992-01-01

    Faraday cage protects electronic and electronically actuated equipment from lightning. Follows standard lightning-protection principles. Whether lightning strikes cage or cables running to equipment, current canceled or minimized in equipment and discharged into ground. Applicable to protection of scientific instruments, computers, radio transmitters and receivers, and power-switching equipment.

  4. Lightning incidents in Mongolia

    Directory of Open Access Journals (Sweden)

    Myagmar Doljinsuren

    2015-11-01

    Full Text Available This is one of the first studies that has been conducted in Mongolia on the distribution of lightning incidents. The study covers a 10-year period from 2004 to 2013. The country records a human death rate of 15.4 deaths per 10 million people per year, which is much higher than that of many countries with similar isokeraunic level. The reason may be the low-grown vegetation observed in most rural areas of Mongolia, a surface topography, typical to steppe climate. We suggest modifications to Gomes–Kadir equation for such countries, as it predicts a much lower annual death rate for Mongolia. The lightning incidents spread over the period from May to August with the peak of the number of incidents occurring in July. The worst lightning affected region in the country is the central part. Compared with impacts of other convective disasters such as squalls, thunderstorms and hail, lightning stands as the second highest in the number of incidents, human deaths and animal deaths. Economic losses due to lightning is only about 1% of the total losses due to the four extreme weather phenomena. However, unless precautionary measures are not promoted among the public, this figure of losses may significantly increase with time as the country is undergoing rapid industrialization at present.

  5. Exploring Lightning Jump Characteristics

    Science.gov (United States)

    Chronis, Themis; Carey, Larry D.; Schultz, Christopher J.; Schultz, Elise; Calhoun, Kristin; Goodman, Steven J.

    2014-01-01

    This study is concerned with the characteristics of storms exhibiting an abrupt temporal increase in the total lightning flash rate (i.e., lightning jump, LJ). An automated storm tracking method is used to identify storm "clusters" and total lightning activity from three different lightning detection systems over Oklahoma, northern Alabama and Washington, D.C. On average and for different employed thresholds, the clusters that encompass at least one LJ (LJ1) last longer, relate to higher Maximum Expected Size of Hail, Vertical Integrated Liquid and lightning flash rates (area-normalized) than the clusters that did not exhibit any LJ (LJ0). The respective mean values for LJ1 (LJ0) clusters are 80 min (35 min), 14 mm (8 mm), 25 kg per square meter (18 kg per square meter) and 0.05 flash per min per square kilometer (0.01 flash per min per square kilometer). Furthermore, the LJ1 clusters are also characterized by slower decaying autocorrelation functions, a result that implies a less "random" behavior in the temporal flash rate evolution. In addition, the temporal occurrence of the last LJ provides an estimate of the time remaining to the storm's dissipation. Depending of the LJ strength (i.e., varying thresholds), these values typically range between 20-60 min, with stronger jumps indicating more time until storm decay. This study's results support the hypothesis that the LJ is a proxy for the storm's kinematic and microphysical state rather than a coincidental value.

  6. The start of lightning: Evidence of bidirectional lightning initiation

    Science.gov (United States)

    Montanyà, Joan; van der Velde, Oscar; Williams, Earle R.

    2015-10-01

    Lightning flashes are known to initiate in regions of strong electric fields inside thunderstorms, between layers of positively and negatively charged precipitation particles. For that reason, lightning inception is typically hidden from sight of camera systems used in research. Other technology such as lightning mapping systems based on radio waves can typically detect only some aspects of the lightning initiation process and subsequent development of positive and negative leaders. We report here a serendipitous recording of bidirectional lightning initiation in virgin air under the cloud base at ~11,000 images per second, and the differences in characteristics of opposite polarity leader sections during the earliest stages of the discharge. This case reveals natural lightning initiation, propagation and a return stroke as in negative cloud-to-ground flashes, upon connection to another lightning channel - without any masking by cloud.

  7. Local lattice relaxations in random metallic alloys: Effective tetrahedron model and supercell approach

    DEFF Research Database (Denmark)

    Ruban, Andrei; Simak, S.I.; Shallcross, S.;

    2003-01-01

    We present a simple effective tetrahedron model for local lattice relaxation effects in random metallic alloys on simple primitive lattices. A comparison with direct ab initio calculations for supercells representing random Ni0.50Pt0.50 and Cu0.25Au0.75 alloys as well as the dilute limit of Au...

  8. Does a sixth mechanism exist to explain lightning injuries?: investigating a possible new injury mechanism to determine the cause of injuries related to close lightning flashes.

    Science.gov (United States)

    Blumenthal, Ryan; Jandrell, Ian R; West, Nicholas J

    2012-09-01

    Five mechanisms have been described in the literature regarding lightning injury mechanisms. A sixth mechanism is proposed in this article, namely, lightning barotrauma. A simple laboratory experiment was conducted using ordnance gelatin for ballistic studies. Lightning was simulated in a high-voltage laboratory using an 8/20-microsecond current impulse generator and discharged through ballistic gel. Temporary and permanent cavity formations were confirmed. The cavities formed were directly proportional to the currents used. Findings suggest that a sixth mechanism of lightning injury, namely, barotrauma, should be considered.

  9. Examination of Height of Transmission Line and Lightning Striking Distance concerning Lightning Shielding Effect Prediction

    Science.gov (United States)

    Sakata, Tadashi; Yamamoto, Kazuo; Sekioka, Shozo; Yokoyama, Shigeru

    We examined the lightning frequency reported by Eriksson and the lightning current distribution shown in IEC 62305-1. The lightning striking coefficient is assumed to be related to height of structures. The lightning current distribution to ground which was applicable to the electro-geometric model is estimated. Using the assumption of lightning striking distance coefficient and the estimated lightning current distribution, we calculated the lightning frequency and the lightning current distribution, concerning lightning shielding effect in transmission lines. The calculation results of the lightning frequency and the lightning current distributions were compared with the observation results, and agree satisfactorily with them.

  10. Lightning not detected on Titan

    Science.gov (United States)

    Tretkoff, Ernie

    2011-05-01

    Scientists have speculated that lightning on Saturn's moon Titan could produce changes in atmospheric chemistry and could even spark production of organic compounds that could be precursors to the evolution of life, but so far there has been no conclusive detection of lightning on Titan. Extending previous searches for lightning on Titan, Fischer and Gurnett analyzed radio data up to the 72nd close flyby of Titan by the Cassini spacecraft. They found no evidence of lightning and concluded that if lightning occurs at all on Titan, it is probably a very rare event. (Geophysical Research Letters, doi:10.1029/2011GL047316, 2011)

  11. Lightning Radio Source Retrieval Using Advanced Lightning Direction Finder (ALDF) Networks

    Science.gov (United States)

    Koshak, William J.; Blakeslee, Richard J.; Bailey, J. C.

    1998-01-01

    A linear algebraic solution is provided for the problem of retrieving the location and time of occurrence of lightning ground strikes from an Advanced Lightning Direction Finder (ALDF) network. The ALDF network measures field strength, magnetic bearing and arrival time of lightning radio emissions. Solutions for the plane (i.e., no Earth curvature) are provided that implement all of tile measurements mentioned above. Tests of the retrieval method are provided using computer-simulated data sets. We also introduce a quadratic planar solution that is useful when only three arrival time measurements are available. The algebra of the quadratic root results are examined in detail to clarify what portions of the analysis region lead to fundamental ambiguities in source location. Complex root results are shown to be associated with the presence of measurement errors when the lightning source lies near an outer sensor baseline of the ALDF network. In the absence of measurement errors, quadratic root degeneracy (no source location ambiguity) is shown to exist exactly on the outer sensor baselines for arbitrary non-collinear network geometries. The accuracy of the quadratic planar method is tested with computer generated data sets. The results are generally better than those obtained from the three station linear planar method when bearing errors are about 2 deg. We also note some of the advantages and disadvantages of these methods over the nonlinear method of chi(sup 2) minimization employed by the National Lightning Detection Network (NLDN) and discussed in Cummins et al.(1993, 1995, 1998).

  12. Charge structure analysis of a severe hailstorm with predominantly positive cloud-to-ground lightning

    Science.gov (United States)

    Pineda, Nicolau; Rigo, Tomeu; Montanyà, Joan; van der Velde, Oscar A.

    2016-09-01

    The present study makes use of cloud-to-ground lightning, three-dimensional mapping from a Lightning Mapping Array and Doppler C-band radar observations to analyze the lightning trends and the underlying electrical charge structure of a large-hail bearing storm that produced important damages on the local agriculture. The analysis reported an extremely active storm, evolving through distinct phases, which stood out from a multicell structure to finally become a supercell. The onset of newer regions of convective development interacting with the main cell made the charge structure to be rather complex during some stages of this long-lived hailstorm. Evidence suggests the presence of regions with the charge layer being inverted from that of normal, non-severe convective storms, producing predominantly positive cloud-to-ground lightning. The analysis also suggests that strong cloud signals were misclassified as low peak current single-stroke negative cloud-to-ground flashes, masking the predominant positive nature of the storm.

  13. Lightning arrester models enabling highly accurate lightning surge analysis; Koseidona kaminari surge kaiseki wo kano ni suru hiraiki model

    Energy Technology Data Exchange (ETDEWEB)

    Ueda, T. [Chubu Electric Power Co. Inc., Nagoya (Japan); Funabashi, T.; Hagiwara, T.; Watanabe, H. [Meidensha Corp., Tokyo (Japan)

    1998-12-28

    Introduced herein are a dynamic behavior model for lightning arresters designed for power stations and substations and a flashover model for a lightning arresting device designed for transmission, both developed by the author et al. The author et al base their zinc oxide type lightning arrester model on the conventional static V-I characteristics, and supplement them with difference in voltage between static and dynamic characteristics. The model is easily simulated using EMTP (Electromagnetic Transients Program) etc. There is good agreement between the results of calculation performed using this model and actually measured values. Lightning arresting devices for transmission have come into practical use, and their effectiveness is introduced on various occasions. For the proper application of such devices, an analysis model capable of faithfully describing the flashover characteristics of arcing horns installed in great numbers along transmission lines, and of lightning arresting devices for transmission, are required. The author et al have newly developed a flashover model for the devices and uses the model for the analysis of lightning surges. It is found that the actually measured values of discharge characteristics of lightning arresting devices for transmission agree well with the values calculated by use of the model. (NEDO)

  14. Lightning Imaging with LOFAR

    Directory of Open Access Journals (Sweden)

    Scholten Olaf

    2017-01-01

    Full Text Available We show that LOFAR can be used as a lightning mapping array with a resolution that is orders of magnitude better than existing arrays. In addition the polarization of the radiation can be used to track the direction of the stepping discharges.

  15. The Origin of Lightning.

    Science.gov (United States)

    Weewish Tree, 1979

    1979-01-01

    A heavenly source gives an orphaned Cherokee boy 12 silver arrows and directs him to kill the chief of the cruel Manitos (spirits). When the boy fails in his mission, the angry Manitos turn him into lightning, condemning him to flash like his silver arrows across the skies forever. (DS)

  16. Location of lightning stroke on OPGW by use of distributed optical fiber sensor

    Science.gov (United States)

    Lu, Lidong; Liang, Yun; Li, Binglin; Guo, Jinghong; Zhang, Hao; Zhang, Xuping

    2014-12-01

    A new method based on a distributed optical fiber sensor (DOFS) to locate the position of lightning stroke on the optical fiber ground wire (OPGW) is proposed and experimentally demonstrated. In the method, the lightning stroke process is considered to be a heat release process at the lightning stroke position, so Brillouin optical time domain reflectometry (BOTDR) with spatial resolution of 2m is used as the distributed temperature sensor. To simulate the lightning stroke process, an electric anode with high pulsed current and a negative electrode (the OPGW) are adopted to form a lightning impulse system with duration time of 200ms. In the experiment, lightning strokes with the quantity of electric discharge of 100 Coul and 200 Coul are generated respectively, and the DOFS can sensitively capture the temperature change of the lightning stroke position in the transient electric discharging process. Experimental results show that DOFS is a feasible instrument to locate the lightning stroke on the OPGW and it has excellent potential for the maintenance of electric power transmission line. Additionally, as the range of lightning stroke is usually within 10cm and the spatial resolution of a typical DOFS is beyond 1m, the temperature characteristics in a small area cannot be accurately represented by a DOFS with a large spatial resolution. Therefore, for further application of distributed optical fiber temperature sensors for lightning stroke location on OPGW, such as BOTDR and ROTDR, it is important to enhance the spatial resolution.

  17. Analysis on Lightning Surge Propagation in Wind Farm

    Science.gov (United States)

    Yasuda, Yoh; Hara, Takehisa; Funabashi, Toshihisa

    Wind power generation is expected to become more important in the future distribution system. Although several prospective reports such as IEC 61400-24 and NREL SR-500-31115 indicate on insulation scheme and grounding design for lightning protection, it still seems that there are not many investigations on the problems. This paper therefore discusses lightning surge analysis using wind farm model with 2 or 10 ideal wind turbines. Changing parameters such as grounding resistance and lightning strike points, several cases were studied. As the result of the analysis using digital simulator ARENE, it is clear that the surge tends to propagate toward the end of a distribution line in a wind farm and there is possibility of insulation accidents at the other wind turbines when lightning attacks a wind turbine.

  18. Lightning protection of flap system for wind turbine blades

    DEFF Research Database (Denmark)

    Candela Garolera, Anna; Madsen, Søren Find

    The aim of this PhD project was to investigate the behaviour of a Controllable Rubber Trailing Edge Flap (CRTEF) in a wind turbine blade when it is exposed to lightning discharges, and find the best technical solution to protect the CRTEF and the controlling system against lightning, based...... on the results of simulation models and high voltage tests. Wind turbines are a common target of lightning due to their height and location, and blades are the components most exposed to direct discharges. Protecting the blades against lightning is specially challenging, mainly because of the combination...... of a broader, EUDP funded project, whose overall objective was to develop a prototype active trailing edge flap system for a wind turbine blade which constitutes a complete, reliable and robust load control flap system for a full scale turbine, ready for prototype testing....

  19. Science of Ball Lightning (Fire Ball)

    Science.gov (United States)

    Ohtsuki, Yoshi-Hiko

    1989-08-01

    The Table of Contents for the full book PDF is as follows: * Organizing Committee * Preface * Ball Lightning -- The Continuing Challenge * Hungarian Ball Lightning Observations in 1987 * Nature of Ball Lightning in Japan * Phenomenological and Psychological Analysis of 150 Austrian Ball Lightning Reports * Physical Problems and Physical Properties of Ball Lightning * Statistical Analysis of the Ball Lightning Properties * A Fluid-Dynamical Model for Ball Lightning and Bead Lightning * The Lifetime of Hill's Vortex * Electrical and Radiative Properties of Ball Lightning * The Candle Flame as a Model of Ball Lightning * A Model for Ball Lightning * The High-Temperature Physico-Chemical Processes in the Lightning Storm Atmosphere (A Physico-Chemical Model of Ball Lightning) * New Approach to Ball Lightning * A Calculation of Electric Field of Ball Lightning * The Physical Explanation to the UFO over Xinjiang, Northern West China * Electric Reconnection, Critical Ionization Velocity, Ponderomotive Force, and Their Applications to Triggered and Ball Lightning * The PLASMAK™ Configuration and Ball Lightning * Experimental Research on Ball Lightning * Performance of High-Voltage Test Facility Designed for Investigation of Ball Lightning * List of Participants

  20. Attempts to Create Ball Lightning with Triggered Lightning

    Science.gov (United States)

    2009-10-01

    fluids, solids, and vegetation , as described in the next section. The experiments were performed during Summer 2008 at the International Center for... filters were used on all 35 mm cameras to prevent over-exposure. There were a total of eight successful triggered lightning events during the ball...Dinnis, Ball Lightning Caused by Oxidation of Nanoparticle Networks from Normal Lightning Strikes in Soil, Nature 403, 519-521, 2000 Paiva, G. and Pavão

  1. Industrial accidents triggered by lightning.

    Science.gov (United States)

    Renni, Elisabetta; Krausmann, Elisabeth; Cozzani, Valerio

    2010-12-15

    Natural disasters can cause major accidents in chemical facilities where they can lead to the release of hazardous materials which in turn can result in fires, explosions or toxic dispersion. Lightning strikes are the most frequent cause of major accidents triggered by natural events. In order to contribute towards the development of a quantitative approach for assessing lightning risk at industrial facilities, lightning-triggered accident case histories were retrieved from the major industrial accident databases and analysed to extract information on types of vulnerable equipment, failure dynamics and damage states, as well as on the final consequences of the event. The most vulnerable category of equipment is storage tanks. Lightning damage is incurred by immediate ignition, electrical and electronic systems failure or structural damage with subsequent release. Toxic releases and tank fires tend to be the most common scenarios associated with lightning strikes. Oil, diesel and gasoline are the substances most frequently released during lightning-triggered Natech accidents.

  2. Lightning hazards overview: Aviation requirements and interests

    Science.gov (United States)

    Corn, P. B.

    1979-01-01

    A ten-year history of USAF lightning incidents is presented along with a discussion of the problems posed by lightning to current aircraft, and the hazards it constitutes to the electrical and electronic subsystems of new technology aircraft. Lightning technical protection technical needs, both engineering and operational, include: (1) in-flight data on lightning electrical parameters; (2) tech base and guidelines for protection of advanced systems and structures; (3) improved laboratory test techniques; (4) analysis techniques for predicting induced effects; (5) lightning strike incident data from general aviation; (6) lightning detection systems; (7) pilot reports on lightning strikes; and (8) better training in lightning awareness.

  3. Lightning protection of PV systems

    OpenAIRE

    Pons, Enrico; Tommasini, Riccardo

    2013-01-01

    Lightning strikes can affect photovoltaic (PV) generators and their installations, involving also the inverter's electronics. It is therefore necessary to evaluate the risk connected to lightning strikes in order to adopt the correct protective measures for the system. The Standard IEC (EN) 62305-2 reports the procedures for the risk calculation and for the choice of proper lightning protection systems. Usually the technical guidelines suggest protecting with SPDs (surge protective devices) b...

  4. Experimental study of lightning protection effects to a overhead ground wire by a lightning rod and projection rods; Yuraishin oyobi dosshi wo mochiita kakuchisen no raigai boshi ni kansuru jikkenteki kento

    Energy Technology Data Exchange (ETDEWEB)

    Katsuragi, Y. [Chubu Electric Power Co. Inc., Nagoya (Japan); Aihara, Y. [Central Research Institute of Electric Power Industry, Tokyo (Japan)

    1995-04-20

    The overhead ground wire is generally used on transmission lines as one of the lightning protection devices for the power conductors. In recent years, the ground wire with an optical fiber cable in it (OPGW) has been employed on the transmission systems. The strands of the ground wire are, however, frequently melted down because of lightning strokes to them not only in summer but also in winter. For this reason, it is necessary to devise the new lightning protection method for the ground wire. As the protection method, lightning rods installed on the transmission tower arms and projection rods wound around a ground wire are proposed by authors. Lightning protection effects of these methods are shown by model experiments which simulate summer and winter lightning strokes. It has been made clear that these methods are useful as one of the lightning protection methods for transmission lines, and application conditions of them for practical use are also shown. 4 refs., 12 figs., 2 tabs.

  5. Lightning Initiation and Propagation

    Science.gov (United States)

    2009-08-22

    measured by the Thunderstorm Energetic Radiation Array ( TERA ), J. Geophys. Res, Vol. 114, accepted for publication, Z. Saleh, 1. Dwyer,1. Howard, M...triggered lightning as measured by the Thunderstorm Energetic Radiation Array ( TERA ), 1. Geophys. Res. VoL 114 accepted for publication, Z. Saleh, 1. Dwyer, 1...Howard, M. Uman, M. Bakhtiari, D. Concha, M. Stapleton, D. Hill, C. Biagi, and H. Rassoul Abstract The Thunderstorm Energetic Radiation Array ( TERA

  6. Modeling of overhead transmission lines for lightning overvoltage calculations

    Energy Technology Data Exchange (ETDEWEB)

    Martinez-Velasco, J.A.; Castro-Aranda, F.

    2010-10-15

    This article discussed the modelling of overhead transmission lines for lightning overvoltage calculations. Such a model must include those parts of the line that get involved when a lightning return stroke hits a wire or a tower and that have some influence on the voltage developed across insulator strings. Modelling guidelines differ depending on whether the goal is to estimate overvoltages or to determine arrester energy stresses. Modelling guidelines were summarized for each component, including shield wires and phase conductors; transmission line towers; insulators; phase voltages at the instant lightning hits the line; surge arresters; and the lightning stroke. The applied Monte Carlo procedure was summarized. For line span models, a constant-parameter model generally suffices when the goal is to calculate overvoltages across insulators or to obtain the flashover rate, but a frequency-dependent parameter model is necessary to estimate the energy discharged by arresters. The model selected for representing towers can have some influence on both flashover rates and arrester energy stresses. The representation of footing impedances is critical for calculating overvoltages and arrester energy stresses, but different modelling techniques produce significantly different results. The models are limited in that the corona effect is not included in the line models, the voltages induced by the electric and magnetic fields of lightning channels to shield wires and phase conductors are neglected, and the footing models are too simple, but they are nonetheless realistic approaches for simulating lightning effects. 2 tabs., 9 figs.

  7. TRIP illumines lightning

    Science.gov (United States)

    Hill, R. D.

    It is 8 yr since important measurements of lightning in single-cell thunderstorms were made during the Thunderstorm Research International Project (TRIP), yet no theoretical interpretation of the lightning generation mechanism from the data has been made. This tardiness in interpreting the data is undoubtedly related to the existing confusion in lightning generation theories.According to Chalmers [1967], there are two classes of thunderstorm charge separation theories: those that rely on gravitation and those that do not involve gravitation. In the gravitational class, Chalmers again distinguished two types of processes: those in which ions are naturally generated (e.g., by cosmic rays, etc.) and are then attached to particles in the cloud and those in which some process (e.g., collision, coagulation, etc.) generates positive and negatively charged particles from neutrals in the cloud. Some of these two process types, cited in Chalmers' work, are given in Table 1, together with some of the scientists who originally proposed these processes.

  8. Terrestrial gamma-ray flash production by lightning

    Science.gov (United States)

    Carlson, Brant E.

    to the results of Monte Carlo simulations of the physics of energetic photon production and propagation in air. These comparisons are used to constrain the TGF source altitude, energy, and directional distribution, and indicate a broadly-beamed low-altitude source inconsistent with production far above thunderstorms as previously suggested. The details of energetic electron production by electric fields in air are then examined. In particular, the source of initial high-energy electrons that are accelerated and undergo avalanche multiplication to produce bremsstrahlung is studied and the properties of these initial seed particles as produced by cosmic rays are determined. The number of seed particles available indicates either extremely large amplification of the number of seed particles or an alternate source of seeds. The low-altitude photon source and alternate source of seed particles required by these studies suggest a production mechanism closely-associated with lightning. A survey of lightning physics in the context of TGF emission indicates that current pulses along lightning channels may trigger TGF production by both producing strong electric fields and a large population of candidate seed electrons. The constraints on lightning physics, thunderstorm physics, and TGF physics all allow production by this mechanism. A computational model of this mechanism is then presented on the basis of a method of moments simulation of charge and current on a lightning channel. Calculation of the nearby electric fields then drives Monte Carlo simulations of energetic electron dynamics which determine the properties of the resulting bremsstrahlung. The results of this model compare quite well with satellite observations of TGFs subject to requirements on the ambient electric field and the current pulse magnitude and duration. The model makes quantitative predictions about the TGF source altitude, directional distribution, and lightning association that are in overall

  9. Characteristics of VLF/LF Sferics from Elve-producing Lightning Discharges

    Science.gov (United States)

    Blaes, P.; Zoghzoghy, F. G.; Marshall, R. A.

    2013-12-01

    Lightning return strokes radiate an electromagnetic pulse (EMP) which interacts with the D-region ionosphere; the largest EMPs produce new ionization, heating, and optical emissions known as elves. Elves are at least six times more common than sprites and other transient luminous events. Though the probability that a lightning return stroke will produce an elve is correlated with the return stroke peak current, many large peak current strokes do not produce visible elves. Apart from the lightning peak current, elve production may depend on the return stroke speed, lightning altitude, and ionospheric conditions. In this work we investigate the detailed structure of lightning that gives rise to elves by analyzing the characteristics of VLF/LF lightning sferics in conjunction with optical elve observations. Lightning sferics were observed using an array of six VLF/LF receivers (1 MHz sample-rate) in Oklahoma, and elves were observed using two high-speed photometers pointed over the Oklahoma region: one located at Langmuir Laboratory, NM and the other at McDonald Observatory, TX. Hundreds of elves with coincident LF sferics were observed during the summer months of 2013. We present data comparing the characteristics of elve-producing and non-elve producing lightning as measured by LF sferics. In addition, we compare these sferic and elve observations with FDTD simulations to determine key properties of elve-producing lightning.

  10. Effects of Location, Size and Number of Wind Turbine Receptors on Blade Lightning Protection

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    Electric and magnetic fields generated by lightning cause a serious hazard to various systems. Now wind turbine installations with higher power capacity are increasing. Higher power capacity requires higher height and so there is more probability of lightning strike. Blades are the most probable components )to be struck by lightning. The most common lightning protection system for the blades consists of several metallic receptors on the blade surface. Those are connected to the ground by metallic down-conductors placed inside the blade shell. This paper studies effects of the receptor configurations on protecting the blade against lightning strike, For this purpose, an analysis procedure based on finite element method (FEM) in COMSOL Multiphysics software environment is used. The voltage distribution around the blade is simulated for various configurations of receptors. The best configuration is presented. Simulations are performed on the blade model of a special wind turbine, which is "VESTAS V47".

  11. Research on Winter Lightning in Japan

    Science.gov (United States)

    Ishii, Masaru

    Winter lightning in Japan is known for such characteristics as frequent occurrence of upward lightning and of positive ground flashes. On the engineering side, higher frequencies of troubles at transmission lines or wind turbines in winter due to lightning than those in summer have been experienced in the winter thunderstorm area of Japan, despite the much smaller number of lightning strokes in winter observed by lightning location systems (LLS). Such frequent troubles by lightning in the cold season are unique in Japan, which have promoted intensive research on winter lightning in Japan since 1980s.

  12. Analysis of Reynolds stress budgets in LES of Langmuir supercells under crosswind currents in a coastal ocean

    Science.gov (United States)

    Tejada-Martinez, Andres; Zhang, Jie

    2016-11-01

    Langmuir supercells (LSCs) in coastal oceans consist of parallel counter rotating vortices engulfing the water column in unstratified conditions. These cells have been observed in continental shelf regions 15-30 meters deep during the passage of storms. LSCs are aligned roughly in the wind direction and are generated via interaction of the wind-driven shear current and Stokes drift velocity induced by surface gravity waves. LSCs have been determined to be an important contributor to the suspension of sediments and their overall transport across shelves. It has also been shown that tidal forcing distorts and weakens LSCs, inhibiting their potential for sediment suspension. Large-eddy simulations of LSCs in flows driven by a surface wind stress and a constant crosswind pressure gradient (representative of crosswind tidal forcing) have been performed. Although a crosswind tidal current stronger than the wind-driven current is able to break up the LSCs giving rise to smaller scale, weaker Langmuir cells (LCs), analysis of Reynolds shear stress budgets reveals that non-local transport remains significant relative to flow without LCs. This demonstrates the need for a non-local transport term in Reynolds shear stress and turbulent scalar flux closures for coastal flows with LCs. Support from the US National Science Foundation and the Gulf of Mexico Research Initiative is gratefully acknowledged.

  13. Lightning and thermal injuries.

    Science.gov (United States)

    Sanford, Arthur; Gamelli, Richard L

    2014-01-01

    Electrical burns are classified as either high voltage (1000 volts and higher) or low voltage (Lightning strikes may conduct millions of volts of electricity, yet the effects can range from minimal cutaneous injuries to significant injury comparable to a high-voltage industrial accident. Lightning strikes commonly result in cardiorespiratory arrest, for which CPR is effective when begun promptly. Neurologic complications from electrical and lightning injuries are highly variable and may present early or late (up to 2 years) after the injury. The prognosis for electricity-related neurologic injuries is generally better than for other types of traumatic causes, suggesting a conservative approach with serial neurologic examinations after an initial CT scan to rule out correctable causes. One of the most common complications of electrical injury is a cardiac dysrhythmia. Because of the potential for large volumes of muscle loss and the release of myoglobin, the presence of heme pigments in the urine must be evaluated promptly. Presence of these products of breakdown of myoglobin and hemoglobin puts the injured at risk for acute renal failure and must be treated. The exact mechanism of nerve injury has not been explained, but both direct injury by electrical current overload or a vascular cause receive the most attention. Because electrical injuries carry both externally visible cutaneous injuries and possible hidden musculoskeletal damage, conventional burn resuscitation formulas based on body surface area injured may not provide enough fluid to maintain urine output. Damaged muscle resulting in swelling within the investing fascia of an extremity may result in compartment syndromes, requiring further attention. If myoglobin has been detected in the urine, treatment is aggressive volume resuscitation and possibly alkalinization of the urine or mannitol is given IV push to minimize pigment precipitation in the renal tubules. Approximately 15% of electrical burn victims

  14. The CHUVA Lightning Mapping Campaign

    Science.gov (United States)

    Goodman, Steven J.; Blakeslee, Richard J.; Bailey, Jeffrey C.; Carey, Lawrence D.; Hoeller, Hartmut; Albrecht, Rachel I.; Morales, Carlos; Pinto, Osmar; Saba, Marcelo M.; Naccarato, Kleber; Hembury, Nikki; Nag, Amitabh; Heckman, Stan; Holzworth, Robert H.; Rudlosky, Scott D.; Betz, Hans-Dieter; Said, Ryan; Rauenzahn, Kim

    2011-01-01

    The primary science objective for the CHUVA lightning mapping campaign is to combine measurements of total lightning activity, lightning channel mapping, and detailed information on the locations of cloud charge regions of thunderstorms with the planned observations of the CHUVA (Cloud processes of tHe main precipitation systems in Brazil: A contribUtion to cloud resolVing modeling and to the GPM (GlobAl Precipitation Measurement) field campaign. The lightning campaign takes place during the CHUVA intensive observation period October-December 2011 in the vicinity of S o Luiz do Paraitinga with Brazilian, US, and European government, university and industry participants. Total lightning measurements that can be provided by ground-based regional 2-D and 3-D total lightning mapping networks coincident with overpasses of the Tropical Rainfall Measuring Mission Lightning Imaging Sensor (LIS) and the SEVIRI (Spinning Enhanced Visible and Infrared Imager) on the Meteosat Second Generation satellite in geostationary earth orbit will be used to generate proxy data sets for the next generation US and European geostationary satellites. Proxy data, which play an important role in the pre-launch mission development and in user readiness preparation, are used to develop and validate algorithms so that they will be ready for operational use quickly following the planned launch of the GOES-R Geostationary Lightning Mapper (GLM) in 2015 and the Meteosat Third Generation Lightning Imager (LI) in 2017. To date there is no well-characterized total lightning data set coincident with the imagers. Therefore, to take the greatest advantage of this opportunity to collect detailed and comprehensive total lightning data sets, test and validate multi-sensor nowcasting applications for the monitoring, tracking, warning, and prediction of severe and high impact weather, and to advance our knowledge of thunderstorm physics, extensive measurements from lightning mapping networks will be collected

  15. A stepped leader model for lightning including charge distribution in branched channels

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Wei; Zhang, Li [School of Electrical Engineering, Shandong University, Jinan 250061 (China); Li, Qingmin, E-mail: lqmeee@ncepu.edu.cn [Beijing Key Lab of HV and EMC, North China Electric Power University, Beijing 102206 (China); State Key Lab of Alternate Electrical Power System with Renewable Energy Sources, Beijing 102206 (China)

    2014-09-14

    The stepped leader process in negative cloud-to-ground lightning plays a vital role in lightning protection analysis. As lightning discharge usually presents significant branched or tortuous channels, the charge distribution along the branched channels and the stochastic feature of stepped leader propagation were investigated in this paper. The charge density along the leader channel and the charge in the leader tip for each lightning branch were approximated by introducing branch correlation coefficients. In combination with geometric characteristics of natural lightning discharge, a stochastic stepped leader propagation model was presented based on the fractal theory. By comparing simulation results with the statistics of natural lightning discharges, it was found that the fractal dimension of lightning trajectory in simulation was in the range of that observed in nature and the calculation results of electric field at ground level were in good agreement with the measurements of a negative flash, which shows the validity of this proposed model. Furthermore, a new equation to estimate the lightning striking distance to flat ground was suggested based on the present model. The striking distance obtained by this new equation is smaller than the value estimated by previous equations, which indicates that the traditional equations may somewhat overestimate the attractive effect of the ground.

  16. Using Total Lightning Observations to Enhance Lightning Safety

    Science.gov (United States)

    Stano, Geoffrey T.

    2012-01-01

    Lightning is often the underrated threat faced by the public when it comes to dangerous weather phenomena. Typically, larger scale events such as floods, hurricanes, and tornadoes receive the vast majority of attention by both the general population and the media. This comes from the fact that these phenomena are large, longer lasting, can impact a large swath of society at one time, and are dangerous events. The threat of lightning is far more isolated on a case by case basis, although millions of cloud-to-ground lightning strikes hit this United States each year. While attention is given to larger meteorological events, lightning is the second leading cause of weather related deaths in the United States. This information raises the question of what steps can be taken to improve lightning safety. Already, the meteorological community s understanding of lightning has increased over the last 20 years. Lightning safety is now better addressed with the National Weather Service s access to the National Lightning Detection Network data and enhanced wording in their severe weather warnings. Also, local groups and organizations are working to improve public awareness of lightning safety with easy phrases to remember, such as "When Thunder Roars, Go Indoors." The impacts can be seen in the greater array of contingency plans, from airports to sports stadiums, addressing the threat of lightning. Improvements can still be made and newer technologies may offer new tools as we look towards the future. One of these tools is a network of sensors called a lightning mapping array (LMA). Several of these networks exist across the United States. NASA s Short-term Prediction Research and Transition Center (SPoRT), part of the Marshall Spaceflight Center, has access to three of these networks from Huntsville, Alabama, the Kennedy Space Center, and Washington D.C. The SPoRT program s mission is to help transition unique products and observations into the operational forecast environment

  17. Phonon dispersion relations of Sb2S3 and Bi2S3 using the supercell force-constant method

    Science.gov (United States)

    Gan, Chee Kwan; Chua, Kun Ting Eddie; Liu, Yun

    2015-03-01

    We present a lattice dynamical study on the orthorhombic antimony sulphide (Sb2S3) and bismuth sulphide (Bi2S3) using the supercell force-constant method. We find that the slow decay of the interatomic force constants for these compounds in the Pnma setting critically demand the use of a large supercell of 2 × 4 × 2 that consists of 320 atoms. To enable a practical calculation the space group information is fully utilized where only inequivalent atoms within the primitive cell are displaced for the force calculations. The effect of Born effective charges is incorporated into the method. We compare our results with that obtained from the density-functional perturbation theory. We found that smaller supercells could lead to unphysical acoustic phonon softening and lifting of the degeneracies along high symmetry directions. Our results provide a proper guideline for the use of the supercell force-constant method: the supercell size must be carefully be tested along with other parameters such as the kinetic energy cutoff, the Brillouin zone sampling or the self-consistent convergence criteria.

  18. Lightning Protection Performance Assessment of Transmission Line Based on ATP model Automatic Generation

    Directory of Open Access Journals (Sweden)

    Luo Hanwu

    2016-01-01

    Full Text Available This paper presents a novel method to solve the initial lightning breakdown current by combing ATP and MATLAB simulation software effectively, with the aims to evaluate the lightning protection performance of transmission line. Firstly, the executable ATP simulation model is generated automatically according to the required information such as power source parameters, tower parameters, overhead line parameters, grounding resistance and lightning current parameters, etc. through an interface program coded by MATLAB. Then, the data are extracted from the generated LIS files which can be obtained by executing the ATP simulation model, the occurrence of transmission lie breakdown can be determined by the relative data in LIS file. The lightning current amplitude should be reduced when the breakdown occurs, and vice the verse. Thus the initial lightning breakdown current of a transmission line with given parameters can be determined accurately by continuously changing the lightning current amplitude, which is realized by a loop computing algorithm that is coded by MATLAB software. The method proposed in this paper can generate the ATP simulation program automatically, and facilitates the lightning protection performance assessment of transmission line.

  19. Lightning Observations with the Upgraded Lanmguir Lab Lightning Mapping Array

    Science.gov (United States)

    Rison, W.; Krehbiel, P. R.; Hunyady, S.; Edens, H. E.; Aulich, G. D.

    2010-12-01

    The Langmuir Lab Lightning Mapping Array (LMA) is located on and around the Magdalena Mountains in central New Mexico. Recently there have been several improvements to the LMA which have dramatically increased its sensitivity. By switching most stations to solar power (which allows us to place them far from buildings and power lines) and reducing the noise of the power supply, the station-generated and local environmental noise has been reduced to levels near the theoretical thermal value. Because of the recent switch to digital television, the LMA is no longer degraded by the anthropogenic noise of distant VHF television transmitters, due to the stations mostly being switched to UHF. The distant interference was a particularly bad problem for the stations located high in the Magdalena Mountains. The combination of lower threshold values and increasing the number of stations to 16 enables lower-power sources to be detected above the local noise levels and hence located by the system. We are now able to observe the positive leaders (which produce a much lower level of VHF radiation than negative leaders) which propagate upward from a triggering rocket. Lightning channels in natural lightning discharges are also much more clearly defined than in the past. Minor discharges (with one or a few LMA-detected sources) between larger lightning flashes are routinely observed. Much more detail is observed from distant lightning discharges. (However, the increased sensitivity does not reduce the vertical and radial errors for lightning observed outside the array.) In addition to the more sensitive LMA, we continue to improve our array of high-resolution electrostatic field change stations, which provides considerable information on lightning-induced charge transfer. We will present examples of observations of natural and triggered lightning, showing the increased detail now available from the recent improvements to the Langmuir Lab LMA.

  20. Variation in Regional and Global Lightning

    Science.gov (United States)

    Holzworth, R. H., II; Brundell, J. B.; McCarthy, M.; Virts, K.; Hutchins, M. L.; Jacobson, A. R.; Heckman, S.

    2015-12-01

    Daily global lightning variation over oceans and orography, caused by major weather patterns such as typhoons and seasonal weather oscillations, are determined with high time resolution. Observations of strong variations in global lightning are used to study possible variations in magnetospheric particle densities. Strong lightning patterns associated with ocean currents are demonstrated with a study of the Gulf Stream. We located all major lightning producing storms, using a clustering algorithm on 10 years of World Wide Lightning Location Network (WWLLN) data to reduce the influence of rapidly increasing lightning network detection efficiency on temporal studies. The clustered storms are used to study the variations and patterns of global and regional lightning activity. WWLLN and Earth Networks lightning detection networks have been used to show the energy per flash of lightning over the oceans is higher than over land, and the sharp contrast at the coasts will be examined.

  1. Finite Field Methods for the Supercell Modelling of Charged Insulator-Electrolyte Interfaces

    CERN Document Server

    Zhang, Chao

    2016-01-01

    Surfaces of ionic solids interacting with an ionic solution can build up charge by exchange of ions. The surface charge is compensated by a strip of excess charge at the border of the electrolyte forming an electric double layer. These electric double layers are very hard to model using the supercells methods of computational condensed phase science. The problem arises when the solid is an electric insulator (as most ionic solids are) permitting a finite interior electric field over the width of the slab representing the solid in the supercell. The slab acts as a capacitor. The stored charge is a deficit in the solution failing to compensate fully for the solid surface charge. Here we show how these problems can be overcome using the finite field methods developed by Stengel, Spaldin and Vanderbilt [Nat. Phys. 5, 304, (2009)]. We also show how the capacitance of the double layer can be computed once overall electric neutrality of the double layer is restored by application of a finite macroscopic field E or a...

  2. Lightning electromagnetic field generated by grounding electrode considering soil ionization

    Institute of Scientific and Technical Information of China (English)

    ZENG Rong; HE Jinliang; ZHANG Bo; GAO Yanqing

    2006-01-01

    A circuit model with lumped time-variable parameter is proposed to calculate the transient characteristic of grounding electrode under lightning current, which takes into consideration the dynamic and nonlinear effect of soil ionization around the grounding electrode. The ionization phenomena in the soil are simulated by means of time-variable parameters under appropriate conditions. The generated electromagnetic field in the air is analyzed by using electrical dipole theory and image theory when the lightning current flows into the grounding electrode. The influence of soil ionization on the electromagnetic field is investigated.

  3. The role of charged ice hydrometeors in lightning initiation

    DEFF Research Database (Denmark)

    Babich, L. P.; Bochkov, E. I.; Neubert, Torsten

    2017-01-01

    In connection with the lightning initiation problem, we consider positive streamer formation around charged, needle-shaped ice hydrometeors in an external electric field. We present results of numerical simulations of the streamer discharges that include the ice dielectric polarization and conduc...

  4. 2016 T Division Lightning Talks

    Energy Technology Data Exchange (ETDEWEB)

    Ramsey, Marilyn Leann [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Theoretical Division; Adams, Luke Clyde [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Theoretical Division; Ferre, Gregoire Robing [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Theoretical Division; Grantcharov, Vesselin [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Theoretical Division; Iaroshenko, Oleksandr [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Theoretical Division; Krishnapriyan, Aditi [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Theoretical Division; Kurtakoti, Prajvala Kishore [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Theoretical Division; Le Thien, Minh Quan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Theoretical Division; Lim, Jonathan Ng [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Theoretical Division; Low, Thaddeus Song En [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Theoretical Division; Lystrom, Levi Aaron [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Theoretical Division; Ma, Xiaoyu [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Theoretical Division; Nguyen, Hong T. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Theoretical Division; Pogue, Sabine Silvia [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Theoretical Division; Orandle, Zoe Ann [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Theoretical Division; Reisner, Andrew Ray [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Theoretical Division; Revard, Benjamin Charles [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Theoretical Division; Roy, Julien [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Theoretical Division; Sandor, Csanad [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Theoretical Division; Slavkova, Kalina Polet [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Theoretical Division; Weichman, Kathleen Joy [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Theoretical Division; Wu, Fei [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Theoretical Division; Yang, Yang [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Theoretical Division

    2016-11-29

    These are the slides for all of the 2016 T Division lightning talks. There are 350 pages worth of slides from different presentations, all of which cover different topics within the theoretical division at Los Alamos National Laboratory (LANL).

  5. Lightning Caused Fires and Acres

    Data.gov (United States)

    Bureau of Land Management, Department of the Interior — Number of wildland fires and acres burned as a result of lightning, from 2001 through 2008 (updated annually). Displayed by the eleven Geographic Areas used by the...

  6. Meteosat Third Generation Lightning Imager: a discussion on user requirements and instrument features.

    Science.gov (United States)

    Biron, D.; de Leonibus, L.; Zauli, F.; Melfi, D.; Laquale, P.; Labate, D.

    2009-04-01

    For the next generation of earth observation geostationary satellite, major operating agencies are planning to insert an optical imaging mission, that continuously observes lightning pulses in the atmosphere; EUMETSAT has decided at the end of 2008 that one of the mission to be flown on MTG is LI, a Lightning Imager. The Centro Nazionale di Meteorologia e Climatologia Aeronautica recently hosted a fellowship sponsored by Selex Galileo, with the intent to study and perform a simulation of Meteosat Third Generation - Lightning Imager (MTG-LI) sensor behavior through Tropical Rainfall Measuring Mission - Lightning Imaging Sensor data (TRMM-LIS). MTG-LI mission has no Meteosat Second Generation heritage, but users need to evaluate the possible real time data output of the instrument to agree in inserting it on MTG payload. Authors took the expected LI design from MTG Mission Requirement Document, and reprocess real lightning dataset, acquired from space by TRMM-LIS instrument, to produce a simulated MTG-LI lightning dataset. The simulation is performed in several run, varying Minimum Detectable Energy, taking into account processing steps from event detection to final lightning information. A discussion on user requirements and instrument features is presented.

  7. Lightning Imaging via VHF Emission

    Science.gov (United States)

    Kawasaki, Z.

    2015-12-01

    Osaka University has been developing interferometric lightning mapping systems for some time, first with narrow band VHF interferometers, and then with broadband digital VHF interferometers (DITF). Recently, a collaboration between New Mexico Tech and Osaka University resulted in the development of the NMT INTF. All of these interferometric lightning mapping systems have added greatly to our understanding of lightning physics. The next generation of digital broadband VHF interferometer is now being developed in Osaka, called the Lightning Imaging via VHF Emission (LIVE) interferometer. LIVE is capable of mapping lightning in real-time with sub-millisecond time resolution, or through post processing with sub-microsecond time resolution. Near-field corrections have been developed, so that sources very close to the array can be located accurately, and so that the baselines can lengthened for improved angular resolution. LIVE is capable of locating lighting over more than a 75 dB range of brightnesses, allowing the system to be extremely sensitive, and the long baselines allow for location uncertainties as low as tens of meters. Presented are observations of lightning recorded in the Kasai area of Japan, as well as the Pengerang region of Malaysia showing the capabilities of the LIVE interferometer.

  8. The effect of lightning NOx production on surface ozone in the continental United States

    Directory of Open Access Journals (Sweden)

    Y. Choi

    2008-03-01

    Full Text Available Lightning NOx emissions calculated using the U.S. National Lightning Detection Network data were found to account for 30% of the total NOx emissions for July–August 2004, a period chosen both for having higher lightning NOx production and high ozone levels, thus maximizing the likelihood that such emissions could impact peak ozone levels. Including such emissions led to modest, but sometimes significant increases in simulated surface ozone when using the Community Multi-scale Air Quality Model (CMAQ. Three model simulations were performed, two with the addition of lightning NOx emissions, and one without. Domain-wide daily maximum 8-h ozone changes due to lightning NOx were less than 2 ppbv in 71% of the cases with a maximum of 10-ppbv; whereas the difference in 1-h ozone was less than 2 ppbv in 77% of the cases with a maximum of 6 ppbv. Daily maximum 1-h and 8-h ozone for grids containing O3 monitoring stations changed slightly, with more than 43% of the cases differing less than 2 ppbv. The greatest differences were 42-ppbv for both 1-h and 8-h O3, though these tended to be on days of lower ozone. Lightning impacts on the season-wide maximum 1-h and 8-h averaged ozone decreased starting from the 1st to 4th highest values (an average of 4th highest, 8-h values is used for attainment demonstration in the U.S.. Background ozone values from the y-intercept of O3 versus NOz curve were 42.2 and 43.9 ppbv for simulations without and with lightning emissions, respectively. Results from both simulations with lightning NOx suggest that while North American lightning production of NOx can lead to significant local impacts on a few occasions, they will have a relatively small impact on typical maximum levels and determination of Policy Relevant Background levels.

  9. International Aerospace and Ground Conference on Lightning and Static Electricity, Technical Papers: The Key to Lightning Technology Held in Orlando, Florida on 26-28 June 1984.

    Science.gov (United States)

    1984-12-01

    lower end of the %ire was held in place by a nylon string 31-4 . - . Table 1 Comparison ot Temperature Measurement Methods Type Advantages Disadvantages I...produced, etc.. Effective warning against lightning d&nger, hardening or immunisation of the air- craft against lightning Etrike, laboratory simulation...would provide together with The replacement of D by q has the the theory a solid base for the study of additional advantage that at the metal- the

  10. Interaction between Adjacent Lightning Discharges in Clouds

    Institute of Scientific and Technical Information of China (English)

    WANG Yanhui; ZHANG Guangshu; ZHANG Tong; LI Yajun; WU Bin; ZHANG Tinglong

    2013-01-01

    Using a 3D lightning radiation source locating system (LLS),three pairs of associated lightning discharges (two or more adjacent lightning discharges following an arbitrary rule that their space-gap was less than 10 km and their time-gap was less than 800 ms) were observed,and the interaction between associated lightning discharges was analyzed.All these three pairs of associated lightning discharges were found to involve three or more charge regions (the ground was considered as a special charge region).Moreover,at least one charge region involved two lightning discharges per pair of associated lightning discharges.Identified from electric field changes,the subsequent lightning discharges were suppressed by the prior lightning discharges.However,it is possible that the prior lightning discharge provided a remaining discharge channel to facilitate the subsequent lightning discharge.The third case provided evidence of this possibility.Together,the results suggested that,if the charges in the main negative charge region can be consumed using artificial lightning above the main negative charge regions,lightning accidents on the ground could be greatly reduced,on the condition that the height of the main negative charge region and the charge intensity of the lower positive charge region are suitable.

  11. A Lightning Channel Retrieval Algorithm for the North Alabama Lightning Mapping Array (LMA)

    Science.gov (United States)

    Koshak, William; Arnold, James E. (Technical Monitor)

    2002-01-01

    A new multi-station VHF time-of-arrival (TOA) antenna network is, at the time of this writing, coming on-line in Northern Alabama. The network, called the Lightning Mapping Array (LMA), employs GPS timing and detects VHF radiation from discrete segments (effectively point emitters) that comprise the channel of lightning strokes within cloud and ground flashes. The network will support on-going ground validation activities of the low Earth orbiting Lightning Imaging Sensor (LIS) satellite developed at NASA Marshall Space Flight Center (MSFC) in Huntsville, Alabama. It will also provide for many interesting and detailed studies of the distribution and evolution of thunderstorms and lightning in the Tennessee Valley, and will offer many interesting comparisons with other meteorological/geophysical wets associated with lightning and thunderstorms. In order to take full advantage of these benefits, it is essential that the LMA channel mapping accuracy (in both space and time) be fully characterized and optimized. In this study, a new revised channel mapping retrieval algorithm is introduced. The algorithm is an extension of earlier work provided in Koshak and Solakiewicz (1996) in the analysis of the NASA Kennedy Space Center (KSC) Lightning Detection and Ranging (LDAR) system. As in the 1996 study, direct algebraic solutions are obtained by inverting a simple linear system of equations, thereby making computer searches through a multi-dimensional parameter domain of a Chi-Squared function unnecessary. However, the new algorithm is developed completely in spherical Earth-centered coordinates (longitude, latitude, altitude), rather than in the (x, y, z) cartesian coordinates employed in the 1996 study. Hence, no mathematical transformations from (x, y, z) into spherical coordinates are required (such transformations involve more numerical error propagation, more computer program coding, and slightly more CPU computing time). The new algorithm also has a more realistic

  12. On the Lightning Electromagnetic Fields due to Channel with Variable Return Stroke Velocity

    Directory of Open Access Journals (Sweden)

    M. Izadi

    2015-01-01

    Full Text Available Numerical field expressions are proposed to evaluate the electromagnetic fields due to the lightning channel with variable values of return stroke velocity. Previous calculation methods generally use an average value for the return stroke velocity along a lightning channel. The proposed method can support different velocity profiles along a lightning channel in addition to the widely used channel-base current functions and also the general form of the engineering current models directly in the time domain without the need to apply any extra conversions. Moreover, a sample of the measured lightning current is used to validate the proposed method while the velocity profile is simulated by the general velocity function. The simulated fields based on constant and variable values of velocity are compared to the corresponding measured fields. The results show that the simulated fields based on the proposed method are in good agreement with the corresponding measured fields.

  13. Multivariate Statistical Inference of Lightning Occurrence, and Using Lightning Observations

    Science.gov (United States)

    Boccippio, Dennis

    2004-01-01

    Two classes of multivariate statistical inference using TRMM Lightning Imaging Sensor, Precipitation Radar, and Microwave Imager observation are studied, using nonlinear classification neural networks as inferential tools. The very large and globally representative data sample provided by TRMM allows both training and validation (without overfitting) of neural networks with many degrees of freedom. In the first study, the flashing / or flashing condition of storm complexes is diagnosed using radar, passive microwave and/or environmental observations as neural network inputs. The diagnostic skill of these simple lightning/no-lightning classifiers can be quite high, over land (above 80% Probability of Detection; below 20% False Alarm Rate). In the second, passive microwave and lightning observations are used to diagnose radar reflectivity vertical structure. A priori diagnosis of hydrometeor vertical structure is highly important for improved rainfall retrieval from either orbital radars (e.g., the future Global Precipitation Mission "mothership") or radiometers (e.g., operational SSM/I and future Global Precipitation Mission passive microwave constellation platforms), we explore the incremental benefit to such diagnosis provided by lightning observations.

  14. A Lightning Activity Forecast Scheme Developed for Summer Thunderstorms in South China

    Institute of Scientific and Technical Information of China (English)

    WANG Fei; ZHANG Yijun; DONG Wansheng

    2010-01-01

    Based on the relationship between lightning flash density and radar echoes and a statistical analysis using satellite and radar observations,a scheme was introduced into the mesoscale model GRAPES(Global and Regional Assimilation and PrEdiction System)to forecast the cloud to ground(CC)flash activities.Because the relationship is a necessary but not sufficient condition for lightning,an additional constraint condition related to temperature of cloud top is added into the scheme to determine whether the lightning activity really occurs.Only if the lightning activity meets the criterion to occur,the CG flash density in a grid is considered to be valid.This was proved to be necessary for reducing the false prediction.Two cases that occurred on the edge of the subtropical high in coastal regions of South China were simulated to examine the efficiency of the scheme.The results showed that the scheme was capable of forecasting lightning activities in South China.The simulated lightning areas agreed with the CG flash observations,and the CG flash density forecast by the model was also consistent with observational results in magnitude.In consideration of the forecast aging of the explicit cloud microphysical scheme in GRAPES,lightning activities can now be forecast accurately within 6 h.

  15. Infrasonic Observations from Triggered Lightning

    Science.gov (United States)

    Arechiga, R. O.; Johnson, J. B.; Edens, H. E.; Rison, W.; Thomas, R. J.; Eack, K.; Eastvedt, E. M.

    2009-12-01

    We measured acoustic signals during both triggered and natural lightning. A comparative analysis of simultaneous data from the Lightning Mapping Array (LMA), acoustic measurements and digital high-speed photography operating in the same area was made. Acoustic emissions, providing quantitative estimates of acoustic power and spectral content, will complement coincident investigations, such as X-ray emissions. Most cloud-to-ground lightning flashes lower negative charge to ground, but flashes that lower positive charge to ground are often unusually destructive and are less understood. The New Mexico Tech Lightning Mapping Array (LMA) locates the sources of impulsive RF radiation produced by lightning flashes in three spatial dimensions and time, operating in the 60 - 66 MHz television band. However, positive breakdown is rarely detected by the LMA and positive leader channels are outlined only by recoil events. Positive cloud-to-ground (CG) channels are usually not mapped (or partially mapped because they may have recoil events). Acoustic and electric field instruments are a good complement to the LMA, since they can detect both negative and positive leaders. An array of five stations was deployed during the Summer of 2009 (July 20 to August 13) in the Magdalena mountains of New Mexico, to monitor infrasound (below 20 Hz) and audio range sources due to natural and triggered lightning. The stations were located at close (57 m), medium (303 and 537 m) and far (1403 and 2556 m) distances surrounding the triggering site. Each station consisted of five sensors, one infrasonic and one in the audio range at the center, and three infrasonic in a triangular configuration. This research will provide a more complete picture, and provide further insight into the nature of lightning.

  16. Protection of LV system against lightning

    OpenAIRE

    Yordanova Nedyalkova, Greta

    2010-01-01

    Lightning is a natural hazard and one of the greatest local mysteries. Scientists have not fully understood the mechanism of lightning. It is one of the most beautiful displays in nature and one of the nature's most dangerous phenomenon known to man. Overvoltage due to lightning is a very important problem of LV systems. Some lightning flashes damage buildings and a few kill or injure people and animals, either directly or indirectly, by causing fire and explosions. The need for protect...

  17. Space Launching Site Protection against Lightning Hazards

    OpenAIRE

    Issac, F.; Bachelier, E.; Prost, D.; Enjalbert, V.; Mohedano, L.

    2012-01-01

    International audience; A launching pad, because of its activity, is particularly sensitive to the risk of lightning. The use of Standard IEC62305 "Protection against lightning" establishes the general framework for the Lightning Protection System (LPS). However, the specific activity of a launching pad requires special analysis on specific points of the LPS. Indeed, it is necessary to take into account the lightning conductor system particularity on the one hand, and the launcher electromagn...

  18. Lightning transient analysis in wind turbine blades

    DEFF Research Database (Denmark)

    Candela Garolera, Anna; Holbøll, Joachim; Madsen, Søren Find

    2013-01-01

    The transient behavior of lightning surges in the lightning protection system of wind turbine blades has been investigated in this paper. The study is based on PSCAD models consisting of electric equivalent circuits with lumped and distributed parameters involving different lightning current...

  19. Wind turbine with lightning protection system

    DEFF Research Database (Denmark)

    2016-01-01

    The present invention relates to a wind turbine comprising a lightning protection system comprising a waveguide interconnecting a communication device and a signal-carrying structure. In other aspects, the present invention relates to the use of a waveguide in a lightning protection system...... of a wind turbine, a power splitter and its use in a lightning protection system of a wind turbine....

  20. Experimental generation of volcanic lightning

    Science.gov (United States)

    Cimarelli, Corrado; Alatorre-Ibargüengoitia, Miguel; Kueppers, Ulrich; Scheu, Bettina; Dingwell, Donald B.

    2014-05-01

    Ash-rich volcanic plumes that are responsible for injecting large quantities of aerosols into the atmosphere are often associated with intense electrical activity. Direct measurement of the electric potential at the crater, where the electric activity in the volcanic plume is first observed, is severely impeded, limiting progress in its investigation. We have achieved volcanic lightning in the laboratory during rapid decompression experiments of gas-particle mixtures under controlled conditions. Upon decompression (from ~100 bar argon pressure to atmospheric pressure), loose particles are vertically accelerated and ejected through a nozzle of 2.8 cm diameter into a large tank filled with air at atmospheric conditions. Because of their impulsive character, our experiments most closely represent the conditions encountered in the gas-thrust region of the plume, when ash is first ejected from the crater. We used sieved natural ash with different grain sizes from Popocatépetl (Mexico), Eyjafjallajökull (Iceland), and Soufrière Hills (Montserrat) volcanoes, as well as micrometric glass beads to constrain the influence of material properties on lightning. We monitored the dynamics of the particle-laden jets with a high-speed camera and the pressure and electric potential at the nozzle using a pressure transducer and two copper ring antennas connected to a high-impedance data acquisition system, respectively. We find that lightning is controlled by the dynamics of the particle-laden jet and by the abundance of fine particles. Two main conditions are required to generate lightning: 1) self-electrification of the particles and 2) clustering of the particles driven by the jet fluid dynamics. The relative movement of clusters of charged particles within the plume generates the gradient in electrical potential, which is necessary for lightning. In this manner it is the gas-particle dynamics together with the evolving particle-density distribution within different regions of

  1. Tropic lightning: myth or menace?

    Science.gov (United States)

    McCarthy, John

    2014-11-01

    Lightning is one of the leading causes of death related to environmental disaster. Of all lightning fatalities documented between 2006 and 2012, leisure activities contributed the largest proportion of deaths, with water-associated, sports, and camping being the most common. Despite the prevalence of these activities throughout the islands, Hawai'i has had zero documented lightning fatalities since weather data tracking was initiated in 1959. There is a common misconception that lightning does not strike the ground in Hawai'i. This myth may contribute to a potentially dangerous false sense of security, and recognition of warning signs and risk factor modification remain the most important prevention strategies. Lightning damage occurs on a spectrum, from minor burns to multi-organ dysfunction. After injury, initial treatment should focus on "reverse triage" and immediate cardiopulmonary resuscitation when indicated, followed by transfer to a healthcare facility. Definitive treatment entails monitoring and management of potential sequelae, to include cardiovascular, neurologic, dermatologic, ophthalmologic, audiovestibular, and psychiatric complications.

  2. Positive lightning and severe weather

    Science.gov (United States)

    Price, C.; Murphy, B.

    2003-04-01

    In recent years researchers have noticed that severe weather (tornados, hail and damaging winds) are closely related to the amount of positive lightning occurring in thunderstorms. On 4 July 1999, a severe derecho (wind storm) caused extensive damage to forested regions along the United States/Canada border, west of Lake Superior. There were 665,000 acres of forest destroyed in the Boundary Waters Canoe Area Wilderness (BWCAW) in Minnesota and Quetico Provincial Park in Canada, with approximately 12.5 million trees blown down. This storm resulted in additional severe weather before and after the occurrence of the derecho, with continuous cloud-to-ground (CG) lightning occurring for more than 34 hours during its path across North America. At the time of the derecho the percentage of positive cloud-to-ground (+CG) lightning measured by the Canadian Lightning Detection Network (CLDN) was greater than 70% for more than three hours, with peak values reaching 97% positive CG lightning. Such high ratios of +CG are rare, and may be useful indicators for short-term forecasts of severe weather.

  3. Fire Environment Mechanism of Lightning Fire for Daxing an Mountains

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Lightning fire is one of natural fires; its mechanism is very complex and difficult to control. Daxing'an Mountain is the main region that lightning fires occur in China. Research on lightning fires indicates that special fuel, dry-storm weather and high altitude form the lightning fire environment. Lightning fires have close relation with lights. When lightning occurs, especially dry-lightning which brings little precipitation with surface temperature growing and fuel dehydrating, these often lead to l...

  4. Lightning Damage of Carbon Fiber/Epoxy Laminates with Interlayers Modified by Nickel-Coated Multi-Walled Carbon Nanotubes

    Science.gov (United States)

    Dong, Qi; Wan, Guoshun; Xu, Yongzheng; Guo, Yunli; Du, Tianxiang; Yi, Xiaosu; Jia, Yuxi

    2017-02-01

    The numerical model of carbon fiber reinforced polymer (CFRP) laminates with electrically modified interlayers subjected to lightning strike is constructed through finite element simulation, in which both intra-laminar and inter-laminar lightning damages are considered by means of coupled electrical-thermal-pyrolytic analysis method. Then the lightning damage extents including the damage volume and maximum damage depth are investigated. The results reveal that the simulated lightning damages could be qualitatively compared to the experimental counterparts of CFRP laminates with interlayers modified by nickel-coated multi-walled carbon nanotubes (Ni-MWCNTs). With higher electrical conductivity of modified interlayer and more amount of modified interlayers, both damage volume and maximum damage depth are reduced. This work provides an effective guidance to the anti-lightning optimization of CFRP laminates.

  5. High-Resolution Analysis Products to Support Severe Weather and Cloud-to-Ground Lightning Threat Assessments over Florida

    Science.gov (United States)

    Case, Jonathan; Spratt, Scott; Sharp, David

    2006-01-01

    The Applied Meteorology Unit (AMU) located at the Kennedy Space Center (KSC)/Cape Canaveral Air Force Station (CCAFS) implemented an operational configuration of the Advanced Regional Prediction System (ARPS) Data Analysis System (ADAS), as well as the ARPS numerical weather prediction (NWP) model. Operational, high-resolution ADAS analyses have been produced from this configuration at the National Weather Service in Melbourne, FL (NWS MLB) and the Spaceflight Meteorology Group (SMG) over the past several years. Since that time, ADAS fields have become an integral part of forecast operations at both NWS MLB and SMG. To continue providing additional utility, the AMU has been tasked to implement visualization products to assess the potential for supercell thunderstorms and significant tornadoes, and to improve assessments of short-term cloud-to-ground (CG) lightning potential. This paper and presentation focuses on the visualization products developed by the AMU for the operational high-resolution ADAS and AR.PS at the NWS MLB and SMG. The two severe weather threat graphics implemented within ADAS/ARPS are the Supercell Composite Parameter (SCP) and Significant Tornado Parameter (SIP). The SCP was designed to identify areas with supercell thunderstorm potential through a combination of several instability and shear parameters. The SIP was designed to identify areas that favor supercells producing significant tornadoes (F2 or greater intensity) versus non-tornadic supercells. Both indices were developed by the NOAAINWS Storm Prediction Center (SPC) and were normalized by key threshold values based on previous studies. The indices apply only to discrete storms, not other convective modes. In a post-analysis mode, the AMU calculated SCP and SIP for graphical output using an ADAS configuration similar to the operational set-ups at NWS MLB and SMG. Graphical images from ADAS were generated every 15 minutes for 13 August 2004, the day that Hurricane Charley approached and

  6. Evaluation of lightning accommodation systems for wind-driven turbine rotors

    Energy Technology Data Exchange (ETDEWEB)

    Bankaitis, H

    1982-03-01

    Several concepts of lightning accommodation systems for wind-driven turbine rotor blades were evaluated by submitting them to simulated lightning tests. Test samples representative of epoxy-fiberglass and wood-epoxy composite structural materials were submitted to a series of high-voltage and high-current damage tests. The high-voltage tests were designed to determine the strike points and current paths through the sample and the need for, and the most proper type of, lightning accommodation. The high-current damage tests were designed to determine the capability of the potential lightning accommodation system to sustain the 200-kA lightning current without causing damage to the composite structure. The observations and data obtained in the series of tests of lightning accommodation systems clearly led to the conclusions that composite-structural-material rotor blades require a lightning accommodation system; that the concepts tested prevent internal streamering; and that keeping discharge currents on the blade surface precludes structure penetration. Induced voltage effects or any secondary effects on the integral components of the total system could not be addressed. Further studies should be carried out to encompass effects on the total system design.

  7. Lightning and Life on Exoplanets

    Science.gov (United States)

    Rimmer, Paul; Ardaseva, Aleksandra; Hodosan, Gabriella; Helling, Christiane

    2016-07-01

    Miller and Urey performed a ground-breaking experiment, in which they discovered that electric discharges through a low redox ratio gas of methane, ammonia, water vapor and hydrogen produced a variety of amino acids, the building blocks of proteins. Since this experiment, there has been significant interest on the connection between lightning chemistry and the origin of life. Investigation into the atmosphere of the Early Earth has generated a serious challenge for this project, as it has been determined both that Earth's early atmosphere was likely dominated by carbon dioxide and molecular nitrogen with only small amounts of hydrogen, having a very high redox ratio, and that discharges in gases with high redox ratios fail to yield more than trace amounts of biologically relevant products. This challenge has motivated several origin of life researchers to abandon lightning chemistry, and to concentrate on other pathways for prebiotic synthesis. The discovery of over 2000 exoplanets includes a handful of rocky planets within the habitable zones around their host stars. These planets can be viewed as remote laboratories in which efficient lightning driven prebiotic synthesis may take place. This is because many of these rocky exoplanets, called super-Earths, have masses significantly greater than that of Earth. This higher mass would allow them to more retain greater amounts hydrogen within their atmosphere, reducing the redox ratio. Discharges in super-Earth atmospheres can therefore result in a significant yield of amino acids. In this talk, I will discuss new work on what lightning might look like on exoplanets, and on lightning driven chemistry on super-Earths. Using a chemical kinetics model for a super-Earth atmosphere with smaller redox ratios, I will show that in the presence of lightning, the production of the amino acid glycine is enhanced up to a certain point, but with very low redox ratios, the production of glycine is again inhibited. I will conclude

  8. Lightning hazard reduction at wind farms

    Energy Technology Data Exchange (ETDEWEB)

    Kithil, R. [National Lightning Safety Institute, Louisville, CO (United States)

    1997-12-31

    The USA wind farm industry (WFI) largely is centered in low-lightning areas of the State of California. While some evidence of lightning incidents is reported here, the problem is not regarded as serious by most participants. The USA WFI now is moving eastward, into higher areas of lightning activity. The European WFI has had many years experience with lightning problems. One 1995 German study estimated that 80% of wind turbine insurance claims paid for damage compensation were caused by lightning strikes. The European and USA WFI have not adopted site criteria, design fundamentals, or certification techniques aimed at lightning safety. Sufficient evidence about lightning at wind farms is available to confirm that serious potential problems exist.

  9. 广东地区变电站出线断路器侵入波过电压实时数字仿真分析%Realtime Digital Simulation of Lightning Surge Intrusion on Outlet Circuit Breakers of Substations in Guangdong Region

    Institute of Scientific and Technical Information of China (English)

    彭向阳; 姚森敬; 郭婷; 周文俊

    2012-01-01

    General situation of substation outlet circuit breaker faults caused by lightning surge intrusion occurred in Guangdong region before the installation of outlet arrester is described, and it is clarified that the lightning surge intrusion protection for outlet circuit breakers during its reclosure must be reinforced, i.e., outlet arresters must be installed in front of outlet circuit breakers. Utilizing real-time" digital simulator (RTDS), the overvoltage caused by lightning surge intrusion during the reclosure of outlet circuit breaker is simulated, and the effect of enhancing insulation level of transmission line and the protection result of adding outlet arresters are evaluated as well. Simulation results show that after outlet arrester is installed, although the insulation level of transmission line is strengthened considerably, dangerous lightning surge intrusion will not appear on outlet circuit breaker, thus the operating condition of lightning protection for substation can be effectively improved.%介绍广东地区变电站未安装出线避雷器前雷电侵入波事故概况,明确了必须加强出线断路器重合闸期间的侵入波保护,即应安装出线断路器前置避雷器。利用实时数字仿真器(real.timedigitalsimulator,RTDS)分析变电站出线断路器开断期间雷电侵入波过电压,并对加强线路绝缘的影响以及出线避雷器的保护效果进行评估。计算结果表明:变电站装设出线避雷器后,即使大幅提高输电线路绝缘水平,也不会在出线断路器产生危险的雷电侵入波过电压,能有效地改善变电站防雷运行工况。

  10. STUDY ON SURGE ARRESTER PERFORMANCE DUE TO LIGHTNING STROKE IN 20 KV DISTRIBUTION LINES

    Directory of Open Access Journals (Sweden)

    Agung Warsito

    2012-02-01

    Full Text Available Electric energy has been transmiting from power station to end user with transmission and distribution lines.Lightning strokes are problems that occure in transmission and distribution lines and make them fault when theelectric energy were transmited. Surge Diverter or Lightning Arrester has been installing to reduce these faults.In this paper the simulation of lightning stroke and lightning arrester performance on distribution lines 20 kVwere done using EMTP (Electromagnetic Transient Program. Some parameters such us impuls voltage andincreasing voltage on distribution line was inverstigated. As case study in this simulation, Mojosongo 1 mainfeeder 20 kV three phase lines were used.The simulation results show that the lightning stroke 20 kA in By1-61-61E-84-9I on S phase at 0,1 ms, makevoltage on S phase was increased about 1,3054 MV. For R phase and T phase will increase of induced voltagewere 0.79539 MV and 0.80484 MV. We also show the performance of MOV Arrester (Metal Oxide Varistor inovercoming lightning stroke trouble, where arrester can decrease voltage up to 15.198 kV on S phase, while atR phase and T phase arrester can decrease voltage up to 11.375 kV and 13.616 kV.

  11. Modeling Lightning Impact Thermo-Mechanical Damage on Composite Materials

    Science.gov (United States)

    Muñoz, Raúl; Delgado, Sofía; González, Carlos; López-Romano, Bernardo; Wang, De-Yi; LLorca, Javier

    2014-02-01

    Carbon fiber-reinforced polymers, used in primary structures for aircraft due to an excellent strength-to-weight ratio when compared with conventional aluminium alloy counterparts, may nowadays be considered as mature structural materials. Their use has been extended in recent decades, with several aircraft manufacturers delivering fuselages entirely manufactured with carbon composites and using advanced processing technologies. However, one of the main drawbacks of using such composites entails their poor electrical conductivity when compared with aluminium alloy competitors that leads to lightning strikes being considered a significant threat during the service life of the aircraft. Traditionally, this problem was overcome with the use of a protective copper/bronze mesh that added additional weight and reduced the effectiveness of use of the material. Moreover, this traditional sizing method is based on vast experimental campaigns carried out by subjecting composite panels to simulated lightning strike events. While this method has proven its validity, and is necessary for certification of the structure, it may be optimized with the aid provided by physically based numerical models. This paper presents a model based on the finite element method that includes the sources of damage observed in a lightning strike, such as thermal damage caused by Joule overheating and electromagnetic/acoustic pressures induced by the arc around the attachment points. The results of the model are compared with lightning strike experiments carried out in a carbon woven composite.

  12. Lightning protection of wind turbines

    Energy Technology Data Exchange (ETDEWEB)

    Soerensen, T.; Brask, M.H. [DEFU (Denmark); Jensen, F.V.; Raben, N. [SEAS (Denmark); Saxov, J. [Nordjyllandsvaerket (Denmark); Nielsen, L. [Vestkraft (Denmark); Soerensen, P.E. [Risoe National Lab. (Denmark)

    1999-03-01

    Lightning damage to wind turbines is a serious problem for Danish power companies, who have experienced some cases with very costly lightning damage and a large number of cases with minor damage. The most costly cases include one catastrophic damage to an entire wind turbine, and several cases of destruction of blades, main bearings, generators and control systems. Over the years there have been several hundreds of cases with minor damage - typically damage and interruptions of the control and communication systems, or the power systems. The Danish power companies anticipate that the lightning threat will be even bigger for the large off-shore wind turbine installations that are currently being planned in Denmark. Furthermore, it is known from the off-shore wind turbines at Vindeby in Denmark that the costs of inspection and particularly repair work must be expected to be much higher off-shore as compared to wind turbines on land. These considerations was the background for a two year project concerned with investigation of lighting damages and with the formulation of a DEFU Recommendation for lightning protection of wind turbines, which was published in January 1999. The project was funded by the Danish power companies Elsam, Eltra, Elkraft and by DEFU. (au)

  13. Aircraft Lightning Electromagnetic Environment Measurement

    Science.gov (United States)

    Ely, Jay J.; Nguyen, Truong X.; Szatkowski, George N.

    2011-01-01

    This paper outlines a NASA project plan for demonstrating a prototype lightning strike measurement system that is suitable for installation onto research aircraft that already operate in thunderstorms. This work builds upon past data from the NASA F106, FAA CV-580, and Transall C-180 flight projects, SAE ARP5412, and the European ILDAS Program. The primary focus is to capture airframe current waveforms during attachment, but may also consider pre and post-attachment current, electric field, and radiated field phenomena. New sensor technologies are being developed for this system, including a fiber-optic Faraday polarization sensor that measures lightning current waveforms from DC to over several Megahertz, and has dynamic range covering hundreds-of-volts to tens-of-thousands-of-volts. A study of the electromagnetic emission spectrum of lightning (including radio wave, microwave, optical, X-Rays and Gamma-Rays), and a compilation of aircraft transfer-function data (including composite aircraft) are included, to aid in the development of other new lightning environment sensors, their placement on-board research aircraft, and triggering of the onboard instrumentation system. The instrumentation system will leverage recent advances in high-speed, high dynamic range, deep memory data acquisition equipment, and fiber-optic interconnect.

  14. A Conjecture Concerning Ball Lightning

    CERN Document Server

    Sturrock, P A

    2016-01-01

    There is at present no theory that can explain the curious properties of ball lightning. This suggests that we may not be using the most appropriate concepts. The concept of a 'parallel space' may point the way to a valid theory.

  15. Jovian Lightning and Moonlit Clouds

    Science.gov (United States)

    1997-01-01

    Jovian lightning and moonlit clouds. These two images, taken 75 minutes apart, show lightning storms on the night side of Jupiter along with clouds dimly lit by moonlight from Io, Jupiter's closest moon. The images were taken in visible light and are displayed in shades of red. The images used an exposure time of about one minute, and were taken when the spacecraft was on the opposite side of Jupiter from the Earth and Sun. Bright storms are present at two latitudes in the left image, and at three latitudes in the right image. Each storm was made visible by multiple lightning strikes during the exposure. Other Galileo images were deliberately scanned from east to west in order to separate individual flashes. The images show that Jovian and terrestrial lightning storms have similar flash rates, but that Jovian lightning strikes are a few orders of magnitude brighter in visible light.The moonlight from Io allows the lightning storms to be correlated with visible cloud features. The latitude bands where the storms are seen seem to coincide with the 'disturbed regions' in daylight images, where short-lived chaotic motions push clouds to high altitudes, much like thunderstorms on Earth. The storms in these images are roughly one to two thousand kilometers across, while individual flashes appear hundreds of kilometer across. The lightning probably originates from the deep water cloud layer and illuminates a large region of the visible ammonia cloud layer from 100 kilometers below it.There are several small light and dark patches that are artifacts of data compression. North is at the top of the picture. The images span approximately 50 degrees in latitude and longitude. The lower edges of the images are aligned with the equator. The images were taken on October 5th and 6th, 1997 at a range of 6.6 million kilometers by the Solid State Imaging (SSI) system on NASA's Galileo spacecraft.The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office

  16. The Colorado Lightning Mapping Array

    Science.gov (United States)

    Rison, W.; Krehbiel, P. R.; Thomas, R. J.; Rodeheffer, D.; Fuchs, B.

    2012-12-01

    A fifteen station Lightning Mapping Array (LMA) was installed in northern Colorado in the spring of 2012. While the driving force for the array was to produce 3-dimensional lightning data to support the Deep Convective Clouds and Chemistry (DC3) Experiment (Barth, this conference), data from the array are being used for several other projects. These include: electrification studies in conjunction with the CSU CHILL radar (Lang et al, this conference); observations of the parent lightning discharges of sprites (Lyons et al, this conference); trying to detect upward discharges triggered by wind turbines, characterizing conditions in which aircraft flying through clouds produce discharges which can be detected by the LMA, and other opportunities, such as observations of lightning in pyrocumulus clouds produced by the High Park Fire west of Fort Collins, CO. All the COLMA stations are solar-powered, and use broadband cellular modems for data communications. This makes the stations completely self-contained and autonomous, allowing a station to be installed anywhere a cellular signal is available. Because most of the stations were installed well away from anthropogenic noise sources, the COLMA is very sensitive. This is evidenced by the numerous plane tracks detected in its the vicinity. The diameter, D, of the COLMA is about 100 km, significantly larger than other LMAs. Because the error in the radial distance r is proportional to (r/D)2, and the error in the altitude z is proportional to (z/D)2, the larger array diameter greatly expands the usable range of the COLMA. The COLMA is able to detect and characterize lighting flashes to a distance of about 350 km from the array center. In addition to a web-based display (lightning.nmt.edu/colma), geo-referenced images are produced and updated at one-minute intervals. These geo-referenced images can be used to overlay the real-time lightning data on Google Earth and other mapping software. These displays were used by the DC3

  17. Analysis of Transient Phenomena Due to a Direct Lightning Strike on a Wind Energy System

    Directory of Open Access Journals (Sweden)

    João P. S. Catalão

    2012-07-01

    Full Text Available This paper is concerned with the protection of wind energy systems against the direct effects of lightning. As wind power generation undergoes rapid growth, lightning damages involving wind turbines have come to be regarded as a serious problem. Nevertheless, very few studies exist yet in Portugal regarding lightning protection of wind energy systems using numerical codes. A new case study is presented in this paper, based on a wind turbine with an interconnecting transformer, for the analysis of transient phenomena due to a direct lightning strike to the blade. Comprehensive simulation results are provided by using models of the Restructured Version of the Electro-Magnetic Transients Program (EMTP, and conclusions are duly drawn.

  18. Interference and k-point sampling in the supercell approach to phase-coherent transport - art. no. 0333401

    DEFF Research Database (Denmark)

    Thygesen, Kristian Sommer; Jacobsen, Karsten Wedel

    2005-01-01

    We present a systematic study of interference and k-point sampling effects in the supercell approach to phase-coherent electron transport. We use a representative tight-binding model to show that interference between the repeated images is a small effect compared to the error introduced by using...... only the Gamma-point for a supercell containing (3,3) sites in the transverse plane. An insufficient k-point sampling can introduce strong but unphysical features in the transmission function which can be traced to the presence of van Hove singularities in the lead. We present a first......-principles calculation of the transmission through a Pt contact which shows that the k-point sampling is also important for realistic systems....

  19. Competition Mechanism of Lightning Upward Leaders Issued from UHVDC Transmission Lines

    Institute of Scientific and Technical Information of China (English)

    SHI Wei; LI Qingmin; LU Xinchang; ZOU Liang; SUN Qiuqin

    2012-01-01

    Research on the lightning shielding failure characteristics of UHVDC transmission lines is important for adequate transmission line protection and safe operation of a power grid. Focusing the competition characteristics of upward leaders in the lightning attachment process, this work provides technical reference for efficient evaluations of lightning shielding failures and reliable lightning protection designs of UHVDC transmission lines. The charge simulation method is employed to calculate electric field distributions. Based on the calculation and some data obtained by recent long-gap discharge and lightning observations, the effect of several upward leaders starting from UHVDC transmission lines on lightning attachment processes is studied by numerical simulation. The results show that the upward leader inception is delayed, the propagation velocity is smaller, and the propagation direction of the upward leader is changed with interaction among all upward leaders, which influences the selection of lightning striking point. Therefore, in order to improve the accuracy of calculating the lightning shielding failure rate of UHVDC transmission lines, the interaction characteristics of upward leaders should be taken into account . In addition, an analysis of the influence of operating voltage and the protection angle of UHVDC transmission lines based on competition mechanism of upward leaders is made. It is found that the existence of operating voltage mainly affects the ability of the conductor and the overhead ground wire at the same side to incept upward leaders, while the protection angle mainly affects the position of the "starting points" of upward leaders. The results indicate that positive polar conductors should be installed closer to hillsides and the negative protection angle of towers is suggested.

  20. Where are the lightning hotspots on Earth?

    Science.gov (United States)

    Albrecht, R. I.; Goodman, S. J.; Buechler, D. E.; Blakeslee, R. J.; Christian, H. J., Jr.

    2015-12-01

    The first lightning observations from space date from the early 1960s and more than a dozen spacecraft orbiting the Earth have flown instruments that recorded lightning signals from thunderstorms over the past 45 years. In this respect, the Tropical Rainfall Measuring Mission (TRMM) Lightning Imaging Sensor (LIS), having just completed its mission (1997-2015), provides the longest and best total (intracloud and cloud-to-ground) lightning data base over the tropics.We present a 16 year (1998-2013) reprocessed data set to create very high resolution (0.1°) TRMM LIS total lightning climatology. This detailed very high resolution climatology is used to identify the Earth's lightning hotspots and other regional features. Earlier studies located the lightning hotspot within the Congo Basin in Africa, but our very high resolution lightning climatology found that the highest lightning flash rate on Earth actually occurs in Venezuela over Lake Maracaibo, with a distinct maximum during the night. The higher resolution dataset clearly shows that similar phenomenon also occurs over other inland lakes with similar conditions, i.e., locally forced convergent flow over a warm lake surface which drives deep nocturnal convection. Although Africa does not have the top lightning hotspot, it comes in a close second and it is the continent with the highest number of lightning hotspots, followed by Asia, South America, North America, and Oceania. We also present climatological maps for local hour and month of lightning maxima, along with a ranking of the highest five hundred lightning maxima, focusing discussion on each continent's 10 highest lightning maxima. Most of the highest continental maxima are located near major mountain ranges, revealing the importance of local topography in thunderstorm development. These results are especially relevant in anticipation of the upcoming availability of continuous total lightning observations from the Geostationary Lightning Mapping (GLM

  1. Lightning attachment process to common buildings

    Science.gov (United States)

    Saba, M. M. F.; Paiva, A. R.; Schumann, C.; Ferro, M. A. S.; Naccarato, K. P.; Silva, J. C. O.; Siqueira, F. V. C.; Custódio, D. M.

    2017-05-01

    The physical mechanism of lightning attachment to grounded structures is one of the most important issues in lightning physics research, and it is the basis for the design of the lightning protection systems. Most of what is known about the attachment process comes from leader propagation models that are mostly based on laboratory observations of long electrical discharges or from observations of lightning attachment to tall structures. In this paper we use high-speed videos to analyze the attachment process of downward lightning flashes to an ordinary residential building. For the first time, we present characteristics of the attachment process to common structures that are present in almost every city (in this case, two buildings under 60 m in São Paulo City, Brazil). Parameters like striking distance and connecting leaders speed, largely used in lightning attachment models and in lightning protection standards, are revealed in this work.Plain Language SummarySince the time of Benjamin Franklin, no one has ever recorded high-speed video images of a lightning connection to a common building. It is very difficult to do it. Cameras need to be very close to the structure chosen to be observed, and long observation time is required to register one lightning strike to that particular structure. Models and theories used to determine the zone of protection of a lightning rod have been developed, but they all suffer from the lack of field data. The submitted manuscript provides results from high-speed video observations of lightning attachment to low buildings that are commonly found in almost every populated area around the world. The proximity of the camera and the high frame rate allowed us to see interesting details that will improve the understanding of the attachment process and, consequently, the models and theories used by lightning protection standards. This paper also presents spectacular images and videos of lightning flashes connecting lightning rods that

  2. The 1st Asian Lightning Protection Forum

    Institute of Scientific and Technical Information of China (English)

    2004-01-01

    @@ The First Asian Lightning Protection Forum was held on October 28-29, 2003 in Beijing, China.The forum was sponsored by the China Association for Standardization and was organized by Chinese National Committee for Lightning Protection Technology Standardization, Department of Electrical Engineering Tsinghua University, China Electricity Council, Zhongguang High-tech Industrial Development Co.,Ltd, and Lightning Protection Center of Guangdong Province.

  3. Geological Effects on Lightning Strike Distributions

    KAUST Repository

    Berdahl, J. Scott

    2016-05-16

    Recent advances in lightning detection networks allow for detailed mapping of lightning flash locations. Longstanding rumors of geological influence on cloud-to-ground (CG) lightning distribution and recent commercial claims based on such influence can now be tested empirically. If present, such influence could represent a new, cheap and efficient geophysical tool with applications in mineral, hydrothermal and oil exploration, regional geological mapping, and infrastructure planning. This project applies statistical analysis to lightning data collected by the United States National Lightning Detection Network from 2006 through 2015 in order to assess whether the huge range in electrical conductivities of geological materials plays a role in the spatial distribution of CG lightning. CG flash densities are mapped for twelve areas in the contiguous United States and compared to elevation and geology, as well as to the locations of faults, railroads and tall towers including wind turbines. Overall spatial randomness is assessed, along with spatial correlation of attributes. Negative and positive polarity lightning are considered separately and together. Topography and tower locations show a strong influence on CG distribution patterns. Geology, faults and railroads do not. This suggests that ground conductivity is not an important factor in determining lightning strike location on scales larger than current flash location accuracies, which are generally several hundred meters. Once a lightning channel is established, however, ground properties at the contact point may play a role in determining properties of the subsequent stroke.

  4. Impact and Improvement Method of the Biological Effects during the Transmission Tower Being Lightning Struck

    Science.gov (United States)

    Hengzhen, Li; Youguang, Mo; Guanghui, Sun; Pengcheng, Wang; Han, Xu; Zhijie, He

    2017-05-01

    When lightning strikes the transmission line towers, the lightning current flow through the overhead line shunted along the grounding conductor dispersed in the earth, the lightning current amplitude of tens of thousands of amperes or even hundreds of thousands of amperes, making the local current density is very large, seriously affecting the surrounding biological safety. This paper analyzes that different fish fatalities in fish ponds after lightning strikes the transmission line towers, the typical accident towers were simulated and the correctness of the model was verified by CDEGS. Meanwhile the effects of lightning current on fish were simulated, according to the simulation results that the fish current density is related to body length and the current angle in the electric field. By comparing the simulated results with the fish tolerance limits, we can quantitatively evaluate the fish bioelectromagnetism of the relationship between soil resistivity and fishpond distance. The modification of the external grounding network based on the insulated lead wire can be used to guide the related grounding devices.

  5. Indirect Lightning Safety Assessment Methodology

    Energy Technology Data Exchange (ETDEWEB)

    Ong, M M; Perkins, M P; Brown, C G; Crull, E W; Streit, R D

    2009-04-24

    Lightning is a safety hazard for high-explosives (HE) and their detonators. In the However, the current flowing from the strike point through the rebar of the building The methodology for estimating the risk from indirect lighting effects will be presented. It has two parts: a method to determine the likelihood of a detonation given a lightning strike, and an approach for estimating the likelihood of a strike. The results of these two parts produce an overall probability of a detonation. The probability calculations are complex for five reasons: (1) lightning strikes are stochastic and relatively rare, (2) the quality of the Faraday cage varies from one facility to the next, (3) RF coupling is inherently a complex subject, (4) performance data for abnormally stressed detonators is scarce, and (5) the arc plasma physics is not well understood. Therefore, a rigorous mathematical analysis would be too complex. Instead, our methodology takes a more practical approach combining rigorous mathematical calculations where possible with empirical data when necessary. Where there is uncertainty, we compensate with conservative approximations. The goal is to determine a conservative estimate of the odds of a detonation. In Section 2, the methodology will be explained. This report will discuss topics at a high-level. The reasons for selecting an approach will be justified. For those interested in technical details, references will be provided. In Section 3, a simple hypothetical example will be given to reinforce the concepts. While the methodology will touch on all the items shown in Figure 1, the focus of this report is the indirect effect, i.e., determining the odds of a detonation from given EM fields. Professor Martin Uman from the University of Florida has been characterizing and defining extreme lightning strikes. Using Professor Uman's research, Dr. Kimball Merewether at Sandia National Laboratory in Albuquerque calculated the EM fields inside a Faraday-cage type

  6. Lightning Protection and Detection System

    Science.gov (United States)

    Dudley, Kenneth L. (Inventor); Szatkowski, George N. (Inventor); Woodard, Marie (Inventor); Nguyen, Truong X. (Inventor); Ely, Jay J. (Inventor); Wang, Chuantong (Inventor); Mielnik, John J. (Inventor); Koppen, Sandra V. (Inventor); Smith, Laura J. (Inventor)

    2017-01-01

    A lightning protection and detection system includes a non-conductive substrate material of an apparatus; a sensor formed of a conductive material and deposited on the non-conductive substrate material of the apparatus. The sensor includes a conductive trace formed in a continuous spiral winding starting at a first end at a center region of the sensor and ending at a second end at an outer corner region of the sensor, the first and second ends being open and unconnected. An electrical measurement system is in communication with the sensor and receives a resonant response from the sensor, to perform detection, in real-time, of lightning strike occurrences and damage therefrom to the sensor and the non-conductive substrate material.

  7. Overview of Saturn lightning observations

    CERN Document Server

    Fischer, G; Kurth, W S; Gurnett, D A; Zarka, P; Barry, T; Delcroix, M; Go, C; Peach, D; Vandebergh, R; Wesley, A

    2011-01-01

    The lightning activity in Saturn's atmosphere has been monitored by Cassini for more than six years. The continuous observations of the radio signatures called SEDs (Saturn Electrostatic Discharges) combine favorably with imaging observations of related cloud features as well as direct observations of flash-illuminated cloud tops. The Cassini RPWS (Radio and Plasma Wave Science) instrument and ISS (Imaging Science Subsystem) in orbit around Saturn also received ground-based support: The intense SED radio waves were also detected by the giant UTR-2 radio telescope, and committed amateurs observed SED-related white spots with their backyard optical telescopes. Furthermore, the Cassini VIMS (Visual and Infrared Mapping Spectrometer) and CIRS (Composite Infrared Spectrometer) instruments have provided some information on chemical constituents possibly created by the lightning discharges and transported upward to Saturn's upper atmosphere by vertical convection. In this paper we summarize the main results on Satur...

  8. A Case Study of Assimilating Lightning-Proxy Relative Humidity with WRF-3DVAR

    Directory of Open Access Journals (Sweden)

    Ying Wang

    2017-03-01

    Full Text Available Lightning network data, considered as a useful supplement to radar observations, are a good indicator of severe convection, and has high temporal and spatial resolution. In Numerical Weather Prediction (NWP models, lightning data are a new source of data to improve the forecasting of convective systems. In this case study, lightning data assimilation is conducted by converting lightning data to water vapor mixing ratio via a simple smooth continuous function, with input variables of total flash rate and simulated graupel mixing ratio at 9 km gridded resolution. Relative humidity converted from the retrieved water vapor mixing ratio is assimilated into the background field utilizing the three-dimensional variational (3DVAR method in WRFDA (the Weather Research and Forecasting model Data Assimilation system. The benefits of assimilating lightning data are demonstrated in a series of experiments using data from a strong convection event that affected Beijing, Tianjin, Hebei and Shandong Province, on 31 July 2007. A nested domain with resolutions of 9 km and 3 km is implemented. For this case, assimilating lightning data shows some improvements in predictions of both reflectivity and neighboring precipitation, and in the temperature, dew-point temperature and relative humidity profile after seven hours.

  9. Methodology for the assessment of possible damages in low voltage equipment due to lightning surges

    Energy Technology Data Exchange (ETDEWEB)

    Matsuo, Nelson M.; Kagan, Nelson [University of Sao Paulo (USP), SP (Brazil)], Emails: matsuonm@usp.br, nelsonk@pea.usp.br; Domingues, Ivo T. [AES Eletropaulo, SP (Brazil); Jesus, Nelson C. de [AES Sul, Porto Alegre, RS (Brazil); Silva, Marcelo H.I. da [Grupo Rede, Sao Paulo, SP (Brazil); Takauti, Edson H. [Bandeirante, Sao Paulo, SP (Brazil)

    2007-07-01

    This paper deals with the development of a methodology to assess the possibility of equipment damages in low voltage customers due to lightning surges. The main objective is to incorporate this methodology in a computation system that supports distribution companies to determine the possible causes of equipment damages claimed by customers and to decide whether the claims are to be reimbursed or not. The proposed methodology determines whether a specific customer could be affected by a lightning strike according to his/her location and to the lightning main parameters, by using data from a lightning detection system and from the specific equipment surge withstand capability. A specific study using ATP (Alternative Transients Program) was carried out to assess the propagation of lightning surges in electric power distribution systems and their impact over low voltage customers. On the other hand, the withstand capability of the main household appliances was determined by a series of tests carried out in the University's power quality laboratory. The paper details the modeling used for simulation, such as network configuration, grounding points, and modelling of insulator flashover, distribution transformer, low voltage loads. It also presents some results regarding the evaluation of over voltages in low voltage customers installations. A practical method is proposed for assessing the possibility of equipment damage and describes how the existing uncertainties were handled. Also, some issues regarding the withstand capability of electric household appliances to lightning surges are discussed and some results of the laboratory tests are presented. (author)

  10. An Intrinsic Fiber-Optic Sensor for Structure Lightning Current Measurement

    Science.gov (United States)

    Nguyen, Truong X.; Ely, Jay J.; Szatkowski, George N.; Mata, Carlos T.; Mata, Angel. G.; Snyder, Gary P.

    2014-01-01

    An intrinsic optical-fiber sensor based on Faraday Effect is developed that is highly suitable for measuring lightning current on aircraft, towers and complex structures. Originally developed specifically for aircraft installations, it is light-weight, non-conducting, structure conforming, and is immune to electromagnetic interference, hysteresis and saturation. It can measure total current down to DC. When used on lightning towers, the sensor can help validate other sensors and lightning detection network measurements. Faraday Effect causes light polarization to rotate when the fiber is exposed to a magnetic field in the direction of light propagation. Thus, the magnetic field strength can be determined from the light polarization change. By forming closed fiber loops and applying Ampere's law, measuring the total light rotation yields the total current enclosed. A broadband, dual-detector, reflective polarimetric scheme allows measurement of both DC component and AC waveforms with a 60 dB dynamic range. Two systems were built that are similar in design but with slightly different sensitivities. The 1310nm laser system can measure 300 A - 300 kA, and has a 15m long sensing fiber. It was used in laboratory testing, including measuring current on an aluminum structure simulating an aircraft fuselage or a lightning tower. High current capabilities were demonstrated up to 200 kA at a lightning test facility. The 1550nm laser system can measure 400 A - 400 kA and has a 25m fiber length. Used in field measurements, excellent results were achieved in the summer of 2012 measuring rocket-triggered lightning at the International Center for Lightning Research and Testing (ICLRT), Camp Blanding, Florida. In both systems increased sensitivity can be achieved with multiple fiber loops. The fiber optic sensor provides many unique capabilities not currently possible with traditional sensors. It represents an important new tool for lightning current measurement where low weight

  11. Ice multiplication by mechanical breakup and lightning

    Science.gov (United States)

    Phillips, Vaughan; Yano, Jun-Ichi

    2016-04-01

    Laboratory studies have proven the existence of several pathways for fragmentation of ice. One of these is the rime-splintering of graupel or hail in the -3 to -8 degC region (the Hallett-Mossop process). In some clouds, however, the cloud-base is too cold for this process to be active. Instead, breakup can occur by fragmentation of ice mechanically in re-bounding collisions between crystals, snow, graupel or hail. A new theoretical formulation of this mechanical breakup process of multiplication is presented for these types of ice. A numerical scheme is derived by simulation of published laboratory experiments. The role of such breakup in clouds is quantified by 3D simulations with a cloud-resolving aerosol-cloud model with emulated bin microphysics, detailed treatment of ice morphology and 7 chemical species of aerosol. Graupel-graupel collisions are predicted to produce copious numbers of ice crystals in the cold-base convective cloud simulated over Kansas. Implications for lightning from such multiplication, also simulated numerically, are discussed.

  12. An Evaluation of Lightning Flash Rate Parameterizations Based on Observations of Colorado Storms during DC3

    Science.gov (United States)

    Basarab, B.; Fuchs, B.; Rutledge, S. A.

    2013-12-01

    Predicting lightning activity in thunderstorms is important in order to accurately quantify the production of nitrogen oxides (NOx = NO + NO2) by lightning (LNOx). Lightning is an important global source of NOx, and since NOx is a chemical precursor to ozone, the climatological impacts of LNOx could be significant. Many cloud-resolving models rely on parameterizations to predict lightning and LNOx since the processes leading to charge separation and lightning discharge are not yet fully understood. This study evaluates predicted flash rates based on existing lightning parameterizations against flash rates observed for Colorado storms during the Deep Convective Clouds and Chemistry Experiment (DC3). Evaluating lightning parameterizations against storm observations is a useful way to possibly improve the prediction of flash rates and LNOx in models. Additionally, since convective storms that form in the eastern plains of Colorado can be different thermodynamically and electrically from storms in other regions, it is useful to test existing parameterizations against observations from these storms. We present an analysis of the dynamics, microphysics, and lightning characteristics of two case studies, severe storms that developed on 6 and 7 June 2012. This analysis includes dual-Doppler derived horizontal and vertical velocities, a hydrometeor identification based on polarimetric radar variables using the CSU-CHILL radar, and insight into the charge structure using observations from the northern Colorado Lightning Mapping Array (LMA). Flash rates were inferred from the LMA data using a flash counting algorithm. We have calculated various microphysical and dynamical parameters for these storms that have been used in empirical flash rate parameterizations. In particular, maximum vertical velocity has been used to predict flash rates in some cloud-resolving chemistry simulations. We diagnose flash rates for the 6 and 7 June storms using this parameterization and compare

  13. [Lightning strikes and lightning injuries in prehospital emergency medicine. Relevance, results, and practical implications].

    Science.gov (United States)

    Hinkelbein, J; Spelten, O; Wetsch, W A

    2013-01-01

    Up to 32.2% of patients in a burn center suffer from electrical injuries. Of these patients, 2-4% present with lightning injuries. In Germany, approximately 50 people per year are injured by a lightning strike and 3-7 fatally. Typically, people involved in outdoor activities are endangered and affected. A lightning strike usually produces significantly higher energy doses as compared to those in common electrical injuries. Therefore, injury patterns vary significantly. Especially in high voltage injuries and lightning injuries, internal injuries are of special importance. Mortality ranges between 10 and 30% after a lightning strike. Emergency medical treatment is similar to common electrical injuries. Patients with lightning injuries should be transported to a regional or supraregional trauma center. In 15% of all cases multiple people may be injured. Therefore, it is of outstanding importance to create emergency plans and evacuation plans in good time for mass gatherings endangered by possible lightning.

  14. Change of the Microstructure of ZnO Arrester Block by Lightning Surge Current and Ageing Test

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Bok Hee; Kang, Sung Man [Inha University (Korea)

    2000-07-01

    This paper deals with the change of the micro-structure of ZnO associated with lightning surge current and ageing test. In this work, a surge current generator which can produce 8/20 [{mu}s],6 [kA] impulse current is designed and fabricated to simulate the lightning impulse current. The residual voltage and leakage current flowing to ZnO blocks are observed. Also a compensation circuit was used in resistive current measurement. The micro-structures of ZnO arrester block were significantly changed by lightning surge current and accelerated temperature ageing test. (author). 6 refs., 7 figs., 1 tab.

  15. Analytic Perturbation Method for Estimating Ground Flash Fraction from Satellite Lightning Observations

    Science.gov (United States)

    Koshak, William; Solakiewicz, Richard

    2013-01-01

    An analytic perturbation method is introduced for estimating the lightning ground flash fraction in a set of N lightning flashes observed by a satellite lightning mapper. The value of N is large, typically in the thousands, and the observations consist of the maximum optical group area produced by each flash. The method is tested using simulated observations that are based on Optical Transient Detector (OTD) and Lightning Imaging Sensor (LIS) data. National Lightning Detection NetworkTM (NLDN) data is used to determine the flash-type (ground or cloud) of the satellite-observed flashes, and provides the ground flash fraction truth for the simulation runs. It is found that the mean ground flash fraction retrieval errors are below 0.04 across the full range 0-1 under certain simulation conditions. In general, it is demonstrated that the retrieval errors depend on many factors (i.e., the number, N, of satellite observations, the magnitude of random and systematic measurement errors, and the number of samples used to form certain climate distributions employed in the model).

  16. Integral lightning protection system in petroleum facilities

    Energy Technology Data Exchange (ETDEWEB)

    Torres, Horacio; Gallego, Luis; Montana, Johny; Younes, Camilo; Rondon, Daniel; Gonzalez, Diego; Herrera, Javier; Perez, Ernesto; Vargas, Mauricio; Quintana, Carlos; Salgado, Milton [Universidad Nacional de Colombia, Bogota (Colombia)]. E-mail: paas@paas.unal.edu.co

    2001-07-01

    This paper presents an Integral Lightning Protection System, focused mainly in petroleum facilities and applied to a real case in Colombia, South America. As introduction it is presented a summary of the incidents happened in last years, a diagnosis and the proposal of solution. Finally, as part of the analysis, a lightning risk assessment for the Central Process Facility is showed. (author)

  17. Lightning-caused fires in Central Spain

    DEFF Research Database (Denmark)

    Nieto Solana, Hector; Aguado, Inmaculada; García, Mariano;

    2012-01-01

    a high occurrence. The research was conducted between May and September, which happens to be the most lightning-fire prone period in Spain, for a three year interval starting in 2002 up to 2004. A time-invariant model for lightning-caused fire occurrence was developed for each region at a spatial...

  18. A model for lightning in littoral areas

    NARCIS (Netherlands)

    Blaj, M.A.; Leferink, Frank Bernardus Johannes

    2009-01-01

    The littoral or coastal areas are different compared to the maritime or continental areas considering lightning. Only the last years some research about these areas has been carried out. The need for a model, regarding the lightning activity in these areas is much needed. And now, with the changes i

  19. Lightning protecting materials used on radar system

    NARCIS (Netherlands)

    Blaj, M.A.; Damstra, Geert C.; Buesink, Frederik Johannes Karel; Leferink, Frank Bernardus Johannes

    2009-01-01

    Because of the extensive use in modern systems of very sensitive electronic components, lightning strikes does not represent only a threat, but something that cannot be neglected anymore and safety hazards caused by direct and indirect lightning to the aircraft or naval industry. Everyday new materi

  20. When Lightning Strikes a Second Time

    Science.gov (United States)

    Allen, Kent

    2017-01-01

    The chances of lightning striking twice are infinitesimal, at best. What are the odds, in middle age, of being struck with a jarring bolt of figurative lightning, then a few months later being an eyewitness as the same sizzle in the sky jolts a group of students--those decision-makers of tomorrow? The author describes two experiences that proved…

  1. Magnetic exchange interactions and critical temperature of the nanolaminate M n2GaC from first-principles supercell methods

    Science.gov (United States)

    Thore, A.; Dahlqvist, M.; Alling, B.; Rosen, J.

    2016-02-01

    In this work, we employ and critically evaluate a first-principles approach based on supercell calculations for predicting the magnetic critical order-disorder temperature Tc. As a model material we use the recently discovered nanolaminate M n2GaC . First, we derive the exchange interaction parameters Ji j between pairs of Mn atoms on sites i and j of the bilinear Heisenberg Hamiltonian using the novel magnetic direct cluster averaging method (MDCA), and then compare the J's from the MDCA calculations to the same parameters calculated using the Connolly-Williams method. We show that the two methods yield closely matching results, but observe that the MDCA method is computationally less effective when applied to highly ordered phases such as M n2GaC . Secondly, Monte Carlo simulations are used to derive the magnetic energy, specific heat, and Tc. For M n2GaC , we find Tc=660 K . The uncertainty in the calculated Tc caused by possible uncertainties in the J's is discussed and exemplified in our case by an analysis of the impact of the statistical uncertainties of the MDCA-derived J's , resulting in a Tc distribution with a standard deviation of 133 K.

  2. The GOES-R Lightning Mapper Sensor

    Science.gov (United States)

    Buechler, Dennis; Christian, Hugh; Goodman, Steve

    2004-01-01

    The Lightning Mapper Sensor on GOES-R builds on previous measurements of lightning from low earth orbit by the OTD (Optical Transient Detector) and LIS (Lightning Imaging Sensor) sensors. Unlike observations from low earth orbit, the GOES-R platform will allow continuous monitoring of lightning activity over the Continental United States and southern Canada, Central and South America, and portions of the Atlantic and Pacific Oceans. The LMS will detect total (cloud-to-ground and intracloud) lightning at storm scale resolution (approx. 8 km) using a highly sensitive Charge Coupled Device (CCD) detector array. Discrimination between lightning optical transients and a bright sunlit background scene is accomplished by employing spectral, spatial, and temporal filtering along with a background subtraction technique. The result is 24 hour detection capability of total lightning. These total lightning observations can be made available to users within about 20 seconds. Research indicates a number of ways that total lightning observations from LMS could benefit operational activities, including 1) potential increases in lead times and reduced false alarms for severe thunderstorm and tornado Warnings, 2) improved routing of &rail around thunderstorms, 3) support for spacecraft launches and landings, 4) improved ability to monitor tropical cyclone intensity, 5) ability to monitor thunderstorm intensification/weakening during radar outages or where radar coverage is poor, 6) better identification of deep convection for the initialization of numerical prediction models, 7) improved forest fire forecasts, 8) identification of convective initiation, 9) identification of heavy convective snowfall, and 10) enhanced temporal resolution of storm evolution (1 minute) than is available from radar observations. Total lightning data has been used in an operational environment since July 2003 at the Huntsville, Alabama National Weather Service office. Total lightning measurements are

  3. Lightning Protection of Floating Roof Tanks

    Directory of Open Access Journals (Sweden)

    Adekitan,

    2013-10-01

    Full Text Available Prior to export, processed crude oil is stored in Floating Roof Tanks (FRT to further allow any trapped gas within the crude oil to escape, as this stabilises the crude oil. In the oil and gas industry, FRT’s are vital in the processing of crude oil to the acceptable export specification.In the tropics and other lightning prone regions, lightning induced floating roof tank fire constitutes a major threat to crude oil production. Among others, a single lightning incident could result in the loss of life, product and production time, avoidable incident review time, damaged equipment, wasted repair cost, bad publicity and loss of income.This paper therefore, is aimed at providing an effective solution to the menace of lightning induced tank fire by focussing on the starting process of the lightning induced fire and proposing alternative concepts for breaking the fire triangle before fire ensues

  4. Lightning-caused fires in Central Spain

    DEFF Research Database (Denmark)

    Nieto Solana, Hector; Aguado, Inmaculada; García, Mariano;

    2012-01-01

    Lightning-caused fire occurrence has been modelled for two different Spanish regions, Madrid andAragon, based on meteorological, terrain, and vegetation variables. The model was built on two very contrasting regions, one presenting low number of lightning-caused fires whereas the other presented...... a high occurrence. The research was conducted between May and September, which happens to be the most lightning-fire prone period in Spain, for a three year interval starting in 2002 up to 2004. A time-invariant model for lightning-caused fire occurrence was developed for each region at a spatial...... resolution of 3 km ×3 km. The probabilistic models were based on the logistic regression, aiming to explain the probability of having at least a lightning-fire during the three year period. Results showed that the number of thunderstorms during the three-year period was the most significantvariable...

  5. Lightning injuries in sports and recreation.

    Science.gov (United States)

    Thomson, Eric M; Howard, Thomas M

    2013-01-01

    The powers of lightning have been worshiped and feared by all known human cultures. While the chance of being struck by lightning is statistically very low, that risk becomes much greater in those who frequently work or play outdoors. Over the past 2 yr, there have been nearly 50 lightning-related deaths reported within the United States, with a majority of them associated with outdoor recreational activities. Recent publications primarily have been case studies, review articles, and a discussion of a sixth method of injury. The challenge in reducing lightning-related injuries in organized sports has been addressed well by both the National Athletic Trainers' Association and the National Collegiate Athletic Association in their guidelines on lightning safety. Challenges remain in educating the general population involved in recreational outdoor activities that do not fall under the guidelines of organized sports.

  6. Draft IEC 61400-24 wind turbines: lightning protection blades

    OpenAIRE

    Hermoso Alameda, Blas; Montañá Puig, Juan

    2009-01-01

    Wind turbine blades are the most exposed parts of the turbine, and would experience the full impact from the electric fields as associated with the lightning attachment process, the lightning currents, and the magnetic field associated with lightning currents.At some point in time hopes were high that lightning would not strike blades made of non-conducting material only, but practical experiences have clearly demonstrated that this is not the case. Lightning does in fact st...

  7. Spatial Variation of the Correlated Color Temperature of Lightning Channel

    OpenAIRE

    Shimoji, Nobuaki; Aoyama, Ryoma

    2014-01-01

    In present work, we propose the analysis method of lightning based on the color analysis. We analyzed the digital still images in which the cloud-to-ground (CG) and intracloud (IC) lightning flashes are shown. Applying some digital image processing techniques, we extracted lightning channels. Then, the correlated color temperature (CCT) of the extracted lightning channels was obtained by mapping digital pixels of the extracted lightning channels to CIE 1931 xy-chromaticity diagram. Our result...

  8. Image navigation and registration for the geostationary lightning mapper (GLM)

    Science.gov (United States)

    van Bezooijen, Roel W. H.; Demroff, Howard; Burton, Gregory; Chu, Donald; Yang, Shu S.

    2016-10-01

    The Geostationary Lightning Mappers (GLM) for the Geostationary Operational Environmental Satellite (GOES) GOES-R series will, for the first time, provide hemispherical lightning information 24 hours a day from longitudes of 75 and 137 degrees west. The first GLM of a series of four is planned for launch in November, 2016. Observation of lightning patterns by GLM holds promise to improve tornado warning lead times to greater than 20 minutes while halving the present false alarm rates. In addition, GLM will improve airline traffic flow management, and provide climatology data allowing us to understand the Earth's evolving climate. The paper describes the method used for translating the pixel position of a lightning event to its corresponding geodetic longitude and latitude, using the J2000 attitude of the GLM mount frame reported by the spacecraft, the position of the spacecraft, and the alignment of the GLM coordinate frame relative to its mount frame. Because the latter alignment will experience seasonal variation, this alignment is determined daily using GLM background images collected over the previous 7 days. The process involves identification of coastlines in the background images and determination of the alignment change necessary to match the detected coastline with the coastline predicted using the GSHHS database. Registration is achieved using a variation of the Lucas-Kanade algorithm where we added a dither and average technique to improve performance significantly. An innovative water mask technique was conceived to enable self-contained detection of clear coastline sections usable for registration. Extensive simulations using accurate visible images from GOES13 and GOES15 have been used to demonstrate the performance of the coastline registration method, the results of which are presented in the paper.

  9. An Integrated 0-1 Hour First-Flash Lightning Nowcasting, Lightning Amount and Lightning Jump Warning Capability

    Science.gov (United States)

    Mecikalski, John; Jewett, Chris; Carey, Larry; Zavodsky, Brad; Stano, Geoffrey

    2015-01-01

    Lightning one of the most dangerous weather-related phenomena, especially as many jobs and activities occur outdoors, presenting risk from a lightning strike. Cloud-to-ground (CG) lightning represents a considerable safety threat to people at airfields, marinas, and outdoor facilities-from airfield personnel, to people attending outdoor stadium events, on beaches and golf courses, to mariners, as well as emergency personnel. Holle et al. (2005) show that 90% of lightning deaths occurred outdoors, while 10% occurred indoors despite the perception of safety when inside buildings. Curran et al. (2000) found that nearly half of fatalities due to weather were related to convective weather in the 1992-1994 timeframe, with lightning causing a large component of the fatalities, in addition to tornadoes and flash flooding. Related to the aviation industry, CG lightning represents a considerable hazard to baggage-handlers, aircraft refuelers, food caterers, and emergency personnel, who all become exposed to the risk of being struck within short time periods while convective storm clouds develop. Airport safety protocols require that ramp operations be modified or discontinued when lightning is in the vicinity (typically 16 km), which becomes very costly and disruptive to flight operations. Therefore, much focus has been paid to nowcasting the first-time initiation and extent of lightning, both of CG and of any lightning (e.g, in-cloud, cloud-to-cloud). For this project three lightning nowcasting methodologies will be combined: (1) a GOESbased 0-1 hour lightning initiation (LI) product (Harris et al. 2010; Iskenderian et al. 2012), (2) a High Resolution Rapid Refresh (HRRR) lightning probability and forecasted lightning flash density product, such that a quantitative amount of lightning (QL) can be assigned to a location of expected LI, and (3) an algorithm that relates Pseudo-GLM data (Stano et al. 2012, 2014) to the so-called "lightning jump" (LJ) methodology (Shultz et al

  10. Apparent Negative Reflection with the Gradient Acoustic Metasurface by Integrating Supercell Periodicity into the Generalized Law of Reflection

    Science.gov (United States)

    Liu, Bingyi; Zhao, Wenyu; Jiang, Yongyuan

    2016-12-01

    As the two dimensional version of the functional wavefront manipulation metamaterial, metasurface has become a research hot spot for engineering the wavefront at will with a subwavelength thickness. The wave scattered by the gradient metasurface, which is composed by the periodic supercells, is governed by the generalized Snell’s law. However, the critical angle that derived from the generalized Snell’s law circles the domain of the incident angles that allow the occurrence of the anomalous reflection and refraction, and no free space scattering waves could exist when the incident angle is beyond the critical angle. Here we theoretically demonstrate that apparent negative reflection can be realized by a gradient acoustic metasurface when the incident angle is beyond the critical angle. The underlying mechanism of the apparent negative reflection is understood as the higher order diffraction arising from the interaction between the local phase modulation and the non-local effects introduced by the supercell periodicity. The apparent negative reflection phenomena has been perfectly verified by the calculated scattered acoustic waves of the reflected gradient acoustic metasurface. This work may provide new freedom in designing functional acoustic signal modulation devices, such as acoustic isolator and acoustic illusion device.

  11. Apparent Negative Reflection with the Gradient Acoustic Metasurface by Integrating Supercell Periodicity into the Generalized Law of Reflection.

    Science.gov (United States)

    Liu, Bingyi; Zhao, Wenyu; Jiang, Yongyuan

    2016-12-05

    As the two dimensional version of the functional wavefront manipulation metamaterial, metasurface has become a research hot spot for engineering the wavefront at will with a subwavelength thickness. The wave scattered by the gradient metasurface, which is composed by the periodic supercells, is governed by the generalized Snell's law. However, the critical angle that derived from the generalized Snell's law circles the domain of the incident angles that allow the occurrence of the anomalous reflection and refraction, and no free space scattering waves could exist when the incident angle is beyond the critical angle. Here we theoretically demonstrate that apparent negative reflection can be realized by a gradient acoustic metasurface when the incident angle is beyond the critical angle. The underlying mechanism of the apparent negative reflection is understood as the higher order diffraction arising from the interaction between the local phase modulation and the non-local effects introduced by the supercell periodicity. The apparent negative reflection phenomena has been perfectly verified by the calculated scattered acoustic waves of the reflected gradient acoustic metasurface. This work may provide new freedom in designing functional acoustic signal modulation devices, such as acoustic isolator and acoustic illusion device.

  12. The Impact of Mesoscale Environmental Uncertainty on the Prediction of a Tornadic Supercell Storm Using Ensemble Data Assimilation Approach

    Directory of Open Access Journals (Sweden)

    Nusrat Yussouf

    2013-01-01

    Full Text Available Numerical experiments over the past years indicate that incorporating environmental variability is crucial for successful very short-range convective-scale forecasts. To explore the impact of model physics on the creation of environmental variability and its uncertainty, combined mesoscale-convective scale data assimilation experiments are conducted for a tornadic supercell storm. Two 36-member WRF-ARW model-based mesoscale EAKF experiments are conducted to provide background environments using either fixed or multiple physics schemes across the ensemble members. Two 36-member convective-scale ensembles are initialized using background fields from either fixed physics or multiple physics mesoscale ensemble analyses. Radar observations from four operational WSR-88Ds are assimilated into convective-scale ensembles using ARPS model-based 3DVAR system and ensemble forecasts are launched. Results show that the ensemble with background fields from multiple physics ensemble provides more realistic forecasts of significant tornado parameter, dryline structure, and near surface variables than ensemble from fixed physics background fields. The probabilities of strong low-level updraft helicity from multiple physics ensemble correlate better with observed tornado and rotation tracks than probabilities from fixed physics ensemble. This suggests that incorporating physics diversity across the ensemble can be important to successful probabilistic convective-scale forecast of supercell thunderstorms, which is the main goal of NOAA’s Warn-on-Forecast initiative.

  13. Lightning activity and precipitation structure of hailstorms

    Institute of Scientific and Technical Information of China (English)

    FENG GuiLi; QIE XiuShu; YUAN Tie; NIU ShuZhen

    2007-01-01

    By using the cloud-to-ground (CG) lightning location data from the lightning detection network of Henan Province, surface Doppler radar data and standard orbit data of PR, TMI and LIS on TRMM satellite, the apatjal and temporal characteristice of CG lightning flashes in 10 severe hailstorms are analyzed. The results show that the percentage of+CG lightning in these hailstorms is high with an average value of 45.5%.There is a distinct increase in CG flash rate during the rapid development stage of hailstorms. The hailstone falling corresponds to an active positive flash period, and the increase of+CG flash rate is generally accompanied with a decrease of-CG flash rate. The flash rate declines rapidly during the dissipating stage of hailstorms. The precipitation structure and lightning activity in two typical hailstorms are studied in detail. It is found that strong convective cells with reflectivity greater than 30dBZ mainly are situated in the front region of hailstorms, whereas the trailing stratiform region is in the rear part of the hailstorme. The maximum heights of echo top are higher than 14km.Convective rain contributes much more rainfall to the total than stratiform rain, and the convective rain takes about 85% and 97% of the total in the two cases, respectively. Total lightning in the hailstorms is very active with the flash rate up to 183 fl/min and 55 fl/min, respectively. The results also indicate that most lightning flashes occurred in the echo region greater than 30dBZ and its immediate periphery. The probability of lightning occurrence is 20 times higher in the convective region than in the stratiform region. The result suggests that the lightning information is helpful to the identification of convective rain region. The linear relationship between flash rate and ice water content is disclosed primarily.

  14. Lightning activity and precipitation structure of hailstorms

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    By using the cloud-to-ground (CG) lightning location data from the lightning detection network of He- nan Province, surface Doppler radar data and standard orbit data of PR, TMI and LIS on TRMM satellite, the spatial and temporal characteristics of CG lightning flashes in 10 severe hailstorms are analyzed. The results show that the percentage of +CG lightning in these hailstorms is high with an average value of 45.5%. There is a distinct increase in CG flash rate during the rapid development stage of hailstorms. The hailstone falling corresponds to an active positive flash period, and the increase of +CG flash rate is generally accompanied with a decrease of –CG flash rate. The flash rate declines rapidly during the dissipating stage of hailstorms. The precipitation structure and lightning activity in two typical hail- storms are studied in detail. It is found that strong convective cells with reflectivity greater than 30dBZ mainly are situated in the front region of hailstorms, whereas the trailing stratiform region is in the rear part of the hailstorms. The maximum heights of echo top are higher than 14 km. Convective rain con- tributes much more rainfall to the total than stratiform rain, and the convective rain takes about 85% and 97% of the total in the two cases, respectively. Total lightning in the hailstorms is very active with the flash rate up to 183 fl/min and 55 fl/min, respectively. The results also indicate that most lightning flashes occurred in the echo region greater than 30 dBZ and its immediate periphery. The probability of lightning occurrence is 20 times higher in the convective region than in the stratiform region. The result suggests that the lightning information is helpful to the identification of convective rain region. The linear relationship between flash rate and ice water content is disclosed primarily.

  15. Impact of the assimilation of lightning data on the precipitation forecast at different forecast ranges

    Science.gov (United States)

    Federico, Stefano; Petracca, Marco; Panegrossi, Giulia; Transerici, Claudio; Dietrich, Stefano

    2017-06-01

    This study investigates the impact of the assimilation of total lightning data on the precipitation forecast of a numerical weather prediction (NWP) model. The impact of the lightning data assimilation, which uses water vapour substitution, is investigated at different forecast time ranges, namely 3, 6, 12, and 24 h, to determine how long and to what extent the assimilation affects the precipitation forecast of long lasting rainfall events (> 24 h). The methodology developed in a previous study is slightly modified here, and is applied to twenty case studies occurred over Italy by a mesoscale model run at convection-permitting horizontal resolution (4 km). The performance is quantified by dichotomous statistical scores computed using a dense raingauge network over Italy. Results show the important impact of the lightning assimilation on the precipitation forecast, especially for the 3 and 6 h forecast. The probability of detection (POD), for example, increases by 10 % for the 3 h forecast using the assimilation of lightning data compared to the simulation without lightning assimilation for all precipitation thresholds considered. The Equitable Threat Score (ETS) is also improved by the lightning assimilation, especially for thresholds below 40 mm day-1. Results show that the forecast time range is very important because the performance decreases steadily and substantially with the forecast time. The POD, for example, is improved by 1-2 % for the 24 h forecast using lightning data assimilation compared to 10 % of the 3 h forecast. The impact of the false alarms on the model performance is also evidenced by this study.

  16. ROMANIAN TERMINOLOGY IN THE METEOROLOGY OF SEVERE WEATHER – CASE STUDY OF THE SUPERCELL FROM ARAD COUNTRY ON THE 14TH OF JUNE 2010

    Directory of Open Access Journals (Sweden)

    O. SCRIDONESI

    2011-03-01

    Full Text Available Romanian terminology in the meteorology of severe weather – Case study of the supercell from the 14th of June 2010. Using the ingredients-based methodology, the low precipitation supercell storm from the 14th of June 2010 in the Arad county is analyzed in terms of conditions of development, evolution and structure. To address such a topic an important issue is the lack of meteorological terms in the Romanian language to enable the completion of such analysis of supercell storms or other severe weather phenomena. Finding terms that correspond to the best of the English language during the analysis is performed either by direct translation into romanian, either by replacing the terms that best fit the context and the use of each term is motivated.

  17. Lightning strike-induced brachial plexopathy.

    Science.gov (United States)

    Bhargava, Amita N; Kasundra, Gaurav M; Khichar, Subhakaran; Bhushan, Bharat S K

    2014-10-01

    We describe a patient who presented with a history of lightning strike injury. Following the injury, he sustained acute right upper limb weakness with pain. Clinically, the lesion was located to the upper and middle trunk of the right brachial plexus, and the same confirmed with electrophysiological studies. Nerve damage due to lightning injuries is considered very rare, and a plexus damage has been described infrequently, if ever. Thus, the proposed hypothesis that lightning rarely causes neuropathy, as against high-voltage electric current, due to its shorter duration of exposure not causing severe burns which lead to nerve damage, needs to be reconsidered.

  18. Lightning Attachment Estimation to Wind Turbines by Utilizing Lightning Location Systems

    DEFF Research Database (Denmark)

    Vogel, Stephan; Holbøll, Joachim; Lopez, Javier

    2016-01-01

    The goal of a lightning exposure assessment is to identify the number, type and characteristics of lightning discharges to a certain structure. There are various Lightning Location System (LLS) technologies available, each of them are characterized by individual performance characteristics...... three different wind power plant locations are analyzed and the impact of varying data qualities is evaluated regarding the ability to detect upward lightning. This work provides a variety of background information which is relevant to the exposure assessment of wind turbine and includes practical...

  19. Combining Analysis of Coupled Electrical-Thermal and BLOW-OFF Impulse Effects on Composite laminate Induced by Lightning Strike

    Science.gov (United States)

    Liu, Z. Q.; Yue, Z. F.; Wang, F. S.; Ji, Y. Y.

    2015-04-01

    A comprehensive simulation procedure combining electrical-thermal analysis and BLOW-OFF impulse (BOI) analysis was conducted to investigate lightning direct effects on damage behavior of composite. The nonlinear material model was elaborated combining the damage mechanism of composite laminate subjected to lightning strike. Results of electrical-thermal analysis indicated that temperature distribution of composite laminate is mainly affected by the electrical anisotropy because of Joule heating. By comparing results of BOI analysis with lightning test, it can be found that strain fields of analysis meet well with the damage pattern of lightning specimen. It could be concluded that the analysis procedure is suitable for modeling damage of composite due to lighting strike, and results of logarithmic strain field can be used to help estimate the zone which need to be repaired for composite.

  20. 3D modeling of lightning-induced electromagnetic pulses on Venus, Jupiter and Saturn

    Science.gov (United States)

    Pérez-Invernón, Francisco J.; Luque, Alejandro; Gordillo-Vázquez, Francisco J.

    2017-04-01

    powerful tool to obtain information about planetary atmospheres, such as density profiles of electrons or other components. Our model may also be useful to extend some studies about the chemical impact of EMP pulses in the terrestrial atmosphere [4]. References [1] Luque, A., D. Dubrovin, F. J. Gordillo-Vázquez, U. Ebert, F. C. Parra-Rojas, Y. Yair, and C. Price (2014), Coupling between atmospheric layers in gaseous giant planets due to lightning-generated electromagnetic pulses, J. Geophys. Res. (Space Phys), 119, 8705, doi: 10.1002/2014JA020457. [2] Pérez-Invernón, F. J., A. Luque, and F. J. Gordillo-Vázquez (2016), Mesospheric optical signatures of possible lightning on Venus, J. Geophys. Res. (Space Phys), 121, 7026, doi: 10.1029/2016JA022886. [3] Lee, J. H., and D. K. Kalluri (1999), Three-dimensional FDTD simulation of electromagnetic wave transformation in a dynamic inhomogeneous magnetized plasma, IEEE Transactions on Antennas and Propagation, 47, 1146, doi:10.1109/8.785745. [4] Marshall, R. A., U. S. Inan, and V. S. Glukhov (2010), Elves and associated electron density changes due to cloud-to-ground and in-cloud lightning discharges, J. Geophys. Res. (Space Phys), 115, A00E17, doi:10.1029/2009JA014469.

  1. Structural and erosive Effects of Lightning on Sandstone: An Experimental Investigation

    Science.gov (United States)

    Haddad, Houssam; Ebert, Matthias; Kenkmann, Thomas; Thoma, Klaus; Nau, Siegfried; Schäfer, Frank

    2016-04-01

    Recent prognoses predict an average temperature increase of the world's climate of about 1.5 to 2 °C until the end of 21st century. This change leads not only to a rise of the sea level but also to an increase of thunderstorms and therefore to a ~25 percent increase of cloud-to-ground lightning events (Romps et al., 2014). It is known that (i) lightning strikes are able to fragment surface rocks, which probably influences the erosion rates at exposed mountain areas (Knight and Grab, 2014), and (ii) the efficiency of the process increases due to the predicted climate change. However, our knowledge about the electro-mechanical destruction of rocks caused by high energetic lightning is incomplete. In this study, laboratory experiments of lightning strikes were performed in order to understand the fragmentation of rocks and changes to landforms by lightning. The artificial lightning with known electric current was simulated by a high-current generator in the laboratories of the Fraunhofer Ernst-Mach Institute for High-Speed Dynamics (Freiburg, Germany). Different currents were transferred over a distance of ~2mm onto water-saturated sandstones by using a copper cathode (3 experiments; U, I, E, Δt: 6 kV, 200 kA, 0.1 MJ, 0.7 ms; 9 kV, 300 kA, 0.19 MJ, 0.9 ms; 12 kV, 400 kA, 0.35 MJ, 0.5 ms). The damaged sandstones were investigated by means of optical and electron-optical methods as well as by X-ray computed tomography to determine the modes and dimensions of melting and fragmentation. Digital elevation models of craters formed by ejection were obtained by white-light interferometry. The lightning experiments produced small craters (~1 cm in diameter, ~0.5 cm depth) which surfaces and sub-surfaces consist of silicate melts (molten quartz and phyllosilicates). The silicate melts reach several hundred micrometers into the sub-surface and resemble the appearance of natural fulgurites. Melting of quartz indicate temperatures of at least 1650 °C. In addition, the

  2. Data Retrieval Algorithms for Validating the Optical Transient Detector and the Lightning Imaging Sensor

    Science.gov (United States)

    Koshak, W. J.; Blakeslee, R. J.; Bailey, J. C.

    2000-01-01

    A linear algebraic solution is provided for the problem of retrieving the location and time of occurrence of lightning ground strikes from an Advanced Lightning Direction Finder (ALDF) network. The ALDF network measures field strength, magnetic bearing, and arrival time of lightning radio emissions. Solutions for the plane (i.e., no earth curvature) are provided that implement all of these measurements. The accuracy of the retrieval method is tested using computer-simulated datasets, and the relative influence of bearing and arrival time data an the outcome of the final solution is formally demonstrated. The algorithm is sufficiently accurate to validate NASA:s Optical Transient Detector and Lightning Imaging Sensor. A quadratic planar solution that is useful when only three arrival time measurements are available is also introduced. The algebra of the quadratic root results are examined in detail to clarify what portions of the analysis region lead to fundamental ambiguities in sc)iirce location, Complex root results are shown to be associated with the presence of measurement errors when the lightning source lies near an outer sensor baseline of the ALDF network. For arbitrary noncollinear network geometries and in the absence of measurement errors, it is shown that the two quadratic roots are equivalent (no source location ambiguity) on the outer sensor baselines. The accuracy of the quadratic planar method is tested with computer-generated datasets, and the results are generally better than those obtained from the three-station linear planar method when bearing errors are about 2 deg.

  3. Modelling of lightning streamer formation and propagation in wind turbine blades

    DEFF Research Database (Denmark)

    Candela Garolera, Anna; Holbøll, Joachim; Madsen, Søren Find

    2013-01-01

    The positioning of lightning air terminations along a wind turbine blade is a complex issue to consider when designing the lightning protection of wind turbine blades. According to the IEC 61400-24 on lightning protection of wind turbines, the interception efficiency depends on the effectiveness ...... models can involve a high level of detail and therefore be used in the detailed positioning of air terminations in blades equipped with conductive elements such as carbon fiber or electrical monitoring systems (load, temperature, etc.)....... setups. Furthermore, the tests may need to be repeated when a new conducting element is included in the blade with unpredictable effects for the lightning protection system. Numerical methods to determine the areas of a structure more likely to be struck by lightning have proved to be a useful tool....... The present paper presents a method to investigate the origin and propagation of streamers from different conductive elements of the blade when exposed to a high electric field. The calculations are performed using dynamic simulations with the finite element method, and the results have been correlated...

  4. Variation of Tower Footing Resistance on the Lightning Surge Propagation through Overhead Power Distribution Lines

    Directory of Open Access Journals (Sweden)

    MARIUT, E. L.

    2016-02-01

    Full Text Available This paper deals with the analysis of the effects of electromagnetic transients generated by lightning on power distribution lines, considering the influence of tower footing resistance variation. Both types of lightning stroke, direct and induced, are considered. The model of a 20 kV three-phase overhead power distribution line is performed considering a simple line circuit with triangle canopy and 50/8 mm2 Ol-Al conductors. The model of the power distribution line is done considering a Multistory tower model. New concepts regarding lightning assessment through Electromagnetic Transients program and Finite Element Method are implemented. The simulations are performed based on a time domain analysis, considering the lightning stroke as an electromagnetic perturbation within frequency range of 10-100 kHz. A contribution to value creation is the design of the Multistory tower model, used for electromagnetic transients analysis for medium voltage power distribution lines. Excepting previous research, current study was done by considering the variation of tower footing resistance of the tower, between 4-35 ohms. The novelty of the study is the analysis of the dependency determined by the variation of tower footing resistance on the lightning surge propagation through power distribution networks and subsequent consumers.

  5. Lightning activity during the 1999 Superior derecho

    Science.gov (United States)

    Price, Colin G.; Murphy, Brian P.

    2002-12-01

    On 4 July 1999, a severe convective windstorm, known as a derecho, caused extensive damage to forested regions along the United States/Canada border, west of Lake Superior. There were 665,000 acres of forest destroyed in the Boundary Waters Canoe Area Wilderness (BWCAW) in Minnesota and Quetico Provincial Park in Canada, with approximately 12.5 million trees blown down. This storm resulted in additional severe weather before and after the occurrence of the derecho, with continuous cloud-to-ground (CG) lightning occurring for more than 34 hours during its path across North America. At the time of the derecho the percentage of positive cloud-to-ground (+CG) lightning measured by the Canadian Lightning Detection Network (CLDN) was greater than 70% for more than three hours, with peak values reaching 97% positive CG lightning. Such high ratios of +CG are rare, and may be useful indicators of severe weather.

  6. Lightning phenomenology in the Tampa Bay Area

    Science.gov (United States)

    Peckham, D. W.; Uman, M. A.; Wilcox, C. E., Jr.

    1984-01-01

    A commercial lightning-locating system (LLS) was employed in the study of lightning phenomenology in the Tampa Bay area of Florida. The LLS output included the time, location, number of strokes per flash, and initial peak magnetic field value of first strokes for lightning ground flashes lowering negative charge. Attention is given to the design and the operation of the LLS, and the experimental results. Measured properties of each of 111 storms are given in a number of tables. It was observed that the apparent motion associated with the lightning activity in storm systems was not due to the motion of the individual single-peak and multiple-peak storms but rather to the successive growth of new storms near previously active storms.

  7. Central hyperadrenergic state after lightning strike.

    Science.gov (United States)

    Parsaik, Ajay K; Ahlskog, J Eric; Singer, Wolfgang; Gelfman, Russell; Sheldon, Seth H; Seime, Richard J; Craft, Jennifer M; Staab, Jeffrey P; Kantor, Birgit; Low, Phillip A

    2013-08-01

    To describe and review autonomic complications of lightning strike. Case report and laboratory data including autonomic function tests in a subject who was struck by lightning. A 24-year-old man was struck by lightning. Following that, he developed dysautonomia, with persistent inappropriate sinus tachycardia and autonomic storms, as well as posttraumatic stress disorder (PTSD) and functional neurologic problems. The combination of persistent sinus tachycardia and episodic exacerbations associated with hypertension, diaphoresis, and agitation was highly suggestive of a central hyperadrenergic state with superimposed autonomic storms. Whether the additional PTSD and functional neurologic deficits were due to a direct effect of the lightning strike on the central nervous system or a secondary response is open to speculation.

  8. Lightning frequency over the Italian peninsula

    Science.gov (United States)

    Turoldo, F.; Stel, F.; Giaiotti, D. B.; Bernardi, M.; Adamo, C.; Rovelli, C.; Dietrich, S.; Goi, D.

    2010-09-01

    The aim of this work is to analize the spatial frequency of lightning over Italy and to interpret the observed features in relationship with topography and with the climatic characteristics of the area. The data used to perform this analysis are : i) cloud to ground measurem ents (CG) from 1995 to 2000 given by CESI/SIRF (Sistem a Italiano Rilevamento Fulmini); ii) total flash measurements from 1995 to 2000 obtained trough the OTD system (Optical Transient Detector) given by NASA; iii) topography measurements obtained trough the ETOPO -2 database downloaded from NOAA. Both the yearly number of positive and negative CG lightning decrease with the increasing of topographic height. The number of positive and negative CG lightning decreases with the same derivative even if it seems that only below 1000 m it is possible to reach ratios between positive over negative CG lightning higher than 1. These values are observed only in the North African area present in the ranges of our analysis , that is from longitude 5 to 11 °E and from latitude 36 to 37 °N. Future studies will confirm if this is a real effect or an observational bias. The behavior of total lightning activity (IC and CG) in relationship with CG lightning activity and with topography is studied by means of OTD data. Being OTD data retrieved trough satellites, the analysis is done making us e of the flash rate per squared kilometer and per year instead of the number of lightning. Flash rate is computed using data on a re solution of 0.5°x0.5° and keping into account the changes in the surface due to the changes in latitude and longitude. This work confirms the observation (made even by other authors) that CG lightning frequency decreases as topographic height increases. A similar trend is found in total lightning flash rate, which is essentially due to the contribution of IC lightning. These observations are explained assuming that thunderstorm activity decreases with the increasing of topographic height

  9. A Spherical Earth Solution for TOA Lightning Location Retrieval

    Science.gov (United States)

    Koshak, W. J.; Solakiewicz, R. J.

    1999-01-01

    The problem of retrieving ligntning, ground-strike location on a spherical Earth surface using a network of 4 or more time-of-arrival (TOA) sensors is considered, It is shown that this problem has an analytic solution and therefore does not require the use of nonlinear estimation theory (e.g., minimization). The mathematical robustness of the analytic solution is tested using computer-generated lightning sources and simulated TOA measurement errors. A summary of a quasi-analytic extension of the spherical Earth solution to an oblate spheroid Earth geometry is also provided.

  10. Scientific Lightning Detection Network for Kazakhstan

    Science.gov (United States)

    Streltsov, A. V.; Lozbin, A.; Inchin, A.; Shpadi, Y.; Inchin, P.; Shpadi, M.; Ayazbayev, G.; Bykayev, R.; Mailibayeva, L.

    2015-12-01

    In the frame of grant financing of the scientific research in 2015-2017 the project "To Develop Electromagnetic System for lightning location and atmosphere-lithosphere coupling research" was found. The project was start in January, 2015 and should be done during 3 years. The purpose is to create a system of electromagnetic measurements for lightning location and atmosphere-lithosphere coupling research consisting of a network of electric and magnetic sensors and the dedicated complex for data processing and transfer to the end user. The main tasks are to set several points for electromagnetic measurements with 100-200 km distance between them, to develop equipment for these points, to develop the techniques and software for lightning location (Time-of-arrival and Direction Finding (TOA+DF)) and provide a lightning activity research in North Tien-Shan region with respect to seismicity and other natural and manmade activities. Also, it is planned to use lightning data for Global Electric Circuit (GEC) investigation. Currently, there are lightning detection networks in many countries. In Kazakhstan we have only separate units in airports. So, we don't have full lightning information for our region. It is planned, to setup 8-10 measurement points with magnetic and electric filed antennas for VLF range. The final data set should be including each stroke location, time, type (CG+, CG-, CC+ or CC-) and waveform from each station. As the magnetic field lightning antenna the ferrite rod VLF antenna will be used. As the electric field antenna the wide range antenna with specific frequencies filters will be used. For true event detection TOA and DF methods needs detected stroke from minimum 4 stations. In this case we can get location accuracy about 2-3 km and better.

  11. Z-M in Lightning Forecasting

    Science.gov (United States)

    2009-03-01

    reflectivity 20-25 dBZ which maintained their electric field for many tens of minutes well downstream of the 34 convective core. Dye and Willett (2007...concede that although the two anvils did not produce lightning, the electric field was probably sufficient to trigger lightning for many tens of minutes...online at: http://ghrc.msfc.nasa.gov/ uso /readme/ldar.html.] Greene, Douglas R. and Robert A. Clark, 1972: Vertically integrated liquid water—A new

  12. Lightning protection system for a wind turbine

    Science.gov (United States)

    Costin, Daniel P [Chelsea, VT; Petter, Jeffrey K [Williston, VT

    2008-05-27

    In a wind turbine (104, 500, 704) having a plurality of blades (132, 404, 516, 744) and a blade rotor hub (120, 712), a lightning protection system (100, 504, 700) for conducting lightning strikes to any one of the blades and the region surrounding the blade hub along a path around the blade hub and critical components of the wind turbine, such as the generator (112, 716), gearbox (708) and main turbine bearings (176, 724).

  13. A Fossilized Energy Distribution of Lightning

    Science.gov (United States)

    Pasek, Matthew A.; Hurst, Marc

    2016-07-01

    When lightning strikes soil, it may generate a cylindrical tube of glass known as a fulgurite. The morphology of a fulgurite is ultimately a consequence of the energy of the lightning strike that formed it, and hence fulgurites may be useful in elucidating the energy distribution frequency of cloud-to-ground lightning. Fulgurites from sand mines in Polk County, Florida, USA were collected and analyzed to determine morphologic properties. Here we show that the energy per unit length of lightning strikes within quartz sand has a geometric mean of ~1.0 MJ/m, and that the distribution is lognormal with respect to energy per length and frequency. Energy per length is determined from fulgurites as a function of diameter, and frequency is determined both by cumulative number and by cumulative length. This distribution parallels those determined for a number of lightning parameters measured in actual atmospheric discharge events, such as charge transferred, voltage, and action integral. This methodology suggests a potential useful pathway for elucidating lightning energy and damage potential of strikes.

  14. On the initiation of lightning in thunderclouds.

    Science.gov (United States)

    Chilingarian, Ashot; Chilingaryan, Suren; Karapetyan, Tigran; Kozliner, Lev; Khanikyants, Yeghia; Hovsepyan, Gagik; Pokhsraryan, David; Soghomonyan, Suren

    2017-05-02

    The relationship of lightning and elementary particle fluxes in the thunderclouds is not fully understood to date. Using the particle beams (the so-called Thunderstorm Ground Enhancements - TGEs) as a probe we investigate the characteristics of the interrelated atmospheric processes. The well-known effect of the TGE dynamics is the abrupt termination of the particle flux by the lightning flash. With new precise electronics, we can see that particle flux decline occurred simultaneously with the rearranging of the charge centers in the cloud. The analysis of the TGE energy spectra before and after the lightning demonstrates that the high-energy part of the TGE energy spectra disappeared just after lightning. The decline of particle flux coincides on millisecond time scale with first atmospheric discharges and we can conclude that Relativistic Runaway Electron Avalanches (RREA) in the thundercloud assist initiation of the negative cloud to ground lightning. Thus, RREA can provide enough ionization to play a significant role in the unleashing of the lightning flash.

  15. Error Analyses of the North Alabama Lightning Mapping Array (LMA)

    Science.gov (United States)

    Koshak, W. J.; Solakiewicz, R. J.; Blakeslee, R. J.; Goodman, S. J.; Christian, H. J.; Hall, J. M.; Bailey, J. C.; Krider, E. P.; Bateman, M. G.; Boccippio, D. J.

    2003-01-01

    Two approaches are used to characterize how accurately the North Alabama Lightning Mapping Array (LMA) is able to locate lightning VHF sources in space and in time. The first method uses a Monte Carlo computer simulation to estimate source retrieval errors. The simulation applies a VHF source retrieval algorithm that was recently developed at the NASA-MSFC and that is similar, but not identical to, the standard New Mexico Tech retrieval algorithm. The second method uses a purely theoretical technique (i.e., chi-squared Curvature Matrix theory) to estimate retrieval errors. Both methods assume that the LMA system has an overall rms timing error of 50ns, but all other possible errors (e.g., multiple sources per retrieval attempt) are neglected. The detailed spatial distributions of retrieval errors are provided. Given that the two methods are completely independent of one another, it is shown that they provide remarkably similar results, except that the chi-squared theory produces larger altitude error estimates than the (more realistic) Monte Carlo simulation.

  16. Lightning NOx Production in CMAQ Part I – Using Hourly NLDN Lightning Strike Data

    Science.gov (United States)

    Lightning-produced nitrogen oxides (NOX=NO+NO2) in the middle and upper troposphere play an essential role in the production of ozone (O3) and influence the oxidizing capacity of the troposphere. Despite much effort in both observing and modeling lightning NOX during the past dec...

  17. Multiple Lightning Discharges in Wind Turbines Associated with Nearby Cloud-to-Ground Lightning

    DEFF Research Database (Denmark)

    Candela Garolera, Anna; Cummins, Kenneth L.; Madsen, Søren Find;

    2015-01-01

    This paper presents the analysis of five events where simultaneous lightning currents were registered in different wind turbines of a wind farm with lightning monitoring equipment installed. Measurements from current monitoring devices installed at the wind turbines and observations from auto-tri...

  18. Lightning NOx Production in CMAQ Part I – Using Hourly NLDN Lightning Strike Data

    Science.gov (United States)

    Lightning-produced nitrogen oxides (NOX=NO+NO2) in the middle and upper troposphere play an essential role in the production of ozone (O3) and influence the oxidizing capacity of the troposphere. Despite much effort in both observing and modeling lightning NOX during the past dec...

  19. Lightning Performance on Overhead Distribution Lines : After Improvement Field Observation

    Directory of Open Access Journals (Sweden)

    Reynaldo Zoro

    2009-11-01

    Full Text Available Two feeders of 20 kV overhead distribution lines which are located in a high lightning density area are chosen to be observed as a field study due to their good lightning performance after improvement of lightning protection system. These two feeders used the new overhead ground wire and new line arrester equipped with lightning counter on the main lines. The significant reduced of lines outages are reported. Study was carried out to observe these improvements by comparing to the other two feeders line which are not improved and not equipped yet with the ground wire and line arrester. These two feeders located in the nearby area. Two cameras were installed to record the trajectory of the lightning strikes on the improved lines. Lightning peak currents are measured using magnetic tape measurement system installed on the grounding lead of lightning arrester. Lightning overvoltage calculations are carried out by using several scenarios based on observation results and historical lightning data derived from lightning detection network. Lightning overvoltages caused by indirect or direct strikes are analyzed to get the lightning performance of the lines. The best scenario was chosen and performance of the lines were improved significantly by installing overhead ground wire and improvement of lightning arrester installation.

  20. Spatiotemporal characteristics of positive cloud-to-ground lightning discharges and bidirectional leader of the lightning

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The three-dimension spatiotemporal development characteristics of positive cloud-toground (CG) lightning discharges have been analyzed by using the data measured by the lightning mapping array system with high time and space resolution. The results indicate that a positive CG lightning discharge can be divided into three stages based on the characteristics of its development. The first stage is discharge process in cloud with a long duration preceding the return stroke. This process with an average of 370 ms propagated at velocity of 105 m/s and produced intensive radiation with a magnitude equal to that of the negative leader. During this stage, the lightning channels developed horizontally in the positive charge region with few branches as the negative polarity breakdown. During the stage after the return stroke of the positive CG lightning, the lightning channels propagated at velocity of 2 times faster than that before the return stroke. This stage involved lots of positive fast impulses and corresponded to the continuing current process producing less and dispersed radiation points and more intensive radiation powers. During the final stage of the positive CG lightning, the lightning channels developed at velocity equal to that before the return stroke and the radiation points appeared mainly at the ends of channel. The spatiotemporal development characteristics of the positive CG lightning are very different from that of the negative CG lightning. All of the radiation points of the positive CG lightning appeared in the positive charge region of cloud. Little or no radiation was detected during the positive leader just before the return stroke. The duration of the positive CG lightning was an average of 730 ms. The positive CG lightning discharges with lasting time of 500-600 ms were 43%. 90% of the positive CG lightning discharges involved one return stroke, the most return stroke number being four. The current of the return stroke was an average of 36.5 k

  1. Frequency domain analysis of lightning protection using four lightning protection rods

    Directory of Open Access Journals (Sweden)

    Javor Vesna

    2008-01-01

    Full Text Available In this paper the lightning discharge channel is modeled as a vertical monopole antenna excited by a pulse generator at its base. The lightning electromagnetic field of a nearby lightning discharge in the case of lightning protection using four vertical lightning protection rods was determined in the frequency domain. Unknown current distributions were determined by numerical solving of a system of integral equations of two potentials using the Point Matching Method and polynomial approximation of the current distributions. The influence of the real ground, treated as homogeneous loss half-space of known electrical parameters, expressed through a Sommerfeld integral kernel, was modeled using a new Two-image approximation which gives good results in both near and far fields.

  2. Franklin Lecture: Lightning in Planetary Atmospheres

    Science.gov (United States)

    Gurnett, D. A.

    2006-12-01

    A broad overview is given of lightning in planetary atmospheres. Searches for lightning using spacecraft-borne instrumentation have now been conducted at almost all of the planets in the solar system, the exceptions being Mercury, which has no appreciable atmosphere, and Pluto which has not yet been visited by a spacecraft. The techniques used include (1) imaging observations to detect optical flashes produced by lightning; (2) high-frequency radio measurements to detect the impulsive broadband radio bursts, called spherics, produced by lightning discharges; and (3) low-frequency plasma wave measurements to detect the whistling tones, called whistlers, produced by lightning. Using these techniques, lightning has been reported at five planets other than Earth. These are: Venus, Jupiter, Saturn, Uranus, and Neptune. Of these, the existence of lightning at Venus is doubtful, and the evidence of lightning at Neptune is at best marginal. Jupiter and Saturn have by far the most intense and well documented lightning activity. During the Voyager 1 flyby of Jupiter, whistlers and intense optical flashes, comparable to those from terrestrial superbolts, were observed by the plasma wave and optical imaging instruments. However, no impulsive high-frequency radio bursts were observed. Two factors may be responsible for the absence of high-frequency radio signals: (1) the very strong magnetic field of Jupiter, which blocks the escape of the extra-ordinary mode; and (2) the relatively high electron collision frequency in the ionosphere, which increases the absorption of radio waves. During the Voyager 1 and 2 flybys of Saturn many very strong high-frequency radio bursts, called Saturn Electrostatic Discharges (SEDs), were detected. Although the origin of these impulsive radio bursts was initially uncertain, strong evidence now exists that SEDs are produced by lightning. Recent optical imaging and radio measurements from the Cassini spacecraft clearly show that SEDs originate from

  3. On the association of lightning activity and projected change in climate over the Indian sub-continent

    Science.gov (United States)

    Saha, Upal; Siingh, Devendraa; Kamra, A. K.; Galanaki, Elissavet; Maitra, Animesh; Singh, R. P.; Singh, A. K.; Chakraborty, Swastika; Singh, Rajesh

    2017-01-01

    The association of lightning activity with the long-term as well as seasonal spatio-temporal distribution of convective available potential energy (CAPE), surface convective precipitation, vegetation cover and anthropogenic aerosol loading over the Indian sub-continent has been studied for the period 2000-2014. The north-east to north-west arc including the foothills of the Himalayas is the primary seats of lightning occurrences. The correlations of lightning activity with each of aerosol loading, vegetation cover, convective instability and convective precipitation helps us in understanding the definite entity that is responsible for changing the lightning activity in different parts of this tropical region. Lightning flash rate (LFR) has significant positive correlations (r 0.5-0.7) with AOD, CAPE and surface convective precipitation but significant negative correlation (r - 0.4) with Normalized Difference Vegetation Index (NDVI). Using global circulation models from the Climate Model Intercomparison Project Phase 5 (CMIP5), time-series of observed and projected upper tropospheric water vapor, surface convective precipitation and aerosol optical depth (AOD) from the historical simulations (1996-2005) and RCP8.5 emission scenario (2036-2045) are analyzed over the Indian region that are vulnerable to climate change in terms of occurrence of convective events and associated hazardous lightning phenomena. This study indicates that upper tropospheric water vapor (300 hPa) has a significant linkage with the lightning occurrences associated with convective activities and strong updraft. During the mid- 21st century, AOD, surface convective precipitation and specific humidity are projected to increase by 1.42%, 2.01% and 1.40%, respectively which may result in regional changes in lightning activity over the Indian sub-continent.

  4. Effectiveness of Lightning Protection Devices%雷电保护装置的有效性研究

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    In addition to the conventional Franklin Rod, many non-conventional air terminals are being used as lightning protection devices. As cited in previous works, these non-conventional devices emit space charge in the vicinity of the terminals during the process of lightning stroke. A number of factors affect the performance of these lightning protection devices, among them are geometry and dimension of the devices, location of the device above the ground, height of the cloud above the ground, and polarity of the lightning stroke. The performance of these lightning protection devices has been a topic of discussion by researchers for many years. Some studies focused on the magnitude of emission current from these devices as a criterion to evaluate their performances. The critical flashover voltage (CFO) between the devices and a metal screen simulating cloud can also be used as another criterion to evaluate the performance of the devices. Laboratory measurements were conducted in controlled conditions on different types of lightning protection devices to compare their performance. Four different types of devices were used in the present study:Franklin Rod, TerraStat models TS 100, TS 400, and Spline Ball Ionizer. The study focused on the CFO voltage of the air gap between devices and the metal screen. The CFO voltage was evaluated using standard switching and lightning impulses. The measurements were recorded for positive as well as negative polarity. The air gap between the devices and metal screen was selected at 2 m and 3 m. The results obtained provide a better understanding of the electrical performance of lightning protection devices.

  5. Lightning: Nature's Probe of Severe Weather for Research and Operations

    Science.gov (United States)

    Blakeslee, R.J.

    2007-01-01

    Lightning, the energetic and broadband electrical discharge produced by thunderstorms, provides a natural remote sensing signal for the study of severe storms and related phenomena on global, regional and local scales. Using this strong signal- one of nature's own probes of severe weather -lightning measurements prove to be straightforward and take advantage of a variety of measurement techniques that have advanced considerably in recent years. We briefly review some of the leading lightning detection systems including satellite-based optical detectors such as the Lightning Imaging Sensor, and ground-based radio frequency systems such as Vaisala's National Lightning Detection Network (NLDN), long range lightning detection systems, and the Lightning Mapping Array (LMA) networks. In addition, we examine some of the exciting new research results and operational capabilities (e.g., shortened tornado warning lead times) derived from these observations. Finally we look forward to the next measurement advance - lightning observations from geostationary orbit.

  6. Numerical tools for lightning protection of wind turbines

    DEFF Research Database (Denmark)

    Madsen, Søren Find; Mieritz, Casper Falkenstrøm; Candela Garolera, Anna

    2013-01-01

    The present paper presents the different numerical tools used for lightning protection analysis. Initially the risk assessment considering attachment point distribution and location of vulnerable points on the wind turbine will be discussed, where also the term Lightning Protection Coordination (...

  7. Lightning NOx Production per Flash based on OMI NO2 Observations

    Science.gov (United States)

    Ring, A.; Pickering, K. E.; Allen, D. J.; Bucsela, E. J.; Holzworth, R. H.; Damon, M.

    2013-12-01

    Lightning production of nitrogen oxides (NOx) in the middle and upper troposphere contributes significantly to the production of ozone. Improved estimates of the lightning NOx (LNOx) produced per flash are imperative to determine the natural source strength of NOx and ultimately upper troposphere ozone. An algorithm to derive LNOx from Ozone Monitoring Instrument (OMI) data has been developed. Key elements of the algorithm include subtraction of the stratospheric and tropospheric background components from the total column NO2, and the use of an air mass factor appropriate for LNOx. The stratospheric NO2 columns from the NASA standard OMI retrieval are used. The tropospheric background is based on the OMI tropospheric column data on days surrounding the day being processed. Simulations 'with lightning' and 'without lightning' for the 2007 to 2012 period were executed using the NASA Global Modeling Initiative (GMI) Chemical Transport Model. The combination of these GMI simulations is used to derive model-based tropospheric profiles of LNO2 and LNOx that are used in the air mass factor calculation and in the conversion of OMI LNO2 to LNOx. Daily data sets containing OMI LNOx estimates on the GMI 2 x 2.5 degree grid were generated, and compared to lightning flash rates from the adjusted World Wide Lightning Location Network (WWLLN), a ground based global network formed in 2004 that detects very low frequency (VLF) radio waves emitted by lightning strokes. WWLLN's global coverage allows for meaningful comparison and adjustment for detection efficiency based the data collected by the Optical Transient Detector and Lightning Imaging Sensor (OTD/LIS). Estimates of LNOx production per flash are generated using total flashes for 6 hours, 3 hours, 2 hours, and 1 hour periods prior to OMI overpass in conjunction with the OMI based LNOx fields. Global estimates of LNOx production in moles per flash and regional estimates for Central America, Central Africa, Indonesia, India

  8. An Operational Perspective of Total Lightning Information

    Science.gov (United States)

    Nadler, David J.; Darden, Christopher B.; Stano, Geoffrey; Buechler, Dennis E.

    2009-01-01

    The close and productive collaborations between the NWS Warning and Forecast Office, the Short Term Prediction and Research Transition Center at NASA Marshall Space Flight Center and the University of Alabama in Huntsville have provided a unique opportunity for science sharing and technology transfer. One significant technology transfer that has provided immediate benefits to NWS forecast and warning operations is the use of data from the North Alabama Lightning Mapping Array. This network consists of ten VHF receivers deployed across northern Alabama and a base station located at the National Space Science and Technology Center. Preliminary investigations done at WFO Huntsville, along with other similar total lightning networks across the country, have shown distinct correlations between the time rate-of-change of total lightning and trends in intensity/severity of the parent convective cell. Since May 2003 when WFO HUN began receiving these data - in conjunction with other more traditional remotely sensed data (radar, satellite, and surface observations) -- have improved the situational awareness of the WFO staff. The use of total lightning information, either from current ground based systems or future space borne instrumentation, may substantially contribute to the NWS mission, by enhancing severe weather warning and decision-making processes. Operational use of the data has been maximized at WFO Huntsville through a process that includes forecaster training, product implementation, and post event analysis and assessments. Since receiving these data, over 50 surveys have been completed highlighting the use of total lightning information during significant events across the Tennessee Valley. In addition, around 150 specific cases of interest have been archived for collaborative post storm analysis. From these datasets, detailed trending information from radar and total lightning can be compared to corresponding damage reports. This presentation will emphasize

  9. Lightning chemistry on Earth-like exoplanets

    Science.gov (United States)

    Ardaseva, Aleksandra; Rimmer, Paul B.; Waldmann, Ingo; Rocchetto, Marco; Yurchenko, Sergey N.; Helling, Christiane; Tennyson, Jonathan

    2017-09-01

    We present a model for lightning shock-induced chemistry that can be applied to atmospheres of arbitrary H/C/N/O chemistry, hence for extrasolar planets and brown dwarfs. The model couples hydrodynamics and the STAND2015 kinetic gas-phase chemistry. For an exoplanet analogue to the contemporary Earth, our model predicts NO and NO2 yields in agreement with observation. We predict height-dependent mixing ratios during a storm soon after a lightning shock of NO ≈10-3 at 40 km and NO2 ≈10-4 below 40 km, with O3 reduced to trace quantities (≪10-10). For an Earth-like exoplanet with a CO2/N2 dominated atmosphere and with an extremely intense lightning storm over its entire surface, we predict significant changes in the amount of NO, NO2, O3, H2O, H2 and predict a significant abundance of C2N. We find that, for the Early Earth, O2 is formed in large quantities by lightning but is rapidly processed by the photochemistry, consistent with previous work on lightning. The chemical effect of persistent global lightning storms are predicted to be significant, primarily due to NO2, with the largest spectral features present at ∼3.4 and ∼6.2 μm. The features within the transmission spectrum are on the order of 1 ppm and therefore are not likely detectable with the James Webb Space Telescope. Depending on its spectral properties, C2N could be a key tracer for lightning on Earth-like exoplanets with a N2/CO2 bulk atmosphere, unless destroyed by yet unknown chemical reactions.

  10. North Alabama Total Lightning Climatology in Support of Lightning Safety Operations

    Science.gov (United States)

    Stano, G. T.; Schultz, C. J.; Koshak, W. J.

    2015-12-01

    The North Alabama Lightning Mapping Array (NALMA) was installed in 2001 to observe total lightning (cloud-to-ground and intra-cloud) and study its relationship to convective activity. NALMA has served as ground-truth for the Tropical Rainfall Measuring Mission Lightning Imager (TRMM-LIS) and will again for the GOES-R Geostationary Lightning Mapper (GLM). Also, NASA's Short-term Prediction Research and Transition Center (SPoRT) has transitioned these data to National Weather Service Weather Forecast Offices to evaluate the impact in operations since 2003. This study focuses on seasonal and diurnal observations from NALMA's 14 year history. This is initially intended to improve lightning safety at Marshall Space Flight Center, but has other potential applications. Improvements will be made by creating a dataset to investigate temporal, spatial, and seasonal patterns in total lightning over the Tennessee Valley, compare these observations to background environmental parameters and the TRMM-LIS climatology, and investigate applying these data to specific points of interest. Unique characteristics, such as flash extent density and length of flashes can be investigated, which are unavailable from other lightning networks like the National Lightning Detection Network (NLDN). The NALMA and NLDN data can be combined such that end users can use total lightning to gain lead time on the initial cloud-to-ground flash of a storm and identify if lightning is extending far from the storm's core. This spatial extent can be analyzed to determine how often intra-cloud activity may impinge on a region of interest and how often a cloud-to-ground strike may occur in the region. The seasonal and diurnal lightning maps can aid with planning of various experiments or tests that often require some knowledge about future weather patterns months in advance. The main goal is to develop a protocol to enhance lightning safety everywhere once the Geostationary Lightning Mapper (GLM) is on orbit

  11. Lightning Mapping Array flash detection performance with variable receiver thresholds

    Science.gov (United States)

    Chmielewski, Vanna C.; Bruning, Eric C.

    2016-07-01

    This study characterizes Lightning Mapping Array performance for networks that participated in the Deep Convective Clouds and Chemistry field program using new Monte Carlo and curvature matrix model simulations. These open-source simulation tools are readily adapted to real-time operations or detailed studies of performance. Each simulation accounted for receiver threshold and location, as well as a reference distribution of source powers and flash sizes based on thunderstorm observations and the mechanics of station triggering. Source and flash detection efficiency were combined with solution bias and variability to predict flash area distortion at long ranges. Location errors and detection efficiency were highly dependent on the station configuration and thresholds, especially at longer ranges, such that performance varied more than expected across different networks and with azimuth within networks. Error characteristics matched prior studies, which led to an increase in flash distortion with range. Predicted flash detection efficiency exceeded 95% within 100 km of all networks.

  12. Influence of line isolation overlappings on formation of lightning overvoltages

    Directory of Open Access Journals (Sweden)

    Antropov I. M.

    2015-12-01

    Full Text Available The model of substation protection against lightning waves with considered multiple overlappings of line isolation has been presented. Influence of multiple overlapping of isolation on line support on formation of lightning overvoltages has been shown. Ambiguity of determination of lightning current dangerous parameters at the fixed length of its front has been revealed

  13. Modelling lightning caused transmission line outages in Alberta

    Energy Technology Data Exchange (ETDEWEB)

    Wu, M.; Shen, S.S.P. [Alberta Univ., Edmonton, AB (Canada). Dept. of Mathematical and Statistical Sciences; Koval, D.O. [Alberta Univ., Edmonton, AB (Canada). Dept. of Electrical Engineering

    2005-07-01

    The characteristics of lightning and the relationship between lightning and transmission line outages is not fully understood by utility planners. This study used 20 year data sets of lightning events to investigate the spatial and temporal patterns of lightning in Alberta. Studies of geographical and temporal characteristics of lightning caused transmission line outages for several voltage level transmission lines were also examined. A lasso regression variable selection procedure and Cp criterion were used to model the duration of the lightning-caused transmission line outages as a function of weather and lightning patterns. The province was divided into 110 by 110 grids, and lightning variables were calculated for each cell. All the lightning variables for each cell were then averaged based on their areas. The overall cloud-ground lightning flashes 20-year mean frequency and the physical locations of power transmission lines were then plotted. Estimated probability density functions of the duration of lightning caused transmission line outages were classified by their voltage levels. The study showed that the characteristics of the lightning caused outages were different for different voltage levels of the transmission lines. Results suggested that the findings will have a significant impact on the accuracy of reliability methodologies that use the average duration of transmission line outages in their calculations. It was concluded that the new methodology can be applied to any transmission line system operating in a unique geographical environmental area. 11 refs., 3 tabs., 5 figs.

  14. Statistical Evolution of the Lightning Flash

    Science.gov (United States)

    Zoghzoghy, F. G.; Cohen, M.; Said, R.; Inan, U. S.

    2012-12-01

    Natural lightning is one of the most fascinating and powerful electrical processes on Earth. To date, the physics behind this natural phenomenon are not fully understood, due primarily to the difficulty of obtaining measurements inside thunderstorms and to the wide range of timescales involved (from nanoseconds to seconds). Our aim is to use accurate lightning geo-location data from the National Lightning Detection Network (NLDN) to study statistical patterns in lightning, taking advantage of the fact that millions of lightning flashes occur around the globe every day. We present two sets of results, one involving the patterns of flashes in a storm, and a second involving the patterns of strokes in a flash. These patterns can provide a surrogate measure of the timescales and the spatial extents of the underlying physical processes. First, we study the timescales of charge buildup inside thunderstorms. We find that, following a lightning flash, the probability of another neighboring flash decreases and takes tens of seconds to recover. We find that this suppression effect is a function of flash type, stroke peak current, cloud-to-ground (CG) stroke multiplicity, and other lightning and geographical parameters. We find that the probabilities of subsequent flashes are more suppressed following oceanic lightning, or following flashes with higher peak currents and/or higher multiplicities (for CG flashes). Second, we use NLDN data to study the evolution of the strokes within a CG flash. A CG flash typically includes multiple return strokes, which can occur in the same channel or in multiple channels within a few kilometers. We cluster NLDN stroke data into flashes and produce the probability density function of subsequent strokes as a function of distance and time-delays relative to the previous stroke. Using this technique, we investigate processes which occur during the CG lightning flash with nanosecond to millisecond timescales. For instance, our results suggest

  15. Climate Change and Tropical Total Lightning

    Science.gov (United States)

    Albrecht, R.; Petersen, W.; Buechler, D.; Goodman, S.; Blakeslee, R.; Christian, H.

    2009-01-01

    While global warming is regarded as a fact by many in the scientific community, its future impact remains a challenge to be determined and measured. The International Panel on Climate Change (IPCC) assessment report (IPCC, 2007) shows inconclusive answers on global rainfall trends and general agreement on a future drier climate with increased global warming. The relationship between temperature, humidity and convection is not linear and is strongly dependent on regional scale features, such as topography and land cover. Furthermore, the relationship between convective lightning production (thunderstorms) and temperature is even more complicated, being subjected to the cloud dynamics and microphysics. Total lightning (intracloud and cloud-to-ground) monitoring is a relatively new field of observation. Global and tropical total lightning began to be more extensively measured by satellites in the mid 90s. In this scope, the Lightning Imaging Sensor (LIS) onboard of the Tropical Rainfall Measurement Mission (TRMM) has been operational for over 11 years. Here we address total lightning trends observed by LIS from 1998 to 2008 in different temporal (annual and seasonal) and spatial (large and regional) scales. The observed 11-year trends are then associate to different predicted/hypothesized climate change scenarios.

  16. An FDTD Model for Low and High Lightning Generated Electromagnetic Fields

    Science.gov (United States)

    Knyazeva, Svetlana

    One of the natural sources of the electric current is the lightning discharge in the ionosphere. The electro-magnetic wave produced by intense lightning, like sprites, can significantly alter electrostatic, electromagnetic, acoustic, radar, and radio-frequency measurements in ionosphere and on the ground. There are numerous studies performed on the sprites and other types of lightning discharge activities. This study concentrates on very low frequency (VLF, 3-20 kHz) and extremely low frequency (ELF, 3-3000 Hz) electromagnetic waves radiated by lightning currents. These frequencies have very low attenuation rate and make the ground a good enough conductor where the radio wave arrives at the surface entering the ground nearly independent of the incident angle. The Earth curvature can be neglected for frequencies up to ˜ 12 kHz since the wave incident angles are very small. Method being used is Finite-Difference Time-Domain (FDTD) in the two-dimensional cylindrical simulation environment. Surface impedance boundary condition is used for the air-ground interface; and Nearly Perfect Match Layer is implemented as absorbing boundary condition on the top and sides of the simulation domain.

  17. Application and Analysis for Surge Arrester on Lightning Protection of Distribution Network

    Directory of Open Access Journals (Sweden)

    Wang Daxing

    2016-01-01

    Full Text Available In order to effectively reduce lightning stroke outage rate, effect of lightning protection with surge arrester on transmission line has been generally acknowledged relative to other lightning protection measures. This article introduces in such aspects as the working principle of line surge arrester and effect of lightning protection, and also explores application for lightning arrester of distribution network to achieve difference lightning protection and improve the lightning protection performance of distribution network.

  18. Application and Analysis for Surge Arrester on Lightning Protection of Distribution Network

    Directory of Open Access Journals (Sweden)

    Wang Daxing

    2015-01-01

    Full Text Available In order to effectively reduce lightning stroke outage rate, effect of lightning protection with surge arrester on transmission line has been generally acknowledged relative to other lightning protection measures. This article introduces in such aspects as the working principle of line surge arrester and effect of lightning protection, and also explores application for lightning arrester of distribution network to achieve difference lightning protection and improve the lightning protection performance of distribution network.

  19. Long-term impacts of aerosols on precipitation and lightning over the Pearl River Delta megacity area in China

    Directory of Open Access Journals (Sweden)

    Y. Wang

    2011-12-01

    Full Text Available Seven-year measurements of precipitation, lightning flashes, and visibility from 2000 to 2006 have been analyzed in the Pearl River Delta (PRD region, China, with a focus on the Guangzhou megacity area. Statistical analysis shows that the occurrence of heavy rainfall (>25 mm per day and frequency of lightning strikes are reversely correlated to visibility during this period. To elucidate the effects of aerosols on cloud processes, precipitation, and lightning activity, a cloud resolving – Weather Research and Forecasting (CR-WRF model with a two-moment bulk microphysical scheme is employed to simulate a mesoscale convective system occurring on 28 Match 2009 in the Guangzhou megacity area. The model predicted evolutions of composite radar reflectivity and accumulated precipitation are in agreement with measurements from S-band weather radars and automatic gauge stations. The calculated lightning potential index (LPI exhibits temporal and spatial consistence with lightning flashes recorded by a local lightning detection network. Sensitivity experiments have been performed to reflect aerosol conditions representative of polluted and clean cases. The simulations suggest that precipitation and LPI are enhanced by about 16% and 50%, respectively, under the polluted aerosol condition. Our results suggest that elevated aerosol loading suppresses light and moderate precipitation (less than 25 mm per day, but enhances heavy precipitation. The responses of hydrometeors and latent heat release to different aerosol loadings reveal the physical mechanism for the precipitation and lightning enhancement in the Guangzhou megacity area, showing more efficient mixed phase processes and intensified convection under the polluted aerosol condition.

  20. Vertical profiles of lightning-produced NO2 enhancements in the upper troposphere observed by OSIRIS

    Directory of Open Access Journals (Sweden)

    P. F. Bernath

    2007-08-01

    Full Text Available The purpose of this study is to perform a global search of the upper troposphere (z≥10 km for enhancements of nitrogen dioxide and determine their sources. This is the first application of satellite-based limb scattering to study upper tropospheric NO2. We have searched two years (May 2003–May 2005 of OSIRIS (Optical Spectrograph and Infrared Imager System operational NO2 concentrations (version 2.3/2.4 to find large enhancements in the observations by comparing with photochemical box model calculations and by identifying local maxima in NO2 volume mixing ratio. We find that lightning is the main production mechanism responsible for the large enhancements in OSIRIS NO2 observations as expected. Similar patterns in the abundances and spatial distribution of the NO2 enhancements are obtained by perturbing the lightning within the GEOS-Chem 3-dimensional chemical transport model. In most cases, the presence of lightning is confirmed with coincident imagery from LIS (Lightning Imaging Sensor and the spatial extent of the NO2 enhancement is mapped using nadir observations of tropospheric NO2 at high spatial resolution from SCIAMACHY (Scanning Imaging Absorption Spectrometer for Atmospheric Chartography and OMI (Ozone Monitoring Instrument. The combination of the lightning and chemical sensors allows us to investigate globally the role of lightning to the abundance of NO2 in the upper troposphere (UT. Lightning contributes 60% of the tropical upper tropospheric NO2 in GEOS-Chem simulations. The spatial and temporal distribution of NO2 enhancements from lightning (May 2003–May 2005 is investigated. The enhancements generally occur at 12 to 13 km more frequently than at 10 to 11 km. This is consistent with the notion that most of the NO2 is forming and persisting near the cloud top altitude in the tropical upper troposphere. The latitudinal distribution is mostly as expected. In general, the thunderstorms exhibiting weaker vertical development (e

  1. Objective Lightning Probability Forecast Tool Phase II

    Science.gov (United States)

    Lambert, Winnie

    2007-01-01

    This presentation describes the improvement of a set of lightning probability forecast equations that are used by the 45th Weather Squadron forecasters for their daily 1100 UTC (0700 EDT) weather briefing during the warm season months of May-September. This information is used for general scheduling of operations at Cape Canaveral Air Force Station and Kennedy Space Center. Forecasters at the Spaceflight Meteorology Group also make thunderstorm forecasts during Shuttle flight operations. Five modifications were made by the Applied Meteorology Unit: increased the period of record from 15 to 17 years, changed the method of calculating the flow regime of the day, calculated a new optimal layer relative humidity, used a new smoothing technique for the daily climatology, and used a new valid area. The test results indicated that the modified equations showed and increase in skill over the current equations, good reliability, and an ability to distinguish between lightning and non-lightning days.

  2. Lightning and severe thunderstorms in event management.

    Science.gov (United States)

    Walsh, Katie M

    2012-01-01

    There are a few national position stands/guidelines that address environmental conditions in athletics, yet they do not govern all outdoor sports. Extreme heat and cold, lightning, and severe wind can all be fatal, yet the majority of outdoor sports have no published guidelines addressing these conditions in relation to activity. Available research on extreme heat and cold conditions in athletics provides prevention strategies, to include acclimatization. Lightning and severe wind are two environmental conditions to which humans cannot accommodate, and they both can be deadly. There are strong positions on extreme heat/cold and lightning safety in athletics, but none affiliated with severe winds. Medical personnel involved in planning large outdoor sporting events must know of the presence of nationally published weather-related documents and apply them to their event. In addition, research needs to be expanded in the realm of establishing guidelines for safety to participants and spectators in severe wind conditions.

  3. Development of lightning-resistant overhead ground wire

    Energy Technology Data Exchange (ETDEWEB)

    Yokoya, Munehisa; Katsuragi, Yukio (Chubu Electric Power Co., Inc., Nagoya (Japan)); Goda, Yutaka (Central Research Inst. of the Electric Power Industry, Yokosuka (Japan)); Nagata, Yutaka; Asano, Yuji (Fujikura Ltd., Tokyo (Japan))

    1994-07-01

    Overhead ground wires (GW) are vulnerable to strand breakage due to lightning strikes. With the wider application in recent years of Composite Fiber Optic Ground Wire (OPGW), it becomes more important to protect GW from such damage. In this paper, the authors present the results of various investigations made in developing lightning-resistant GW/OPGW. Investigations included field experiments using rocket-triggered lightning, studies on materials and designs to improve lightning characteristics and various evaluation tests, such as DC arc tests, of several prototypes. As a result, the authors have developed excellent lightning-resistant GW/OPGW applicable for conventional transmission lines.

  4. On ULF Signatures of Lightning Discharges

    Science.gov (United States)

    Bösinger, T.; Shalimov, S. L.

    2008-06-01

    Recent works on magnetic signatures due to distant lightning discharges are reviewed. Emphasis is laid on magnetic signatures in the ULF range (in the old definition from less than 1 mHz up to 1 Hz), that is in the frequency range below the Schumann resonance. These signatures are known to be of importance for the excitation of the ionospheric Alfvén resonator (IAR) which works only at night time conditions. This emphasizes the difference between night and day time ULF signatures of lightning. The IAR forms a link between the atmosphere and magnetosphere. Similarities and differences of this link in the VLF (Trimpi effect) and ULF range are worked out. A search for a unique signature of sprite-associated positive cloud-to-ground (+CG) lightning discharges ended with a negative result. In this context, however, a new model of lightning-associated induced mesospheric currents was built. Depending on mesospheric condition it can produce magnetic signatures in the entire frequency range from VLF, ELF to ULF. In the latter case it can explain signatures known as the Ultra Slow Tail of +CG lightning discharges. A current problem on the magnetic background noise intensity has been solved by taking more seriously the contribution of +CG lightning discharges to the overall background noise. Their low occurrence rate is more than compensated by their large and long lasting continuing currents. By superposed epoch analysis it could be shown that the ULF response to -CG is one to two orders smaller that in case of +CG with similar peak current values of the return stroke.

  5. Artificial Neural Network applied to lightning flashes

    Science.gov (United States)

    Gin, R. B.; Guedes, D.; Bianchi, R.

    2013-05-01

    The development of video cameras enabled cientists to study lightning discharges comportment with more precision. The main goal of this project is to create a system able to detect images of lightning discharges stored in videos and classify them using an Artificial Neural Network (ANN)using C Language and OpenCV libraries. The developed system, can be split in two different modules: detection module and classification module. The detection module uses OpenCV`s computer vision libraries and image processing techniques to detect if there are significant differences between frames in a sequence, indicating that something, still not classified, occurred. Whenever there is a significant difference between two consecutive frames, two main algorithms are used to analyze the frame image: brightness and shape algorithms. These algorithms detect both shape and brightness of the event, removing irrelevant events like birds, as well as detecting the relevant events exact position, allowing the system to track it over time. The classification module uses a neural network to classify the relevant events as horizontal or vertical lightning, save the event`s images and calculates his number of discharges. The Neural Network was implemented using the backpropagation algorithm, and was trained with 42 training images , containing 57 lightning events (one image can have more than one lightning). TheANN was tested with one to five hidden layers, with up to 50 neurons each. The best configuration achieved a success rate of 95%, with one layer containing 20 neurons (33 test images with 42 events were used in this phase). This configuration was implemented in the developed system to analyze 20 video files, containing 63 lightning discharges previously manually detected. Results showed that all the lightning discharges were detected, many irrelevant events were unconsidered, and the event's number of discharges was correctly computed. The neural network used in this project achieved a

  6. Visual Analysis for Nowcasting of Multidimensional Lightning Data

    Directory of Open Access Journals (Sweden)

    Stefan Peters

    2013-08-01

    Full Text Available Globally, most weather-related damages are caused by thunderstorms. Besides floods, strong wind, and hail, one of the major thunderstorm ground effects is lightning. Therefore, lightning investigations, including detection, cluster identification, tracking, and nowcasting are essential. To enable reliable decisions, current and predicted lightning cluster- and track features as well as analysis results have to be represented in the most appropriate way. Our paper introduces a framework which includes identification, tracking, nowcasting, and in particular visualization and statistical analysis of dynamic lightning data in three-dimensional space. The paper is specifically focused on enabling users to conduct the visual analysis of lightning data for the purpose of identification and interpretation of spatial-temporal patterns embedded in lightning data, and their dynamics. A graphic user interface (GUI is developed, wherein lightning tracks and predicted lightning clusters, including their prediction certainty, can be investigated within a 3D view or within a Space-Time-Cube. In contrast to previous work, our approach provides insight into the dynamics of past and predicted 3D lightning clusters and cluster features over time. We conclude that an interactive visual exploration in combination with a statistical analysis can provide new knowledge within lightning investigations and, thus, support decision-making in weather forecast or lightning damage prevention.

  7. Statistical analysis of lightning electric field measured under Malaysian condition

    Science.gov (United States)

    Salimi, Behnam; Mehranzamir, Kamyar; Abdul-Malek, Zulkurnain

    2014-02-01

    Lightning is an electrical discharge during thunderstorms that can be either within clouds (Inter-Cloud), or between clouds and ground (Cloud-Ground). The Lightning characteristics and their statistical information are the foundation for the design of lightning protection system as well as for the calculation of lightning radiated fields. Nowadays, there are various techniques to detect lightning signals and to determine various parameters produced by a lightning flash. Each technique provides its own claimed performances. In this paper, the characteristics of captured broadband electric fields generated by cloud-to-ground lightning discharges in South of Malaysia are analyzed. A total of 130 cloud-to-ground lightning flashes from 3 separate thunderstorm events (each event lasts for about 4-5 hours) were examined. Statistical analyses of the following signal parameters were presented: preliminary breakdown pulse train time duration, time interval between preliminary breakdowns and return stroke, multiplicity of stroke, and percentages of single stroke only. The BIL model is also introduced to characterize the lightning signature patterns. Observations on the statistical analyses show that about 79% of lightning signals fit well with the BIL model. The maximum and minimum of preliminary breakdown time duration of the observed lightning signals are 84 ms and 560 us, respectively. The findings of the statistical results show that 7.6% of the flashes were single stroke flashes, and the maximum number of strokes recorded was 14 multiple strokes per flash. A preliminary breakdown signature in more than 95% of the flashes can be identified.

  8. Characteristics of Lightning Discharges and Electric Structure of Thunderstorm

    Institute of Scientific and Technical Information of China (English)

    Qie Xiushu; Zhang Yijun; Zhang Qilin

    2006-01-01

    Progresses in the research on physical processes of lightning discharge and electric structure of thunderstorm in the last decade in China have been reviewed. By using the self-developed lightning detecting and locating techniques with high temporal and spatial resolution, the characteristics and parameters of lightning discharge in some representative areas in China have been obtained. Observations on lightning activity were conducted for the first time in the Qinghai-Tibetan Plateau in 2002-2005, and the special characteristics of the thunderstorm and lightning activity in the plateau were revealed. The lightning spectra in the band of visible light were recorded, and the spectral lines were identified in detail with introduction of modern theories of atomic structure. The techniques on artificially altitude triggered lightning and related measurements under a harsh electromagnetic environment have been well developed. Evidences of bi-directional leader propagation were observed by means of optics and VHF radiation during the triggered lightning discharges. Some lightning protection devices have been tested using the artificial lightning triggering techniques. In addition, the correlation between lightning activities and weather and climate was preliminarily studied.

  9. The lightning activities in super typhoons over the Northwest Pacific

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The spatial and temporal characteristics of lightning activities have been studied in seven super typhoons from 2005 to 2008 over the Northwest Pacific, using data from the World Wide Lightning Location Network (WWLLN). The results indicated that there were three distinct lightning flash regions in mature typhoon, a significant maximum in the eyewall regions (20-80 km from the center), a minimum from 80-200 km, and a strong maximum in the outer rainbands (out of 200 km from the center). The lightning flashes in the outer rainbands were much more than those in the inner rainbands, and less than 1% of flashes occurred within 100 km of the center. Each typhoon produced eyewall lightning outbreak during the periods of its intensification, usually several hours prior to its maximum intensity, indicating that lightning activity might be used as a proxy of intensification of super typhoon. Little lightning occurred near the center after landing of the typhoon.

  10. Irregularities of ionospheric VTEC during lightning activity over Antarctic Peninsula

    Science.gov (United States)

    Suparta, W.; Nor, W. N. A. Wan Mohd

    2017-05-01

    This paper investigates the irregularities of vertical total electron content (VTEC) during lightning activity and geomagnetic quiet days over Antarctic Peninsula in year 2014. During the lightning event, the ionosphere may be disturbed which may cause disruption in the radio signal. Thus, it is important to understand the influence of lightning on VTEC in the study of upper-lower interaction. The lightning data is obtained from World Wide Lightning Location Network (WWLLN) and the VTEC data has analyzed from Global Positioning System (GPS) for O’Higgins (OHI3), Palmer (PALV), and Rothera (ROTH). The results demonstrate the VTEC variation of ∼0.2 TECU during low lightning activity which could be caused by energy dissipation through lightning discharges from troposphere into the thermosphere.

  11. Estimation of Lightning Return Stroke Speed Using Elve Observations

    Science.gov (United States)

    Blaes, P.; Marshall, R. A.; Inan, U.

    2014-12-01

    Elves are optical emissions in the D-region ionosphere that are a result of collisional heating from the intense lightning electromagnetic pulse (EMP). The shape of elves is determined by the EMP radiation pattern at D-region altitudes, which is in turn controlled by the geometry and current propagation properties of the return stroke channel. In particular, numerical simulation of the EMP-ionosphere interaction shows a strong relationship between the elve "hole" radius and the current return stroke speed. During the summer of 2013, hundreds of elves were observed from Langmuir Laboratory, in New Mexico, with the PIPER high-speed photometer. Of these, 55 had an appropriate viewing geometry in which the elve hole is observable and is not corrupted by cloud flashes or sprites. An "emission profile", characterizing the elve emissions versus radius and time, is fit to each of these events using a constrained least squares reconstruction, allowing easy extraction of the elve hole radius. Using these measured radii in conjunction with the numerical EMP model, we perform Bayesian inference to estimate the distribution of return stroke speeds. The MTLL engineering model is assumed for the current propagation with reasonable priors for the parameters. The results show a maximum a posteriori probability return stroke speed estimate of 0.64c for elve producing lightning.

  12. A Multipole Expansion Method for Analyzing Lightning Field Changes

    Science.gov (United States)

    Koshak, William J.; Krider, E. Philip; Murphy, Martin J.

    1999-01-01

    Changes in the surface electric field are frequently used to infer the locations and magnitudes of lightning-caused changes in thundercloud charge distributions. The traditional procedure is to assume that the charges that are effectively deposited by the flash can be modeled either as a single point charge (the Q model) or a point dipole (the P model). The Q model has four unknown parameters and provides a good description of many cloud-to-ground (CG) flashes. The P model has six unknown parameters and describes many intracloud (IC) discharges. In this paper we introduce a new analysis method that assumes that the change in the cloud charge can be described by a truncated multipole expansion, i.e., there are both monopole and dipole terms in the unknown source distribution, and both terms are applied simultaneously. This method can be used to analyze CG flashes that are accompanied by large changes in the cloud dipole moment and complex IC discharges. If there is enough information content in the measurements, the model can also be generalized to include quadrupole and higher order terms. The parameters of the charge moments are determined using a dme-dimensional grid search in combination with a linear inversion, and because of this, local minima in the error function and the associated solution ambiguities are avoided. The multipole method has been tested on computer-simulated sources and on natural lightning at the NASA Kennedy Space Center and U.S. Air Force Eastern Range.

  13. A Fiber-Optic Aircraft Lightning Current Measurement Sensor

    Science.gov (United States)

    Nguyen, Truong X.; Ely, Jay J.; Szatkowski, George N.

    2013-01-01

    A fiber-optic current sensor based on the Faraday Effect is developed for aircraft installations. It can measure total lightning current amplitudes and waveforms, including continuing current. Additional benefits include being small, lightweight, non-conducting, safe from electromagnetic interference, and free of hysteresis and saturation. The Faraday Effect causes light polarization to rotate in presence of magnetic field in the direction of light propagation. Measuring the total induced light polarization change yields the total current enclosed. The system operates at 1310nm laser wavelength and can measure approximately 300 A - 300 kA, a 60 dB range. A reflective polarimetric scheme is used, where the light polarization change is measured after a round-trip propagation through the fiber. A two-detector setup measures the two orthogonal polarizations for noise subtraction and improved dynamic range. The current response curve is non-linear and requires a simple spline-fit correction. Effects of high current were achieved in laboratory using combinations of multiple fiber and wire loops. Good result comparisons against reference sensors were achieved up to 300 kA. Accurate measurements on a simulated aircraft fuselage and an internal structure illustrate capabilities that maybe difficult with traditional sensors. Also tested at a commercial lightning test facility from 20 kA to 200 kA, accuracy within 3-10% was achieved even with non-optimum setups.

  14. The verification of lightning location accuracy in Finland deduced from lightning strikes to trees

    Science.gov (United States)

    Mäkelä, Antti; Mäkelä, Jakke; Haapalainen, Jussi; Porjo, Niko

    2016-05-01

    We present a new method to determine the ground truth and accuracy of lightning location systems (LLS), using natural lightning strikes to trees. Observations of strikes to trees are being collected with a Web-based survey tool at the Finnish Meteorological Institute. Since the Finnish thunderstorms tend to have on average a low flash rate, it is often possible to identify from the LLS data unambiguously the stroke that caused damage to a given tree. The coordinates of the tree are then the ground truth for that stroke. The technique has clear advantages over other methods used to determine the ground truth. Instrumented towers and rocket launches measure upward-propagating lightning. Video and audio records, even with triangulation, are rarely capable of high accuracy. We present data for 36 quality-controlled tree strikes in the years 2007-2008. We show that the average inaccuracy of the lightning location network for that period was 600 m. In addition, we show that the 50% confidence ellipse calculated by the lightning location network and used operationally for describing the location accuracy is physically meaningful: half of all the strikes were located within the uncertainty ellipse of the nearest recorded stroke. Using tree strike data thus allows not only the accuracy of the LLS to be estimated but also the reliability of the uncertainty ellipse. To our knowledge, this method has not been attempted before for natural lightning.

  15. Fluctuations and Anharmonicity in Lead Iodide Perovskites from Molecular Dynamics Supercell Simulationss

    KAUST Repository

    Carignano, Marcelo Andrés

    2017-09-05

    We present a systematic study based on first principles molecular dynamics simulations of lead iodide perovskites with three different cations, including methylammonium (MA), formamidinium (FA) and cesium. Using the high temperature perovskite structure as a reference, we investigate the instabilities that develop as the material is cooled down to 370 K. All three perovskites display anharmonicity in the motion of the iodine atoms, with the stronger effect observed for the MAPbI$_3$ and CsPbI$_3$. At high temperature, this behavior can be traced back to the reduced effective size of the Cs$^+$ and MA$^+$ cations. MAPbI$_3$ undergoes a spontaneous phase transition within our simulation model driven by the dipolar interaction between neighboring MA cations as the temperature is decreased from 450 K. The reverse transformation from tetragonal to cubic is also monitored through the large distribution of the octahedral tilting angles accompanied by an increase in the anharmonicity of the iodine atoms motion. Both MA and FA hybrid perovskites show a strong coupling between the molecular orientations and the local lattice deformations, suggesting mixed order-disorder/displacive characters of the high temperature phase transitions.

  16. Lightning Pin Injection Testing on MOSFETS

    Science.gov (United States)

    Ely, Jay J.; Nguyen, Truong X.; Szatkowski, George N.; Koppen, Sandra V.; Mielnik, John J.; Vaughan, Roger K.; Wysocki, Philip F.; Celaya, Jose R.; Saha, Sankalita

    2009-01-01

    Lightning transients were pin-injected into metal-oxide-semiconductor field-effect transistors (MOSFETs) to induce fault modes. This report documents the test process and results, and provides a basis for subsequent lightning tests. MOSFETs may be present in DC-DC power supplies and electromechanical actuator circuits that may be used on board aircraft. Results show that unprotected MOSFET Gates are susceptible to failure, even when installed in systems in well-shielded and partial-shielded locations. MOSFET Drains and Sources are significantly less susceptible. Device impedance decreased (current increased) after every failure. Such a failure mode may lead to cascading failures, as the damaged MOSFET may allow excessive current to flow through other circuitry. Preliminary assessments on a MOSFET subjected to 20-stroke pin-injection testing demonstrate that Breakdown Voltage, Leakage Current and Threshold Voltage characteristics show damage, while the device continues to meet manufacturer performance specifications. The purpose of this research is to develop validated tools, technologies, and techniques for automated detection, diagnosis and prognosis that enable mitigation of adverse events during flight, such as from lightning transients; and to understand the interplay between lightning-induced surges and aging (i.e. humidity, vibration thermal stress, etc.) on component degradation.

  17. Lightning driven EMP in the upper atmosphere

    Science.gov (United States)

    Rowland, H. L.; Fernsler, R. F.; Huba, J. D.; Bernhardt, P. A.

    1995-01-01

    Large lightning discharges can drive electromagnetic pulses (EMP) that cause breakdown of the neutral atmosphere between 80 and 95 km leading to order of magnitude increases in the plasma density. The increase in the plasma density leads to increased reflection and absorption, and limits the pulse strength that propagates higher into the ionosphere.

  18. 14 CFR 35.38 - Lightning strike.

    Science.gov (United States)

    2010-01-01

    ... Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: PROPELLERS Tests and Inspections § 35.38 Lightning strike. The applicant must demonstrate, by tests, analysis based on tests, or experience on similar designs, that the propeller can withstand...

  19. Lightning detection and exposure algorithms for smartphones

    Science.gov (United States)

    Wang, Haixin; Shao, Xiaopeng; Wang, Lin; Su, Laili; Huang, Yining

    2015-05-01

    This study focuses on the key theory of lightning detection, exposure and the experiments. Firstly, the algorithm based on differential operation between two adjacent frames is selected to remove the lightning background information and extract lighting signal, and the threshold detection algorithm is applied to achieve the purpose of precise detection of lightning. Secondly, an algorithm is proposed to obtain scene exposure value, which can automatically detect external illumination status. Subsequently, a look-up table could be built on the basis of the relationships between the exposure value and average image brightness to achieve rapid automatic exposure. Finally, based on a USB 3.0 industrial camera including a CMOS imaging sensor, a set of hardware test platform is established and experiments are carried out on this platform to verify the performances of the proposed algorithms. The algorithms can effectively and fast capture clear lightning pictures such as special nighttime scenes, which will provide beneficial supporting to the smartphone industry, since the current exposure methods in smartphones often lost capture or induce overexposed or underexposed pictures.

  20. Supercell convergence of charge-transfer energies in pentacene molecular crystals from constrained DFT

    CERN Document Server

    Turban, David H P; O'Regan, David D; Hine, Nicholas D M

    2016-01-01

    Singlet fission (SF) is a multi-exciton generation process that could be harnessed to improve the efficiency of photovoltaic devices. Experimentally, systems derived from the pentacene molecule have been shown to exhibit ultrafast SF with high yields. Charge-transfer (CT) configurations are likely to play an important role as intermediates in the SF process in these systems. In molecular crystals, electrostatic screening effects and band formation can be significant in lowering the energy of CT states, enhancing their potential to effectively participate in SF. In order to simulate these, it desirable to adopt a computational approach which is acceptably accurate, relatively inexpensive, which and scales well to larger systems, thus enabling the study of screening effects. We propose a novel, electrostatically-corrected constrained Density Functional Theory (cDFT) approach as a low-cost solution to the calculation of CT energies in molecular crystals such as pentacene. Here we consider an implementation in th...

  1. Acute transient hemiparesis induced by lightning strike.

    Science.gov (United States)

    Rahmani, Seyed Hesam; Faridaalaee, Gholamreza; Jahangard, Samira

    2015-07-01

    According to data from the National Oceanic and Atmospheric Administration,in the years from 1959 to 1994, lightning was responsible for more than 3000 deaths and nearly 10,000 casualties. The most important characteristic features of lightning injuries are multisystem involvement and widely variable severity. Lightning strikes are primarily a neurologic injury that affects all 3 components of the nervous system: central, autonomic,and peripheral. Neurologic complications of lightning strikes vary from transient benign symptoms to permanent disability. Many patients experience a temporary paralysis called keraunoparalysis. Here we reported a 22-year-old mountaineer man with complaining of left sided hemiparesis after being hit by a lightning strike in the mountain 3 hours ago. There was no loss of consciousness at hitting time. On arrival the patient was alert, awake and hemodynamically stable. In neurologic examination cranial nerves were intact, left sided upper and lower extremity muscle force was I/V with a combination of complete sensory loss, and right-sided muscle force and sensory examination were normal. There is not any evidence of significant vascular impairment in the affected extremities. Brain MRI and CT scan and cervical MRI were normal. During 2 days of admission, with intravenous hydration, heparin 5000 unit SC q12hr and physical therapy of the affected limbs, motor and sensory function improved and was normal except mild paresthesia. He was discharged 1 day later for outpatient follow up while vitamin B1 100mg orally was prescribed.Paresthesia improved after 3 days without further sequels.

  2. Ionospheric effects of whistler waves from rocket-triggered lightning

    Science.gov (United States)

    Cotts, B. R. T.; Gołkowski, M.; Moore, R. C.

    2011-12-01

    Lightning-induced electron precipitation (LEP) is one of the primary mechanisms for energetic electron loss from Earth's radiation belts. While previous works have emphasized lightning location and the return stroke peak current in quantifying lightning's role in radiation belt electron loss, the spectrum of the lightning return stroke has received far less attention. Rocket-triggered lightning experiments performed at the International Center for Lightning Research and Testing (ICLRT) at Camp Blanding, Florida, provide a means to directly measure the spectral content of individual lightning return strokes. Using an integrated set of numerical models and directly observed rocket-triggered lightning channel-base currents we calculate the latitudinal dependence of the precipitation signature. Model results indicate that rocket-triggered lightning may produce detectable LEP events and that return strokes with higher ELF (3 Hz-3 kHz) content cause proportionally more ionospheric ionization and precipitate more electrons at higher latitudes than return strokes with proportionally higher VLF (3 kHz-30 kHz) content. The predicted spatio-temporal signature of the induced electron precipitation is highly dependent upon the return stroke spectral content. As a result, we postulate that rocket-triggered lightning experiments enable us to the estimate the spectral profile of energetic electrons precipitated from the Earth's radiation belts.

  3. Lightning Sensors for Observing, Tracking and Nowcasting Severe Weather

    Science.gov (United States)

    Price, Colin

    2008-01-01

    Severe and extreme weather is a major natural hazard all over the world, often resulting in major natural disasters such as hail storms, tornados, wind storms, flash floods, forest fires and lightning damages. While precipitation, wind, hail, tornados, turbulence, etc. can only be observed at close distances, lightning activity in these damaging storms can be monitored at all spatial scales, from local (using very high frequency [VHF] sensors), to regional (using very low frequency [VLF] sensors), and even global scales (using extremely low frequency [ELF] sensors). Using sensors that detect the radio waves emitted by each lightning discharge, it is now possible to observe and track continuously distant thunderstorms using ground networks of sensors. In addition to the number of lightning discharges, these sensors can also provide information on lightning characteristics such as the ratio between intra-cloud and cloud-to-ground lightning, the polarity of the lightning discharge, peak currents, charge removal, etc. It has been shown that changes in some of these lightning characteristics during thunderstorms are often related to changes in the severity of the storms. In this paper different lightning observing systems are described, and a few examples are provided showing how lightning may be used to monitor storm hazards around the globe, while also providing the possibility of supplying short term forecasts, called nowcasting. PMID:27879700

  4. ALDF Data Retrieval Algorithms for Validating the Optical Transient Detector (OTD) and the Lightning Imaging Sensor (LIS)

    Science.gov (United States)

    Koshak, W. J.; Blakeslee, R. J.; Bailey, J. C.

    1997-01-01

    A linear algebraic solution is provided for the problem of retrieving the location and time of occurrence of lightning ground strikes from in Advanced Lightning Direction Finder (ALDF) network. The ALDF network measures field strength, magnetic bearing, and arrival time of lightning radio emissions and solutions for the plane (i.e.. no Earth curvature) are provided that implement all of these measurements. The accuracy of the retrieval method is tested using computer-simulated data sets and the relative influence of bearing and arrival time data on the outcome of the final solution is formally demonstrated. The algorithm is sufficiently accurate to validate NASA's Optical Transient Detector (OTD) and Lightning Imaging System (LIS). We also introduce a quadratic planar solution that is useful when only three arrival time measurements are available. The algebra of the quadratic root results are examined in detail to clarify what portions of the analysis region lead to fundamental ambiguities in source location. Complex root results are shown to be associated with the presence of measurement errors when the lightning source lies near an outer sensor baseline of the ALDF network. For arbitrary noncollinear network geometries and in the absence of measurement errors, it is shown that the two quadratic roots are equivalent (no source location ambiguity) on the outer sensor baselines. The accuracy of the quadratic planar method is tested with computer-generated data sets and the results are generally better than those obtained from the three station linear planar method when bearing errors are about 2 degrees.

  5. Coarse graining approach to First principles modeling of radiation cascade in large Fe super-cells

    Science.gov (United States)

    Odbadrakh, Khorgolkhuu; Nicholson, Don; Rusanu, Aurelian; Wang, Yang; Stoller, Roger; Zhang, Xiaoguang; Stocks, George

    2012-02-01

    First principles techniques employed to understand systems at an atomistic level are not practical for large systems consisting of millions of atoms. We present an efficient coarse graining approach to bridge the first principles calculations of local electronic properties to classical Molecular Dynamics (MD) simulations of large structures. Local atomic magnetic moments in crystalline Fe are perturbed by radiation generated defects. The effects are most pronounced near the defect core and decay with distance. We develop a coarse grained technique based on the Locally Self-consistent Multiple Scattering (LSMS) method that exploits the near-sightedness of the electron Green function. The atomic positions were determined by MD with an embedded atom force field. The local moments in the neighborhood of the defect cores are calculated with first-principles based on full local structure information. Atoms in the rest of the system are modeled by representative atoms with approximated properties. This work was supported by the Center for Defect Physics, an Energy Frontier Research Center funded by the US Department of Energy, Office of Science, Office of Basic Energy Sciences.

  6. Lightning Processes And Dynamics Of Large Scale Optical Emissions In Long Delayed Sprites

    Science.gov (United States)

    Li, J.; Cummer, S. A.; Lyons, W. A.; Nelson, T. E.; Hu, W.

    2006-12-01

    Simultaneous measurements of high altitude optical emissions and the magnetic field produced by sprite-associated lightning discharges enable a close examination of the link between low altitude lightning process and high altitude sprite process. In this work, we report results of the coordinated analysis of high speed (1000--10000 frames per second) sprite video and wideband (0.1 Hz to 30 kHz) magnetic field measurements made simultaneously at the Yucca Ridge Field Station and Duke University during the June through August 2005 campaign period. We investigate the relationship of lightning charge transfer characteristics and long delayed (>30 ms) sprites after the lightning return stroke. These long delayed sprites initiated after a total vertical charge moment change from a few thousand C km to more than ten thousand C km. Continuing currents provide about 50% to 90% of this total charge transfer depending on the sprite delayed time and amplitude of continuing current. Our data also show that intense continuing current bigger than a few kA plays an important role in sprites whose primary optical emissions last unusually long (>30 ms). On one observation night (4 July 2005), a large mesoscale convective system produced many sprites that were part of complex transient luminous event (TLE) sequences that included optical emission elements that appear well after any return stroke and initiate at apparently relatively low altitudes (~ 50 km). These low initiation altitude sprite events are typically associated with intense continuing currents and total charge moment changes of 4000 C km or more. With the estimated lightning source current moment waveform, we also employ a 2-D FDTD model to numerically simulate the electric field at different altitudes and compare it with the breakdown field. This reveals the initiation altitude of those long delayed sprites and the effect of electric field dependence of the electron mobility.

  7. A model for electric field enhancement in lightning leader tips to levels allowing X-ray and γ ray emissions

    DEFF Research Database (Denmark)

    Babich, L. P.; Bochkov, E. I.; Kutsyk, I. M.;

    2015-01-01

    A model is proposed capable of accounting for the local electric field increase in front of the lightning stepped leader up to magnitudes allowing front electrons to overcome the runaway energy threshold and thus to initiate relativistic runaway electron avalanches capable of generating X......-ray and ray bursts observed in negative lightning leader. The model is based on an idea that an ionization wave, propagating in a preionized channel, is being focused, such that its front remains narrow and the front electric field is being enhanced. It is proposed that when a space leader segment, formed...... ahead of a negative lightning leader, connects to the leader, the electric potential of the leader is transferred through the space leader in an ionizing wave that continues into the partly ionized channels of preexisting streamers of the space leader. It is shown with numerical simulations...

  8. Electric Field Change and VHF Radiation during Lightning Initiation

    Science.gov (United States)

    Marshall, T. C.; Karunarathne, S.; Bandara, S. A.; Karunarathne, N. D.; Siedlecki, R.; Stolzenburg, M.

    2016-12-01

    Recent studies of lightning initiation [e.g., Marshall et al., JGR 2014; Marshall et al., AGU 2015] have shown that an initial electric field change (IEC) occurs for about 1 ms before the first initial breakdown (IB) pulse in most (and perhaps all) lightning flashes. The same studies indicate that the IEC itself begins after an event that radiates strongly in the VHF radio band; this event seems to be the real lightning initiation event [e.g., Rison et al., Nature Communications 2016]. During the summer of 2016 we used an array of E-change sensors and VHF sensors located in north Mississippi to obtain correlated data on the VHF lightning initiation event, the IEC, and the IB pulses of nearby lightning flashes. In this presentation we show examples of lightning initiation events and their subsequent IECs at multiple sensors. In addition, we show examples of the VHF radiation associated with IB pulses.

  9. Weekly Cycle of Lightning: Evidence of Storm Invigoration by Pollution

    Science.gov (United States)

    Bell, Thomas L.; Rosenfeld, Daniel; Kim, Kyu-Myong

    2009-01-01

    We have examined summertime 1998 2009 U.S. lightning data from the National Lightning Detection Network (NLDN) to look for weekly cycles in lightning activity. As was found by Bell et al. (2008) for rain over the southeast U.S., there is a significant weekly cycle in afternoon lightning activity that peaks in the middle of the week there. The weekly cycle appears to be reduced over population centers. Lightning activity peaks on weekends over waters near the SE U.S. The statistical significance of weekly cycles over the western half of the country is generally small. We found no evidence of a weekly cycle of synoptic-scale forcing that might explain these patterns. The lightning behavior is entirely consistent with the explanation suggested by Bell et al. (2008) for the cycles in rainfall and other atmospheric data from the SE U.S., that aerosols can cause storms to intensify in humid, convectively unstable environments.

  10. Chasing Lightning: Sferics, Tweeks and Whistlers

    Science.gov (United States)

    Webb, P. A.; Franzen, K.; Garcia, L.; Schou, P.; Rous, P.

    2008-12-01

    We all know what lightning looks like during a thunderstorm, but the visible flash we see is only part of the story. This is because lightning also generates light with other frequencies that we cannot perceive with our eyes, but which are just as real as visible light. Unlike the visible light from lightning, these other frequencies can carry the lightning's energy hundreds or thousands of miles across the surface of the Earth in the form of special signals called "tweeks" and "sferics". Some of these emissions can even travel tens of thousands of miles out into space before returning to the Earth as "whistlers". The INSPIRE Project, Inc is a non-profit scientific and educational corporation whose beginning mission was to bring the excitement of observing these very low frequency (VLF) natural radio waves emissions from lightning to high school students. Since 1989, INSPIRE has provided specially designed radio receiver kits to over 2,600 participants around the world to make observations of signals in the VLF frequency range. Many of these participants are using the VLF data they collect in very creative projects that include fiction, music and art exhibitions. During the Fall 2008 semester, the first INSPIRE based university-level course was taught at University of Maryland Baltimore County (UMBC) as part of its First-Year Seminar (FYS) series. The FYS classes are limited to 20 first-year students per class and are designed to create an active-learning environment that encourages student participation and discussion that might not otherwise occur in larger first-year classes. This presentation will cover the experiences gained from using the INSPIRE kits as the basis of a university course. This will include the lecture material that covers the basic physics of lightning, thunderstorms and the Earth's atmosphere, as well as the electronics required to understand the basic workings of the VLF kit. It will also cover the students assembly of the kit in an

  11. Mechanisms of the global electric circuit and lightning variability on the ENSO time scale

    Science.gov (United States)

    Mareev, Evgeny; Volodin, Evgeny; Slyunyaev, Nikolay

    2017-04-01

    Many studies of lightning activity on the El Niño-Southern Oscillation (ENSO) time scale show increased activity over tropical land areas during the warm El Niño phase (e.g., Satori et al., 2009; Price, 2009). The mechanisms of this variability—particularly in terms of its role in the global electric circuit (GEC)—are still under debate (e.g., Williams and Mareev, 2014). In this study a general circulation model of the atmosphere and ocean INMCM4.0 (Institute of Numerical Mathematics Coupled Model) is used for modelling the GEC variability on the ENSO time scale. The ionospheric potential (IP) and the lightning flash rate are calculated to study regional peculiarities and possible mechanisms of lightning variation. The IP parameterisation is used (Mareev and Volodin, 2014) which takes into account quasi-stationary currents of electrified clouds (including thunderstorms) as principal contributors into the DC global circuit. The account of conductivity variation in the IP parameterisation is suggested based on the approach realised in (Slyunyaev et al., 2014). Comparison of simulation results with the observational data on lightning activity on the ENSO time scale is discussed. Numerical simulations suggest that the inter-annual IP variability is low and does not exceed 1% of the mean value, being tightly correlated with the mean sea surface temperature (SST) in the Pacific Ocean (180W-100W, 5S-5N—El Niño area). The IP maximum corresponds to the SST minimum. This result can be explained taking into account that during El Niño (positive temperature anomaly) precipitations in the equatorial part of the Pacific increase while in other tropic zones including the land areas they decrease. Comparison of simulation results with the observational data on lightning activity on the ENSO time scale is discussed. During the El Niño period in the model, the mean aerosol content in the atmosphere decrease, which is caused by the weakening of the winds over Sahara and

  12. Synthesis of nitrous oxide by lightning in the early anoxic Earth's atmosphere

    Science.gov (United States)

    Navarro, K. F.; Navarro-Gonzalez, R.; McKay, C. P.

    2013-12-01

    Carbon dioxide (CO2) was the main atmospheric component of the early Earth's atmosphere and exerted a key role in climate by maintaining a hydrosphere during a primitive faint Sun [1]; however, CO2 was eventually removed from the atmosphere by rock weathering and sequestered in the Earth's crust and mantle [1]. Nitric oxide (NO) was fixed by lightning discharges at a rate of 1×1016 molecules J-1 in CO2 (50-80%) rich atmospheres [2]. As the levels of atmospheric CO2 dropped to 20%, the production rate of NO by lightning rapidly decreased to 2×1014 molecules J-1 and then slowly diminished to 1×1014 molecules J-1 at CO2 levels of about 2.5% [2]. In order to maintain the existence of liquid water in the early Earth, it is required to warm up the planet with other greenhouse gases such as methane (CH4) [3]. Here we report an experimental study of the effects of lightning discharges on the nitrogen fixation rate during the evolution of the Earth's early atmosphere from 10 to 0.8 percent of carbon dioxide with methane concentrations from 0 to 1,000 ppm in molecular nitrogen. Lightning was simulated in the laboratory by a plasma generated with a pulsed Nd-YAG laser [2]. Our results show that the production of NO by lightning is independent of the presence of methane but drops from 3×1014 molecules J-1 in 10% CO2 to 5×1013 molecules J-1 in 1% CO2. Surprisingly, nitrous oxide (N2O) is also produced at a rate of 4×1013 molecules J-1 independent of the levels of CH4 and CO2. N2O is produced by lightning in the contemporaneous oxygenated Earth's atmosphere at a comparable rate of (0.4-1.5)×1013 molecules J-1 [4, 5], but was not detected in nitrogen-carbon dioxide mixtures in the absence of oxygen [6]. The only previously reported abiotic synthesis of N2O was by corona discharges in rich CO2 atmospheres (20-80%) with a production rate of 8×1012 molecules J-1 [6]; however at lower CO2 (atmosphere was the main source of N2O in nitrogen dominated atmospheres. N2O is not

  13. Protection of large wind turbine blades against lightning

    OpenAIRE

    Montañá Puig, Juan; Rachidi-Haeri, Farhad; Rubinstein, Marcos; Bermúdez, José Luis; Solà de Las Fuentes, Gloria; Hermoso Alameda, Blas

    2008-01-01

    Lightning protection of modern wind turbines presents a number of new challenges due to the geometrical, electrical and mechanical particularities of the turbines. The risk assessment requires the estimation of the number of expected strikes. In the case of modern turbines, most of the expected lightning flashes will be upward. In addition, due to the rotation of the blades, modern wind turbines may trigger their own lightning. Moreover, since wind turbines are becoming tall struc...

  14. Total Lightning Characteristics and Electric Structure Evolution in a Hailstorm

    Institute of Scientific and Technical Information of China (English)

    ZHENG Dong; ZHANG Yijun; MENG Qing; LU Weitao; YI Xiaoyuan

    2009-01-01

    In this paper, total lightning data observed by SAFIR3000 3-D Lightning Locating System was combined with radar data to analyze characteristics of the lightning activity and electric structure of a hailstorm that occurred in Beijing on 31 May 2005. The results indicated that there were two active periods for the lightning activity during the hailstorm process. The hail shooting was found in the first period. After the end of the hail shooting, lightning frequency decreased suddenly. However, more active lightning activities occurred in the second period with lots of them appearing in the cloud anvil region. The peak of the lightning frequency came about 5 rain prior to the hail shooting. Only 6.16% of the total lightning was cloud-to-ground (CG) lightning, among which 20% had positive polarity. This percentage was higher than that in normal thunderstorms. In addition, heavier positive CG lightning discharge occurred before rather than after the hail shooting. In the stage of the hail shooting, the electric structure of the hailstorm was inverted, with the main negative charge region located around the -40℃ level and the main positive charge region around the -15℃ level. In addition, a weak negative charge region existed below the positive charge region transitorily. After the hail shooting, the electric structure underwent fast and persistent adjustments and became a normal tripole, with positive charge in the upper and lower levels and negative charge in the middle levels. However, the electric structure was tilted under the influence of the westerly wind in the middle and upper levels. The lightning activity and electric structure were closely related to the dynamic and microphysical processes of the hailstorm. It was believed that severe storms with stronger updrafts were more conducive to an inverted tripolar electric structure than normal thunderstorms, and the inverted distribution could then facilitate more positive CG lightning in the severe storms.

  15. OBSERVATIONAL STUDY OF LIGHTNING CHARACTERISTICS IN HAIL-PRODUCING CLOUDS

    Institute of Scientific and Technical Information of China (English)

    LI Zhao-rong; FU Shuang-xi; LI Bao-zi; JIANG Lin

    2006-01-01

    @@ 1 INTRODUCTION Lightning is a phenomenon of atmospheric electricity with convective storms. Since the 1960's, its characteristics during weather processes of torrential rain, hails and tornadoes have been widely studied and a lot of attempts made to probe into the mechanisms responsible for the formation of lightning[1], giving rise to two theories explaining the lightning genesis, from the points of convection and ice-phase precipitation,respectively.

  16. New method for lightning location using optical ground wire

    Institute of Scientific and Technical Information of China (English)

    Zhaoyu Qin; Zhaogu Cheng; Zhiping Zhang; Jianqiang Zhu; Feng Li

    2006-01-01

    A new technology of lightning location is described, which is based on detecting the state of polarization(SOP) fluctuation of the laser light in the optic ground wire (OPGW). Compared with the conventional lightning location method, the new method is more accurate, more stable, and cheaper. Theories of Stokes generated by lightning strike can still be accurately identified by detecting the velocity of polarization motion. A new algorithm to quantify the velocity is also introduced.

  17. The lightning heart: a case report and brief review of the cardiovascular complications of lightning injury.

    Science.gov (United States)

    McIntyre, William F; Simpson, Christopher S; Redfearn, Damian P; Abdollah, Hoshiar; Baranchuk, Adrian

    2010-09-05

    Lightning strike is a rare natural phenomenon, which carries a risk of dramatic medical complications to multiple organ systems and a high risk of fatality. The known complications include but are not limited to: myocardial infarction, arrhythmia, cardiac contusion, stroke, cutaneous burns, respiratory disorders, neurological disorders, acute kidney injury and death. We report a case of a healthy young man who suffered a lightning injury and discuss the cardiovascular complications of lightning injury, ranging from ECG changes to death. The patient in our case, a 27-year old previously healthy male, developed a syndrome of rhabdomyolysis and symptomatic cardiogenic pulmonary edema. Electrocardiographic findings included transient T-wave inversions, late transition shift and long QT. His clinical condition improved with supportive measures.Early recognition of lightning injury syndromes and anticipation of complications may help us improve outcomes for these patients. Evaluation of patients having experienced a lightning injury should include a minimum of a detailed history and physical examination, 12-lead ECG and drawing of baseline troponins. Prolonged electrocardiographical monitoring (for monitoring of ventricular arrhythmias) and assessment for signs and symptoms of hemodynamic compromise may be warranted.

  18. Nowcasting of Lightning-Related Accidents in Africa

    Science.gov (United States)

    Ihrlich, Laura; Price, Colin

    2016-04-01

    Tropical Africa is the world capital of thunderstorm activity with the highest density of strikes per square kilometer per year. As a result it is also the continent with perhaps the highest casualties and injuries from direct lightning strikes. This region of the globe also has little lightning protection of rural homes and schools, while many casualties occur during outdoor activities (e.g. farming, fishing, sports, etc.) In this study we investigated two lightning-caused accidents that got wide press coverage: A lightning strike to a Cheetah Center in Namibia which caused a huge fire and great destruction (16 October 2013), and a plane crash in Mali where 116 people died (24 July 2014). Using data from the World Wide Lightning Location Network (WWLLN) we show that the lightning data alone can provide important early warning information that can be used to reduce risks and damages and loss of life from lightning strikes. We have developed a now-casting scheme that allows for early warnings across Africa with a relatively low false alarm rate. To verify the accuracy of our now-cast, we have performed some statistical analysis showing relatively high skill at providing early warnings (lead time of a few hours) based on lightning alone. Furthermore, our analysis can be used in forensic meteorology for determining if such accidents are caused by lightning strikes.

  19. High lightning activity in maritime clouds near Mexico

    Directory of Open Access Journals (Sweden)

    B. Kucienska

    2012-01-01

    Full Text Available Lightning activity detected by the World Wide Lightning Location Network (WWLLN over oceanic regions adjacent to Mexico is often as high as that observed over the continent. In order to explore the possible cause of the observed high flash density over those regions, the relationships between lightning, rainfall, vertical hydrometeor profiles, latent heating, wind variability and aerosol optical thickness are analyzed. The characteristics of lightning and precipitation over four oceanic zones adjacent to Mexican coastlines are contrasted against those over the continent. In addition, we compare two smaller regions over the Tropical Pacific Ocean: one located within the Inter-Tropical Converge Zone and characterized by high rainfall and weak lightning activity and the other influenced by a continental jet and presenting high rainfall and strong lightning activity over the Gulf of Tehuantepec. Maritime precipitating clouds that develop within the region influenced by offshore winds exhibit similar properties to continental clouds: large content of precipitation ice and an increased height range of coexistence of precipitation ice and cloud water. During the rainy season, monthly distribution of lightning within the region influenced by the continental jet is contrary to that of rainfall. Moreover, the monthly variability of lightning is very similar to the variability of the meridional wind component and it is also related to the variability of aerosol optical depth. The analysis strongly suggests that the high lightning activity observed over the Gulf of Tehuantepec is caused by continental cloud condensation nuclei advected over the ocean.

  20. Predicting the Probability of Lightning Occurrence with Generalized Additive Models

    Science.gov (United States)

    Fabsic, Peter; Mayr, Georg; Simon, Thorsten; Zeileis, Achim

    2017-04-01

    This study investigates the predictability of lightning in complex terrain. The main objective is to estimate the probability of lightning occurrence in the Alpine region during summertime afternoons (12-18 UTC) at a spatial resolution of 64 × 64 km2. Lightning observations are obtained from the ALDIS lightning detection network. The probability of lightning occurrence is estimated using generalized additive models (GAM). GAMs provide a flexible modelling framework to estimate the relationship between covariates and the observations. The covariates, besides spatial and temporal effects, include numerous meteorological fields from the ECMWF ensemble system. The optimal model is chosen based on a forward selection procedure with out-of-sample mean squared error as a performance criterion. Our investigation shows that convective precipitation and mid-layer stability are the most influential meteorological predictors. Both exhibit intuitive, non-linear trends: higher values of convective precipitation indicate higher probability of lightning, and large values of the mid-layer stability measure imply low lightning potential. The performance of the model was evaluated against a climatology model containing both spatial and temporal effects. Taking the climatology model as a reference forecast, our model attains a Brier Skill Score of approximately 46%. The model's performance can be further enhanced by incorporating the information about lightning activity from the previous time step, which yields a Brier Skill Score of 48%. These scores show that the method is able to extract valuable information from the ensemble to produce reliable spatial forecasts of the lightning potential in the Alps.

  1. Experiments of Wind Turbine Blades with Rocket Triggered Lightning

    Science.gov (United States)

    Minowa, Masayuki; Sumi, Shinichi; Minami, Masayasu; Horii, Kenji

    This paper describes the results of the experiments of wind turbine blades with rocket triggered lightning. A number of wind power stations have been projected and planted. Lightning damage to wind turbines has been an increasing problem recently. So development on protection of wind power plants from lightning is necessary to be fully run for the future. In the experiments, the 1.8m long blade was struck by the lightning discharge triggered by rocket. For the blade kept dry inside, the very strong discharge of positive peak current 28kV, total charge 520 Coulombs, was triggered, but the breakdown did not occur through the blade into inside. Another blade polluted by salty wet inside was struck by the lightning discharge of negative peak current of 4kA with 0.5 Coulombs. The lightning was small, nevertheless, the blade was broken at the upper edge and the blade was disconnected by crack. For the protection of blade, the blade surface was covered with stainless steel plate. The blade itself was safe when the big positive lightning discharged, while most part of stainless steel cover was burned out. Supplement breakdown tests of wind turbine blade were carried out with lightning impulse voltage in laboratory. As a result, it became clear that the blade kept dry inside was an effective lightning protection of wind turbine blades.

  2. Analysis of Conditions favorable for Ball Lightning Creation

    CERN Document Server

    Boerner, H

    2016-01-01

    This report uses a few well documented cases of Ball Lightning (or BL for short) observations to demonstrate a correlation between BL and positive lightning, especially strong positive lightning. This allows to draw conclusions and predictions about future BL observations and the pro- duction of these objects in the laboratory. Contrary to many current BL theories, these objects can be created without direct contact to a lightning channel. Very high electric fields appear to be essential for the creation, together with the proper temporal structure of the field. So far no experiments have been performed along the ideas presented in this report.

  3. Cochlear implantation for severe sensorineural hearing loss caused by lightning.

    Science.gov (United States)

    Myung, Nam-Suk; Lee, Il-Woo; Goh, Eui-Kyung; Kong, Soo-Keun

    2012-01-01

    Lightning strike can produce an array of clinical symptoms and injuries. It may damage multiple organs and cause auditory injuries ranging from transient hearing loss and vertigo to complete disruption of the auditory system. Tympanic-membrane rupture is relatively common in patients with lightning injury. The exact pathogenetic mechanisms of auditory lesions in lightning survivors have not been fully elucidated. We report the case of a 45-year-old woman with bilateral profound sensorineural hearing loss caused by a lightning strike, who was successfully rehabilitated after a cochlear implantation. Copyright © 2012 Elsevier Inc. All rights reserved.

  4. New method for lightning location using optical ground wire

    Science.gov (United States)

    Qin, Zhaoyu; Cheng, Zhaogu; Zhang, Zhiping; Zhu, Jianqiang; Li, Feng

    2006-12-01

    A new technology of lightning location is described, which is based on detecting the state of polarization (SOP) fluctuation of the laser light in the optic ground wire (OPGW). Compared with the conventional lightning location method, the new method is more accurate, more stable, and cheaper. Theories of Stokes parameters and Poincare sphere are introduced to analyze the SOP at the lightning strike point. It can be concluded that although the initial points of SOP on the Poincare sphere are random, the SOP fluctuation generated by lightning strike can still be accurately identified by detecting the velocity of polarization motion. A new algorithm to quantify the velocity is also introduced.

  5. Dust cloud lightning in extraterrestrial atmospheres

    CERN Document Server

    Helling, Christiane; Diver, Declan; Witte, Soeren

    2012-01-01

    Lightning is present in all solar system planets which form clouds in their atmospheres. Cloud formation outside our solar system is possible in objects with much higher temperatures than on Earth or on Jupiter: Brown dwarfs and giant extrasolar gas planets form clouds made of mixed materials and a large spectrum of grain sizes. These clouds are globally neutral obeying dust-gas charge equilibrium which is, on short timescales, inconsistent with the observation of stochastic ionization events of the solar system planets. We argue that a significant volume of the clouds in brown dwarfs and extrasolar planets is susceptible to local discharge events and that the upper cloud layers are most suitable for powerful lightning-like discharge events. We discuss various sources of atmospheric ionisation, including thermal ionisation and a first estimate of ionisation by cosmic rays, and argue that we should expect thunderstorms also in the atmospheres of brown dwarfs and giant gas planets which contain mineral clouds.

  6. Lightning Strikes and Attribution of Climatic Change

    CERN Document Server

    Webster, Anthony J

    2015-01-01

    Using lightning strikes as an example, two possible schemes are discussed for the attribution of changes in event frequency to climate change, and estimating the cost associated with them. The schemes determine the fraction of events that should be attributed to climatic change, and the fraction that should be attributed to natural chance. They both allow for the expected increase in claims and the fluctuations about this expected value. Importantly, the attribution fraction proposed in the second of these schemes is necessarily different to that found in epidemiological studies. This ensures that the statistically expected fraction of attributed claims is correctly equal to the expected increase in claims. The analysis of lightning data highlights two particular difficulties with data-driven, as opposed to modeled, attribution studies. The first is the possibility of unknown "confounding" variables that can influence the strike frequency. This is partly accounted for here by considering the influence of temp...

  7. Ionospheric effects of thunderstorms and lightning

    Energy Technology Data Exchange (ETDEWEB)

    Lay, Erin H. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2014-02-03

    Tropospheric thunderstorms have been reported to disturb the lower ionosphere (~65-90 km) by convective atmospheric gravity waves and by electromagnetic field changes produced by lightning discharges. However, due to the low electron density in the lower ionosphere, active probing of its electron distribution is difficult, and the various perturbative effects are poorly understood. Recently, we have demonstrated that by using remotely-detected ?me waveforms of lightning radio signals it is possible to probe the lower ionosphere and its fluctuations in a spatially and temporally-resolved manner. Here we report evidence of gravity wave effects on the lower ionosphere originating from the thunderstorm. We also report variations in the nighttime ionosphere atop a small thunderstorm and associate the variations with the storm’s electrical activity. Finally, we present a data analysis technique to map ionospheric acoustic waves near thunderstorms.

  8. Runaway breakdown and hydrometeors in lightning initiation.

    Science.gov (United States)

    Gurevich, A V; Karashtin, A N

    2013-05-03

    The particular electric pulse discharges are observed in thunderclouds during the initiation stage of negative cloud-to-ground lightning. The discharges are quite different from conventional streamers or leaders. A detailed analysis reveals that the shape of the pulses is determined by the runaway breakdown of air in the thundercloud electric field initiated by extensive atmospheric showers (RB-EAS). The high amplitude of the pulse electric current is due to the multiple microdischarges at hydrometeors stimulated and synchronized by the low-energy electrons generated in the RB-EAS process. The series of specific pulse discharges leads to charge reset from hydrometeors to the free ions and creates numerous stretched ion clusters, both positive and negative. As a result, a wide region in the thundercloud with a sufficiently high fractal ion conductivity is formed. The charge transport by ions plays a decisive role in the lightning leader preconditioning.

  9. An Assessment of Land Surface and Lightning Characteristics Associated with Lightning-Initiated Wildfires

    Science.gov (United States)

    Coy, James; Schultz, Christopher J.; Case, Jonathan L.

    2017-01-01

    Can we use modeled information of the land surface and characteristics of lightning beyond flash occurrence to increase the identification and prediction of wildfires? Combine observed cloud-to-ground (CG) flashes with real-time land surface model output, and Compare data with areas where lightning did not start a wildfire to determine what land surface conditions and lightning characteristics were responsible for causing wildfires. Statistical differences between suspected fire-starters and non-fire-starters were peak-current dependent 0-10 cm Volumetric and Relative Soil Moisture comparisons were statistically dependent to at least the p = 0.05 independence level for both polarity flash types Suspected fire-starters typically occurred in areas of lower soil moisture than non-fire-starters. GVF value comparisons were only found to be statistically dependent for -CG flashes. However, random sampling of the -CG non-fire starter dataset revealed that this relationship may not always hold.

  10. Lightning Protection for the Orion Space Vehicle

    Science.gov (United States)

    Scully, Robert

    2015-01-01

    The Orion space vehicle is designed to requirements for both direct attachment and indirect effects of lightning. Both sets of requirements are based on a full threat 200kA strike, in accordance with constraints and guidelines contained in SAE ARP documents applicable to both commercial and military aircraft and space vehicles. This paper describes the requirements as levied against the vehicle, as well as the means whereby the design shows full compliance.

  11. Joint voltages resulting from lightning currents.

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, William Arthur; Warne, Larry Kevin; Merewether, Kimball O.; Chen, Kenneth C.

    2007-03-01

    Simple formulas are given for the interior voltages appearing across bolted joints from exterior lightning currents. External slot and bolt inductances as well as internal slot and bolt diffusion effects are included. Both linear and ferromagnetic wall materials are considered. A useful simplification of the slot current distribution into linear stripline and cylindrical parts (near the bolts) allows the nonlinear voltages to be estimated in closed form.

  12. An overview of the lightning and atmospheric electricity observations collected in Southern France during the HYdrological cycle in Mediterranean EXperiment (HyMeX, Special Observation Period 1

    Directory of Open Access Journals (Sweden)

    E. Defer

    2014-08-01

    Full Text Available The PEACH (Projet en Electricité Atmosphérique pour la Campagne HyMeX – the Atmospheric Electricity Project of HyMeX Program project is the Atmospheric Electricity component of the HyMeX (Hydrology cycle in the Mediterranean Experiment experiment and is dedicated to the observation of both lightning activity and electrical state of continental and maritime thunderstorms in the area of the Mediterranean Sea. During the HyMeX SOP1 (Special Observation Period; 5 September–6 November 2012, four European Operational Lightning Locating Systems (OLLSs (ATDNET, EUCLID, LINET, ZEUS and the HyMeX Lightning Mapping Array network (HyLMA were used to locate and characterize the lightning activity over the Southeastern Mediterranean at flash, storm and regional scales. Additional research instruments like slow antennas, video cameras, micro-barometer and microphone arrays were also operated. All these observations in conjunction with operational/research ground-based and airborne radars, rain gauges and in situ microphysical records aimed at characterizing and understanding electrically active and highly precipitating events over Southeastern France that often lead to severe flash floods. Simulations performed with Cloud Resolving Models like Meso-NH and WRF are used to interpret the results and to investigate further the links between dynamics, microphysics, electrification and lightning occurrence. A description of the different instruments deployed during the field campaign as well as the available datasets is given first. Examples of concurrent observations from radio frequency to acoustic for regular and atypical lightning flashes are then presented showing a rather comprehensive description of lightning flashes available from the SOP1 records. Then examples of storms recorded during HyMeX SOP1 over Southeastern France are briefly described to highlight the unique and rich dataset collected. Finally the next steps of the work required for the

  13. Acoustic vs Interferometric Measurements of Lightning

    Science.gov (United States)

    Arechiga, R. O.; Erives, H.; Sonnenfeld, R. G.; Stanley, M. A.; Rison, W.; Thomas, R. J.; Edens, H. E.; Lapierre, J. L.; Stock, M.; Jensen, D.; Morris, K.

    2015-12-01

    During the summer of 2015 we acquired acoustic and RF data on severalflashes from thunderstorms over Fort Morgan CO. and Langmuir Laboratoryin the Magdalena mountains of central New Mexico. The acoustic arrayswere located at a distance of roughly 150 m from the interferometers.Lightning mapping array and slow antenna data were also obtained. Theacoustic arrays consist of arrays of five audio-range and six infrasoundmicrophones operating at 50 KHz and 1 KHz respectively. The lightninginterferometer at Fort Morgan CO. consists of three flat-plate, 13" diameterantennas at the vertices of an equilateral 50 m per side triangle. Theinterferometer at Langmuir Laboratory consists of three 13" dishes separatedby about 15 m. Both interferometers, operating at 180 Megasamples persecond, use the analysis software and digitizer hardware pioneered byStanley, Stock et al. The high data rate allows for excellent spatialresolution of high speed (and typically high current) processes such asK-changes, return strokes and dart-leaders. In previous studies, we haveshown the usefulness of acoustic recordings to locate thunder sources aswell as infrasound pulses from lightning. This work will present acomparison of Acoustic and Interferometric measurements from lightning,using some interesting flashes, including a positive cloud to ground,that occurred in these campaigns.

  14. Aerodynamically generated noise by lightning arrester

    Directory of Open Access Journals (Sweden)

    Váchová J.

    2007-10-01

    Full Text Available This paper presents the general solution of aerodynamically generated noise by lightning arrester. Governing equations are presented in form of Lighthill acoustic analogy, as embodied in the Ffowcs Williams-Hawkings (FW-H equation. This equation is based on conservation laws of fluid mechanics rather than on the wave equation. Thus, the FW-H equation is valid even if the integration surface is in nonlinear region. That’s why the FWH method is superior in aeroacoustics. The FW-H method is implemented in program Fluent and the numerical solution is acquired by Fluent code.The general solution of acoustic signal generated by lightning arrester is shown and the results in form of acoustic pressure and frequency spectrum are presented. The verification of accuracy was made by evaluation of Strouhal number. A comparison of Strouhal number for circumfluence of a cylinder and the lightning arrester was done, because the experimental data for cylinder case are known and these solids are supposed to be respectively in shape relation.

  15. Impact of lightning strikes on hospital functions.

    Science.gov (United States)

    Mortelmans, Luc J M; Van Springel, Gert L J; Van Boxstael, Sam; Herrijgers, Jan; Hoflacks, Stefaan

    2009-01-01

    Two regional hospitals were struck by lightning during a one-month period. The first hospital, which had 236 beds, suffered a direct strike to the building. This resulted in a direct spread of the power peak and temporary failure of the standard power supply. The principle problems, after restoring standard power supply, were with the fire alarm system and peripheral network connections in the digital radiology systems. No direct impact on the hardware could be found. Restarting the servers resolved all problems. The second hospital, which had 436 beds, had a lightning strike on the premises and mainly experienced problems due to induction. All affected installations had a cable connection from outside in one way or another. The power supplies never were endangered. The main problem was the failure of different communication systems (telephone, radio, intercom, fire alarm system). Also, the electronic entrance control went out. During the days after the lightening strike, multiple software problems became apparent, as well as failures of the network connections controlling the technical support systems. There are very few ways to prepare for induction problems. The use of fiber-optic networks can limit damage. To the knowledge of the authors, these are the first cases of lightning striking hospitals in medical literature.

  16. Lightning flash multiplicity in eastern Mediterranean thunderstorms

    Science.gov (United States)

    Yair, Y.; Shalev, S.; Erlich, Z.; Agrachov, A.; Katz, E.; Saaroni, H.; Price, C.; Ziv, B.

    2014-02-01

    Cloud-to-ground lightning flashes usually consist of one or several strokes coming in very short temporal succession and close spatial proximity. A commonly used method for converting stroke data into flashes is using the National Lightning Detection Network (NLDN) thresholds of maximum temporal separation of 0.5 s and maximum lateral distance of 10 km radius between successive strokes. In the present study, we tested a location-based algorithm with several spatial and temporal ranges, and analyzed stroke data obtained by the Israel Lightning Location System (ILLS) during one year (1.8.2009-31.7.2010). We computed the multiplicity, the percentage of single stroke flashes and the geographical distribution of average multiplicity values for thunderstorms in the Eastern Mediterranean region. Results show that for the NLDN thresholds, the percentage of single stroke flashes in Israel was 37% and the average multiplicity was 1.7. We reanalyzed the data with a spatial range that equals twice the ILLS location error and shorter times. For the new thresholds of maximum distance of 2.5 km and maximum allowed temporal separation of 0.2 s we find that the mean multiplicity of negative CGs is lowered to 1.4 and find a percentage of 58% of single stroke flashes. A unique severe storm from 30 October 2009 is analyzed and compared with the annual average of 2009/2010, showing that large deviations from the mean values can occur in specific events.

  17. An Overview of the Lightning - Atmospheric Chemistry Aspects of the Deep Convective Clouds and Chemistry (DC3) Experiment

    Science.gov (United States)

    Pickering, K. E.; Barth, M. C.; Koshak, W.; Bucsela, E. J.; Allen, D. J.; Weinheimer, A.; Ryerson, T.; Huntrieser, H.; Bruning, E.; MacGorman, D.; Krehbiel, P.; Thomas, R.; Carey, L.

    2012-01-01

    Some of the major goals of the DC3 experiment are to determine the contribution of lightning to NO(x) in the anvils of observed thunderstorms, examine the relationship of lightning NO(x) production to flash rates and to lightning channel lengths, and estimate the relative production per flash for cloud-to-ground flashes and intracloud flashes. In addition, the effects of lightning NO(x) production on photochemistry downwind of thunderstorms is also being examined. The talk will survey the observation types that were conducted during DC3 relevant to these goals and provide an overview of the analysis and modeling techniques which are being used to achieve them. NO(x) was observed on three research aircraft during DC3 (the NCAR G-V, the NASA DC-8, and the DLR Falcon) in flights through storm anvils in three study regions (NE Colorado, Central Oklahoma to West Texas, and northern Alabama) where lightning mapping arrays (LMAs) and radar coverage were available. Initial comparisons of the aircraft NOx observations in storm anvils relative to flash rates have been conducted, which will be followed with calculations of the flux of NO(x) through the anvils, which when combined with observed flash rates can be used to estimate storm-average lightning NOx production per flash. The WRF-Chem model will be run for cloud-resolved simulations of selected observed storms during DC3. Detailed lightning information from the LMAs (flash rates and flash lengths as a function of time and vertical distributions of flash channel segments) will be input to the model along with assumptions concerning NO(x) production per CG flash and per IC flash. These assumptions will be tested through comparisons with the aircraft NOx data from anvil traverses. A specially designed retrieval method for lightning NO2 column amounts from the OMI instrument on NASA fs Aura satellite has been utilized to estimate NO2 over the region affected by selected DC3 storms. Combined with NO(x) to NO2 ratios from the

  18. Review of the Lightning Shielding Against Direct Lightning Strokes Based on Laboratory Long Air Gap Discharges

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    It is one of the most effective ways to use laboratory long air gap discharges tbr investigating the fundamental process involved in the lightning strike. During the 1960s and the 1970s, the electro-geometrical method (EGM) and the rolling sphere method were developed base on the breakdown characteristics of negative long spark discharges, which have been widely used to design the lightning shielding system of transmission lines and structures. In recent years, the scale of the power facilities is increased dramatically with the rising of power grid's voltage level.

  19. Numerical study on Rayleigh-Taylor instabilities in the lightning return stroke

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Qiang, E-mail: cq0405@126.com [National Key Laboratory of Electromagnetic Environment and Electro-optical Engineering, PLA University of Science and Technology, Nanjing 210007 (China); Luoyang Electronic Equipment Testing Center, Luoyang 471000 (China); Chen, Bin, E-mail: emcchen@163.com; Shi, Lihua; Yi, Yun [National Key Laboratory of Electromagnetic Environment and Electro-optical Engineering, PLA University of Science and Technology, Nanjing 210007 (China); Wang, Yangyang [Department of Electro-optical Engineering, Electronic Engineering Institute of PLA, Hefei 230037 (China)

    2015-09-15

    The Rayleigh-Taylor (R-T) instabilities are important hydrodynamics and magnetohydrodynamics (MHD) phenomena that are found in systems in high energy density physics and normal fluids. The formation and evolution of the R-T instability at channel boundary during back-flow of the lightning return stroke are analyzed using the linear perturbation theory and normal mode analysis methods, and the linear growth rate of the R-T instability in typical condition for lightning return stroke channel is obtained. Then, the R-T instability phenomena of lightning return stroke are simulated using a two-dimensional Eulerian finite volumes resistive radiation MHD code. The numerical results show that the evolution characteristics of the R-T instability in the early stage of back-flow are consistent with theoretical predictions obtained by linear analysis. The simulation also yields more evolution characteristics for the R-T instability beyond the linear theory. The results of this work apply to some observed features of the return stroke channel and further advance previous theoretical and experimental work.

  20. Numerical study on Rayleigh-Taylor instabilities in the lightning return stroke

    Science.gov (United States)

    Chen, Qiang; Chen, Bin; Shi, Lihua; Yi, Yun; Wang, Yangyang

    2015-09-01

    The Rayleigh-Taylor (R-T) instabilities are important hydrodynamics and magnetohydrodynamics (MHD) phenomena that are found in systems in high energy density physics and normal fluids. The formation and evolution of the R-T instability at channel boundary during back-flow of the lightning return stroke are analyzed using the linear perturbation theory and normal mode analysis methods, and the linear growth rate of the R-T instability in typical condition for lightning return stroke channel is obtained. Then, the R-T instability phenomena of lightning return stroke are simulated using a two-dimensional Eulerian finite volumes resistive radiation MHD code. The numerical results show that the evolution characteristics of the R-T instability in the early stage of back-flow are consistent with theoretical predictions obtained by linear analysis. The simulation also yields more evolution characteristics for the R-T instability beyond the linear theory. The results of this work apply to some observed features of the return stroke channel and further advance previous theoretical and experimental work.

  1. Analysis and Identification of Corona Parameters on Overhead Power Lines in Case of Direct Lightning Strikes

    Institute of Scientific and Technical Information of China (English)

    Bajorek J; Maslowski G; Ziemba R

    2013-01-01

    This paper presents a method for determining specific models of overhead power lines with presence of corona phenomenon.The obtained models provide stable numerical solutions for computer simulation of transients caused by direct lightning strikes.The corona nonlinear charge-voltage characteristics obtained from experimental tests are used for identification of the corona parameters based on System Identification Toolbox implemented in Matlab package.Different transfer functions,which give the same waveshapes of overvoltages are determined using two parametric models.A circuit representation of the obtained transfer functions is proposed and the corona model is implemented in the EMTP-RV as a hierarchical structure composed of a overhead power line divided into sections with corona branches.Some computer simulations of lightning overvoltages propagated in a typical 220 kV power line due to direct lightning strikes to a line tower are presented.The proposed method and the model implemented in EMTP-RV are still valid for multi-conductor lines and for higher voltages of power lines but new corona nonlinear charge-voltage characteristics are required as an input parameter for the identification procedure.

  2. Quantification and identification of lightning damage in tropical forests.

    Science.gov (United States)

    Yanoviak, Stephen P; Gora, Evan M; Burchfield, Jeffrey M; Bitzer, Phillip M; Detto, Matteo

    2017-07-01

    Accurate estimates of tree mortality are essential for the development of mechanistic forest dynamics models, and for estimating carbon storage and cycling. However, identifying agents of tree mortality is difficult and imprecise. Although lightning kills thousands of trees each year and is an important agent of mortality in some forests, the frequency and distribution of lightning-caused tree death remain unknown for most forests. Moreover, because all evidence regarding the effects of lightning on trees is necessarily anecdotal and post hoc, rigorous tests of hypotheses regarding the ecological effects of lightning are impossible. We developed a combined electronic sensor/camera-based system for the location and characterization of lightning strikes to the forest canopy in near real time and tested the system in the forest of Barro Colorado Island, Panama. Cameras mounted on towers provided continuous video recordings of the forest canopy that were analyzed to determine the locations of lightning strikes. We used a preliminary version of this system to record and locate 18 lightning strikes to the forest over a 3-year period. Data from field surveys of known lightning strike locations (obtained from the camera system) enabled us to develop a protocol for reliable, ground-based identification of suspected lightning damage to tropical trees. In all cases, lightning damage was relatively inconspicuous; it would have been overlooked by ground-based observers having no knowledge of the event. We identified three types of evidence that can be used to consistently identify lightning strike damage in tropical forests: (1) localized and directionally biased branch mortality associated with flashover among tree and sapling crowns, (2) mortality of lianas or saplings near lianas, and (3) scorched or wilting epiphytic and hemiepiphytic plants. The longitudinal trunk scars that are typical of lightning-damaged temperate trees were never observed in this study. Given the

  3. On the VHF Source Retrieval Errors Associated with Lightning Mapping Arrays (LMAs)

    Science.gov (United States)

    Koshak, W.

    2016-01-01

    This presentation examines in detail the standard retrieval method: that of retrieving the (x, y, z, t) parameters of a lightning VHF point source from multiple ground-based Lightning Mapping Array (LMA) time-of-arrival (TOA) observations. The solution is found by minimizing a chi-squared function via the Levenberg-Marquardt algorithm. The associated forward problem is examined to illustrate the importance of signal-to-noise ratio (SNR). Monte Carlo simulated retrievals are used to assess the benefits of changing various LMA network properties. A generalized retrieval method is also introduced that, in addition to TOA data, uses LMA electric field amplitude measurements to retrieve a transient VHF dipole moment source.

  4. TOA Lightning Location Retrieval on Spherical and Oblate Spheroidal Earth Geometries

    Science.gov (United States)

    Koshak, W. J.; Solakiewicz, R. J.; Arnold, James E. (Technical Monitor)

    2000-01-01

    A simple linear algebraic solution is introduced for retrieving the location and time-of-occurrence of lightning ground strikes on a spherical Earth from a network of four or more time-of-arrival (TOA) sensors. Since the solution accounts for Earth curvature, it represents an extension to earlier planar model results described by Koshak et al. A test of the retrieval method is provided using computer-simulated data sets. The method is easy to comprehend and completely avoids reference to the mathematics of spherical hyperbolas such as discussed by Lewis. A quasi-analytic extension to the spherical Earth solution is provided for an oblate spheroidal Earth geometry, and the importance/relevance of oblate effects are discussed. Future application of these methods in support of the North American National Lightning Detection Network (NALDN) described by Cummins et al. is desirable, but additional theoretical investigations are required to incorporate magnetic bearing information into the present solution process.

  5. Lightning climatology in the Congo Basin

    Science.gov (United States)

    Soula, S.; Kasereka, J. Kigotsi; Georgis, J. F.; Barthe, C.

    2016-09-01

    The lightning climatology of the Congo Basin including several countries of Central Africa is analysed in detail for the first time. It is based on data from the World Wide Lightning Location Network (WWLLN), for the period from 2005 to 2013. A comparison of these data with Lightning Imaging Sensor (LIS) data for the same period shows the relative detection efficiency of the WWLLN (DE) in the 2500 km × 2500 km region increases from about 1.70% in the beginning of the period to 5.90% in 2013, and it is in agreement with previous results for other regions of the world. However, the increase of DE is not uniform over the whole region. The average monthly flash rate describes an annual cycle with a strong activity from October to March and a low one from June to August, associated with the ITCZ migration but not exactly symmetrical on both sides of the equator. The zonal distribution of the lightning flashes exhibits a maximum between 1°S and 2°S and about 56% of the flashes are located south of the equator in the 10°S-10°N interval. The diurnal evolution of the flash rate has a maximum between 1400 and 1700 UTC, according to the reference year. The annual flash density and number of stormy days show a sharp maximum localized in the eastern part of Democratic Republic of Congo (DRC) regardless of the reference year and the period of the year. These maxima reach 12.86 fl km- 2 and 189 days, respectively, in 2013, and correspond to a very active region located at the rear of the Virunga mountain range at altitudes that exceed 3000 m. The presence of these mountains plays a role in the thunderstorm development along the year. The estimation of this local maximum of the lightning density by taking into account the DE, leads to a value consistent with that of the global climatology by Christian et al. (2003).

  6. Cellular automaton modelling of lightning-induced and man made forest fires

    Directory of Open Access Journals (Sweden)

    R. Krenn

    2009-10-01

    Full Text Available The impact of forest fires on nature and civilisation is conflicting: on one hand, they play an irreplaceable role in the natural regeneration process, but on the other hand, they come within the major natural hazards in many regions. Their frequency-area distributions show power-law behaviour with scaling exponents α in a quite narrow range, relating wildfire research to the theoretical framework of self-organised criticality. Examples of self-organised critical behaviour can be found in computer simulations of simple cellular automaton models. The established self-organised critical Drossel-Schwabl forest fire model is one of the most widespread models in this context. Despite its qualitative agreement with event-size statistics from nature, its applicability is still questioned. Apart from general concerns that the Drossel-Schwabl model apparently oversimplifies the complex nature of forest dynamics, it significantly overestimates the frequency of large fires. We present a modification of the model rules that distinguishes between lightning-induced and man made forest fires and enables a systematic increase of the scaling exponent α by approximately 1/3. In addition, combined simulations using both the original and the modified model rules predict a dependence of the overall event-size distribution on the ratio of lightning induced and man made fires as well as a splitting of their partial distributions. Lightning is identified as the dominant mechanism in the regime of the largest fires. The results are confirmed by the analysis of the Canadian Large Fire Database and suggest that lightning-induced and man made forest fires cannot be treated separately in wildfire modelling, hazard assessment and forest management.

  7. Cellular automaton modelling of lightning-induced and man made forest fires

    Science.gov (United States)

    Krenn, R.; Hergarten, S.

    2009-10-01

    The impact of forest fires on nature and civilisation is conflicting: on one hand, they play an irreplaceable role in the natural regeneration process, but on the other hand, they come within the major natural hazards in many regions. Their frequency-area distributions show power-law behaviour with scaling exponents α in a quite narrow range, relating wildfire research to the theoretical framework of self-organised criticality. Examples of self-organised critical behaviour can be found in computer simulations of simple cellular automaton models. The established self-organised critical Drossel-Schwabl forest fire model is one of the most widespread models in this context. Despite its qualitative agreement with event-size statistics from nature, its applicability is still questioned. Apart from general concerns that the Drossel-Schwabl model apparently oversimplifies the complex nature of forest dynamics, it significantly overestimates the frequency of large fires. We present a modification of the model rules that distinguishes between lightning-induced and man made forest fires and enables a systematic increase of the scaling exponent α by approximately 1/3. In addition, combined simulations using both the original and the modified model rules predict a dependence of the overall event-size distribution on the ratio of lightning induced and man made fires as well as a splitting of their partial distributions. Lightning is identified as the dominant mechanism in the regime of the largest fires. The results are confirmed by the analysis of the Canadian Large Fire Database and suggest that lightning-induced and man made forest fires cannot be treated separately in wildfire modelling, hazard assessment and forest management.

  8. Unusual features caused by lightning impact in West Greenland

    DEFF Research Database (Denmark)

    Appel, P.; Abrahamsen, N.; Rasmussen, T.

    2006-01-01

    that a strong electric current indeed traversed the boulder. A few years later a second lightning impacted on a mountaintop close to the first impact. The second lightning left a trail on the rock surface covered by a thin layer of glass. The glass displays spectacular colours ranging from metallic blue, to red...

  9. Designing concept on lightning protection of overhead power distribution line

    Energy Technology Data Exchange (ETDEWEB)

    Yokoyama, Shigeru [Central Research Institute of Electric Power Industry, Kanagawa-ken (Japan)], E-mail: yokoyama@criepi.denken.or.jp

    2007-07-01

    The principle is shown for lightning protection of power distribution lines taking the effects of surge arresters, overhead ground wires and their combined use into consideration. Moreover an outline of a rational design method targeting direct lightning hits, induced over voltages and back flow currents from high structures. (author)

  10. Lightning location system supervising Swedish power transmission network

    Science.gov (United States)

    Melin, Stefan A.

    1991-01-01

    For electric utilities, the ability to prevent or minimize lightning damage on personnel and power systems is of great importance. Therefore, the Swedish State Power Board, has been using data since 1983 from a nationwide lightning location system (LLS) for accurately locating lightning ground strikes. Lightning data is distributed and presented on color graphic displays at regional power network control centers as well as at the national power system control center for optimal data use. The main objectives for use of LLS data are: supervising the power system for optimal and safe use of the transmission and generating capacity during periods of thunderstorms; warning service to maintenance and service crews at power line and substations to end operations hazardous when lightning; rapid positioning of emergency crews to locate network damage at areas of detected lightning; and post analysis of power outages and transmission faults in relation to lightning, using archived lightning data for determination of appropriate design and insulation levels of equipment. Staff have found LLS data useful and economically justified since the availability of power system has increased as well as level of personnel safety.

  11. Integration of Lightning- and Human-Caused Wildfire Occurrence Models

    DEFF Research Database (Denmark)

    Vilar, Lara; Nieto Solana, Hector; Martín, M. Pilar

    2010-01-01

    Fire risk indices are useful tools for fire prevention actions by fire managers. A fire ignition is either the result of lightning or human activities. In European Mediterranean countries most forest fires are due to human activities. However, lightning is still an important fire ignition source ...

  12. 21st Century Lightning Protection for High Altitude Observatories

    Science.gov (United States)

    Kithil, Richard

    2013-05-01

    One of the first recorded lightning insults to an observatory was in January 1890 at the Ben Nevis Observatory in Scotland. In more recent times lightning has caused equipment losses and data destruction at the US Air Force Maui Space Surveillance Complex, the Cerro Tololo observatory and the nearby La Serena scientific and technical office, the VLLA, and the Apache Point Observatory. In August 1997 NOAA's Climate Monitoring and Diagnostic Laboratory at Mauna Loa Observatory was out of commission for a month due to lightning outages to data acquisition computers and connected cabling. The University of Arizona has reported "lightning strikes have taken a heavy toll at all Steward Observatory sites." At Kitt Peak, extensive power down protocols are in place where lightning protection for personnel, electrical systems, associated electronics and data are critical. Designstage lightning protection defenses are to be incorporated at NSO's ATST Hawaii facility. For high altitude observatories lightning protection no longer is as simple as Franklin's 1752 invention of a rod in the air, one in the ground and a connecting conductor. This paper discusses selection of engineered lightning protection subsystems in a carefully planned methodology which is specific to each site.

  13. Lightning characteristics of derecho producing mesoscale convective systems

    Science.gov (United States)

    Bentley, Mace L.; Franks, John R.; Suranovic, Katelyn R.; Barbachem, Brent; Cannon, Declan; Cooper, Stonie R.

    2016-06-01

    Derechos, or widespread, convectively induced wind storms, are a common warm season phenomenon in the Central and Eastern United States. These damaging and severe weather events are known to sweep quickly across large spatial regions of more than 400 km and produce wind speeds exceeding 121 km h-1. Although extensive research concerning derechos and their parent mesoscale convective systems already exists, there have been few investigations of the spatial and temporal distribution of associated cloud-to-ground lightning with these events. This study analyzes twenty warm season (May through August) derecho events between 2003 and 2013 in an effort to discern their lightning characteristics. Data used in the study included cloud-to-ground flash data derived from the National Lightning Detection Network, WSR-88D imagery from the University Corporation for Atmospheric Research, and damaging wind report data obtained from the Storm Prediction Center. A spatial and temporal analysis was conducted by incorporating these data into a geographic information system to determine the distribution and lightning characteristics of the environments of derecho producing mesoscale convective systems. Primary foci of this research include: (1) finding the approximate size of the lightning activity region for individual and combined event(s); (2) determining the intensity of each event by examining the density and polarity of lightning flashes; (3) locating areas of highest lightning flash density; and (4) to provide a lightning spatial analysis that outlines the temporal and spatial distribution of flash activity for particularly strong derecho producing thunderstorm episodes.

  14. Lightning, IT Diffusion and Economic Growth across US States

    DEFF Research Database (Denmark)

    Andersen, Thomas Barnebeck; Bentzen, Jeanet; Dalgaard, Carl-Johan Lars;

    Empirically, a higher frequency of lightning strikes is associated with slower growth in labor productivity across the 48 contiguous US states after 1990; before 1990 there is no correlation between growth and lightning. Other climate variables (e.g., temperature, rainfall and tornadoes) do not c...

  15. 14 CFR 23.954 - Fuel system lightning protection.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Fuel system lightning protection. 23.954 Section 23.954 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION... Fuel System § 23.954 Fuel system lightning protection. The fuel system must be designed and arranged...

  16. 14 CFR 29.610 - Lightning and static electricity protection.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Lightning and static electricity protection... § 29.610 Lightning and static electricity protection. (a) The rotorcraft structure must be protected... electricity must— (1) Minimize the accumulation of electrostatic charge; (2) Minimize the risk of electric...

  17. 14 CFR 27.610 - Lightning and static electricity protection.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Lightning and static electricity protection....610 Lightning and static electricity protection. (a) The rotorcraft must be protected against... static electricity must— (1) Minimize the accumulation of electrostatic charge; (2) Minimize the risk of...

  18. Lightning Sensors for Observing, Tracking and Nowcasting Severe Weather.

    Science.gov (United States)

    Price, Colin

    2008-01-21

    Severe and extreme weather is a major natural hazard all over the world, oftenresulting in major natural disasters such as hail storms, tornados, wind storms, flash floods,forest fires and lightning damages. While precipitation, wind, hail, tornados, turbulence,etc. can only be observed at close distances, lightning activity in these damaging stormscan be monitored at all spatial scales, from local (using very high frequency [VHF]sensors), to regional (using very low frequency [VLF] sensors), and even global scales(using extremely low frequency [ELF] sensors). Using sensors that detect the radio wavesemitted by each lightning discharge, it is now possible to observe and track continuouslydistant thunderstorms using ground networks of sensors. In addition to the number oflightning discharges, these sensors can also provide information on lightningcharacteristics such as the ratio between intra-cloud and cloud-to-ground lightning, thepolarity of the lightning discharge, peak currents, charge removal, etc. It has been shownthat changes in some of these lightning characteristics during thunderstorms are oftenrelated to changes in the severity of the storms. In this paper different lightning observingsystems are described, and a few examples are provided showing how lightning may beused to monitor storm hazards around the globe, while also providing the possibility ofsupplying short term forecasts, called nowcasting.

  19. Improvement of RAMS precipitation forecast at the short-range through lightning data assimilation

    Science.gov (United States)

    Federico, Stefano; Petracca, Marco; Panegrossi, Giulia; Dietrich, Stefano

    2017-01-01

    % for daily precipitation, depending on the precipitation threshold considered. Score differences between simulations with or without data assimilation are significant at 95 % level for most scores and thresholds considered, showing the positive and statistically robust impact of the lightning data assimilation on the precipitation forecast.

  20. A Lightning Detector Onboard Austrian Nanosatellite (LiNSAT)

    Science.gov (United States)

    Jaffer, G.; Koudelka, O.; Schwingenschuh, K.; Eichelberger, H.

    2010-12-01

    This paper presents architecture of a lightning detector onboard future Austrian Lightning Nanosatellite (LiNSAT) in low-earth-orbit (LEO) and results of two terrestrial measurement campaigns to geo-locate and discriminate lightning types in presence of noise sources. The LiNSAT is proposed to be launched with three satellites constellation for the purpose of Time-of-Arrival technique. Our main scientific objective is to investigate lightning events by the observation of VHF electromagnetic signals (Sferics) and to derive the signatures of lightning. One of the important parameters is lightning flash rate, which can be used as a proxy for locating severe weather activity. Another objective is to discriminate the discharges of lightning events evaluated by the inherent features and to differentiate cloud discharges (IC; intercloud and Intracloud) from ground discharges (CG; cloud-to-ground), return strokes, leaders and transionospheric pulse pairs. The discrimination is important because the ratio of the two (IC/CG) is a good indicator of convective storm development. We conducted two measurement campaigns; one for artificial lightning produced in high voltage chamber and second natural lightning recorded at urban environment. We focus mainly on envelopes of the received time series including noisy features and narrowband carriers to extract characteristic parameters. We determined the chamber inter-walls distance by considering reflections in the first measurements. Initially the algorithm for the instruments onboard electronics has been developed and verified in Matlab and will be transformed to machine language. Next consideration is to use existing lightning data from previous French mission “DEMETER” to validate the accomplished results. The lightning detector onboard has to perform tasks like determination of pulse-width, pulse-count, pulse rise/fall time etc; we get noise possibly from narrowband carriers and artifacts from satellite itself (EMC) in

  1. Bayesian techniques to analyze and merge lightning locating system data

    Science.gov (United States)

    Bitzer, Phillip M.; Burchfield, Jeffrey C.

    2016-12-01

    As more lightning locating systems (LLSs) become available, there is a growing need to assess how each LLS performs and how to best merge data from multiple LLSs. A Bayesian analysis is used to compare the worldwide data of LLSs from three providers for November 2014 to October 2015: Earth Networks Total Lightning Network (ENTLN, Earth Networks), the combined data from the Global Lightning Detection 360 and National Lightning Detection Network (Vaisala), and the World Wide Lightning Location Network (WWLLN, University of Washington). By using the union of the data sets we are able to determine an estimate for the upper limit of the absolute detection efficiency of each system. Globally, ENTLN detected 56.8% of the discharges, the combined Vaisala networks detected 59.8%, and WWLLN detected 7.9%. In addition, there were 2.842 × 109 unique discharges detected by these LLSs, an average of 90.1 strokes/s.

  2. General Survey for Lightning Protection Standards Development in China

    Institute of Scientific and Technical Information of China (English)

    2004-01-01

    @@ The introduction of IEC/TC81 Thunderstorms are natural weather phenomena and there are no devices or methods capable of preventing lightning discharges. Lightning flashes striking structures or services entering the structures, or striking earth nearby are hazardous to people, to the structures themselves, their contents and installations, as well as to services.Hence lightning protection is very important for national economic development. The international trade in lightning protection measures integrat ed in plants or buildings is of increasing importance:more than 500 million USD, world wide are estimated today; consequent loss, where protection measures are not provided, is some order of magnitude higher.The number of countries where lightning protection is required either by law or by insurance companies is growing. Some countries have conflicting national rules and many developing countries do not have the relevant international standards, making the need for such standards all the more urgent.

  3. Spatial Variation of the Correlated Color Temperature of Lightning Channel

    CERN Document Server

    Shimoji, Nobuaki; Sakihama, Singo

    2014-01-01

    In this paper, we studied the spatial variation of the correlated color temperature (CCT) of lightning channel. We also discussed the energy of lightning channels relating to the CCT . First we applied digital image processing techniques to lightning images. In order to reduce the chromatic aberration, we created the reduction technique algorithm of the chromatic aberration on digital still images. We applied the reduction technique of the chromatic aberration to digital still images, and then the obtained results was mapped to the xy-chromaticity diagram. The CCT of the lightning channel was decided on the xy-chromaticity diagram. From results, the spatial variation of the CCT of the lightning channel was confirmed. Then the energy associated with the the CCT was discussed.

  4. Integration of Lightning- and Human-Caused Wildfire Occurrence Models

    DEFF Research Database (Denmark)

    Vilar, Lara; Nieto Solana, Hector; Martín, M. Pilar

    2010-01-01

    Fire risk indices are useful tools for fire prevention actions by fire managers. A fire ignition is either the result of lightning or human activities. In European Mediterranean countries most forest fires are due to human activities. However, lightning is still an important fire ignition source...... in some regions. Integration of lightning and human fire occurrence probability into fire risk indices would be necessary to have a complete picture of the causal agents and their relative importance in fire occurrence. We present two methods for the integration of lightning and human fire occurrence...... probability models at 1 × 1 km grid cell resolution in two regions of Spain: Madrid, which presents a high fire incidence due to human activities; and Aragón, one of the most affected regions in Spain by lightning-fires. For validation, independent fire ignition points were used to compute the Receiver...

  5. Lightning, IT Diffusion and Economic Growth across US States

    DEFF Research Database (Denmark)

    Andersen, Thomas Barnebeck; Bentzen, Jeanet; Dalgaard, Carl-Johan Lars

    Empirically, a higher frequency of lightning strikes is associated with slower growth in labor productivity across the 48 contiguous US states after 1990; before 1990 there is no correlation between growth and lightning. Other climate variables (e.g., temperature, rainfall and tornadoes) do...... not conform to this pattern. A viable explanation is that lightning influences IT diffusion. By causing voltage spikes and dips, a higher frequency of ground strikes leads to damaged digital equipment and thus higher IT user costs. Accordingly, the flash density (strikes per square km per year) should...... adversely affect the speed of IT diffusion. We find that lightning indeed seems to have slowed IT diffusion, conditional on standard controls. Hence, an increasing macroeconomic sensitivity to lightning may be due to the increasing importance of digital technologies for the growth process....

  6. Seasonal and Local Characteristics of Lightning Outages of Power Distribution Lines in Hokuriku Area

    Science.gov (United States)

    Sugimoto, Hitoshi; Shimasaki, Katsuhiko

    The proportion of the lightning outages in all outages on Japanese 6.6kV distribution lines is high with approximately 20 percent, and then lightning protections are very important for supply reliability of 6.6kV lines. It is effective for the lightning performance to apply countermeasures in order of the area where a large number of the lightning outages occur. Winter lightning occurs in Hokuriku area, therefore it is also important to understand the seasonal characteristics of the lightning outages. In summer 70 percent of the lightning outages on distribution lines in Hokuriku area were due to sparkover, such as power wire breakings and failures of pole-mounted transformers. However, in winter almost half of lightning-damaged equipments were surge arrester failures. The number of the lightning outages per lightning strokes detected by the lightning location system (LLS) in winter was 4.4 times larger than that in summer. The authors have presumed the occurrence of lightning outages from lightning stroke density, 50% value of lightning current and installation rate of lightning protection equipments and overhead ground wire by multiple regression analysis. The presumed results suggest the local difference in the lightning outages.

  7. Lightning Jump Algorithm and Relation to Thunderstorm Cell Tracking, GLM Proxy and other Meteorological Measurements

    Science.gov (United States)

    Schultz, Christopher J.; Carey, Larry; Cecil, Dan; Bateman, Monte; Stano, Geoffrey; Goodman, Steve

    2012-01-01

    Objective of project is to refine, adapt and demonstrate the Lightning Jump Algorithm (LJA) for transition to GOES -R GLM (Geostationary Lightning Mapper) readiness and to establish a path to operations Ongoing work . reducing risk in GLM lightning proxy, cell tracking, LJA algorithm automation, and data fusion (e.g., radar + lightning).

  8. Observation of Lightning Ball (Ball Lightning): A new phenomenological description of the phenomenon

    CERN Document Server

    Tar, Domokos

    2009-01-01

    The author (physicist)has observed the very strange,beautiful and frightening Lightning Ball (LB). He has never forgotten this phenomenon. During his working life he could not devote himself to the problem of LB-formation.Only two years ago as he has been reading different unbelievable models of LB-formation, he decided to work on this problem. By studying the literature and the crucial points of his observation the author succeeded in creating a completely new model of Lightning Ball(LB) and Ball Lightning(BL)-formation based on the symmetry breaking of the hydrodynamic vortex ring.This agrees fully with the observation and overcomes the shortcomings of current models of LB formation. This model provides answers to the questions: Why are LBs so rarely observed,why do BLs in rare cases have such a high energy and how can we generate LB in the laboratory? Moreover the author differentiates between LB and BL, the latter having a high energy and occuring in 5 % of the observations. Keywords: ball lightning, hydr...

  9. On the Relationship between Observed NLDN Lightning Strikes and Modeled Convective Precipitation Rates Parameterization of Lightning NOx Production in CMAQ

    Science.gov (United States)

    Lightning-produced nitrogen oxides (NOX=NO+NO2) in the middle and upper troposphere play an essential role in the production of ozone (O3) and influence the oxidizing capacity of the troposphere. Despite much effort in both observing and modeling lightning NOX during the past dec...

  10. Lightning Location With Single-Station Observation of VLF Spherics

    Science.gov (United States)

    Nagano, I.; Yagitani, S.; Komonmae, H.; Takezono, N.

    2001-12-01

    Most of the lightning location systems recently available require the simultaneous reception of lightning-generated radio pulses (spherics) at multiple stations. In this work, we develop a lightning location system to determine both the direction and range of a lightning stroke with a single-station observation of VLF spherics. The technique used here is a rather classical one, but we try to improve the ranging accuracy by applying sophisticated signal processing techniques, and our final goal is to develop a portable lightning locator. We observe wave forms of two horizontal magnetic fields and one vertical electric field of VLF spherics, each of which usually consists of a couple of sequential pulses. The first pulse comes directly from a lightning return stroke, and is used for the direction finding of the stroke. On the other hand, the second and later pulses are the multiple reflections of the first pulse inside the Earth-ionosphere waveguide. Since the time-of-arrival (ToA) of each pulse is determined by its propagation path length in the waveguide, by using the observed difference in ToA of two or more pulses, we can inversely estimate not only the reflection height at the ionosphere but also the range of the lightning stroke. By installing the developed system at Kanazawa University, we have been observing lightning-generated spherics since April, 2000. Compared with the lightning location data provided by a local power company, preliminary analysis shows that this system can locate each lightning stroke within several hundred km with a sufficient accuracy.

  11. High lightning activity in maritime clouds near Mexico

    Science.gov (United States)

    Kucienska, B.; Raga, G. B.; Romero-Centeno, R.

    2012-09-01

    Lightning activity detected by the World Wide Lightning Location Network (WWLLN) over oceanic regions adjacent to Mexico is often as high as that observed over the continent. In order to explore the possible causes of the observed high flash density over those regions, the relationships between lightning, rainfall, vertical hydrometeor profiles, latent heating, wind variability and aerosol optical depth are analyzed. The characteristics of lightning and precipitation over four oceanic zones adjacent to Mexican coastlines are contrasted against those over the continent. The number of flashes per rainfall over some coastal maritime regions is found to be higher than over the continent. The largest number of flashes per rainfall is observed during the biomass burning season. In addition, we compare two smaller areas of the Tropical Pacific Ocean: one located within the Inter-Tropical Convergence Zone and characterized by high rainfall and weak lightning activity and the other one influenced by a continental wind jet and characterized by high rainfall and strong lightning activity. During the rainy season, the monthly distribution of lightning within the region influenced by the continental wind jet is contrary to that of rainfall. Moreover, the monthly variability of lightning is very similar to the variability of the meridional wind component and it is also related to the variability of aerosol optical depth. The analysis suggests that the high lightning activity observed over coastal Pacific region is linked to the continental cloud condensation nuclei advected over the ocean. Analysis of daily observations indicates that the greatest lightning density is observed for moderate values of the aerosol optical depth, between 0.2 and 0.35.

  12. Lightning Magnetic Field Measurements around Langmuir Laboratory

    Science.gov (United States)

    Stock, M.; Krehbiel, P. R.; Rison, W.; Aulich, G. D.; Edens, H. E.; Sonnenfeld, R. G.

    2010-12-01

    In the absence of artificial conductors, underground lightning transients are produced by diffusion of the horizontal surface magnetic field of a return stroke vertically downward into the conducting earth. The changing magnetic flux produces an orthogonal horizontal electric field, generating a dispersive, lossy transverse electromagnetic wave that penetrates a hundred meters or more into the ground according to the skin depth of the medium. In turn, the electric field produces currents that flow toward or away from the channel to ground depending on the stroke polarity. The underground transients can produce large radial horizontal potential gradients depending on the distance from the discharge and depth below the surface. In this study we focus on the surface excitation field. The goal of the work is to compare measurements of surface magnetic field waveforms B(t) at different distances from natural lightning discharges with simple and detailed models of the return stroke fields. In addition to providing input to the diffusion mechanism, the results should aid in further understanding return stroke field generation processes. The observational data are to be obtained using orthogonal sets of straightened Rogowski coils to measure magnetic field waveforms in N-S and E-W directions. The waveforms are sampled at 500 kS/s over 1.024 second time intervals and recorded directly onto secure digital cards. The instrument operates off of battery power for several days or weeks at a time in remote, unattended locations and measures magnetic field strengths of up to several tens of amperes/meter. The observations are being made in conjunction with collocated slow electric field change measurements and under good 3-D lightning mapping array (LMA) and fast electric field change coverage.

  13. Detection of lightning in Saturn's Northern Hemisphere

    CERN Document Server

    Moghimi, Mohsen Hassanzadeh

    2012-01-01

    During Cassini flyby of Saturn at a radial distance 6.18R_s (Saturn Radius), a signal was detected from about 200 to 430 Hz that had the proper dispersion characteristics to be a whistler. The frequency-time dispersion of the whistler was found to be 81 Hz1/2s. Based on this dispersion constant, we determined, from a travel time computation, that the whistler must have originated from lightning in the northern hemisphere of Saturn. Using a simple centrifugal potential model consisting of water group ions, and hydrogen ions we also determine the fractional concentration and scale height that gave the best fit to the observed dispersion.

  14. Sistem Informasi Petir (SIP dengan Metode Lightning Distribution (LD di Wilayah Sumatera Barat

    Directory of Open Access Journals (Sweden)

    Andrew Kurniawan Vadreas

    2014-09-01

    Full Text Available This paper mapped 200 locations of lightning strikes in West Sumatra province. Mapping the location of lightning strikes as part of Lightning Information System was designed with the method of Lightning Distribution (LD. To get the location of lightning strikes obtained from the calculation reflection of ionosphere method to determine the distance of a lightning strike from stations of lightning and methods of Magnetic Direction Finding (MDF to get directions from the lightning strike. Direction data obtained processed to generate a lightning incident location, then that location will be displayed on Google Maps. After that in the process of Lightning Distribution method which is a form of lightning strike density mapping by using the "File Format" grid, where each grid was measured to be 1 x 1 km2 called the Local Density Flash (LFD. If there are multiple point strikes on the grid will change the color that is on the map fit how many number of strikes on the grid which is a Probabilistic computation Flash Density (PFD. The depiction of the scale of danger lightning in the form of variations color changes at the point where the bolt of green color represents the minimum number density of lightning strikes that contains a single point and the red color represents the maximum number density of strikes which contains more than ten points strike. Based on the color distribution of lightning strikes and Payakumbuh Agam area has the highest rate of lightning strikes in the study period.

  15. Beijing Lightning Network (BLNET): Configuration, Function and Preliminary Results

    Science.gov (United States)

    Qie, X.; Wang, D.; Wang, Y.; Liu, M.; Tian, Y.; Lu, G.

    2015-12-01

    A regional multi-frequency-band lightning detection network in Beijing (BLNET) has been developed for both research and operational purposes. The network is employed in the experiment of Dynamic-microphysical-electrical Processes in Severe Thunderstorms and Lightning Hazards (Storm973), supported by Ministry of Science and Technology as National Key Basic Research Program of China or 973 Program. The network consisted of 16 stations in 2015 covering most part of The "Jing-Jin-Ji" (Beijing-Tianjin-Hebei) metropolis zone, one of the most developed areas in China. Four different sensors, including slow antenna, fast antenna, magnetic antenna, and VHF antenna, are integrated in each station to detect lightning radiation signals in different frequency band. The Chan algorithm and Levenberg-Marquardt method are adopted jointly in the lightning location algorithm. In addition to locate the lightning radiation pulses in two-dimension or three-dimension in different band, the charge source neutralized by the lightning discharge can be retrieved either. The theoretical horizontal error over the network is less than 200 m and the vertical error is less than 500 m over the network. The comparison of total lightning location results with corresponding radar echoes for thunderstorm cases indicates the good performance of BLNET in the severe convection surveillance. The actual two-dimensional location error in VLF/LF band, compared with a ground truth that acquired with a GPS-synchronized high-speed video camera, is about 250 m.

  16. Extensive air showers, lightning, and thunderstorm ground enhancements

    Science.gov (United States)

    Chilingarian, A.; Hovsepyan, G.; Kozliner, L.

    2016-09-01

    For lightning research, we monitor particle fluxes from thunderclouds, the so-called thunderstorm ground enhancements (TGEs) initiated by runaway electrons, and extensive air showers (EASs) originating from high-energy protons or fully stripped nuclei that enter the Earth's atmosphere. We also monitor the near-surface electric field and atmospheric discharges using a network of electric field mills. The Aragats "electron accelerator" produced several TGEs and lightning events in the spring of 2015. Using 1-s time series, we investigated the relationship between lightning and particle fluxes. Lightning flashes often terminated the particle flux; in particular, during some TGEs, lightning events would terminate the particle flux thrice after successive recovery. It was postulated that a lightning terminates a particle flux mostly in the beginning of a TGE or in its decay phase; however, we observed two events (19 October 2013 and 20 April 2015) when the huge particle flux was terminated just at the peak of its development. We discuss the possibility of a huge EAS facilitating lightning leader to find its path to the ground.

  17. Lightning flash density in relation to aerosol over Nanjing (China)

    Science.gov (United States)

    Tan, Y. B.; Peng, L.; Shi, Z.; Chen, H. R.

    2016-06-01

    Time series data of lightning flash density, aerosol optical depth (AOD), surface temperature, convective available potential energy (CAPE) and thunderstorm days for 10 years (2002-2011), cloud-to-ground lightning (CG), and AOD of 5 years for summer season, i.e., June, July, and August over Nanjing, China, have been analyzed, to investigate the impact of aerosols on lightning. The results indicate that the radiative effect of aerosol may be one of the main reason for the decrease of the lightning flash density in a long period, while the aerosol microphysical effect may be a major role in the increase of the percent of + CG flashes (P+ CG). The dependence of surface temperature, CAPE, and thunderstorm days on AOD (R = - 0.748, - 0.741, - 0.744), and the negative correlation (R = - 0.634) between lightning flash density and AOD may lend support for the radiative effect of aerosol on lightning. In addition, elevated aerosols may change the charge distribution in thundercloud, hence enhancing the positive cloud-to-ground lightning (+ CG) activity, as P+ CG is positively correlated with AOD.

  18. Lightning and radar observations of hurricane Rita landfall

    Energy Technology Data Exchange (ETDEWEB)

    Henderson, Bradley G [Los Alamos National Laboratory; Suszcynsky, David M [Los Alamos National Laboratory; Hamlin, Timothy E [Los Alamos National Laboratory; Jeffery, C A [Los Alamos National Laboratory; Wiens, Kyle C [TEXAS TECH U.; Orville, R E [TEXAS A& M

    2009-01-01

    Los Alamos National Laboratory (LANL) owns and operates an array of Very-Low Frequency (VLF) sensors that measure the Radio-Frequency (RF) waveforms emitted by Cloud-to-Ground (CG) and InCloud (IC) lightning. This array, the Los Alamos Sferic Array (LASA), has approximately 15 sensors concentrated in the Great Plains and Florida, which detect electric field changes in a bandwidth from 200 Hz to 500 kHz (Smith et al., 2002). Recently, LANL has begun development of a new dual-band RF sensor array that includes the Very-High Frequency (VHF) band as well as the VLF. Whereas VLF lightning emissions can be used to deduce physical parameters such as lightning type and peak current, VHF emissions can be used to perform precise 3d mapping of individual radiation sources, which can number in the thousands for a typical CG flash. These new dual-band sensors will be used to monitor lightning activity in hurricanes in an effort to better predict intensification cycles. Although the new LANL dual-band array is not yet operational, we have begun initial work utilizing both VLF and VHF lightning data to monitor hurricane evolution. In this paper, we present the temporal evolution of Rita's landfall using VLF and VHF lightning data, and also WSR-88D radar. At landfall, Rita's northern eyewall experienced strong updrafts and significant lightning activity that appear to mark a transition between oceanic hurricane dynamics and continental thunderstorm dynamics. In section 2, we give a brief overview of Hurricane Rita, including its development as a hurricane and its lightning history. In the following section, we present WSR-88D data of Rita's landfall, including reflectivity images and temporal variation. In section 4, we present both VHF and VLF lightning data, overplotted on radar reflectivity images. Finally, we discuss our observations, including a comparison to previous studies and a brief conclusion.

  19. Near ground gamma radiation associated with lightning

    Science.gov (United States)

    Sakuma, K.; Greenfield, M. B.; Ikeda, Y.; Kubo, K.

    2004-03-01

    Increases in the atmospheric gamma radiation of 22 to 82above normal background have been observed after the onset of lightning fifteen times since March 2001[1]. Gamma rays have been observed with up to four 12.9 cm3 NaI detectors and recently with a high resolution Ge detector positioned 6-21 m and 15 m above ground, respectively. The tail of the observed background subtracted gamma ray rates GRR were fitted with exponential decay curves yielding typical correlation coefficients of 0.95 to 0.99 and half-lives of 52.7 +/-4.81 min and 52.8+/-10.95 min, without and with precipitation, respectively. The GRR above 300 KeV from radon progeny due to precipitation were subtracted [2]. The 3x3 Ge detector with 2 KeV resolution positioned about 2 m from one of the NaI detectors observed increases in GRR minutes after the onset of lightning with a delayed 50 min exponential decay which was concurrently observed in the NaI detector. [1] M. B. Greenfield et al., Journal of Applied Physics 93 no. 3 (2003) pp 1839-1844. [2] M. B. Greenfield et al., Journal of Applied Physics 93 no. 9 (2003) pp 5733-5741.

  20. Fast radio bursts as pulsar lightning

    Science.gov (United States)

    Katz, J. I.

    2017-07-01

    There are striking phenomenological similarities between fast radio bursts (FRBs) and lightning in the Earth's and planetary atmospheres. Both have very low duty factors, ≲10-8-10-5 for FRBs and (very roughly) ˜10-4 for the main return strokes in an active thundercloud. Lightning occurs in an electrified insulating atmosphere when a conducting path is created by and permits current flow. FRBs may occur in neutron star magnetospheres whose plasma is believed to be divided by vacuum gaps. Vacuum is a perfect insulator unless electric fields are sufficient for electron-positron pair production by curvature radiation, a high-energy analogue of electrostatic breakdown in an insulating gas. FRB may be 'electrars' powered by the release of stored electrostatic energy, counterparts to soft gamma repeaters powered by the release of stored magnetostatic energy (magnetars). This frees pulsar FRB models from the constraint that their power not exceeds the instantaneous spin-down power. Energetic constraints imply that the sources of more energetic FRBs have shorter spin-down lifetimes, perhaps even less than the 3 yr over which FRB 121102 has been observed to repeat.

  1. Magnetotelluric distortions directly observed with lightning data

    Science.gov (United States)

    Hennessy, Lachlan; Macnae, James

    2017-08-01

    Galvanic distortions complicate magnetotelluric (MT) soundings. In this research, we use lightning network data to identify specific sferics in MT measurements and analyse these events on the basis of the lightning source location. Without source information, identification and removal of galvanic distortion is a fundamentally ill-posed problem, unless data are statistically decomposed into determinable and indeterminable parts. We use realistic assumptions of the earth-ionosphere waveguide propagation velocity to accurately predict the time of arrival, azimuth and amplitude for every significant sferic in our time-series data. For each sferic with large amplitude, we calculate the rotation of the electric field from the measured to the predicted arrival azimuth. This rotation of the electric field is a primary parameter of distortion. Our results demonstrate that a rudimentary model for near-surface galvanic distortion consistently fits observed electric field rotations. When local features rotate regional electric fields, then counter-rotating data to predicted arrival azimuths should correct the directional dependence of static shift. Although we used amplitude thresholds to simplify statistical processing, future developments should incorporate both signal-to-noise improvements and multisite decompositions. Lower amplitude signal may also be useful after the appropriate signal processing for noise reduction. We anticipate our approach will be useful for further work on MT distortion.

  2. LDA DFT simulations of an isolated silicon donor on the (110) surface of GaAs

    Science.gov (United States)

    Tilley, F. J.; Roy, Mervyn; Maksym, P. A.

    2014-06-01

    The convergence of the band gap state of a single silicon dopant on the (110) surface of GaAs was investigated. By simulating different sized super-cells we were able to show that a 3x4 super-cell provides a well converged calculation for modelling an isolated dopant, with the total energy being converged to 1 part in 1000. The local density of the silicon band gap state was then checked against a number of more intensive calculations and was found to be well converged, with an eigenvalue accurate to within 3 meV.

  3. Properties of Lightning Strike Protection Coatings

    Science.gov (United States)

    Gagne, Martin

    Composite materials are being increasingly used by many industries. In the case of aerospace companies, those materials are installed on their aircraft to save weight, and thus, fuel costs. These aircraft are lighter, but the loss of electrical conductivity makes aircraft vulnerable to lightning strikes, which hit commercial aircrafts on average once per year. This makes lightning strike protection very important, and while current metallic expanded copper foils offer good protection, they increase the weight of composites. Therefore, under the CRIAQ COMP-502 project, a team of industrial partners and academic researchers are investigating new conductive coatings with the following characteristics: High electromagnetic protection, high mechanical resistance, good environmental protection, manufacturability and moderate cost. The main objectives of this thesis, as part of this project, was to determine the main characteristics, such as electrical and tribomechanical properties, of conductive coatings on composite panels. Their properties were also to be tested after destructive tests such as current injection and environmental testing. Bombardier Aerospace provided the substrate, a composite of carbon fiber reinforced epoxy matrix, and the current commercial product, a surfacing film that includes an expanded copper foil used to compare with the other coatings. The conductive coatings fabricated by the students are: silver nanoparticles inside a binding matrix (PEDOT:PSS or a mix of Epoxy and PEDOT:PSS), silvered carbon nanofibers embedded in the surfacing film, cold sprayed tin, graphene oxide functionalized with silver nanowires, and electroless plated silver. Additionally as part of the project and thesis, magnetron sputtered aluminum coated samples were fabricated. There are three main types of tests to characterize the conductive coatings: electrical, mechanical and environmental. Electrical tests consist of finding the sheet resistance and specific resistivity

  4. Transcranial stimulability of phosphenes by long lightning electromagnetic pulses

    CERN Document Server

    Peer, J

    2010-01-01

    The electromagnetic pulses of rare long (order of seconds) repetitive lightning discharges near strike point (order of 100m) are analyzed and compared to magnetic fields applied in standard clinical transcranial magnetic stimulation (TMS) practice. It is shown that the time-varying lightning magnetic fields and locally induced potentials are in the same order of magnitude and frequency as those established in TMS experiments to study stimulated perception phenomena, like magnetophosphenes. Lightning electromagnetic pulse induced transcranial magnetic stimulation of phosphenes in the visual cortex is concluded to be a plausible interpretation of a large class of reports on luminous perceptions during thunderstorms.

  5. Transcranial stimulability of phosphenes by long lightning electromagnetic pulses

    Energy Technology Data Exchange (ETDEWEB)

    Peer, J. [Institut fuer Ionenphysik und Angewandte Physik, Universitaet Innsbruck, A-6020 Innsbruck (Austria); Kendl, A., E-mail: alexander.kendl@uibk.ac.a [Institut fuer Ionenphysik und Angewandte Physik, Universitaet Innsbruck, A-6020 Innsbruck (Austria)

    2010-06-28

    The electromagnetic pulses of rare long (order of seconds) repetitive lightning discharges near strike point (order of 100 m) are analyzed and compared to magnetic fields applied in standard clinical transcranial magnetic stimulation (TMS) practice. It is shown that the time-varying lightning magnetic fields and locally induced electric fields are in the same order of magnitude and frequency as those established in TMS experiments to study stimulated perception phenomena, like magnetophosphenes. Lightning electromagnetic pulse induced transcranial magnetic stimulation of phosphenes in the visual cortex is concluded to be a plausible interpretation of a large class of reports on luminous perceptions during thunderstorms.

  6. The effects of lightning on digital flight control systems

    Science.gov (United States)

    Plumer, J. A.; Malloy, W. A.; Craft, J. B.

    1976-01-01

    Present practices in lightning protection of aircraft deal primarily with the direct effects of lightning, such as structural damage and ignition of fuel vapors. There is increasing evidence of troublesome electromagnetic effects, however, in aircraft employing solid-state microelectronics in critical navigation, instrumentation and control functions. The potential impact of these indirect effects on critical systems such as digital fly by wire (DFBW) flight controls was studied. The results indicate a need for positive steps to be taken during the design of future fly by wire systems to minimize the possibility of hazardous effects from lightning.

  7. A brief review of the problem of lightning initiation and a hypothesis of initial lightning leader formation

    Science.gov (United States)

    Petersen, Danyal; Bailey, Matthew; Beasley, William H.; Hallett, John

    2008-09-01

    A brief review of hypothesized mechanisms of lightning initiation is presented, with the suggestion that these mechanisms provide an incomplete picture of lightning initiation. This is followed by two ideas: (1) a combination of previously hypothesized lightning initiation mechanisms as a means for local intensification of the thundercloud electric field, and (2) a process for the formation of a hot lightning leader channel that is analogous to the space leader phase of the laboratory negative stepped leader. Thundercloud electric field observations have consistently yielded peak values that are an order of magnitude weaker than the dielectric strength of air. Various mechanisms have been proposed to explain how lightning can initiate in such weak electric fields, including hydrometeor-initiated positive streamers and cosmic ray-initiated runaway breakdown. The historically favored positive streamer mechanisms are problematic due to requiring electric fields two to three times larger than peak observed fields. The recently favored runaway breakdown mechanisms appear capable of developing in conditions comparable to peak observed fields although it is not clear how these diffuse discharges can lead to creation of a lightning leader. This paper proposes a solution whereby runaway breakdown and hydrometeor-initiated positive streamer systems serve to locally intensify the electric field. Following this local field intensification, it is hypothesized that formation of the initial lightning leader channel is analogous to the formation of a space leader in a laboratory negative stepped leader.

  8. Radar Differential Phase Signatures of Ice Orientation for the Prediction of Lightning Initiation and Cessation

    Science.gov (United States)

    Carey, L.D.; Petersen, W.A.; Deierling, W.

    2009-01-01

    other co-polar back-scattering radar measurements like differential reflectivity (Z(sub dr)) typically measured by operational dual-polarimetric radars are not sensitive to these changes in ice crystal orientation. However, prior research has demonstrated that oriented ice crystals cause significant propagation effects that can be routinely measured by most dual-polarimetric radars from X-band (3 cm) to S-band (10 cm) wavelengths using the differential propagation phase shift (often just called differential phase, phi(sub dp)) or its range derivative, the specific differential phase (K(sub dp)). Advantages of the differential phase include independence from absolute or relative power calibration, attenuation, differential attenuation and relative insensitivity to ground clutter and partial beam occultation effects (as long as the signal remains above noise). In research mode, these sorts of techniques have been used to anticipate initial cloud electrification, lightning initiation, and cessation. In this study, we develop a simplified model of ice crystal size, shape, orientation, dielectric, and associated radar scattering and propagation effects in order to simulate various idealized scenarios of ice crystals responding to a hypothetical electric field and their dual-polarimetric radar signatures leading up to lightning initiation and particularly cessation. The sensitivity of the K(sub dp) ice orientation signature to various ice properties and radar wavelength will be explored. Since K(sub dp) is proportional to frequency in the Rayleigh- Gans scattering regime, the ice orientation signatures should be more obvious at higher (lower) frequencies (wavelengths). As a result, simulations at radar wavelengths from 10 cm down to 1 cm (Ka-band) will be conducted. Resonance effects will be considered using the T-matrix method. Since most K(sub dp) Vbased observations have been shown at S-band, we will present ice orientation signatures from C-band (UAH/NASA ARMOR) and X

  9. A supercell, Bloch wave method for calculating low-energy electron reflectivity with applications to free-standing graphene and molybdenum disulfide

    Science.gov (United States)

    McClain, John

    This dissertation reports on a novel theoretical and computational framework for calculating low-energy electron reflectivities from crystalline surfaces and its application to two layered systems of two-dimensional materials, graphene and molybdenum disulfide. The framework provides a simple and efficient approach through the matching of a small set of Fourier components of Bloch wave solutions to the Schrodinger Equation in a slab-in-supercell geometry to incoming and outgoing plane waves on both sides of the supercell. The implementation of this method is described in detail for the calculation of reflectivities in the lowest energy range, for which only specular reflection is allowed. This implementation includes the calculation of reflectivities from beams with normal or off-normal incidence. Two different algorithms are described in the case of off-normal incidence which differ in their dependence on the existence of a symmetry with a mirror plane parallel to the crystal surface. Applications to model potentials in one, two, and three dimensions display consistent results when using different supercell sizes and convergent results with the density of Fourier grids. The design of the Bloch wave matching also allows for the accurate modeling of crystalline slabs through the use of realistic potentials determined via density functional theory. The application of the method to low-energy electron scattering from free-standing systems of a few layers of graphene, including the use of these realistic potentials, demonstrates this ability of the method to accurately model real systems. It reproduces the layer-dependent oscillations found in experimental, normal incidence reflectivity curves for a few layers of graphene grown on silicon carbide. The normal incidence reflectivity curves calculated for slabs consisting of few-layer graphene on 10 layers of nickel show some qualitative agreement with experiment. General incidence reflectivity spectra for free

  10. The NASA Lightning Nitrogen Oxides Model (LNOM): Application to Air Quality Modeling

    Science.gov (United States)

    Koshak, William; Peterson, Harold; Khan, Maudood; Biazar, Arastoo; Wang, Lihua

    2011-01-01

    Recent improvements to the NASA Marshall Space Flight Center Lightning Nitrogen Oxides Model (LNOM) and its application to the Community Multiscale Air Quality (CMAQ) modeling system are discussed. The LNOM analyzes Lightning Mapping Array (LMA) and National Lightning Detection Network(TradeMark)(NLDN) data to estimate the raw (i.e., unmixed and otherwise environmentally unmodified) vertical profile of lightning NO(x) (= NO + NO2). The latest LNOM estimates of lightning channel length distributions, lightning 1-m segment altitude distributions, and the vertical profile of lightning NO(x) are presented. The primary improvement to the LNOM is the inclusion of non-return stroke lightning NOx production due to: (1) hot core stepped and dart leaders, (2) stepped leader corona sheath, K-changes, continuing currents, and M-components. The impact of including LNOM-estimates of lightning NO(x) for an August 2006 run of CMAQ is discussed.

  11. Lightning related fatalities in livestock: veterinary expertise and the added value of lightning location data.

    Science.gov (United States)

    Vanneste, E; Weyens, P; Poelman, D R; Chiers, K; Deprez, P; Pardon, B

    2015-01-01

    Although lightning strike is an important cause of sudden death in livestock on pasture and among the main reasons why insurance companies consult an expert veterinarian, scientific information on this subject is limited. The aim of the present study was to provide objective information on the circumstantial evidence and pathological findings in lightning related fatalities (LRF), based on a retrospective analysis of 410 declarations, examined by a single expert veterinarian in Flanders, Belgium, from 1998 to 2012. Predictive logistic models for compatibility with LRF were constructed based on anamnestic, environmental and pathological factors. In addition, the added value of lightning location data (LLD) was evaluated. Pathognomonic singe lesions were present in 84/194 (43%) confirmed reports. Factors which remained significantly associated with LRF in the multivariable model were age, presence of a tree or open water in the near surroundings, tympany and presence of feed in the oral cavity at the time of investigation. This basic model had a sensitivity (Se) of 53.8% and a specificity (Sp) of 88.2%. Relying only on LLD to confirm LRF in livestock resulted in a high Se (91.3%), but a low Sp (41.2%), leading to a high probability that a negative case would be wrongly accepted as an LRF. The best results were obtained when combining the model based on the veterinary expert investigation (circumstantial evidence and pathological findings), together with the detection of cloud-to-ground (CG) lightning at the time and location of death (Se 89.1%; Sp 66.7%). Copyright © 2014 Elsevier Ltd. All rights reserved.

  12. Using lightning locating system based on time-of-arrival technique to study three-dimensional lightning discharge processes

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    A time-of-arrival(TOA) system based on GPS technology for locating VHF radiation sources from lightning has been developed and used in observation sites in the northern Shandong Province,China.The 3D images of the lightning progression have been obtained successfully for the first time in China.The 3D-channel evolutions of typical negative CG,positive CG and IC lightning flashes have been discussed together with the data of fast electric field change.It was found that significant differences existed between the negative and positive CG lightning flashes in terms of the initiation and propagation of the radiation sources.The preliminary breakdown of a negative CG lightning flash propagated at a speed about 5.2×104 m/s.The stepped leader of negative CG lightning flashes was trigged by negative initial breakdown.Thereafter,it propagated downward at a speed of 1.3×105 m/s.The initial process of the positive CG lightning flashes was also a propagation process of negative streamer.These streamers propagated dominantly horizontally in the positive charge region and accumulated positive charges at the origin of the lightning,and as a consequence,initiated downward positive streamers.A new type of lightning discharge that was triggered by a narrow bipolar pulse(NBP) is discussed in this study.The NBP was originated at altitude of about 10.5 km in the upper positive charge region.As a distinct difference from normal IC flash,its channels extended horizontally all around and produced a lot of radiation sources.The source power of the NBP could approach 16.7 kW,which is much greater than that of normal lightning discharge ranging between 100 mW and 500 W.The 3D propagation of this new type of lightning discharge was observed and obtained for the first time in China.The possible initiation mechanism of this new type of light-ning is discussed here.

  13. The Angular Distribution of Electron and X-ray Emission from Triggered Lightning Leader Steps Using the Thunderstorm Energetic Radiation Array (TERA)

    Science.gov (United States)

    Schaal, M.; Dwyer, J. R.; Rassoul, H. K.; Uman, M. A.; Jordan, D. M.; Hill, J. D.

    2012-12-01

    Energetic radiation is known to be produced by thunderclouds and lightning. To investigate the characteristics of these emissions, ground-based observations are being conducted at the International Center for Lightning Research and Testing (ICLRT) at Camp Blanding, FL. Measurements of the electric and magnetic fields, optical emissions, and energetic radiation from both natural and rocket-triggered lightning discharges are recorded at the ICLRT. Specifically, the Thunderstorm Energetic Radiation Array (TERA) is used to measure x-ray and gamma-ray emissions. In total, the ICLRT encompasses 36 NaI and two LaBr3 PMTs as part of TERA. Additionally, these measurements were compared with Monte Carlo simulations of runaway electron propagation and their x-ray emission with the goal of understanding the underlying mechanism of runaway electron production and their role in lightning initiation and propagation. In this study, we investigate individual leader steps to determine if electrons at the source (and hence x-rays) are emitted isotropically or with some degree of anisotropy. This study is motivated by the work of Saleh et al. 2009, which compared distributions of a beamed and an isotropic electron source to radial energy distributions using TERA and determined that the average electron source of emission was isotropic. The anisotropy of the runaway electrons is important because it may provide information on the electric fields near the lightning leader tip.

  14. Response of lightning NOx emissions and ozone production to climate change: Insights from the Atmospheric Chemistry and Climate Model Intercomparison Project

    Science.gov (United States)

    Finney, D. L.; Doherty, R. M.; Wild, O.; Young, P. J.; Butler, A.

    2016-05-01

    Results from an ensemble of models are used to investigate the response of lightning nitrogen oxide emissions to climate change and the consequent impacts on ozone production. Most models generate lightning using a parameterization based on cloud top height. With this approach and a present-day global emission of 5 TgN, we estimate a linear response with respect to changes in global surface temperature of +0.44 ± 0.05 TgN K-1. However, two models using alternative approaches give +0.14 and -0.55 TgN K-1 suggesting that the simulated response is highly dependent on lightning parameterization. Lightning NOx is found to have an ozone production efficiency of 6.5 ± 4.7 times that of surface NOx sources. This wide range of efficiencies across models is partly due to the assumed vertical distribution of the lightning source and partly to the treatment of nonmethane volatile organic compound (NMVOC) chemistry. Careful consideration of the vertical distribution of emissions is needed, given its large influence on ozone production.

  15. Spatially adaptive probabilistic computation of a sub-kilometre resolution lightning climatology for New Zealand

    Science.gov (United States)

    Etherington, Thomas R.; Perry, George L. W.

    2017-01-01

    Lightning is a key component of the Earth's atmosphere and climate systems, and there is a potential positive feedback between a warming climate and increased lightning activity. In the biosphere, lightning is important as the main natural ignition source for wildfires and because of its contribution to the nitrogen cycle. Therefore, it is important to develop lightning climatologies to characterise and monitor lightning activity. While traditional methods for constructing lightning climatologies are suitable for examining lightning's influence on atmospheric processes, they are less well suited for examining questions about biosphere-lightning interactions. For example, examining the interaction between lightning and wildfires requires linking atmospheric processes to finer scale terrestrial processes and patterns. Most wildfires ignited by lightning are less than one hectare in size, and so require lightning climatologies at a comparable spatial resolution. However, such high resolution lightning climatologies cannot be derived using the traditional cell-count methodology. Here we present a novel geocomputational approach for analysing lightning data at high spatial resolutions. Our approach is based on probabilistic computational methods and is capable of producing a sub-kilometre lightning climatology that honours the spatial accuracy of the strike locations and is adaptive to underlying spatial patterns. We demonstrate our methods by applying them to the mid-latitude oceanic landmass of New Zealand, an area with geographic conditions that are under-represented in existing lightning climatologies. Our resulting lightning climatology has unparalleled spatial resolution, and the spatial and temporal patterns we observe in it are consistent with other continental and tropical lightning climatologies. To encourage further use and development of our probabilistic approach, we provide Python scripts that demonstrate the method alongside our resulting New Zealand

  16. Lightning protection of oil and gas industrial plants

    Energy Technology Data Exchange (ETDEWEB)

    Bouquegneau, Christian [Polytechnical University of Mons (Belgium)

    2007-07-01

    The paper brings some cases and presents the general principles, what the IEC 62305 international standard says, the warning and avoidance and the conclusion about lightning protection of oil and gas industrial plants.

  17. Lightning and middle atmospheric discharges in the atmosphere

    Science.gov (United States)

    Siingh, Devendraa; Singh, R. P.; Kumar, Sarvan; Dharmaraj, T.; Singh, Abhay K.; Singh, Ashok K.; Patil, M. N.; Singh, Shubha

    2015-11-01

    Recent development in lightning discharges including transient luminous events (TLEs) and global electric circuit are discussed. Role of solar activity, convective available potential energy, surface temperature and difference of land-ocean surfaces on convection process are discussed. Different processes of discharge initiation are discussed. Events like sprites and halos are caused by the upward quasi-electrostatic fields associated with intense cloud-to-ground discharges while jets (blue starter, blue jet, gigantic jet) are caused by charge imbalance in thunderstorm during lightning discharges but they are not associated with a particular discharge flash. Elves are generated by the electromagnetic pulse radiated during lightning discharges. The present understanding of global electric circuit is also reviewed. Relation between lightning activity/global electric circuit and climate is discussed.

  18. High-altitude electrical discharges associated with thunderstorms and lightning

    Science.gov (United States)

    Liu, Ningyu; McHarg, Matthew G.; Stenbaek-Nielsen, Hans C.

    2015-12-01

    The purpose of this paper is to introduce electrical discharge phenomena known as transient luminous events above thunderstorms to the lightning protection community. Transient luminous events include the upward electrical discharges from thunderstorms known as starters, jets, and gigantic jets, and electrical discharges initiated in the lower ionosphere such as sprites, halos, and elves. We give an overview of these phenomena with a focus on starters, jets, gigantic jets, and sprites, because similar to ordinary lightning, streamers and leaders are basic components of these four types of transient luminous events. We present a few recent observations to illustrate their main properties and briefly review the theories. The research in transient luminous events has not only advanced our understanding of the effects of thunderstorms and lightning in the middle and upper atmosphere, but also improved our knowledge of basic electrical discharge processes critical for sparks and lightning.

  19. A Probabilistic, Facility-Centric Approach to Lightning Strike Location

    Science.gov (United States)

    Huddleston, Lisa L.; Roeder, William p.; Merceret, Francis J.

    2012-01-01

    A new probabilistic facility-centric approach to lightning strike location has been developed. This process uses the bivariate Gaussian distribution of probability density provided by the current lightning location error ellipse for the most likely location of a lightning stroke and integrates it to determine the probability that the stroke is inside any specified radius of any location, even if that location is not centered on or even with the location error ellipse. This technique is adapted from a method of calculating the probability of debris collisionith spacecraft. Such a technique is important in spaceport processing activities because it allows engineers to quantify the risk of induced current damage to critical electronics due to nearby lightning strokes. This technique was tested extensively and is now in use by space launch organizations at Kennedy Space Center and Cape Canaveral Air Force Station. Future applications could include forensic meteorology.

  20. Effects of Lightning Injection on Power-MOSFETs

    Data.gov (United States)

    National Aeronautics and Space Administration — Lightning induced damage is one of the major concerns in aircraft health monitoring. Such short-duration high voltages can cause significant damage to electronic...

  1. An unusual case of late ocular changes after lightning injury.

    Directory of Open Access Journals (Sweden)

    Datta Himadri

    2002-01-01

    Full Text Available We describe a case of late ocular changes after lightning injury. One year after the injury, complete ankyloblepharon, severe dry eye, corneal opacity, healed iritis and mature cataracts were noted in both eyes of the patient.

  2. Direct Write Lightning Protection and Damage Detection Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This project aims to improve conventional lightning strike protection in composite aircraft and proposes a novel method to monitor structures for damage upon...

  3. Convective Induced Turbulence (CIT) Detection via Total Lightning Sensing Project

    Data.gov (United States)

    National Aeronautics and Space Administration — We proposes to build a prototype Convective-Induced Turbulence (CIT) hazard detection system based on total lightning sensing as an indicator of the location and...

  4. Electromagnetic computation methods for lightning surge protection studies

    CERN Document Server

    Baba, Yoshihiro

    2016-01-01

    This book is the first to consolidate current research and to examine the theories of electromagnetic computation methods in relation to lightning surge protection. The authors introduce and compare existing electromagnetic computation methods such as the method of moments (MOM), the partial element equivalent circuit (PEEC), the finite element method (FEM), the transmission-line modeling (TLM) method, and the finite-difference time-domain (FDTD) method. The application of FDTD method to lightning protection studies is a topic that has matured through many practical applications in the past decade, and the authors explain the derivation of Maxwell's equations required by the FDTD, and modeling of various electrical components needed in computing lightning electromagnetic fields and surges with the FDTD method. The book describes the application of FDTD method to current and emerging problems of lightning surge protection of continuously more complex installations, particularly in critical infrastructures of e...

  5. The influence of photolytic effects on modeled lightning-produced nitric oxides for the 10 July STERAO case

    Science.gov (United States)

    Ott, J.; Helsdon, J.; Farley, R.

    2007-12-01

    On July 10, 1996 a convective system developed in the late afternoon over the Cheyenne Ridge near the southern Wyoming-Nebraska border and was observed as part of the Stratospheric-Tropospheric Experiment: Radiation, Aerosols, and Ozone (STERAO) project. The cells moved in a south to southeastward direction crossing into northeastern Colorado before dissipation occurred in the evening hours. One of the main goals of STERAO was to investigate the role thunderstorms play in the redistribution of chemical species in the troposphere. A particular concern in the program was the distribution of odd nitrogen species; primarily focusing on NOx (NOx = NO + NO2) production by lightning and the transport of NOx into the troposphere and lower stratosphere based on the structure of the convective systems. We simulated this well documented storm with our three-dimensional Storm Electrification Model (SEM) with an explicit lightning scheme, which includes chemistry. The NO production is based on the energy dissipation of the lightning discharge including both a pressure dependence and a scheme that accounts for the cloud radiative effects on the chemical rate of photolytic reactions. This scheme is based on the actinic flux in the upper, middle, and lower portions of the thundercloud. The use of such a scheme allows for the effects of radiation transfer on the production of NOx from lightning. The chemical scheme incorporates nine chemical species, including NO, NO2, O3, CO, and CH4. These chemical species take part in eighteen chemical reactions, which include three that are photolytic. We focus our simulations on the production of NOx, with the goal of comparing the production based on three simulations: one with a clear sky photolytic scenario, another using the radiative transfer scheme, and the last scenario with the photolytic reactions turned off to simulate nighttime conditions. This modeling work is currently underway and the most recent results will be presented.

  6. Challenge of lightning detection with LAC on board Akatsuki spacecraft

    Science.gov (United States)

    Takahashi, Yukihiro; Sato, Mitsutero; Imai, Masataka; Yair, Yoav; Fischer, Georg; Aplin, Karen

    2016-04-01

    Even after extensive investigations with spacecraft and ground-based observations, there is still no consensus on the existence of lightning in Venus. It has been reported that the magnetometer on board Venus Express detected whistler mode waves whose source could be lightning discharge occurring well below the spacecraft. On the other hand, with an infrared sensor, VIRTIS of Venus Express, does not show the positive indication of lightning flashes. In order to identify the optical flashes caused by electrical discharge in the atmosphere of Venus, at least, with an optical intensity of 1/10 of the average lightning in the Earth, we built a high-speed optical detector, LAC (Lightning and Airglow Camera), on board Akatsuki spacecraft. The unique performance of the LAC compared to other instruments is the high-speed sampling rate at 32 us interval for all 32 pixels, enabling us to distinguish the optical lightning flash from other pulsing noises. Though, unfortunately, the first attempt of the insertion of Akatsuki into the orbit around Venus failed in December 2010, the second one carried out in December 7 in 2015 was quite successful. We checked out the condition of the LAC on January 5, 2016, and it is healthy as in 2010. Due to some elongated orbit than that planned originally, we have umbra for ~30 min to observe the lightning flash in the night side of Venus every ~10 days, starting on April 2016. Here we would report the instrumental status of LAC and the preliminary results of the first attempt to observe optical lightning emissions.

  7. Usage of Lightning Arrester Line to Feed Light Electrical Loads

    Directory of Open Access Journals (Sweden)

    Hani B. Odeh

    2009-01-01

    Full Text Available In remote areas, light loads (tens of kilowatts are scattered and situated in the field of high voltage lines (66KV and above. These loads are very far from the main feeders/sub-stations (33KV-0.380KV. Feeding such loads in the traditional ways like provision of Diesel-Powered Stations, installation of new distribution lines from the Feeding Centers, or building new Sub-Stations are not practical ways from the economical point of view, because it requires huge additional expenses and will increase electrical power losses. These expenses are not worthy for such loads and therefore, it is necessary to search for other methods to supply them. One of these methods is to use the lightning arrester line as capacitive divider to supply the light loads. In this research, the induced voltage of the lightning arrester line was calculated when it is isolated from the earth. We found the capacitance between lightning arrester line versus the phases and lightning arrester. It was also found the selective power out of the lightning arrester line and the required length which is to be isolated from the earth keeping the main function of the lightning arrester line. When economically comparing between supplying the light electrical loads by traditional ways and the method of lightning arrester, it was found the advantage of using lightning arresters to supply such loads. Also, by using the traditional methods, it was noted that there is a power loss in the power transmission lines by a percentage of 1.8%.

  8. X-ray absorption near edge structure/electron energy loss near edge structure calculation using the supercell orthogonalized linear combination of atomic orbitals method.

    Science.gov (United States)

    Ching, Wai-Yim; Rulis, Paul

    2009-03-11

    Over the last eight years, a large number of x-ray absorption near edge structure (XANES) and/or electron energy loss near edge structure (ELNES) spectroscopic calculations for complex oxides and nitrides have been performed using the supercell-OLCAO (orthogonalized linear combination of atomic orbitals) method, obtaining results in very good agreement with experiments. The method takes into account the core-hole effect and includes the dipole matrix elements calculated from ab initio wavefunctions. In this paper, we describe the method in considerable detail, emphasizing the special advantages of this method for large complex systems. Selected results are reviewed and several hitherto unpublished results are also presented. These include the Y K edge of Y ions segregated to the core of a Σ31 grain boundary in alumina, O K edges of water molecules, C K edges in different types of single walled carbon nanotubes, and the Co K edge in the cyanocobalamin (vitamin B(12)) molecule. On the basis of these results, it is argued that the interpretation of specific features of the calculated XANES/ELNES edges is not simple for complex material systems because of the delocalized nature of the conduction band states. The long-standing notion of the 'fingerprinting' technique for spectral interpretation of experimental data is not tenable. A better approach is to fully characterize the structure under study, using either crystalline data or accurate ab initio modeling. Comparison between calculated XANES/ELNES spectra and available measurements enables us to ascertain the validity of the modeled structure. For complex crystals or structures, it is necessary to use the weighted sum of the spectra from structurally nonequivalent sites for comparison with the measured data. Future application of the supercell-OLCAO method to complex biomolecular systems is also discussed.

  9. X-ray absorption near edge structure/electron energy loss near edge structure calculation using the supercell orthogonalized linear combination of atomic orbitals method

    Energy Technology Data Exchange (ETDEWEB)

    Ching, W.-Y.; Rulis, Paul [Department of Physics, University of Missouri-Kansas City, Kansas City, MO 64110 (United States)

    2009-03-11

    Over the last eight years, a large number of x-ray absorption near edge structure (XANES) and/or electron energy loss near edge structure (ELNES) spectroscopic calculations for complex oxides and nitrides have been performed using the supercell-OLCAO (orthogonalized linear combination of atomic orbitals) method, obtaining results in very good agreement with experiments. The method takes into account the core-hole effect and includes the dipole matrix elements calculated from ab initio wavefunctions. In this paper, we describe the method in considerable detail, emphasizing the special advantages of this method for large complex systems. Selected results are reviewed and several hitherto unpublished results are also presented. These include the Y K edge of Y ions segregated to the core of a {sigma}31 grain boundary in alumina, O K edges of water molecules, C K edges in different types of single walled carbon nanotubes, and the Co K edge in the cyanocobalamin (vitamin B{sub 12}) molecule. On the basis of these results, it is argued that the interpretation of specific features of the calculated XANES/ELNES edges is not simple for complex material systems because of the delocalized nature of the conduction band states. The long-standing notion of the 'fingerprinting' technique for spectral interpretation of experimental data is not tenable. A better approach is to fully characterize the structure under study, using either crystalline data or accurate ab initio modeling. Comparison between calculated XANES/ELNES spectra and available measurements enables us to ascertain the validity of the modeled structure. For complex crystals or structures, it is necessary to use the weighted sum of the spectra from structurally nonequivalent sites for comparison with the measured data. Future application of the supercell-OLCAO method to complex biomolecular systems is also discussed.

  10. X-ray absorption near edge structure/electron energy loss near edge structure calculation using the supercell orthogonalized linear combination of atomic orbitals method

    Science.gov (United States)

    Ching, Wai-Yim; Rulis, Paul

    2009-03-01

    Over the last eight years, a large number of x-ray absorption near edge structure (XANES) and/or electron energy loss near edge structure (ELNES) spectroscopic calculations for complex oxides and nitrides have been performed using the supercell-OLCAO (orthogonalized linear combination of atomic orbitals) method, obtaining results in very good agreement with experiments. The method takes into account the core-hole effect and includes the dipole matrix elements calculated from ab initio wavefunctions. In this paper, we describe the method in considerable detail, emphasizing the special advantages of this method for large complex systems. Selected results are reviewed and several hitherto unpublished results are also presented. These include the Y K edge of Y ions segregated to the core of a Σ31 grain boundary in alumina, O K edges of water molecules, C K edges in different types of single walled carbon nanotubes, and the Co K edge in the cyanocobalamin (vitamin B12) molecule. On the basis of these results, it is argued that the interpretation of specific features of the calculated XANES/ELNES edges is not simple for complex material systems because of the delocalized nature of the conduction band states. The long-standing notion of the 'fingerprinting' technique for spectral interpretation of experimental data is not tenable. A better approach is to fully characterize the structure under study, using either crystalline data or accurate ab initio modeling. Comparison between calculated XANES/ELNES spectra and available measurements enables us to ascertain the validity of the modeled structure. For complex crystals or structures, it is necessary to use the weighted sum of the spectra from structurally nonequivalent sites for comparison with the measured data. Future application of the supercell-OLCAO method to complex biomolecular systems is also discussed.

  11. Reliability of lightning resistant overhead distribution lines

    Energy Technology Data Exchange (ETDEWEB)

    Tolbert, L.M.; Cleveland, J.T.; Degenhardt, L.J.

    1995-04-01

    An assessment of the 32 year historical reliability of the 13.8 kV electrical distribution system at the Oak Ridge National Laboratory (ORNL) in Tennessee has yielded several conclusions useful In the planning of Industrial power Systems. The system configuration at ORNL has essentially remained unchanged in the last 32 years which allows a meaningful comparison of reliability trends for the plant`s eight overhead distribution lines, two of which were built in the 1960`s with lightning resistant construction techniques. Meticulous records indicating the cause, duration, and location of 135 electric outages in the plant`s distribution system have allowed a reliability assessment to be performed. The assessment clearly shows how differences in voltage construction class, length, age, and maximum elevation above a reference elevation influence the reliability of overhead power distribution lines. Comparisons are also made between the ORNL historical data and predicted failure rates from ANSI and IEEE industry surveys.

  12. Broadband interferometer observations of a triggered lightning

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The development of positive leader of an artificially triggered lightning has been analyzed based on the data of electric field change, location of radiation source and frequency spectrum obtained by using the broadband interferometer system. The results indicate that radiation from positive leader could be detected within close distance in spite of the relatively weak radiation, while the radiation from negative breakdown processes was relatively stronger.Positive leader developed with few branches, and the initial progression velocity was of the order of 10s m/s. The distribution of power spectrum by 25 MHz high pass filter indicated that the radiation frequency from positive leader maximized at 25-30 MHz, while that from negative breakdown processes maximized at 60-70 MHz.

  13. Brazil Lightning Bolts Set Shocking World Record

    Institute of Scientific and Technical Information of China (English)

    卞小翩

    2002-01-01

    巴西是世界上最大的地处热带地区的国家,因此,它就成了世界“雷电之国”。让我们吃惊的是,10%of all lightning-rylated deaths in the world竟然发生在巴西!文章出现一个名词词组 power blackouts,而擅长使用词汇connotation的英语也常常“活用”此词。 He had had a blackout after the accident./事故发生后,他晕过去一阵子。

  14. Greased Lightning (GL-10) Flight Testing Campaign

    Science.gov (United States)

    Fredericks, William J.; McSwain, Robert G.; Beaton, Brian F.; Klassman, David W.; Theodore, Colin R.

    2017-01-01

    Greased Lightning (GL-10) is an aircraft configuration that combines the characteristics of a cruise efficient airplane with the ability to perform vertical takeoff and landing (VTOL). This aircraft has been designed, fabricated and flight tested at the small unmanned aerial system (UAS) scale. This technical memorandum will document the procedures and findings of the flight test experiments. The GL-10 design utilized two key technologies to enable this unique aircraft design; namely, distributed electric propulsion (DEP) and inexpensive closed loop controllers. These technologies enabled the flight of this inherently unstable aircraft. Overall it has been determined thru flight test that a design that leverages these new technologies can yield a useful VTOL cruise efficient aircraft.

  15. Sprites, Elves and Intense Lightning Discharges

    CERN Document Server

    Füllekrug, Martin; Rycroft, Michael J

    2006-01-01

    Particularly intense lightning discharges can produce transient luminous events above thunderclouds, termed sprites, elves and jets. These short lived optical emissions in the mesosphere can reach from the tops of thunderclouds up to the ionosphere; they provide direct evidence of coupling from the lower atmosphere to the upper atmosphere. Sprites are arguably the most dramatic recent discovery in solar-terrestrial physics. Shortly after the first ground based video recordings of sprites, observations on board the Space Shuttle detected sprites and elves occurring all around the world. These reports led to detailed sprite observations in North America, South America, Australia, Japan, and Europe. Subsequently, sprites were detected from other space platforms such as the International Space Station and the ROCSAT satellite. During the past 15 years, more than 200 contributions on sprites have been published in the scientific literature to document this rapidly evolving new research area.

  16. Applications of triggered lightning to space vehicle operations

    Science.gov (United States)

    Jafferis, William; Sanicandro, Rocco; Rompalla, John; Wohlman, Richard

    1992-11-01

    Kennedy Space Center (KSC) and the USAF Eastern Space Missile Center (ESMC) covering an area of 25 x 40 km are frequently called America's Spaceport. This title is earned through the integration, by labor and management, of many skills in a wide variety of engineering fields to solve many technical problems that occur during the launch processing of space vehicles. Weather is one of these problems, and although less frequent in time and duration when compared to engineering type problems, has caused costly and life threatening situations. This sensitivity to weather, especially lightning, was recognized in the very early pioneer days of space operations. The need to protect the many v\\facilities, space flight hardware, and personnel from electrified clouds capable of producing lightning was a critical element in improving launch operations. A KSC lightning committee was formed and directed to improve lightning protection, detection, and measuring systems and required that all theoretical studies be confirmed by KSC field data. Over the years, there have been several lightning incidents involving flight vehicles during ground processing as well as launch. Subsequent investigations revealed the need to improve these systems as well as the knowledge of the electrical atmosphere and its effects on operations in regard to cost and safety. Presented here is how, KSC Atmospheric Science Field Laboratory (AFSL), in particular Rocket Triggered Lightning, is being used to solve these problems.

  17. Lightning and 85-GHz MCSs in the Global Tropics

    Science.gov (United States)

    Toracinta, E. Richard; Zipser, E. J.

    1999-01-01

    Numerous observations of tropical convection show that tropical continental mesoscale convective systems (MCSs) are much more prolific lightning producers than their oceanic counterparts. Satellite-based climatologies using 85-GHz passive microwave ice-scattering signatures from the Special Sensor Microwave/Imager (SSM/I) indicate that MCSs of various size and intensity are found throughout the global tropics. In contrast, global lightning distributions show a strong land bias with an order of magnitude difference between land and ocean lightning. This is somewhat puzzling, since 85-GHz ice-scattering and the charge separation processes that lead to lightning are both thought to depend upon the existence of large graupel particles. The fact that low 85-GHz brightness temperatures are observed in tropical oceanic MCSs containing virtually no lightning leads to the postulate that tropical oceanic and tropical continental MCSs have fundamentally different hydrometeor profiles through the mixed phase region of the cloud (0 C mind, this research undertakes a systematic comparison of 85-GHz-defined MCSs and lightning over the global tropics for a full year, as an initial step toward quantifying differences between land and ocean convective systems.

  18. The spectra and temperature of cloud lightning discharge channel

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Spectra of seven cloud lightning discharges are reported for the first time after captured with a Slit-less Spectrograph on Chinese Tibet Plateau. The structural characters are analyzed and compared with the spectra of cloud-to-ground lightning, and the results indicate that the spectra of cloud lightning show two different kinds of structure characteristics. One has the similar structure as those of cloud-to-ground lightning discharge, and the other is absolutely different. Meanwhile, more lines of OII with high excited energy are recorded in the spectra of cloud lightning discharge in comparison with that of cloud-to-ground lighting happening in the same region. Temperatures at different positions are calculated and temperature characteristics of these two sorts are analyzed, based to the wavelength, relative intensities and other transition parameters. We suggest that the physical process in the cloud discharge channels changes with much more rapid velocity and wider range compared to cloud-to-ground lightning. The differences between the two types of cloud discharge also reflect some discrepancies between the discharge characteristics.

  19. Energy dispatching analysis of lightning surges on underground cables in a cable connection station

    Energy Technology Data Exchange (ETDEWEB)

    Hong-Chan Chang; Fu-Hsien Chen; Tai-Hsiang Chen [Department of Electrical Engineering, National Taiwan University of Science and Technology, 43, Sec. 4, Keelung Rd., Taipei (China); Cheng-Chien Kuo [Department of Electrical Engineering, St. John' s University, 499, Sec. 4, TamKing Rd., Tamsui, Taipei (China)

    2011-01-15

    The paper aimed to simulate the transient over-voltage phenomena which occur at 345 kV and 161 kV underground cables, when lighting strikes on or near the cable connection station, by using the Electro-Magnetic Transients Program (EMTP). A feasibility study on changing related parameters, as well as cable connections and grounding methods to reduce the impact caused by lightning strikes, will be thoroughly conducted. The various components required for a detailed simulation including; lightning surges, transmission line and tower, arrester, and underground cables are all considered. Then, the transient voltage of the cables will be analyzed under different situations including; connection methods, grounding locations, length of the grounding wire of arrester, and the grounding resistance for different locations. The simulation results show that the length of the grounding wire is more sensitive to the transient over-voltage which occurred when a common grounding topology was adopted. In contrast, the use of an independent grounding topology resulted in a reduction of the grounding resistance, which effectively decreased the over-voltage, thereby avoiding surpassing the shielding voltage level of the cable, caused by the rise of ground voltage. (author)

  20. Energy dispatching analysis of lightning surges on underground cables in a cable connection station

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Hong-Chan, E-mail: hcchang@mail.ntust.edu.t [Department of Electrical Engineering, National Taiwan University of Science and Technology, 43, Sec. 4, Keelung Rd., Taipei, Taiwan (China); Chen, Fu-Hsien, E-mail: fu@mail.sju.edu.t [Department of Electrical Engineering, National Taiwan University of Science and Technology, 43, Sec. 4, Keelung Rd., Taipei, Taiwan (China); Kuo, Cheng-Chien, E-mail: cckuo@mail.sju.edu.t [Department of Electrical Engineering, St. John' s University, 499, Sec. 4, TamKing Rd., Tamsui, Taipei, Taiwan (China); Chen, Tai-Hsiang, E-mail: thchen@yahoo.com.t [Department of Electrical Engineering, National Taiwan University of Science and Technology, 43, Sec. 4, Keelung Rd., Taipei, Taiwan (China)

    2011-01-15

    The paper aimed to simulate the transient over-voltage phenomena which occur at 345 kV and 161 kV underground cables, when lighting strikes on or near the cable connection station, by using the Electro-Magnetic Transients Program (EMTP). A feasibility study on changing related parameters, as well as cable connections and grounding methods to reduce the impact caused by lightning strikes, will be thoroughly conducted. The various components required for a detailed simulation including; lightning surges, transmission line and tower, arrester, and underground cables are all considered. Then, the transient voltage of the cables will be analyzed under different situations including; connection methods, grounding locations, length of the grounding wire of arrester, and the grounding resistance for different locations. The simulation results show that the length of the grounding wire is more sensitive to the transient over-voltage which occurred when a common grounding topology was adopted. In contrast, the use of an independent grounding topology resulted in a reduction of the grounding resistance, which effectively decreased the over-voltage, thereby avoiding surpassing the shielding voltage level of the cable, caused by the rise of ground voltage.

  1. A History of the Lightning Launch Commit Criteria and the Lightning Advisory Panel for America's Space Program

    Science.gov (United States)

    Merceret, Francis J. (Editor); Willett, John C.; Christian, Hugh J.; Dye, James E.; Krider, E. Phillip; Madura, John T.; OBrien, T. Paul; Rust, W. David; Walterscheid, Richard L.

    2010-01-01

    The history of the Lightning Launch Commit Criteria (LLCC) used at all spaceports under the jurisdiction of the United States is provided. The formation and history of the Lightning Advisory Panel (LAP) that now advises NASA, the Air Force and the Federal Aviation Administration on LLCC development and improvement is emphasized. The period covered extends from the early days of space flight through 2010. Extensive appendices provide significant detail about important aspects that are only summarized in the main text.

  2. Statistical Analysis for Probable Varying Potential Lightnings Strokes to Extended Objects%Statistical Analysis for Probable Varying Potential Lightnings Strokes to Extended Objects

    Institute of Scientific and Technical Information of China (English)

    M. Rezinkina; O. Rezinkin; C. Bean; S.R. Chalise; J. Grastya

    2011-01-01

    In the paper, the statistical modeling method of the lightning attachment process to extended objects has been proposed. The modeling takes into account the probabilities of lightning occurrence with current of different am- plitudes, and nonlinear variation of spark resistance at leader channel growth. The method also takes into considera- tion the dependency of velocity and acceleration of a lightning leader on its potential. The propagation of lightning channel towards the earth is tortuous and random in orientation and does not depend upon ground objects until it en- ters into "last stroke zone". It assumes that the lightning leader channel orientation begins when its streamer zone touches the earth, a grounded object, a grounded lightning rod or a streamer zone of the ascending leader. The proba- ble frequency of lightning strikes to an investigated object can be obtained by the summation of the total probable number of strikes of all possible potentials at each node of the object, appearing with the assigned probability, as well as the points of origin of the heads of lightning leaders from all nodes on the plain (over the object) at corresponding heights. The proposed method is implemented to ealculate the lightning stroke probability to a high voltage substation. Due to lightning attraction from the territory greater than that of the investigated object, the total number of annual probable lightning strokes to the object is increased by 1.28 times in comparison with the case of the same flat territory.

  3. Cloud electrification and lightning activity in a tropical cyclone-like vortex

    Science.gov (United States)

    Barthe, C.; Hoarau, T.; Bovalo, C.

    2016-11-01

    In this study, a high resolution simulation of an electrified tropical cyclone-like vortex was performed with the French mesoscale model Meso-NH coupled to an explicit electrical scheme. The objective was to analyze how graupel characteristics could influence the occurrence of lightning flashes in tropical cyclones. Two simulations were run: a control simulation using a 1-moment mixed phase bulk microphysical scheme, and a second simulation in which the parameters used to describe the graupel mass-diameter and fall speed-diameter relationships were modified to obtain smaller graupel fall speeds. Decreasing the graupel fall speed (vg) resulted in a weaker storm with a larger radius of maximum winds. For both simulated tropical cyclones, a deep mixed phase layer conducive to cloud electrification was observed. However, in the simulation where vg was decreased, the flash rate was almost zero throughout the simulation, whereas it reached a few flashes per minute in the control simulation. Several reasons that can explain this difference in the total flash rate are highlighted. Decreasing vg resulted in graupel being spread horizontally over a broader area by the secondary circulation. The more pronounced tilting observed with slower vg meant that poles of charges were not vertically aligned and thus the vertical electric field was reduced. In this study, the difference in the total flash rate mainly arose from changes in the mass and charge transfer rates due to changes in the parameters used to define the mass-diameter and particle-diameter relationships. Cloud electrification and lightning flashes being threshold-processes, a small change in the model physics can have a dramatic impact on the total flash rate.

  4. Lightning-induced overvoltages in medium voltage distribution systems and customer experienced voltage spikes

    Energy Technology Data Exchange (ETDEWEB)

    Sabiha, N. A.

    2010-07-01

    In Finland, distribution transformers are frequently subjected to lightning strokes for which they are continuously protected by spark-gaps. So, the breakdown probability of medium voltage (MV) spark-gaps is modeled using the Gaussian distribution function under an impulse voltage test in accordance with the IEC 60060-1 standard. The model is presented in the form of the well-known Gaussian tail probability. Accordingly, a modified probabilistic model is proposed to study the effect of impulse voltage superimposed on the ac voltage on the breakdown probability of MV spark-gaps. The modified model is verified using experimental data, where the experimental setup is arranged to generate a range of impulse voltages superimposed on the ac voltages. The experimental verification shows evidence of the efficacy of the proposed probabilistic model. Furthermore, the proposed model is used to evaluate single-phase, two-phase and three-phase spark-gap breakdown probabilities in the case of lightning induced overvoltages. These breakdown probabilities are used along with the simplified Rusck expression to evaluate the performance of MV overhead lines above a perfectly conducting ground under lightning-induced overvoltages using a statistical approach. In order to study the overvoltages propagating through the transformer to its low voltage side, the high frequency model of the transformer is investigated. First, the investigation is carried out using model introduced by Piantini at no-load condition. This model is modified to take more than one resonance frequency into consideration. Therefore, the frequency response of the simulated transient voltage is improved. A verification of the modified model is carried out through the comparison between the experimental and simulation results, in which the time domain simulation is carried out using ATP/EMTP while MATLAB is used to identify the model parameters. As this model is found suitable only for unloaded transformer, an

  5. Relationship between lightning activity and tropospheric nitrogen dioxide and the estimation of lightning-produced nitrogen oxides over China

    Science.gov (United States)

    Guo, Fengxia; Ju, Xiaoyu; Bao, Min; Lu, Ganyi; Liu, Zupei; Li, Yawen; Mu, Yijun

    2017-02-01

    To better understand the relationship between lightning activity and nitrogen oxides (NO X ) in the troposphere and to estimate lightning-produced NO X (LNO X ) production in China more precisely, spatial and temporal distributions of vertical column densities of tropospheric nitrogen dioxide (NO2 VCDs) and lightning activity were analyzed using satellite measurements. The results showed that the spatial distribution of lightning activity is greater in the east than in the west of China, as with NO2 VCDs. However, the seasonal and annual variation between lightning and NO2 density show different trends in the east and west. The central Tibetan Plateau is sparsely populated without modern industry, and NO2 VCDs across the plateau are barely affected by anthropogenic sources. The plateau is an ideal area to study LNO X . By analyzing 15 years of satellite data from that region, it was found that lightning density is in strong agreement with annual, spatial and seasonal variations of NO2 VCDs, with a correlation coefficient of 0.79 from the linear fit. Combining Beirle's method and the linear fit equation, LNO X production in the Chinese interior was determined to be 0.07 (0.02-0.27) TgN yr-1 for 1997-2012, within the range of 0.016-0.384 TgN yr-1 from previous estimates.

  6. TRAMWAY SYSTEM VULNERABILITIES CAUSED BY STORM. CASE STUDY: LIGHTNING IN ORADEA, 10-TH JUNE 2013

    Directory of Open Access Journals (Sweden)

    CSUZI I.

    2016-09-01

    Full Text Available Short history, theoretical presentation, risk analysis of damage probability of extreme weather effects, lightning and storm, technical and economic aspects, recommendation for public transport operators. Case study: example of a lightning damage effects in Oradea.

  7. International Aerospace and Ground Conference on Lightning and Static Electricity. 1984 technical papers. Supplement

    Science.gov (United States)

    1984-01-01

    The indirect effects of lightning on digital systems, ground system protection, and the corrosion properties of conductive materials are addressed. The responses of a UH-60A helicopter and tactical shelters to lightning and nuclear electromagnetic pulses are discussed.

  8. Lightning Detection Efficiency Analysis Process: Modeling Based on Empirical Data

    Science.gov (United States)

    Rompala, John T.

    2005-01-01

    A ground based lightning detection system employs a grid of sensors, which record and evaluate the electromagnetic signal produced by a lightning strike. Several detectors gather information on that signal s strength, time of arrival, and behavior over time. By coordinating the information from several detectors, an event solution can be generated. That solution includes the signal s point of origin, strength and polarity. Determination of the location of the lightning strike uses algorithms based on long used techniques of triangulation. Determination of the event s original signal strength relies on the behavior of the generated magnetic field over distance and time. In general the signal from the event undergoes geometric dispersion and environmental attenuation as it progresses. Our knowledge of that radial behavior together with the strength of the signal received by detecting sites permits an extrapolation and evaluation of the original strength of the lightning strike. It also limits the detection efficiency (DE) of the network. For expansive grids and with a sparse density of detectors, the DE varies widely over the area served. This limits the utility of the network in gathering information on regional lightning strike density and applying it to meteorological studies. A network of this type is a grid of four detectors in the Rondonian region of Brazil. The service area extends over a million square kilometers. Much of that area is covered by rain forests. Thus knowledge of lightning strike characteristics over the expanse is of particular value. I have been developing a process that determines the DE over the region [3]. In turn, this provides a way to produce lightning strike density maps, corrected for DE, over the entire region of interest. This report offers a survey of that development to date and a record of present activity.

  9. Lightning climatology in the Congo Basin: methodology and first results

    Science.gov (United States)

    Kigotsi, Jean; Soula, Serge; Georgis, Jean-François; Barthe, Christelle

    2016-04-01

    The global climatology of lightning issued from space observations (OTD and LIS) clearly showed the maximum of the thunderstorm activity is located in a large area of the Congo Basin, especially in the Democratic Republic of Congo (DRC). The first goal of the present study is to compare observations from the World Wide Lightning Location Network (WWLLN) from the Lightning Imaging Sensor (LIS) over a 9-year period (2005-2013) in this 2750 km × 2750 km area. The second goal is to analyse the lightning activity in terms of time and space variability. The detection efficiency (DE) of the WWLLN relative to LIS has increased between 2005 and 2013, typically from about 1.70 % to 5.90 %, in agreement with previous results for other regions of the world. The mean monthly flash rate describes an annual cycle with a maximum between November and March and a minimum between June and August, associated with the ICTZ migration but not exactly symmetrical on both sides of the equator. The diurnal evolution of the flash rate has a maximum between 1400 and 1700 UTC, depending on the reference year, in agreement with previous works in other regions of the world. The annual flash density shows a sharp maximum localized in eastern DRC regardless of the reference year and the period of the year. This annual maximum systematically located west of Kivu Lake corresponds to that previously identified by many authors as the worldwide maximum which Christian et al. (2013) falsely attributed to Rwanda. Another more extended region within the Congo Basin exhibits moderately large values, especially during the beginning of the period analyzed. A comparison of both patterns of lightning density from the WWLLN and from LIS allows to validate the representativeness of this world network and to restitute the total lightning activity in terms of lightning density and rate.

  10. Nearshore regional behavior of lightning interaction with wind turbines

    Directory of Open Access Journals (Sweden)

    Gilbert A. Malinga

    2016-01-01

    Full Text Available The severity of lightning strikes on offshore wind turbines built along coastal and nearshore regions can pose safety concerns that are often overlooked. In this research study the behavior of electrical discharges for wind turbines that might be located in the nearshore regions along the East Coast of China and Sea of Japan were characterized using a physics-based model that accounted for a total of eleven different geometrical and lightning parameters. Utilizing the electrical potential field predicted using this model it was then possible to estimate the frequency of lightning strikes and the distribution of electrical loads utilizing established semi-empirical relationships and available data. The total number of annual lightning strikes on an offshore wind turbine was found to vary with hub elevation, extent of cloud cover, season and geographical location. The annual lightning strike rate on a wind turbine along the nearshore region on the Sea of Japan during the winter season was shown to be moderately larger compared to the lightning strike frequency on a turbine structure on the East Coast of China. Short duration electrical discharges, represented using marginal probability functions, were found to vary with season and geographical location, exhibiting trends consistent with the distribution of the electrical peak current. It was demonstrated that electrical discharges of moderately long duration typically occur in the winter months on the East Coast of China and the summer season along the Sea of Japan. In contrast, severe electrical discharges are typical of summer thunderstorms on the East Coast of China and winter frontal storm systems along the West Coast of Japan. The electrical charge and specific energy dissipated during lightning discharges on an offshore wind turbine was found to vary stochastically, with severe electrical discharges corresponding to large electrical currents of long duration.

  11. Analysis of Channel Luminosity Characteristics in Rocket-Triggered Lightning

    Institute of Scientific and Technical Information of China (English)

    LU Weitao; ZHANG Yijun; ZHOU Xiuji; MENG Qing; ZHENG Dong; MA Ming; WANG Fei; CHEN Shaodong; QIE Xiushu

    2008-01-01

    A comparison is made of the high-speed(2000 fps)photographic records in rocket-triggered negative lightning between two techniques.The analysis shows that:the initial speed of upward positive leader (UPL)in altitude-triggered negative lightning(ATNL)is about one order of magnitude less than that in classically triggered negative lightning(CTNL),while the triggering height of ATNL is higher than that of CTNL;the afterglow time of metal-vaporized part of the lightning channel Call endure for about 160-170 ms,thus the luminosity of the air-ionized part can reflect the characteristics of the current in the lightning channel better than that of the metal-vaporized part.According to the different characteristics of the luminosity change of the lightning channel,together with the observation of the electric field changes,three kinds of processes after return-stroke(RS)can be distinguished:the continuous decaying type without M component,the isolated type and the continuing type with M component,corresponding to different wave shapes of the continuous current.The geometric mean of the interval of RS with M component is 77 ms,longer than that(37 ms)of RS without M component.And the initial continuous current(ICC)with M component also has a longer duration compared to the ICC without M component.The distinction in the relative luminosity between the lightning channel before RS and that before M component is obvious:the former is very weak or even cannot be observed,while the latter is still considerably luminous.

  12. Lightning safety awareness of visitors in three California national parks.

    Science.gov (United States)

    Weichenthal, Lori; Allen, Jacoby; Davis, Kyle P; Campagne, Danielle; Snowden, Brandy; Hughes, Susan

    2011-09-01

    To assess the level of lightning safety awareness among visitors at 3 national parks in the Sierra Nevada Mountains of California. A 12-question, short answer convenience sample survey was administered to participants 18 years of age and over concerning popular trails and points of interest with known lightning activity. There were 6 identifying questions and 5 knowledge-based questions pertaining to lightning that were scored on a binary value of 0 or 1 for a total of 10 points for the survey instrument. Volunteers in Fresno, California, were used as a control group. Participants were categorized as Sequoia and Kings Canyon National Park (SEKI), frontcountry (FC), or backcountry (BC); Yosemite National Park (YNP) FC or BC; and Fresno. Analysis of variance (ANOVA) was used to test for differences between groups. 467 surveys were included for analysis: 77 in Fresno, 192 in SEKI, and 198 in YNP. National park participants demonstrated greater familiarity with lightning safety than individuals from the metropolitan community (YNP 5.84 and SEKI 5.65 vs Fresno 5.14, P = .0032). There were also differences noted between the BC and FC subgroups (YNP FC 6.07 vs YNP BC 5.62, P = .02; YNP FC 6.07 vs SEKI FC 5.58, P = .02). Overall results showed that participants had certain basic lightning knowledge but lacked familiarity with other key lightning safety recommendations. While there are statistically significant differences in lightning safety awareness between national parks and metropolitan participants, the clinical impact of these findings are debatable. This study provides a starting point for providing educational outreach to visitors in these national parks. Copyright © 2011 Wilderness Medical Society. Published by Elsevier Inc. All rights reserved.

  13. Learning from concurrent Lightning Imaging Sensor and Lightning Mapping Array observations in preparation for the MTG-LI mission

    Science.gov (United States)

    Defer, Eric; Bovalo, Christophe; Coquillat, Sylvain; Pinty, Jean-Pierre; Farges, Thomas; Krehbiel, Paul; Rison, William

    2016-04-01

    The upcoming decade will see the deployment and the operation of French, European and American space-based missions dedicated to the detection and the characterization of the lightning activity on Earth. For instance the Tool for the Analysis of Radiation from lightNIng and Sprites (TARANIS) mission, with an expected launch in 2018, is a CNES mission dedicated to the study of impulsive energy transfers between the atmosphere of the Earth and the space environment. It will carry a package of Micro Cameras and Photometers (MCP) to detect and locate lightning flashes and triggered Transient Luminous Events (TLEs). At the European level, the Meteosat Third Generation Imager (MTG-I) satellites will carry in 2019 the Lightning Imager (LI) aimed at detecting and locating the lightning activity over almost the full disk of Earth as usually observed with Meteosat geostationary infrared/visible imagers. The American community plans to operate a similar instrument on the GOES-R mission for an effective operation in early 2016. In addition NASA will install in 2016 on the International Space Station the spare version of the Lightning Imaging Sensor (LIS) that has proved its capability to optically detect the tropical lightning activity from the Tropical Rainfall Measuring Mission (TRMM) spacecraft. We will present concurrent observations recorded by the optical space-borne Lightning Imaging Sensor (LIS) and the ground-based Very High Frequency (VHF) Lightning Mapping Array (LMA) for different types of lightning flashes. The properties of the cloud environment will also be considered in the analysis thanks to coincident observations of the different TRMM cloud sensors. The characteristics of the optical signal will be discussed according to the nature of the parent flash components and the cloud properties. This study should provide some insights not only on the expected optical signal that will be recorded by LI, but also on the definition of the validation strategy of LI, and

  14. Lightning Observations from the International Space Station (ISS) for Science Research and Operational Applications

    Science.gov (United States)

    Blakeslee, R. J.; Christian, H. J.; Mach, D. M.; Buechler, D. E.; Koshak, W. J.; Walker, T. D.; Bateman, M.; Stewart, M. F.; O'Brien, S.; Wilson, T.; hide

    2015-01-01

    There exist several core science applications of LIS lightning observations, that range from weather and climate to atmospheric chemistry and lightning physics due to strong quantitative connections that can be made between lightning and other geophysical processes of interest. The space-base vantage point, such as provided by ISS LIS, still remains an ideal location to obtain total lightning observations on a global basis.

  15. Lightning NOx Parameterization for Synoptic Meteorological-scale Prediction with Convective Parameterization in WRF-Chem

    Science.gov (United States)

    Wong, J.; Noone, D. C.; Barth, M. C.

    2011-12-01

    Lightning NOx (LNOx) is an important precursor to tropospheric ozone production and monsoonal upper tropospheric ozone enhancement. A parameterization for LNOx emission is designed for convective-parameterized synoptic meteorological-scale predictions in the NCAR Weather Research and Forecasting Model with Chemistry (WRF-Chem). The implementation uses the Price and Rind (1992) flash rate equation to produce a flash density as a function of cloud height. A fixed emission rate of 500 moles NO per flash and Gaussian vertical distributions are then used to produce the predicted LNOx emission. Comparison of the results from a month long simulation over continental United States against a multiyear climatology based on Optical Transient Detector (OTD) computed by Boccippio et al (2000) shows confidence in reproducing the proper geographical distribution. Regional comparison against National Lightning Detection Network (NLDN) data also shows confidence of using a constant tuning parameter to produce a flash density within the order of magnitude of that observed with consideration of model bias in convection. The produced tropospheric NO2 column also matches well (reduced χ2=0.88) with SCHIAMACHY NO2 vertical column density. Several sensitivity simulations are also performed to evaluate the model's response to the parameterization in ozone and related species such as isoprene and formaldehyde. Results show that the species-specific sensitivities to LNOx emission are significantly altered by convective detrainment as well as the variability of NOx residence time throughout the troposphere from the prescribed vertical distribution.

  16. Technique for the comparison of light spectra from natural and laboratory generated lightning current arcs

    Science.gov (United States)

    Mitchard, D.; Clark, D.; Carr, D.; Haddad, A.

    2016-08-01

    A technique was developed for the comparison of observed emission spectra from lightning current arcs generated through self-breakdown in air and the use of two types of initiation wire, aluminum bronze and nichrome, against previously published spectra of natural lightning events. A spectrograph system was used in which the wavelength of light emitted by the lightning arc was analyzed to derive elemental interactions. A lightning impulse of up to 100 kA was applied to a two hemispherical tungsten electrode configuration which allowed the effect of the lightning current and lightning arc length to be investigated. A natural lightning reference spectrum was reconstructed from literature, and generated lightning spectra were obtained from self-breakdown across a 14.0 mm air gap and triggered along initiation wires of length up to 72.4 mm. A comparison of the spectra showed that the generated lightning arc induced via self-breakdown produced a very similar spectrum to that of natural lightning, with the addition of only a few lines from the tungsten electrodes. A comparison of the results from the aluminum bronze initiation wire showed several more lines, whereas results from the nichrome initiation wire differed greatly across large parts of the spectrum. This work highlights the potential use for spectrographic techniques in the study of lightning interactions with surrounding media and materials, and in natural phenomena such as recently observed ball lightning.

  17. Technique for the comparison of light spectra from natural and laboratory generated lightning current arcs

    Energy Technology Data Exchange (ETDEWEB)

    Mitchard, D., E-mail: mitcharddr@cardiff.ac.uk; Clark, D.; Carr, D.; Haddad, A. [Morgan-Botti Lightning Laboratory, Advanced High Voltage Research Centre, School of Engineering, Cardiff University, CF24 3AA Wales (United Kingdom)

    2016-08-29

    A technique was developed for the comparison of observed emission spectra from lightning current arcs generated through self-breakdown in air and the use of two types of initiation wire, aluminum bronze and nichrome, against previously published spectra of natural lightning events. A spectrograph system was used in which the wavelength of light emitted by the lightning arc was analyzed to derive elemental interactions. A lightning impulse of up to 100 kA was applied to a two hemispherical tungsten electrode configuration which allowed the effect of the lightning current and lightning arc length to be investigated. A natural lightning reference spectrum was reconstructed from literature, and generated lightning spectra were obtained from self-breakdown across a 14.0 mm air gap and triggered along initiation wires of length up to 72.4 mm. A comparison of the spectra showed that the generated lightning arc induced via self-breakdown produced a very similar spectrum to that of natural lightning, with the addition of only a few lines from the tungsten electrodes. A comparison of the results from the aluminum bronze initiation wire showed several more lines, whereas results from the nichrome initiation wire differed greatly across large parts of the spectrum. This work highlights the potential use for spectrographic techniques in the study of lightning interactions with surrounding media and materials, and in natural phenomena such as recently observed ball lightning.

  18. Laboratory Calibration of the Optical Transient Detector (OTD) and the Lightning Imaging Sensor (LIS)

    Science.gov (United States)

    Koshak, William J.; Stewart, Mike F.; Christian, Hugh J.; Bergstrom, James W.; Hall, John M.; Solakiewicz, Richard J.

    1994-01-01

    We present in detail the laboratory apparatus and techniques that were used to complete a full radiometric calibration of two space-based lightning detectors developed at NASA Marshall Space Flight Center (MSFC). A discussion of the methods applied to geolocate lightning and to estimate lightning detection efficiency are provided.

  19. 30 CFR 77.508-1 - Lightning arresters; wires entering buildings.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Lightning arresters; wires entering buildings... OF UNDERGROUND COAL MINES Electrical Equipment-General § 77.508-1 Lightning arresters; wires entering buildings. Lightning arresters protecting exposed telephone wires entering buildings shall be provided...

  20. Global lightning and severe storm monitoring from GPS orbit

    Energy Technology Data Exchange (ETDEWEB)

    Suszcynsky, D. M. (David M.); Jacobson, A. R.; Linford, J (Justin); Pongratz, M. B. (Morris B.); Light, T. (Tracy E.); Shao, X. (Xuan-Min)

    2004-01-01

    Over the last few decades, there has been a growing interest to develop and deploy an automated and continuously operating satellite-based global lightning mapper [e.g. Christian et al., 1989; Weber et al., 1998; Suszcynsky et al., 2000]. Lightning is a direct consequence of the electrification and breakdown processes that take place during the convective stages of thunderstorm development. Satellite-based lightning mappers are designed to exploit this relationship by using lightning detection as a proxy for remotely identifying, locating and characterizing strong convective activity on a global basis. Global lightning and convection mapping promises to provide users with (1) an enhanced global severe weather monitoring and early warning capability [e.g. Weber et al., 1998] (2) improved ability to optimize aviation flight paths around convective cells, particularly over oceanic and remote regions that are not sufficiently serviced by existing weather radar [e.g. Weber et al., 1998], and (3) access to regional and global proxy data sets that can be used for scientific studies and as input into meteorological forecast and global climatology models. The physical foundation for satellite-based remote sensing of convection by way of lightning detection is provided by the basic interplay between the electrical and convective states of a thundercloud. It is widely believed that convection is a driving mechanism behind the hydrometeor charging and transport that produces charge separation and lightning discharges within thunderclouds [e.g. see chapter 3 in MacGorman and Rust, 1998]. Although cloud electrification and discharge processes are a complex function of the convective dynamics and microphysics of the cloud, the fundamental relationship between convection and electrification is easy to observe. For example, studies have shown that the strength of the convective process within a thundercell can be loosely parameterized (with large variance) by the intensity of the

  1. Direct satellite observation of lightning-produced NOx

    Directory of Open Access Journals (Sweden)

    T. Wagner

    2010-08-01

    Full Text Available Lightning is an important source of NOx in the free troposphere, especially in the tropics, with high impact on ozone production. However, estimates of lightning NOx (LNOx production efficiency (LNOx per flash are still quite uncertain. In this study we present a systematic analysis of NO2 column densities from SCIAMACHY measurements over active thunderstorms, as detected by the World-Wide Lightning Location Network (WWLLN, where the WWLLN detection efficiency was estimated using the flash climatology of the satellite lightning sensors LIS/OTD. Only events with high lightning activity are considered, where corrected WWLLN flash rate densities inside the satellite pixel within the last hour are above 1 /km2/h. For typical SCIAMACHY ground pixels of 30×60 km2, this threshold corresponds to 1800 flashes over the last hour, which, for literature estimates of lightning NOx production, should result in clearly enhanced NO2 column densities. From 2004–2008, we find 287 coincidences of SCIAMACHY measurements and high WWLLN flash rate densities. For some of these events, a clear enhancement of column densities of NO2 could be observed, indeed. But overall, the measured column densities are below the expected values by more than one order of magnitude, and in most of the cases, no enhanced NO2 could be found at all. Our results are in contradiction to the currently accepted range of LNOx production per flash of 15 (2–40×1025 molec/flash. This probably partly results from the specific conditions for the events under investigation, i.e. events of high lightning activity in the morning (local time and mostly (for 162 out of 287 events over ocean. Within the detected coincidences, the highest NO2 column densities were observed around the US Eastcoast. This might be partly due to interference with ground sources of NOx being uplifted by the convective systems. However, it could also indicate that flashes in this region are particularly productive. We

  2. Response of global lightning activity to air temperature variation

    Institute of Scientific and Technical Information of China (English)

    MA Ming; TAO Shanchang; ZHU Baoyou; L(U) Weitao; TAN Yongbo

    2005-01-01

    It is an issue of great attention but yet not very clear whether lightning activities increase or decrease on a warmer world. Reeve et al. presented that lightning activities in global land and the Northern Hemisphere land have positive response to the increase of wet bulb temperature at 1000hPa. Is this positive response restricted only to wet bulb temperature or in land? What is the response of global lightning activities (in both land and ocean) to the global surface air temperature variation like? This paper, based on the 5-year or 8-year OTD/LIS satellite-based lightning detecting data and the NCEP reanalysis data, makes a reanalysis of the response of the global and regional lightning activities to temperature variations. The results show that on the interannual time scale the global total flash rate has positive response to the variation in global surface air temperature, with the sensitivity of 17±7% K-1. Also, the seasonal mean flash rate of continents all over the world and that of continents in the Northern Hemisphere have sensitive positive response to increase of global surface air temperature and wet bulb temperature, with the sensitivity of about 13±5% K-1, a bit lower than estimation of 40% K-1 in Reeve et al. However, the Southern Hemisphere and other areas like the tropics show no significant correlation.

  3. Lightning-based propagation of convective rain fields

    Directory of Open Access Journals (Sweden)

    S. Dietrich

    2011-05-01

    Full Text Available This paper describes a new multi-sensor approach for continuously monitoring convective rain cells. It exploits lightning data from surface networks to propagate rain fields estimated from multi-frequency brightness temperature measurements taken by the AMSU/MHS microwave radiometers onboard NOAA/EUMETSAT low Earth orbiting operational satellites. Specifically, the method allows inferring the development (movement, morphology and intensity of convective rain cells from the spatial and temporal distribution of lightning strokes following any observation by a satellite-borne microwave radiometer. Obviously, this is particularly attractive for real-time operational purposes, due to the sporadic nature of the low Earth orbiting satellite measurements and the continuous availability of ground-based lightning measurements – as is the case in most of the Mediterranean region. A preliminary assessment of the lightning-based rainfall propagation algorithm has been successfully made by using two pairs of consecutive AMSU observations, in conjunction with lightning measurements from the ZEUS network, for two convective events. Specifically, we show that the evolving rain fields, which are estimated by applying the algorithm to the satellite-based rainfall estimates for the first AMSU overpass, show an overall agreement with the satellite-based rainfall estimates for the second AMSU overpass.

  4. Assessment of Lightning Simulation Test Techniques. Part I.

    Science.gov (United States)

    1981-10-01

    TABLE 2. DATA SUMMARY -CYLINDER WITH WIRE RETURN Geerator 20 kV 376kV 520 kV Arc Induced % of Phak Arc Induced % of Peak Amc Induced % of Peak Wire Type...INCH SPARK GAP, INTERIOR WIRE SHORTED TO CYLINDER 72 I 111 1 Single Interior Wire Interior Wire 1/2 XResonance E Z ._cucc a- 0 10 20 Frequency (MHz

  5. Production of Ionospheric Perturbations by Cloud-to-Ground Lightning and the Recovery of the Lower Ionosphere

    Science.gov (United States)

    Liu, Ningyu; Dwyer, Joseph; Rassoul, Hamid

    2013-04-01

    The fact that lightning/thunderstorm activities can directly modify the lower ionosphere has long been established by observations of the perturbations of very low frequency (VLF) signals propagating in the earth-ionosphere waveguide. These perturbations are known as early VLF events [Inan et al., 2010, JGR, 115, A00E36, 2010]. More recently discovered transient luminous events caused by the lightning/thunderstorm activities only last ~1-100 ms, but studies of the early VLF events show that the lightning ionospheric effects can persist much longer, >10s min [Cotts and Inan, GRL, 34, L14809, 2007; Haldoupis et al., JGR, 39, L16801, 2012; Salut et al., JGR, 117, A08311, 2012]. It has been suggested that the long recovery is caused by long-lasting conductivity perturbations in the lower ionosphere, which can be created by sprites/sprite halos which in turn are triggered by cloud-to-ground (CG) lightning [Moore et al., JGR, 108, 1363, 2003; Haldoupis et al., 2012]. We recently developed a two-dimensional fluid model with simplified ionospheric chemistry for studying the quasi-electrostatic effects of lightning in the lower ionosphere [Liu, JGR, 117, A03308, 2012]. The model chemistry captures major ion species and reactions in the lower ionosphere. Additional important features of the model include self-consistent background ion density profiles and full description of electron and ion transport. In this talk, we present the simulation results on the dynamics of sprite halos caused by negative CG lightning. The modeling results indicate that electron density around 60 km altitude can be enhanced in a region as wide as 80 km. The enhancement reaches its full extent in ~1 s and recovers in 1-10 s, which are on the same orders as the durations of slow onset and post-onset peaks of some VLF events, respectively. In addition, long-lasting electron and ion density perturbations can occur around 80 km altitude due to negative halos as well as positive halos, which can explain

  6. Broadband electromagnetic sensors for aircraft lightning research. [electromagnetic effects of lightning on aircraft digital equipment

    Science.gov (United States)

    Trost, T. F.; Zaepfel, K. P.

    1980-01-01

    A set of electromagnetic sensors, or electrically-small antennas, is described. The sensors are designed for installation on an F-106 research aircraft for the measurement of electric and magnetic fields and currents during a lightning strike. The electric and magnetic field sensors mount on the aircraft skin. The current sensor mounts between the nose boom and the fuselage. The sensors are all on the order of 10 cm in size and should produce up to about 100 V for the estimated lightning fields. The basic designs are the same as those developed for nuclear electromagnetic pulse studies. The most important electrical parameters of the sensors are the sensitivity, or equivalent area, and the bandwidth (or rise time). Calibration of sensors with simple geometries is reliably accomplished by a geometric analysis; all the sensors discussed possess geometries for which the sensitivities have been calculated. For the calibration of sensors with more complex geometries and for general testing of all sensors, two transmission lines were constructed to transmit known pulsed fields and currents over the sensors.

  7. A novel lightning protection technique of wind turbine components

    Directory of Open Access Journals (Sweden)

    M.A. Abd-Allah

    2015-12-01

    Full Text Available The lightning energy can be very harmful to wind turbine (WT farm components; therefore an effective lightning protection technique is required. In this study, a novel technique for WT components protection is presented. This technique used ferromagnetic rings placed around the WT blade roots. Ferrite ring was moulded into particular shapes from the powder of compounds of ferric oxide, manganese, and zinc, and then sintered. The dimensions of rings used are 990 mm (inner diameter, 1030 mm (outer diameter, and 100 mm (thickness. The effectiveness of the novel technique in overvoltage mitigation during lightning strokes is presented and discussed. The results show that the overvoltage is effectively damped with using this technique. The transient overvoltage at control devices is reduced to 16% of its original value, while at distribution system; it is reduced to 5% of its original value.

  8. Total Lightning Flash Activity Response to Aerosol over China Area

    Directory of Open Access Journals (Sweden)

    Pengguo Zhao

    2017-01-01

    Full Text Available Twelve years of measurements of aerosol optical depth (AOD, cloud fraction, cloud top height, ice cloud optical thickness and lightning flash density from 2001 to 2012 have been analyzed to investigate the effect of aerosols on electrical activity over an area of China. The results show that increasing aerosol loading inspires the convective intensity, and then increases the lightning flash density. The spatial distribution of the correlation between aerosol loading and electrical activity shows a remarkable regional difference over China. The high-correlation regions embody the positive aerosol microphysical effect on the intensity of the electrical activity, while the large-scale processes may play the main role in convection development and producing lightning in low-correlation regions.

  9. Estimation of the Current Peak Value Distribution of All Lightning to the Ground by Electro-Geometric Model

    Science.gov (United States)

    Sakata, Tadashi; Yamamoto, Kazuo; Sekioka, Shozo; Yokoyama, Shigeru

    When we examine the lightning frequency and the lightning shielding effect by EGM (electro-geometric model), we need the current distribution of all lightning to the ground. The lightning current distribution to structures is different from this distribution, but it has been used in EGM conventionally. We assumed the lightning striking distance coefficient related to height of structures for getting the result which corresponds to observed lightning frequency to structures, and estimated the current distribution of all lightning to the ground from data listed in IEC 62305 series by EGM. The estimated distribution adjusted by detection efficiency of LLS almost corresponded to observed distribution by LLS.

  10. Modeling the stepping mechanism in negative lightning leaders

    Science.gov (United States)

    Iudin, Dmitry; Syssoev, Artem; Davydenko, Stanislav; Rakov, Vladimir

    2017-04-01

    It is well-known that the negative leaders develop in a step manner using a mechanism of the so-called space leaders in contrary to positive ones, which propagate continuously. Despite this fact has been known for about a hundred years till now no one had developed any plausible model explaining this asymmetry. In this study we suggest a model of the stepped development of the negative lightning leader which for the first time allows carrying out the numerical simulation of its evolution. The model is based on the probability approach and description of temporal evolution of the discharge channels. One of the key features of our model is accounting for the presence of so called space streamers/leaders which play a fundamental role in the formation of negative leader's steps. Their appearance becomes possible due to the accounting of potential influence of the space charge injected into the discharge gap by the streamer corona. The model takes into account an asymmetry of properties of negative and positive streamers which is based on well-known from numerous laboratory measurements fact that positive streamers need about twice weaker electric field to appear and propagate as compared to negative ones. An extinction of the conducting channel as a possible way of its evolution is also taken into account. This allows us to describe the leader channel's sheath formation. To verify the morphology and characteristics of the model discharge, we use the results of the high-speed video observations of natural negative stepped leaders. We can conclude that the key properties of the model and natural negative leaders are very similar.

  11. National Renewable Energy Laboratory program on lightning risk and wind turbine generator protection

    Energy Technology Data Exchange (ETDEWEB)

    Muljadi, E [National Renewable Energy Lab., Golden, CO (United States); McNiff, B [McNiff Light Industry, Blue Hill, ME (United States)

    1997-09-01

    This paper will describe the NREL program for addressing lightning protection for wind turbines. A test program will begin this summer at the Central and South West Services Inc. (CSW) wind farm near Fort Davis, Texas, to assess lightning risk, the frequency of lightning strikes on wind turbines compared to risk assessment predictions, and the effectiveness of some protection techniques. A Web page will be assembled to provide resources for designers and operators and feedback for issues as they arise. Also, a database of lightning events (and corresponding damage) will be collected to assist in maturing the understanding of wind turbine lightning protection.

  12. Research on Line Patrol Strategy of 110kV Transmission Line after Lightning Strike

    Directory of Open Access Journals (Sweden)

    Li Mingjun

    2016-01-01

    Full Text Available Lightning faults occupy in the majority of instantaneous fault and reclosing can usually be successful, so power supply can be restored without immediate patrol in many cases. Firstly, this paper introduces the lightning fault positioning and identifying method. Then test electrical performance of insulators after lightning strike from 110kV lines. Data shows that lightning strike has little effect on the electric performance of insulator. Finally, illustrating disposal process of the 110 kV transmission line after lightning fault, certifying that the power supply reliability be ensured without line patrol.

  13. Lightning Damage to Wind Turbine Blades From Wind Farms in the U.S

    DEFF Research Database (Denmark)

    Candela Garolera, Anna; Madsen, Søren Find; Nissim, Maya;

    2016-01-01

    This paper presents statistical data about lightning damage on wind turbine blades reported at different wind farms in the U.S. The analysis is based on 304 cases of damage due to direct lightning attachment on the blade surface. This study includes a large variety of blades with different lengths......, laminate structure, and lightning protection systems. The statistics consist of the distribution of lightning damage along the blade and classify the damage by severity. In addition, the frequency of lightning damage to more than one blade of a wind turbine after a thunderstorm is assessed. The results...

  14. Fire Environment Mechanism of Lightning-groundfire for Daxing anling Mountains

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Ground fire is an igniting phenomenon that is difficult to control and lightning is the main cause of ground fire. The mechanism of lightning-ground fire is very complex. Daxing'anling Mountains forest region is the place that lighting-groundfire occurs more often and regularly. Our study on lightning-groundfire of this zone in 2002 shows: much more soil near the surface and the ground fuel is the matter preconditions of lightning-groundfire, and the weather conditions hasten the occurrence of lightning...

  15. First results of the Colombia Lightning Mapping Array

    Science.gov (United States)

    López, Jesus; Montanyà, Joan; van der Velde, Oscar; Romero, David; Fabró, Ferran; Taborda, John; Aranguren, Daniel; Torres, Horacio

    2016-04-01

    In April 2015 the 3D Lightning Mapping Array (COLMA) network was installed on Santa Marta area (north of Colombia). The COLMA maps VHF radio emissions of lightning leaders in three dimensions by the time-of-arrival technique (Rison et al., 1999). This array has six sensors with base lines between 5 km to 20 km. The COLMA is the first VHF 3D network operating in the tropics and it has been installed in the frame of ASIM (Atmosphere-Space Interactions Monitor) ESA's mission in order to investigate the electrical characteristics of tropical thunderstorms favorable for the production of Terrestrial Gamma ray Flashes (TGF). In this paper we present COLMA data of several storms. We discuss lightning activity, lightning leader altitudes and thunderstorm charge structures compared to data form our ELMA (Ebro Lightning Mapping Array) at the north-east coast of Spain. The data confirm what we expected, lightning leaders can propagate at higher altitudes compared to mid latitude thunderstorms because the higher vertical development of tropical thunderstorms. A simple inspection of a ten minute period of the 16th of November of 2015 storm shows a tripolar electric charge structure. In that case, the midlevel negative charge region was located between 7 to 9 km. The structure presented a lower positive charge below the midlevel negative and centred at 6.5 km and an upper positive charge region extending from 9 km to slightly more than 15 km. This vertical extension of the upper positive charge where negative leaders evolve is significantly larger compared to the storms at the ELMA area in Spain. COLMA has shown frequent activity of negative leaders reaching altitudes of more than 15 km.

  16. Recent Developments With the New Mexico Tech Lightning Mapping Array

    Science.gov (United States)

    Krehbiel, P. R.; Rison, W. R.; Thomas, R. J.; Edens, H. E.; Aulich, G. D.

    2005-12-01

    Lightning mapping arrays (LMAs) are being operated by NASA in northern Alabama, by the University of Oklahoma and National Severe Storms Laboratory in central Oklahoma, and at Langmuir Laboratory and most recently at White Sands Missile Range in central and south-central New Mexico. In addition we have been developing a portable mapping system for use in field and demonstration programs. Data from the permanently-installed systems are being processed in real time and, in addition to research studies, are being used or are starting to be used in weather nowcasting applications. New metric-based code and algorithms have been developed for optimally processing the time-of-arrival measurements, which provide better solutions in less time than our previous code and have given us new insights into the basic processing issues. We are continuing to develop new techniques and approaches for analyzing the mapping data, such as using them to infer storm charge structure and for determining the direction and speed of initial breakdown of individual flashes, and combining the results with simple theoretical models for electrification and lightning initiation studies. We have also been working to obtain detailed pictures of individual lightning discharges using a compact array having 10-microsecond time resolution at Langmuir Laboratory and to combine these data with slow and fast electric field change measurements to advance our understanding of basic breakdown processes. Finally, the portable LMA will provide new and unique opportunities for studies of convective storms and lightning, such as fully mobile field campaigns, studies of lightning initiation in conjunction with cosmic ray and high energy particle observations, and the development of techniques and systems for monitoring lightning in urban and noisy metropolitan areas.

  17. Lightning climatology in the Congo Basin: detailed analysis

    Science.gov (United States)

    Soula, Serge; Kigotsi, Jean; Georgis, Jean-François; Barthe, Christelle

    2016-04-01

    The lightning climatology of the Congo Basin including several countries of Central Africa is analyzed in detail for the first time. It is based on World Wide Lightning Location Network (WWLLN) data for the period from 2005 to 2013. A comparison of these data with the Lightning Imaging Sensor (LIS) data for the same period shows the WWLLN detection efficiency (DE) in the region increases from about 1.70 % in the beginning of the period to 5.90 % in 2013, relative to LIS data, but not uniformly over the whole 2750 km × 2750 km area. Both the annual flash density and the number of stormy days show sharp maximum values localized in eastern of Democratic Republic of Congo (DRC) and west of Kivu Lake, regardless of the reference year and the period of the year. These maxima reach 12.86 fl km-2 and 189 days, respectively, in 2013, and correspond with a very active region located at the rear of the Virunga mountain range characterised with summits that can reach 3000 m. The presence of this range plays a role in the thunderstorm development along the year. The estimation of this local maximum of the lightning density by taking into account the DE, leads to a value consistent with that of the global climatology by Christian et al. (2003) and other authors. Thus, a mean maximum value of about 157 fl km-2 y-1 is found for the annual lightning density. The zonal distribution of the lightning flashes exhibits a maximum between 1°S and 2°S and about 56 % of the flashes located below the equator in the 10°S - 10°N interval. The diurnal evolution of the flash rate has a maximum between 1400 and 1700 UTC, according to the reference year, in agreement with previous works in other regions of the world.

  18. Relationship between lightning activity and vertical airflow characteristics in thunderstorms

    Science.gov (United States)

    Wang, Chenxi; Zheng, Dong; Zhang, Yijun; Liu, Liping

    2017-07-01

    Cloud-to-ground (CG) lightning data, wind field data derived from dual-Doppler radars, and radar reflectivity data are combined to investigate the relationships between CG lightning and the parameters associated with vertical airflow. A new method for the identification of thunderstorm cells based on the aggregation of flashes is developed. It is found that approximately 79.1% of CG flashes are located in the region featuring weak vertical velocity at the 0 °C level, ranging from - 5 to 5 m s- 1, with the majority in the weak updraft region, especially for negative CG lightning and the CG lightning in the initial stage of thunderstorms. The CG lightning rate is correlated with the volume of updraft for vertical velocities within certain limits. The sum of absolute precipitation ice mass flux in the region from 7 to 11 km is more significantly correlated with the CG flash rate, with correlation coefficients of 0.73, 0.71, and 0.74 for the initial, mature, and dissipating stages of thunderstorms, respectively. On average, the updraft in the thunderstorm at the stage when the last CG flash occurs accounts for a much smaller ratio to the whole volume of the thunderstorm than that corresponding to the first CG flash. The maximum updraft and maximum height of the 10 and 20 m s- 1 updraft speeds are close for the first and last CG flashes, indicating the dependence of the lightning on strength of updraft. It is deduced that layered large-range charges may be more conducive to the generation of CG flashes than charge pockets in the thunderstorm.

  19. Beijing Lightning Network (BLNET) and the observation on preliminary breakdown processes

    Science.gov (United States)

    Wang, Yu; Qie, Xiushu; Wang, Dongfang; Liu, Mingyuan; Su, Debin; Wang, Zhichao; Liu, Dongxia; Wu, Zhijun; Sun, Zhuling; Tian, Ye

    2016-05-01

    Beijing Lightning Network (BLNET), a regional multi-frequency-band lightning detection and location network, has been developed for both research and operational purposes. The network consisted of 15 stations in 2014, covering an area of about 100 km × 85 km in Beijing area. In this paper, we present the configuration of the network and the detailed description on the sensors for the first time. The Chan algorithm and Levenberg-Marquardt method are adopted jointly in the lightning location algorithm. The Monte Carlo simulation reveals that the horizontal and the vertical location errors within BLNET coverage are less than 300 m and 600 m, respectively. The comparison of total lightning location results with the corresponding radar reflectivity for a thunderstorm case indicates that BLNET has a good capability to track thunderstorms in the Beijing area. Besides, we examine the electric field waveforms of the preliminary breakdown process (PBP) of 111 - CG flashes, 92 + CG flashes, 22 normal-polarity IC flashes and 22 inverted-polarity IC flashes. Statistics on the time interval between the largest PBP pulse and the corresponding first RS pulse for CG flash (PB-RS interval), the ratio of the largest PBP pulse to the corresponding first RS pulse for CG flash (PB/RS ratio), the pulse width for individual pulse in the PBP train (Tw) and the time interval between successive pulses in the PBP train (Ti) are presented. The 3D location result shows that the PBP of a - CG flash initiates at an altitude of ~ 6 km and propagates downward to ~ 3 km with a vertical speed of 5.9 × 105 m/s. The initial 10 ms of an IC flash is found to start at ~ 7.2 km and develop upward to ~ 10 km. The vertical propagation speed is estimated to be 4.8 × 105 m/s during the first 6 ms. A PBP with relatively clear branched 3D structure is presented and discussed in the end of the paper. The average 3D propagation speed of two branches is estimated to be 2.1 × 106 m/s and 2.6 × 106 m

  20. Analysis of lightning-ionosphere interaction using simultaneous records of source current and 380 km distant electric field

    Science.gov (United States)

    Azadifar, Mohammad; Li, Dongshuai; Rachidi, Farhad; Rubinstein, Marcos; Diendorfer, Gerhard; Schulz, Wolfgang; Pichler, Hannes; Rakov, Vladimir A.; Paolone, Mario; Pavanello, Davide

    2017-06-01

    We present simultaneous current and wideband electric field waveforms at 380 km associated with upward lightning flashes initiated from the Säntis Tower, Switzerland. To the best of our knowledge, the dataset presented in this study includes the first simultaneous records of lightning currents and associated fields featuring ionospheric reflections for natural upward flashes, and the longest distance at which natural upward lightning fields have been measured simultaneously with their causative currents. The intervals between the groundwave and skywave arrival times are used to estimate ionospheric reflection heights during day and night times using the so-called zero-to-zero and peak-to-peak methods. During daytime, the mean ionospheric reflection heights, obtained using the two different delay estimation approaches, are about 78 and 76 km, corresponding to the D layer. The mean reflection height at nighttime is about 90 and 89 km, corresponding to the E layer. We present a full-wave, finite-difference time-domain (FDTD) analysis of the electric field propagation including the effect of the ionospheric reflections. The FDTD simulation results are compared with the measured fields associated with upward flashes initiated from the Säntis Tower. It is found that the model reproduces reasonably well the measured waveforms and the times of arrival of the one-hop and two-hop skywaves relative to the groundwave.

  1. A possible relationship between Global Warming and Lightning Activity in India during the period 1998-2009

    CERN Document Server

    B., Felix Pereira; Girish, T E

    2010-01-01

    Lightning activity on a global scale has been studied season wise using satellite data for the period from 1998 to 2009. Lightning activity shows an increasing trend during the period of study which is highly correlated with atmospheric warming. A similar increasing trend of lightning activity is observed in the Indian region during the pre-monsoon season which is correlated with global lightning trends and warming trends of surface temperature in India. Key words: Global warming, lightning activity, Solar cycle changes

  2. TVA's experience with the SUNYA lightning detection network

    Energy Technology Data Exchange (ETDEWEB)

    Whitehead, J.; Driggans, R. (Tennessee Valley Authority, Chattanooga, TN (USA))

    1990-10-01

    Since 1987 the Tennessee Valley Authority (TVA) has had access to real-time data on cloud-to-ground lightning strikes in its service area through the Lightning Detection Network (LDN) operated by the State University of New York at Albany (SUNYA). Lightning data are displayed in real-time on personal computer workstations connected to SUNYA via satellite link and are recorded for later analysis. TVA is using these data to analyze transmission line outages (real-time and historical), provide warning of approaching lightning to line crews, develop ground flash density maps to replace isokeraunic maps previously used in designing transmission lines for lightning protection, and to learn more about lightning and its effect on TVA's transmission system. Lightning flashes that cause particular line outages have been identified and their current and multiplicity characteristics studied. This information may be used to allow more cost-effective transmission line design in the future.

  3. Evaluation of Horizontal Electric Field Under Different Lightning Current Models by Perfect Ground Assumption

    Institute of Scientific and Technical Information of China (English)

    LIANG Jianfeng; LI Yanming

    2012-01-01

    Lightning electromagnetics can affect the reliability of the power system or communication system.Therefore,evaluation of electromagnetic fields generated by lightning return stroke is indispensable.Arnold sommerfeld proposed a model to calculate the electromagnetic field,but it involved the time-consuming sommerfeld integral.However,perfect conductor ground assumption can account for fast calculation,thus this paper reviews the perfect ground equation for evaluation of lightning electromagnetic fields,presents three engineering lightning return stroke models,and calculates the horizontal electric field caused by three lightning return stroke models.According to the results,the amplitude of lightning return stroke has a strong impact on horizontal electric fields,and the steepness of lightning return stroke influences the horizontal electric fields.Moreover,the perfect ground method is faster than the sommerfeld integral method.

  4. Thunderbolt in biogeochemistry: galvanic effects of lightning as another source for metal remobilization.

    Science.gov (United States)

    Schaller, Jörg; Weiske, Arndt; Berger, Frank

    2013-11-04

    Iron and manganese are relevant constituents of the earth's crust and both show increasing mobility when reduced by free electrons. This reduction is known to be controlled by microbial dissimilation processes. Alternative sources of free electrons in nature are cloud-to-ground lightning events with thermal and galvanic effects. Where thermal effects of lightning events are well described, less is known about the impact of galvanic lightning effects on metal mobilization. Here we show that a significant mobilization of manganese occurs due to galvanic effects of both positive and negative lightning, where iron seems to be unaffected with manganese being abundant in oxic forms in soils/sediments. A mean of 0.025 mmol manganese (negative lightning) or 0.08 mmol manganese (positive lightning) mobilization may occur. We suggest that lightning possibly influences biogeochemical cycles of redox sensitive elements in continental parts of the tropics/subtropics on a regional/local scale.

  5. Numerical modeling of initiation of lightning leaders from tall structures by sprite-producing lightning discharges

    Science.gov (United States)

    Pasko, V. P.

    2011-12-01

    It is well established by now that large charge transfers between cloud and ground in positive cloud-to-ground lightning discharges (+CGs) can lead to transient electric field enhancements at mesospheric and lower ionospheric altitudes. In these events the electric field can exceed the conventional breakdown field and lead to formation of transient luminous events referred to as sprites and sprite halos [e.g., Qin et al., JGR, 116, A06305, 2011, and references therein]. Stanley and Heavner [Proc. 12th International Conference on Atmospheric Electricity, Versailles, France, 2003] reported that the large and rapid charge transfer of +CGs producing sprites can also initiate upward positive leaders from tall structures. These authors also presented data analysis indicating that structures with >400 m height have a significantly enhanced probability of launching upward positive leaders that may culminate in a -CG return stroke to the structure. The effect can be understood by considering the field intensification at the top of the tall structure combined with fast application of the field preventing formation and shielding effects of ion corona [Brook et al., JGR, 66, 3967, 1961]. In the present work we utilize the most recent modeling approaches developed at Penn State [e.g., Riousset et al., JGR, 115, A00E10, 2010] to quantify the conditions leading to initiation of positive leaders from tall structures following sprite-producing +CGs. Experiments show that the streamer zone transforms into leader when voltage drop along the streamer zone exceeds 400 kV [e.g., Aleksandrov et al., J. Phys. D: Appl. Phys., 38, 1225, 2005]. For a formed leader half of the voltage drops in the streamer zone, and another half in free space ahead of the streamer zone [Bazelyan and Raizer, Lightning physics and lightning protection, p. 62, 2000]. In our analysis therefore we assume that minimum voltage at the tip of the tower should exceed 800 kV for sustainment of upward propagating leader

  6. Location accuracy evaluation of lightning location systems using natural lightning flashes recorded by a network of high-speed cameras

    Science.gov (United States)

    Alves, J.; Saraiva, A. C. V.; Campos, L. Z. D. S.; Pinto, O., Jr.; Antunes, L.

    2014-12-01

    This work presents a method for the evaluation of location accuracy of all Lightning Location System (LLS) in operation in southeastern Brazil, using natural cloud-to-ground (CG) lightning flashes. This can be done through a multiple high-speed cameras network (RAMMER network) installed in the Paraiba Valley region - SP - Brazil. The RAMMER network (Automated Multi-camera Network for Monitoring and Study of Lightning) is composed by four high-speed cameras operating at 2,500 frames per second. Three stationary black-and-white (B&W) cameras were situated in the cities of São José dos Campos and Caçapava. A fourth color camera was mobile (installed in a car), but operated in a fixed location during the observation period, within the city of São José dos Campos. The average distance among cameras was 13 kilometers. Each RAMMER sensor position was determined so that the network can observe the same lightning flash from different angles and all recorded videos were GPS (Global Position System) time stamped, allowing comparisons of events between cameras and the LLS. The RAMMER sensor is basically composed by a computer, a Phantom high-speed camera version 9.1 and a GPS unit. The lightning cases analyzed in the present work were observed by at least two cameras, their position was visually triangulated and the results compared with BrasilDAT network, during the summer seasons of 2011/2012 and 2012/2013. The visual triangulation method is presented in details. The calibration procedure showed an accuracy of 9 meters between the accurate GPS position of the object triangulated and the result from the visual triangulation method. Lightning return stroke positions, estimated with the visual triangulation method, were compared with LLS locations. Differences between solutions were not greater than 1.8 km.

  7. Study on coupling effect between lightning electromagnetic field and unshielded multi-core cable

    Directory of Open Access Journals (Sweden)

    Hao WANG

    2015-04-01

    Full Text Available In order to investigate the terminating load voltage of the unshielded multi-core cable coupled with lightning electromagnetic pulse(LEMP, we simulate LEMP within the bounded-wave transmission line which is input with a lightning surge signal produced by WU-800-type MARX generator and conduct the relevant experiments towards multi-core cable lines radiated by LEMP. We can get the respond laws of induced voltage of the load by changing the length of unshielded multi-core cable, angles between LEMP and cable, waveforms of LEMP as well as cable terminal loads including linear and non-linear loads. Results show that the amplitude of induced voltage is mainly determined by rising part of electromagnetic field waveforms and the pulse width has little effect on the induced voltage. The respond amplitude and the respond frequency are obviously affected by the length of cable. The polarization direction of the electric field has a great impact on the amplitude of terminal response, but it does not change the waveforms of the induced voltage. With the termination of test side increasing, the induced voltage is gradually increased, but the load in the other side has no effect on the induced voltage.

  8. Evaluation of 1-phase, 3-phase and Lightning Faults on Wind Farms using EMTP-RV

    Directory of Open Access Journals (Sweden)

    Saber Arabi Nowdeh

    2014-12-01

    Full Text Available Since the development of wind power plants installation is growing, problems which are related to network connecting, stability and voltage effects become more important. On the other hand, wind farms are often open to lightning because of their long height and specific appearance. In this paper, modeling and simulation of 1-phase, 3-phase and lightning faults in a wind farm consisting of 40 wind turbines and faults impact on wind farm and the network is investigated in EMTP-RV environment. In this field, it’s necessary to develop a precise modeling out of wind power plant in order to evaluate the effects of these power plants on dynamical behavior of the power system. These models can be used in designing new protection systems, new protection algorithms, and new strategies for power plants exploitation improvement. Each wind unit in the farm is connected to the whole units that are connected to the network using a doubly fed induction generator (DFIG.

  9. Lightning protection guidelines and test data for adhesively bonded aircraft structures

    Science.gov (United States)

    Pryzby, J. E.; Plumer, J. A.

    1984-01-01

    The highly competitive marketplace and increasing cost of energy has motivated manufacturers of general aviation aircraft to utilize composite materials and metal-to-metal bonding in place of conventional fasteners and rivets to reduce weight, obtain smoother outside surfaces and reduce drag. The purpose of this program is protection of these new structures from hazardous lightning effects. The program began with a survey of advance-technology materials and fabrication methods under consideration for future designs. Sub-element specimens were subjected to simulated lightning voltages and currents. Measurements of bond line voltages, electrical sparking, and mechanical strength degradation were made to comprise a data base of electrical properties for new technology materials and basic structural configurations. The second hase of the program involved tests on full scale wing structures which contained integral fuel tanks and which were representative of examples of new technology structures and fuel systems. The purpose of these tests was to provide a comparison between full scale structural measurements and those obtained from the sub-element specimens.

  10. Simulation Modeling and Analysis of Lightning Back-striking of 500kV Double Circuit Transmission Line%500kV同塔双回输电线路雷电反击仿真模型的建立与分析

    Institute of Scientific and Technical Information of China (English)

    宋阳; 秦颖; 胡可

    2012-01-01

    雷击是造成输电线路跳闸的主要原因。做好500kV同塔双回输电线路防雷设计,是保证电力系统安全运行的重要环节之一。以某500kV线路为研究背景,用ATP-EMTP软件分别建立雷电流双指数波模型、杆塔分段传输线模型、输电线路Jmarti模型、绝缘子闪络和冲击接地电阻模型,搭建仿真电路,分析了接地电阻和线路档距对500kV同塔双回线路的反击耐雷水平的影响,以期为我国500kV同塔双回线路防雷分析提供参考。%According to the experiences of the power system design and operations,lightning stroke outages is the main reason of transmission line.Lightning protection design is one of important factors to guarantee the safe operation of 500 kV double circuit transmission line.Therefore,in order to provide the reference for our 500 kV double circuit transmission line,with Gui-Fu transmission line as background,the corresponding component models are created by ATP-EMTP.The effect of the grounding resistance and the line span on back striking lightning withstand level are analyzed.

  11. Simulations

    CERN Document Server

    Ngada, N M

    2015-01-01

    The complexity and cost of building and running high-power electrical systems make the use of simulations unavoidable. The simulations available today provide great understanding about how systems really operate. This paper helps the reader to gain an insight into simulation in the field of power converters for particle accelerators. Starting with the definition and basic principles of simulation, two simulation types, as well as their leading tools, are presented: analog and numerical simulations. Some practical applications of each simulation type are also considered. The final conclusion then summarizes the main important items to keep in mind before opting for a simulation tool or before performing a simulation.

  12. Aerosols and lightning activity: The effect of vertical profile and aerosol type

    Science.gov (United States)

    Proestakis, E.; Kazadzis, S.; Lagouvardos, K.; Kotroni, V.; Amiridis, V.; Marinou, E.; Price, C.; Kazantzidis, A.

    2016-12-01

    The Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) instrument on board the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) satellite has been utilized for the first time in a study regarding lightning activity modulation due to aerosols. Lightning activity observations, obtained by the ZEUS long range Lightning Detection Network, European Centre for Medium range Weather Forecasts (ECMWF) Convective Available Potential Energy (CAPE) data and Cloud Fraction (CF) retrieved by MODIS on board Aqua satellite have been combined with CALIPSO CALIOP data over the Mediterranean basin and for the period March to November, from 2007 to 2014. The results indicate that lightning activity is enhanced during days characterized by higher Aerosol Optical Depth (AOD) values, compared to days with no lightning. This study contributes to existing studies on the link between lightning activity and aerosols, which have been based just on columnar AOD satellite retrievals, by performing a deeper analysis into the effect of aerosol profiles and aerosol types. Correlation coefficients of R = 0.73 between the CALIPSO AOD and the number of lightning strikes detected by ZEUS and of R = 0.93 between ECMWF CAPE and lightning activity are obtained. The analysis of extinction coefficient values at 532 nm indicates that at an altitudinal range exists, between 1.1 km and 2.9 km, where the values for extinction coefficient of lightning-active and non-lightning-active cases are statistically significantly different. Finally, based on the CALIPSO aerosol subtype classification, we have investigated the aerosol conditions of lightning-active and non-lightning-active cases. According to the results polluted dust aerosols are more frequently observed during non-lightning-active days, while dust and smoke aerosols are more abundant in the atmosphere during the lightning-active days.

  13. Climatology of lightning activity in South China and its relationships to precipitation and convective available potential energy

    Science.gov (United States)

    Zheng, Dong; Zhang, Yijun; Meng, Qing; Chen, Luwen; Dan, Jianru

    2016-03-01

    This study examined lightning activity and its relationship to precipitation and convective available potential energy (CAPE) in South China during 2001-12, based on data from the Guangdong Lightning Location System, the Tropical Rainfall Measuring Mission satellite, and the ERA-Interim dataset. Two areas of high lightning density are identified: one over the Pearl River Delta, and the other to the north of Leizhou Peninsula. Large peak-current cloud-to-ground (LPCCG) lightning (>75 kA) shows weaker land-offshore contrasts than total CG lightning, in which negative cloud-to-ground (NCG) lightning occurs more prominently than positive cloud-to-ground (PCG) lightning on land. While the frequency of total CG lightning shows a main peak in June and a second peak in August, the LPCCG lightning over land shows only a single peak in June. The ratio of positive LPCCG to total lightning is significantly greater during February-April than during other times of the year. Diurnally, CG lightning over land shows only one peak in the afternoon, whereas CG lightning offshore shows morning and afternoon peaks. The rain yield per flash is on the order of 107-108 kg per flash across the analysis region, and its spatial distribution is opposite to that of lightning density. Our data show that lightning activity over land is more sensitive than that over offshore waters to CAPE. The relationships between lightning activity and both precipitation and CAPE are associated with convection activity in the analysis region.

  14. Evolution of the Total Lightning Activity in a Leading-Line and Trailing Stratiform Mesoscale Convective System over Beijing

    Institute of Scientific and Technical Information of China (English)

    LIU Dongxia; QIE Xiushu; XIONG Yajun; FENG Guili

    2011-01-01

    Data from the Beijing SAFIR 3000 lightning detection system and Doppler radar provided some insights into the three-dimensional lightning structure and evolution of a leading-line and trailing-stratiform (LLTS) mesoscale convective system (MCS) over Beijing on 31 July 2007. Most of the lightning in the LLTS-MCSwas intracloud (IC) lightning, while the mean ratio of positive cloud-to-ground (+CG) lightning to -CG lightning was 1:4, which was higher than the average value from previous studies. The majority of CG limhtning occurred in the convective region of the radar echo, particularly at the leading edge of the front.Little IC lightning and little +CG lightning occurred in the stratiform region. The distribution of the CG lightning indicated that the storm had a tilted dipole structure given the wind shear or the tripole charge structure. During the storm's development, most of the IC lightning occurred at an altitude of ~9.5 km;the lightning rate reached its maximum at 10.5 kmn, the altitude of IC lightning in the mature stage of the storm. When the thunderstorm began to dissipate, the altitude of the IC lightning decreased gradually. The spatial distribution of lightning was well correlated with the rainfall on the ground, although the peak value of rainfall appeared 75 min later than the peak lightning rate.

  15. Ground Level Observations of a Possible Downward-Beamed TGF during a Rocket-Triggered Lightning Flash at Camp Blanding, Florida in August 2014

    Science.gov (United States)

    Bozarth, A.; Dwyer, J. R.; Cramer, E. S.; Rassoul, H.; Uman, M. A.; Jordan, D.; Grove, J. E.

    2015-12-01

    Ground level high-energy observations of an August 2014 rocket-triggered lightning event at the International Center for Lightning Research and Testing (ICLRT) in Camp Blanding, Florida show a 180 µs burst of multiple-MeV photons during the latter part of the Upward Positive Leader (UPL) phase of an altitude-triggered lightning flash, following the first, truncated return stroke. The timing and waveform profile being atypical from x-ray emissions from lightning leaders, our observations suggest the occurrence of a downward beamed terrestrial gamma ray flash (TGF). Instrumentation operating during this event include a set of 16 NaI(TI)/PMT detectors plus 7 1-m2 plastic scintillation detectors spread across the 1 km2 facility, with 38 additional Na(TI)/PMT detectors located inside the 1"-thick Pb-shielded x-ray camera and an x-ray spectrometer. Comparing the location and energy data from these detectors to Monte Carlo simulations of TGFs from the REAM code developed by Dwyer [2003], our analysis investigates possible TGF production regions and determines the likelihood of the observed high-energy emissions being produced by a TGF inside the thunderstorm.

  16. Properties of x-ray emission from natural and rocket triggered lightning as measured by the Thunderstorm Energetic Radiation Array (TERA)

    Science.gov (United States)

    Saleh, Ziad

    The Thunderstorm Energetic Radiation Array (TERA) is an experiment designed to measure energetic radiations (x-rays and gamma-rays) from thunderstorms and lightning. It is located at the International Center for Lightning Research and Testing (ICLRT) facility at Camp Blanding, FL. The array is integrated with the Multiple Station Experiment (MSE) which provides simultaneous measurement of electric and magnetic fields from nearby lightning. Since 2003, the facility has been operated jointly by University of Florida and Florida Institute of Technology. The array contains eight plastic, two Lanthanum Bromide (LaBr3) and 37 Sodium Iodide (NaI) detectors distributed over 25 stations covering the ˜ .5 km2 facility and centered around the rocket launch tower which is used to trigger lightning. A subset of the MSE/TERA network, consisting of 9 stations, is operated as a time of arrival network. From 2005 to 2007, MSE/TERA recorded 9 successful rocket-triggered lightning events and 16 natural flashes, all negative cloud-to-ground. In this dissertation, I present an analysis of the x-ray emission from rocket triggered and natural lightning to study their spatial and temporal variation during the leader formation. The x-rays are emitted in discrete bursts lasting for about 1 musec and observed to occur during the last 10˜100 musec of the dart leader and dart-stepped leader phase of triggered lightning and during the last 1 ms of the stepped leader phase of natural lightning, just prior to the time of the return stroke and ceases afterwards. I propose a model for the x-ray emission from a dart-stepped leader which depicts the seed electrons being accelerated near the leader tip clue to the high electric fields and following the path of the dart-stepped leader. Using detailed 3D Monte Carlo simulations, which fully model the bremsstrahlung production, electron and x-ray propagation, the model shows that the seed electrons are emitted isotropically in the azimuthal angle with

  17. Using Flow Regime Lightning and Sounding Climatologies to Initialize Gridded Lightning Threat Forecasts for East Central Florida

    Science.gov (United States)

    Lambert, Winifred; Short, David; Volkmer, Matthew; Sharp, David; Spratt, Scott

    2007-01-01

    Each morning, the forecasters at the National Weather Service in Melbourne, FL (NWS MLB) produce an experimental cloud-to-ground (CG) lightning threat index map for their county warning area (CWA) that is posted to their web site (httl://www.srh.weather.gov/mlb/ghwo/lightning.shtml) . Given the hazardous nature of lightning in East Central Florida, especially during the warm season months of May September, these maps help users factor the threat of lightning, relative to their location, into their daily plans. The maps are color-coded in five levels from Very Low to Extreme, with threat level definitions based on the probability of lightning occurrence and the expected amount of CG activity. On a day in which thunderstorms are expected, there are typically two or more threat levels depicted spatially across the CWA. The locations of relative lightning threat maxima and minima often depend on the position and orientation of the low-level ridge axis, forecast propagation and interaction of sea/lake/outflow boundaries, expected evolution of moisture and stability fields, and other factors that can influence the spatial distribution of thunderstorms over the CWA. The lightning threat index maps are issued for the 24-hour period beginning at 1200 UTC each day with a grid resolution of 5 km x 5 km. Product preparation is performed on the AWIPS Graphical Forecast Editor (GFE), which is the standard NWS platform for graphical editing. Until recently, the forecasters created each map manually, starting with a blank map. To improve efficiency of the forecast process, NWS MLB requested that the Applied Meteorology Unit (AMU) create gridded warm season lightning climatologies that could be used as first-guess inputs to initialize lightning threat index maps. The gridded values requested included CG strike densities and frequency of occurrence stratified by synoptic-scale flow regime. The intent was to improve consistency between forecasters while allowing them to focus on the

  18. Using Cloud-to-Ground Lightning Climatologies to Initialize Gridded Lightning Threat Forecasts for East Central Florida

    Science.gov (United States)

    Lambert, Winnie; Sharp, David; Spratt, Scott; Volkmer, Matthew

    2005-01-01

    Each morning, the forecasters at the National Weather Service in Melbourn, FL (NWS MLB) produce an experimental cloud-to-ground (CG) lightning threat index map for their county warning area (CWA) that is posted to their web site (http://www.srh.weather.gov/mlb/ghwo/lightning.shtml) . Given the hazardous nature of lightning in central Florida, especially during the warm season months of May-September, these maps help users factor the threat of lightning, relative to their location, into their daily plans. The maps are color-coded in five levels from Very Low to Extreme, with threat level definitions based on the probability of lightning occurrence and the expected amount of CG activity. On a day in which thunderstorms are expected, there are typically two or more threat levels depicted spatially across the CWA. The locations of relative lightning threat maxima and minima often depend on the position and orientation of the low-level ridge axis, forecast propagation and interaction of sea/lake/outflow boundaries, expected evolution of moisture and stability fields, and other factors that can influence the spatial distribution of thunderstorms over the CWA. The lightning threat index maps are issued for the 24-hour period beginning at 1200 UTC (0700 AM EST) each day with a grid resolution of 5 km x 5 km. Product preparation is performed on the AWIPS Graphical Forecast Editor (GFE), which is the standard NWS platform for graphical editing. Currently, the forecasters create each map manually, starting with a blank map. To improve efficiency of the forecast process, NWS MLB requested that the Applied Meteorology Unit (AMU) create gridded warm season lightning climatologies that could be used as first-guess inputs to initialize lightning threat index maps. The gridded values requested included CG strike densities and frequency of occurrence stratified by synoptic-scale flow regime. The intent is to increase consistency between forecasters while enabling them to focus on

  19. Isolated Sensorineural Hearing Loss as a Sequela after Lightning Strike

    Directory of Open Access Journals (Sweden)

    Mahfuz Turan

    2015-01-01

    Full Text Available In most of the surviving patients after a lightning strike, audiovestibular abnormalities have been reported. The most frequently reported type of abnormalities is a tympanic membrane perforation with hearing loss and external ear canal burn. However a sensor neural hearing loss and mixed type hearing loss can also occur, but these occur rarely. A nineteen-year-old female patient had, after a lightning strike, serious burns on the left ear, behind the ear, and on the chest and neck. She also had in her left ear 108 dB hearing loss with irregular central perforation and in her right ear 52 dB sensorineural hearing loss. There was no hearing loss before the strike. A hearing aid was recommended for the right ear and good care and follow-up were recommended for the left ear. A lightning strike can cause serious audiological damage. Therefore, it is necessary to make a careful audiovestibular evaluation of the patients. Although there exist rarely healed cases from sensorineural hearing loss after lightning strike in literature, in our case hearing loss occurred bilaterally and then it healed unilaterally. This condition is quite rare in literature.

  20. Protecting electronic equipment in composite structures against lightning

    NARCIS (Netherlands)

    Blaj, Mihai Alexandru

    2015-01-01

    Damage resulting from an interaction with lightning current in a military naval vessel, especially in a conflict zone and at the time of a conflict, which leads to the incapacitation of vital activities on the ship, is unacceptable. Because many potential conflict zones are in littoral areas, and be

  1. Electric systems failures produced by CG lightning in Eastern Amazonia

    Directory of Open Access Journals (Sweden)

    Ana Paula Paes dos Santos

    2014-12-01

    Full Text Available Operational records of power outages of the electric energy distribution systems in eastern Amazonia presented a large number of events attributed to lightning strikes, during the 2006 to 2009 period. The regional electricity concessionary data were compared to actual lightning observations made by SIPAM's LDN system, over two areas where operational sub systems of transmission lines are installed. Statistical relations were drawn between the monthly lightning occurrence density and the number of power outages of the electric systems for both areas studied. The results showed that, although with some delays between these variables peaks, the number of power disruptions has a tendency to follow the behavior of the lightning occurrence densities variations. The numerical correlations were positive and may be useful to the transmission lines maintenance crews at least for the Belém-Castanhal electricity distribution sub system. Evidence was found, that the SST's over certain areas of the Pacific and Atlantic Oceans, influence convection over the area of interest, and may help to prognosticate the periods of intense electric storms, requiring repair readiness for the regional electric systems.

  2. Objective Lightning Probability Forecasts for East-Central Florida Airports

    Science.gov (United States)

    Crawford, Winfred C.

    2013-01-01

    The forecasters at the National Weather Service in Melbourne, FL, (NWS MLB) identified a need to make more accurate lightning forecasts to help alleviate delays due to thunderstorms in the vicinity of several commercial airports in central Florida at which they are responsible for issuing terminal aerodrome forecasts. Such forecasts would also provide safer ground operations around terminals, and would be of value to Center Weather Service Units serving air traffic controllers in Florida. To improve the forecast, the AMU was tasked to develop an objective lightning probability forecast tool for the airports using data from the National Lightning Detection Network (NLDN). The resulting forecast tool is similar to that developed by the AMU to support space launch operations at Kennedy Space Center (KSC) and Cape Canaveral Air Force Station (CCAFS) for use by the 45th Weather Squadron (45 WS) in previous tasks (Lambert and Wheeler 2005, Lambert 2007). The lightning probability forecasts are valid for the time periods and areas needed by the NWS MLB forecasters in the warm season months, defined in this task as May-September.

  3. High energy radiation from aircraft-triggered lightning and thunderstorm

    Science.gov (United States)

    Kochkin, Pavlo; van Deursen, Alexander P. J.; de Boer, Alte I.; Bardet, Michiel; Boissin, Jean-François

    2016-04-01

    In-flight Lightning Strike Damage Assessment System (ILDAS http://ildas.nlr.nl/) was developed in an EU FP6 project to provide information on threat that lightning poses to aircraft. The system contains one E-field and eight H-field sensors distributed over the fuselage. It has recently been extended to include two LaBr3 scintillation detectors. The scintillation detectors are sensitive to x-ray photons above 30 keV. The entire system is installed on an A-350 aircraft. When triggered by lightning and digitizes data synchronously with 10 ns intervals. Twelve continuously monitoring photon energy channels were implemented for X-ray detectors operating at slower rate (15 ms, pulse counting). In spring of 2014 and 2015 the aircraft flew through thunderstorm cells recording the data from the sensors. Total of 93 lightning strikes to the aircraft are recorded. Eighteen of them are also detected by WWLLN network. One strike consists of six individual strokes within 200 ms that were all synchronously identified by WWLLN. The WWLLN inter-stroke distance is much larger than the aircraft movement. Three of these strokes generated X-ray bursts. One exceptionally bright X-ray pulse of more than 8 MeV has been detected in association with another strike; it probably saturated the detector's photomultiplier. Neither long gamma-ray glow, nor positron annihilation have been detected during the campaign. An explanation is sought in the typical altitude profile of these test flights.

  4. Investigation of the Prediction of Lightning Strikes Using Neural Networks

    Science.gov (United States)

    1990-10-11

    1989: Artificial intelligence and lightning prediction. Final report to Universal Energy Systems on research Acronyms conducted during the summer of 1989...K’ Shuritle Sunway 31 - K Weather Tow 12 14-K Comera SitelS 17 - K Weather Twor 40S 18 - K CorencCoo Sit e 19 - K Weir, Twrg Aea 2K Cae,l 22K CameraS

  5. Global Patterns of Lightning Properties Derived by OTD and LIS

    Science.gov (United States)

    Beirle, Steffen; Koshak, W.; Blakeslee, R.; Wagner, T.

    2014-01-01

    The satellite instruments Optical Transient Detector (OTD) and Lightning Imaging Sensor (LIS) provide unique empirical data about the frequency of lightning flashes around the globe (OTD), and the tropics (LIS), which 5 has been used before to compile a well received global climatology of flash rate densities. Here we present a statistical analysis of various additional lightning properties derived from OTD/LIS, i.e. the number of so-called "events" and "groups" per flash, as well as 10 the mean flash duration, footprint and radiance. These normalized quantities, which can be associated with the flash "strength", show consistent spatial patterns; most strikingly, oceanic flashes show higher values than continental flashes for all properties. Over land, regions with high (Eastern US) 15 and low (India) flash strength can be clearly identified. We discuss possible causes and implications of the observed regional differences. Although a direct quantitative interpretation of the investigated flash properties is difficult, the observed spatial patterns provide valuable information for the 20 interpretation and application of climatological flash rates. Due to the systematic regional variations of physical flash characteristics, viewing conditions, and/or measurement sensitivities, parametrisations of lightning NOx based on total flash rate densities alone are probably affected by regional biases.

  6. High-energy radiation from thunderstorms and lightning with LOFT

    CERN Document Server

    Marisaldi, M; Brandt, S; Briggs, M S; Budtz-Jørgensen, C; Campana, R; Carlson, B E; Celestin, S; Connaughton, V; Cummer, S A; Dwyer, J R; Fishman, G J; Fullekrug, M; Fuschino, F; Gjesteland, T; Neubert, T; Østgaard, N; Tavani, M

    2015-01-01

    This is a White Paper in support of the mission concept of the Large Observatory for X-ray Timing (LOFT), proposed as a medium-sized ESA mission. We discuss the potential of LOFT for the study of high-energy radiation from thunderstorms and lightning. For a summary, we refer to the paper.

  7. Global patterns of lightning properties derived by OTD and LIS

    Directory of Open Access Journals (Sweden)

    S. Beirle

    2014-04-01

    Full Text Available The satellite instruments Optical Transient Detector (OTD and Lightning Imaging Sensor (LIS provide unique empirical data about the frequency of lightning flashes around the globe (OTD, and the tropics (LIS, which have been used before to compile a well received global climatology of flash rate densities. Here we present a statistical analysis of various additional lightning properties derived from OTD/LIS, i.e. the number of so-called "events" and "groups" per flash, as well as the mean flash duration, footprint and radiance. These normalized quantities, which can be associated with the flash "strength", show consistent spatial patterns; most strikingly, oceanic flashes show higher values than continental flashes for all properties. Over land, regions with high (Eastern US and low (India flash strength can be clearly identified. We discuss possible causes and implications of the observed regional differences. Although a direct quantitative interpretation of the investigated flash properties is difficult, the observed spatial patterns provide valuable information for the interpretation and application of climatological flash rates. Due to the systematic regional variations of physical flash characteristics, viewing conditions, and/or measurement sensitivities, parametrisations of lightning NOx based on total flash rate densities alone are probably affected by regional biases.

  8. Fiber-Optic Sensor for Aircraft Lightning Current Measurement

    Science.gov (United States)

    Nguyen, Truong X.; Ely, Jay J.; Szatkowski, George G.; Mata, Carlos T.; Mata, Angel G.; Snyder, Gary P.

    2012-01-01

    An electric current sensor based on Faraday rotation effect in optical fiber was developed for measuring aircraft lightning current. Compared to traditional sensors, the design has many advantages including the ability to measure total current and to conform to structure geometries. The sensor is also small, light weight, non-conducting, safe from interference, and free of hysteresis and saturation. Potential applications include characterization of lightning current waveforms, parameters and paths, and providing environmental data for aircraft certifications. In an optical fiber as the sensing medium, light polarization rotates when exposed to a magnetic field in the direction of light propagation. By forming closed fiber loops around a conductor and applying Ampere s law, measuring the total light rotation yields the enclosed current. A reflective polarimetric scheme is used, where polarization change is measured after the polarized light travels round-trip through the sensing fiber. The sensor system was evaluated measuring rocket-triggered lightning over the 2011 summer. Early results compared very well against a reference current shunt resistor, demonstrating the sensor s accuracy and feasibility in a lightning environment. While later comparisons show gradually increasing amplitude deviations for an undetermined cause, the overall waveforms still compared very well.

  9. Lightning protection of ships in maritime and costal environment

    NARCIS (Netherlands)

    Blaj, M.A.; Leferink, Frank Bernardus Johannes

    2009-01-01

    An electromagnetic pulse due to a nearby lightning stroke generates a high intensity magnetic field. Thin metal layers as applied in composite structures cannot shield such a magnetic field. Electronic equipment inside such structures will suffer from high-induced voltages and damage and interferenc

  10. Arborescent vascular dilatation mimicking Lichtenberg figures from lightning.

    Science.gov (United States)

    Tempark, Therdpong; Iwasaki, Julie; Shwayder, Tor

    2014-01-01

    The clinical presentation of arborizing vascular dilatation can resemble Lichtenberg figures from lightning. Both have a feather-like or ferning pattern. We report an interesting case of pressure-induced vasodilatation (PIV) caused by temporary vascular occlusion from jeans buttons. © 2014 Wiley Periodicals, Inc.

  11. Lightning and Gunpowder in the 18th Century

    Science.gov (United States)

    Krider, E. P.

    2006-12-01

    On or before June, 1751, Benjamin Franklin and co-workers showed that gunpowder could be ignited by a small electric spark, and subsequently people used gunpowder to enhance the explosions of "thunder houses" to demonstrate that grounded metallic rods would protect model structures against lightning damage. Even before the sentry box and kite experiments proved that thunderclouds are electrified and that lightning is an electrical discharge in 1752, Franklin had hypothesized that a tall, well-grounded conductor might reduce or prevent lightning damage by silently discharging the cloud, and if a discharge did occur, then the tall rod would offer a preferred place for the lightning to strike, and the grounding conductors would guide the current into the ground in a harmless fashion. Over the next 10 years, experience gained through practice showed that grounded rods did indeed protect ordinary structures from lightning damage, but a question remained about the best way to protect gunpowder magazines. In 1762, Franklin recommended a tall "mast not far from it, which may reach 15 or 20 feet above the top of it, with a thick iron rod in one piece fastened to it, pointed at the highest end, and reaching down through the earth till it comes to water," and in 1772 he made a similar recommendation for protecting the British powder magazine at Purfleet. In 1780, Jan Ingenhousz asked Franklin to "communicate to me some short hints, which may occur to you about the most convenient manner of constructing gun powder magazines, the manner of preserving the powder from moisture and securing the building in the best manner from the effects of lightning." In his reply, Franklin detailed a method of protection that is almost perfect, "they should be constructed in the Ground; that the Walls should be lin'd with Lead, the Floor Lead, all 1/4 Inch thick & the Joints well solder'd; the Cover Copper; with a little Scuttle to enter, the whole in the Form of a Canister for Tea. If the

  12. Radio signatures of lightning discharges in exoplanets and brown dwarfs

    Science.gov (United States)

    Hodosán, Gabriella; Helling, Christiane; Vorgul, Irena

    2014-05-01

    Lightning related signatures can be found in the whole spectral range from radio to gamma-rays. While for example UV, visible or IR molecular emission (as the lightning discharge causes changes in the local chemistry) depends on the composition of the atmosphere of the extrasolar body, radio signatures do not have this limitation, which means they may give us a universal tool for lightning observations outside the Solar System, both on exoplanets and brown dwarfs. Lightning induced radio signatures have three main types. Sferics emit in the low-frequency (LF) range with a power density peak at 10 kHz on Earth. (Aplin, K. L., 'Electrifying atmospheres', Springer 2013) Whistlers are electromagnetic waves propagating along magnetic field lines and emitting in the very low-frequency (VLF) range. (Desch, S. J. et al. 2002, Rep. Prog. Phys. 65, 955) While Schumann-resonances are VLF lightning discharge-induced electromagnetic oscillations of the earth-ionosphere cavity. (Simões, F. et al. 2012, LPICo 1683, 1052) There are certain factors that limit the observability of radio signatures. Every object with an ionosphere has a low cutoff frequency. This means radio waves with frequencies below this peak-frequency cannot propagate through the atmosphere. For Earth this value is about 5-10 MHz. However, the values for extrasolar atmospheres remain to be determined. Besides that, natural background noises like the galactic radio background or photo-electron noises give a limitation. (Zarka et al. 2012, PSS 74, 156) Putting all together, radio signatures with frequency below 10 MHz might only be observable from space. Waves below 30 kHz would not be able to reach the inner Solar System. (Zarka et al. 2012, PSS 74, 156) We show a general summary of radio signatures and their properties. A table of other lightning discharge signatures that have been observed either on Earth or other Solar System planets is also included. This table, also contains a list of different instruments

  13. Lightning in Colorado forest fire smoke plumes during summer 2012

    Science.gov (United States)

    Lang, T. J.; Krehbiel, P. R.; Dolan, B.; Lindsey, D.; Rutledge, S. A.; Rison, W.

    2012-12-01

    May and June 2012 were unusually hot and dry in Colorado, which was suffering from a strong drought. A major consequence of this climatic regime was one of the most destructive forest fire seasons in state history, with hundreds of thousands of acres of forest and grassland consumed by flames, hundreds of homes burned, and several lives lost. Many of these fires occurred within range of the newly installed Colorado Lightning Mapping Array (COLMA), which provides high-resolution observations of discharges over a large portion of the state. The COLMA was installed in advance of the Deep Convective Clouds and Chemistry (DC3) project. High-altitude lightning was observed to occur sporadically in the smoke plumes over three major fires that occurred during early summer: Hewlett Gulch, High Park, and Waldo Canyon. Additionally, the Colorado State University CHILL (CSU-CHILL) and Pawnee radars observed the Hewlett Gulch plume electrify with detailed polarimetric and dual-Doppler measurements, and also provided these same measurements for the High Park plume when it was not producing lightning. Meanwhile, local Next Generation Radars (NEXRADs) provided observations of the electrified High Park and Waldo Canyon plumes. All of these plumes also were observed by geostationary meteorological satellites. These observations provide an unprecedented dataset with which to study smoke plume and pyrocumulus electrification. The polarimetric data - low reflectivity, high differential reflectivity, low correlation coefficient, and noisy differential phase - were consistent with the smoke plumes and associated pyrocumulus being filled primarily with irregularly shaped ash particles. Lightning was not observed in the plumes until they reached over 10 km above mean sea level, which was an uncommon occurrence requiring explosive fire growth combined with increased meteorological instability and reduced wind shear. Plume updraft intensification and echo-top growth led the occurrence of

  14. Effect of Multiple Lightning Strikes on .the Performance of ZnOLightning Arrester Block%Effect of Multiple Lightning Strikes on .the Performance of ZnOLightning Arrester Block

    Institute of Scientific and Technical Information of China (English)

    Haryono T; Sirait K T; Tumiran; Hamzah Berahim

    2011-01-01

    A lightning arrester is used for electrical equipment protection against damage due to lightning strikes. One example of protected electrical equipment is electrical power transformer. If there is no lightning arrester installed to the transformer, when a lightning strike happens, it may receive a very high lightning overvoltage, which is certainly resulted in the transformer damage at its insulation. Usually, a lightning arrester specification data attached to a light- ning arrester contains the rating data of the lightning arrester current and voltage. In the use of lightning arrester, the possibility of receiving multiple lightning strikes is not taken into account sometimes. In fact, in some places, the number of multiple strikes in short duration is quiet high in number. This condition makes the lightning arrester being stroked by multiple lightning strikes. Therefore, it may change the lightning arrester's properties, and then the arrester may not be able to provide good electrical equipment protection against lightning strike anymore. This condition will result in great loss to electrical companies and electrical consumers. Therefore, this research studied the effect of applying multiple lightning strikes to ZnO lightning arrester block. Every time a group of lightning impulse current is applied to the ZnO lightning arrester block, it is followed by the measuring of its 50 Hz voltage and current characteristic. The changing in the ZnO lightning arrester block 50 Hz characteristic then can be analyzed. It was found that by applying more numbers of lightning strikes which made the arrester becoming worse, even though, actually, the lightning impulse peak current was still under the rating of the lightning arrester current. In this ease for a 5 kA, 24 kV lightning arrester, even though the lightning impulse peak current flowing through the ZnO lightning arrester block was still 2500 A, the lightning arrester ZnO block had already been damaged. Having been

  15. Lightning Reporting at 45th Weather Squadron: Recent Improvements

    Science.gov (United States)

    Finn, Frank C.; Roeder, William P.; Buchanan, Michael D.; McNamara, Todd M.; McAllenan, Michael; Winters, Katherine A.; Fitzpatrick, Michael E.; Huddleston, Lisa L.

    2010-01-01

    The 45th Weather Squadron (45 WS) provides daily lightning reports to space launch customers at CCAFS/KSC. These reports are provided to assess the need to inspect the electronics of satellite payloads, space launch vehicles, and ground support equipment for induced current damage from nearby lightning strokes. The 45 WS has made several improvements to the lightning reports during 2008-2009. The 4DLSS, implemented in April 2008, provides all lightning strokes as opposed to just one stroke per flash as done by the previous system. The 45 WS discovered that the peak current was being truncated to the nearest kilo amp in the database used to generate the daily lightning reports, which led to an up to 4% underestimate in the peak current for average lightning. This error was corrected and led to elimination of this underestimate. The 45 WS and their mission partners developed lightning location error ellipses for 99% and 95% location accuracies tailored to each individual stroke and began providing them in the spring of 2009. The new procedure provides the distance from the point of interest to the best location of the stroke (the center of the error ellipse) and the distance to the closest edge of the ellipse. This information is now included in the lightning reports, along with the peak current of the stroke. The initial method of calculating the error ellipses could only be used during normal duty hours, i.e. not during nights, weekends, or holidays. This method was improved later to provide lightning reports in near real-time, 24/7. The calculation of the distance to the closest point on the ellipse was also significantly improved later. Other improvements were also implemented. A new method t