Sample records for grounding lightning protection

  1. Faraday Cage Protects Against Lightning (United States)

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


    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.

  2. 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)


    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.

  3. Evaluation of Grounding Impedance of a Complex Lightning Protective System Using Earth Ground Clamp Measurements and ATP Modeling (United States)

    Mata, Carlos T.; Rakov, V. A.; Mata, Angel G.


    A new Lightning Protection System (LPS) was designed and built at Launch Complex 39B (LC39B), at the Kennedy Space Center (KSC), Florida, which consists of a catenary wire system (at a height of about 181 meters above ground level) supported by three insulators installed atop three towers in a triangular configuration. A total of nine downconductors (each about 250 meters long, on average) are connected to the catenary wire system. Each of the nine downconductors is connected to a 7.62-meter radius circular counterpoise conductor with six equally spaced 6-meter long vertical grounding rods. Grounding requirements at LC39B call for all underground and above ground metallic piping, enclosures, raceways, and cable trays, within 7.62 meters of the counterpoise, to be bounded to the counterpoise, which results in a complex interconnected grounding system, given the many metallic piping, raceways, and cable trays that run in multiple direction around LC39B. The complexity of this grounding system makes the fall of potential method, which uses multiple metallic rods or stakes, unsuitable for measuring the grounding impedances of the downconductors. To calculate the downconductors grounding impedance, an Earth Ground Clamp (a stakeless grounding resistance measuring device) and a LPS Alternative Transient Program (ATP) model are used. The Earth Ground Clamp is used to measure the loop impedance plus the grounding impedance of each downconductor and the ATP model is used to calculate the loop impedance of each downconductor circuit. The grounding impedance of the downconductors is then calculated by subtracting the ATP calculated loop impedances from the Earth Ground Clamp measurements.

  4. Lightning protection of PV systems


    Pons, Enrico; Tommasini, Riccardo


    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...

  5. 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))


    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.

  6. Protection Method of Biological Lightning Safety around Power Grid Based on Grounding Electrode Structure (United States)

    Sixiang, Chen; Daopin, Chen; Ming, Zhang; Xiao, Huang; Jian, He; Zhijie, He


    Aimed at the actual situation of fish death in fish ponds near the power transmission line towers after the thunderstorm happened in Guangdong Province in China, this paper studied the influence of the ground current on fish in the pond. Firstly, This paper studied the current density of the fish without protection. On this basis, paper studied the horizontal pole with full-shielded, the vertical pole with half-shielded, the horizontal pole with extension three kinds of protective measures and effects. Finally an effective protection scheme was put forward according to the engineering practice. The results can provide some engineering guidance and quantitative basis for the design and modification of grounding devices when the tower is adjacent to the fish ponds in southern China.

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

    Directory of Open Access Journals (Sweden)

    Javor Vesna


    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.

  8. International Aerospace and Ground Conference on Lightning and Static Electricity. 1984 technical papers. Supplement (United States)


    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.

  9. Wind turbine with lightning protection system

    DEFF Research Database (Denmark)


    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....

  10. 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:


    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)

  11. Space Launching Site Protection against Lightning Hazards


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


    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...

  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)


    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. Protection of LV system against lightning


    Yordanova Nedyalkova, Greta


    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...

  14. 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)


    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.

  15. The 1st Asian Lightning Protection Forum

    Institute of Scientific and Technical Information of China (English)


    @@ 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.

  16. Lightning Protection and Detection System (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)


    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.

  17. 21st Century Lightning Protection for High Altitude Observatories (United States)

    Kithil, Richard


    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.

  18. 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:


    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)

  19. 曼型储气柜的防雷接地设计%Lightning Protection & grounding Design of M.A.N Gasholder

    Institute of Scientific and Technical Information of China (English)



    That the M.A.N gasholder belongs to the second lightning protection building was clarified, lightning protection parameters and countermeasures introduced, and the reason that the internal piston does not produce and accumulate static electricity has been given as well.%明确了曼型储气柜属于第二类防雷建筑物,介绍了相应的雷电参数和防雷措施,并给出了曼型储气柜内部活塞不会产生和积聚静电的理由。

  20. Properties of Lightning Strike Protection Coatings (United States)

    Gagne, Martin

    of conductive coatings. Mechanical tests include adhesion, scratch, hardness and Young's modulus of the coatings. The environmental tests are temperature cycling and salt spray cycling. These basic characteristics were investigated first, but further tests also combine the categories, such as electrical tests before, during and after environmental tests, and the effects on the sample's mechanical properties after high electrical current injections. The electrical properties of the conductive coatings have improved and are very close to that of current expanded metallic foil or within an order of magnitude. The mechanical properties of most of these coatings are also good. They exhibit good adhesion, hardness, and no significant loss of flexion properties after current injections. The environmental tests are more mitigated, with some conductive coatings losing their surface conductivity, others having a small increase in specific resistivity, and some were simply unaffected. Tests such as thermogravimetric analysis, scanning electron microscope analysis of scratch tests, and optical microscope observations are included to provide additional analysis of the results of the conductive coatings. The conductive coatings were characterized and tested as part of the CRIAQ project. Lightning strike tests are required to gather further information on these conductive coatings. The main application for these coatings is for lightning strike protection of aircraft, but they can also be used for ground based lightning strike protection and general electromagnetic shielding.

  1. Lightning protection system for a wind turbine (United States)

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


    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).

  2. Lightning protection for wind turbines in Vietnam

    Directory of Open Access Journals (Sweden)

    Thuan Nguyen


    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.

  3. Numerical tools for lightning protection of wind turbines

    DEFF Research Database (Denmark)

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


    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 (...

  4. The protection of photovoltaic power systems from lightning (United States)

    Rogers, C. B.

    Lightning protection techniques at nine prototype photovoltaic power system sites with outputs from 18-225 kW are described. Noting that protection schemes are devised to fit isokeraunic data for specific sites, grounding is cited as a common feature for all systems. The grounds are, in separate instances, connected to junction boxes, frames of the solar cell panels, lead from the dc center, from the dc negative terminal, from the frames and equipment, at the array turntable, or from the building rebar frames. The dc power cables are protected by either metal conduit, metal conduit ground wire, direct burial, by rigid metal conduit, ground conductors, or by ground conductors at the ends of the conduit run. Costs run from 0.01-0.28$/W, with all the systems outfitted with bypass and blocking diodes. Direct stroke protection is viewed as less important than isokeraunic data.

  5. Near ground gamma radiation associated with lightning (United States)

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


    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.

  6. 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


    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.

  7. 基于防雷接地需求的土壤结构模型研究%Model Research of Soil Structure Based on Demand of Lightning Protection Grounding

    Institute of Scientific and Technical Information of China (English)



    确定大地模型和土壤参数是大型地网防雷接地计算的首要工作。土壤电阻率是影响接地阻抗的主要因素之一,它对防雷接地的效果起着重要作用。根据等距四极法测得的土壤视在电阻率,使用遗传算法建立的反演多层水平分层土壤电阻率模型,可反演出土壤的分层结构。三个实例计算结果表明,本模型计算结果和国际著名软件包CDEGS的计算结果非常接近。%Confirming the ground model and soil parameter is the most important work protection grounding computation for large grounding system. The soil resistivity is one of affe of lightning cting ground impedance primary factors; it plays an important role in the lightning protection grounding effect. Based on the equal-space four-pole method measured soil apparent resistivity, the use of genetic algorithm to build the inversion of muhilayer horizontal layered soil resistivity model can be inverted soil layer structure. Three cases show the model calculation results and the famous international software package CDEGS calculation results are close.

  8. New method for lightning location using optical ground wire (United States)

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


    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.

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

    Directory of Open Access Journals (Sweden)

    Wang Daxing


    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.

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

    Directory of Open Access Journals (Sweden)

    Wang Daxing


    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.

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

    Institute of Scientific and Technical Information of China (English)


    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".

  12. Extensive air showers, lightning, and thunderstorm ground enhancements (United States)

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


    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.

  13. 14 CFR 29.610 - Lightning and static electricity protection. (United States)


    ... 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...

  14. 14 CFR 27.610 - Lightning and static electricity protection. (United States)


    ... 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...

  15. 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


    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.

  16. 14 CFR 23.954 - Fuel system lightning protection. (United States)


    ... 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...

  17. Protection of large wind turbine blades against lightning


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


    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...

  18. General Survey for Lightning Protection Standards Development in China

    Institute of Scientific and Technical Information of China (English)


    @@ 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.

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

    Directory of Open Access Journals (Sweden)

    Luo Hanwu


    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.

  20. Lightning protection of oil and gas industrial plants

    Energy Technology Data Exchange (ETDEWEB)

    Bouquegneau, Christian [Polytechnical University of Mons (Belgium)


    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.

  1. Direct Write Lightning Protection and Damage Detection Project (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...

  2. Lightning protecting materials used on radar system

    NARCIS (Netherlands)

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


    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

  3. Lightning Protection of Floating Roof Tanks

    Directory of Open Access Journals (Sweden)



    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. Electromagnetic computation methods for lightning surge protection studies

    CERN Document Server

    Baba, Yoshihiro


    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. 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....

  6. 电子信息系统工程中防雷接地探讨%Electronic Information Systems Engineering Lightning Protection and Grounding Discussion

    Institute of Scientific and Technical Information of China (English)

    徐宝春; 徐亚东


    随着信息与控制技术的飞速发展,电子信息系统日益增加,这些电子信息系统中的电子器件的集成和超大规模集成化,普遍存在着绝缘强度低、过电压耐受能力差等弱点。雷电对这些电子设备潜伏着严重的不安全性,一旦发生雷击事件,导致信息系统无法实时对外提供服务,将造成不可估量的直接与间接的经济损失和影响。%With the rapid development of information and control technology, electronic information systems increasing integration and ultra-large-scale integration, the prevalence of low dielectric strength of these electronic information system of electronic devices, over-voltage tolerance of poor weakness. Lightning serious of these electronic devices lurking insecurity, once lightning incident occurred not real-time information systems to provide services, it will cause immeasurable direct and indirect economic loss and impact.

  7. 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


    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.

  8. Cloud-to-ground lightning activity in Colombia and the influence of topography (United States)

    Aranguren, D.; López, J.; Inampués, J.; Torres, H.; Betz, H.


    Lightning activity on the Colombian mountains, where the altitude varies from 0 to more than 5000 MSL, is studied based on VLF/LF lightning detection data and using a 2012-2013 dataset. The influence of altitude is observed by evaluating cloud-to-ground lightning incidence at different altitude intervals. The relationship between ground flash density and altitude gradient vectors is studied. Results show a clear dependence of the flash density on elevation.

  9. A novel lightning protection technique of wind turbine components

    Directory of Open Access Journals (Sweden)

    M.A. Abd-Allah


    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.

  10. Lightning Protection for the Orion Space Vehicle (United States)

    Scully, Robert


    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. Common Practice Lightning Strike Protection Characterization Technique to Quantify Damage Mechanisms on Composite Substrates (United States)

    Szatkowski, George N.; Dudley, Kenneth L.; Koppen, Sandra V.; Ely, Jay J.; Nguyen, Truong X.; Ticatch, Larry A.; Mielnik, John J.; Mcneill, Patrick A.


    To support FAA certification airworthiness standards, composite substrates are subjected to lightning direct-effect electrical waveforms to determine performance characteristics of the lightning strike protection (LSP) conductive layers used to protect composite substrates. Test results collected from independent LSP studies are often incomparable due to variability in test procedures & applied practices at different organizations, which impairs performance correlations between different LSP data sets. Under a NASA supported contract, The Boeing Company developed technical procedures and documentation as guidance in order to facilitate a test method for conducting universal common practice lightning strike protection test procedures. The procedures obtain conformity in future lightning strike protection evaluations to allow meaningful performance correlations across data sets. This universal common practice guidance provides the manufacturing specifications to fabricate carbon fiber reinforced plastic (CFRP) test panels, including finish, grounding configuration, and acceptable methods for pretest nondestructive inspection (NDI) and posttest destructive inspection. The test operations guidance elaborates on the provisions contained in SAE ARP5416 to address inconsistencies in the generation of damage protection performance data, so as to provide for maximum achievable correlation across capable lab facilities. In addition, the guidance details a direct effects test bed design to aid in quantification of the multi-physical phenomena surrounding a lightning direct attachment supporting validation data requirements for the development of predictive computational modeling. The lightning test bed is designed to accommodate a repeatable installation procedure to secure the test panel and eliminate test installation uncertainty. It also facilitates a means to capture the electrical waveform parameters in 2 dimensions, along with the mechanical displacement and thermal

  12. Statistical Studies of Ground-Based Optical Lightning Signatures (United States)

    Hunt, C. R.; Nemzek, R. J.; Suszcynsky, D. M.


    Most extensive optical studies of lightning have been conducted from orbit, and the statistics of events collected from earth are relatively poorly documented. The time signatures of optical power measured in the presence of clouds are inevitably affected by scattering,which can distort the signatures by extending and delaying the amplitude profile in time. We have deployed two all-sky photodiode detectors, one in New Mexico and one in Oklahoma, which are gathering data alongside electric field change monitors as part of the LANL EDOTX Great Plains Array. Preliminary results show that the photodiode is sensitive to approximately 50% or more of RF events detected at ranges of up to 30 km, and still has some sensitivity at ranges in excess of 60 km (distances determined by the EDOTX field-change array). The shapes of events within this range were assessed, with focus on rise time, width, peak power, and their correlation to corresponding electric field signatures, and these are being compared with published on-orbit and ground-based data. Initial findings suggest a mean characteristic width (ratio of total detected optical energy to peak power) of 291 +/- 12 microseconds and a mean delay between the RF signal peak and optical peak of 121 +/- 17 microseconds. These values fall between prior ground-based measurements of direct return stroke emissions, and scattering-dominated on-orbit measurements. This work will promote better understanding of the correspondence between radio and optical measurements of lightning.

  13. Enhancement of cloud-to-ground lightning over Houston, Texas (United States)

    Orville, Richard E.; Huffines, Gary; Nielsen-Gammon, John; Zhang, Renyi; Ely, Brandon; Steiger, Scott; Phillips, Stephen; Allen, Steve; Read, William

    Cloud-to-ground lightning flash data have been analyzed for the twelve-year period 1989-2000, for a geographical area centered on Houston, Texas. Of the 1.6 million cloud-to-ground flashes in this area of study, approximately 752,000 flashes occurred in the summer months of June, July, and August, and 119,000 flashes in the months of December, January, and February. The highest flash densities, greater than 4 flashes km-2 in the summer and 0.7 flashes/km-2 in the winter, are near the urban areas of Houston. We suggest that the elevated flash densities could result from several factors, including, 1) the convergence due to the urban heat island effect, and 2) the increasing levels of air pollution from anthropogenic sources producing numerous small droplets and thereby suppressing mean droplet size. The latter effect would enable more cloud water to reach the mixed phase region where it is involved in the formation of precipitation and the separation of electric charge, leading to an enhancement of lightning.

  14. 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)


    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.

  15. Estimation of the Current Peak Value Distribution of All Lightning to the Ground by Electro-Geometric Model (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.

  16. FDTD Analysis of the Current Distribution within the Grounding System for a Wind Turbine Generation Tower Struck by Lightning (United States)

    Nagao, Mitsuhiro; Nagaoka, Naoto; Baba, Yoshihiro; Ametani, Akihiro

    Transient current distribution within the grounding system for a wind-turbine-generation tower of height 61m struck by lightning has been calculated using the finite-difference time-domain (FDTD) method. The grounding grid for the lightning-struck tower considered in this paper is connected electrically via an insulated wire to one neighboring-tower grounding grid located 50m away from it. High-frequency components of a lightning current tend to flow in ground through the grounding grid of the lightning-struck tower, and they become larger with increasing the ground conductivity. Relatively-lower-frequency components of the lightning current flow in ground through each of the two grounding grids roughly in inverse proportion to the grounding resistance of each grid. For example, when two identical grounding grids for the lightning-struck tower and the neighboring tower are buried in the same ground, about 50% of the lightning current flows in the grounding grid for the neighboring tower via the insulated wire connecting these two grounding grids. When the grounding resistance of the neighboring tower is about 1/4 of that for the lightning-struck tower, about 4/5 of the lightning current flows in the neighboring-tower grounding grid. This agrees well with the trend shown by Nagaoka et al. from their measurement in the grounding system for an actual wind-turbine-generation tower struck by natural lightning.

  17. 基于IEC62305避雷针最大保护角法防雷效果分析%Analysis of Lightning Protection Effect Based on Lightning Rod Maximum Protection Angle in IEC 62305

    Institute of Scientific and Technical Information of China (English)

    李家启; 王代新; 江孟蜀


    针对闪电对地物发生闪击的瞬间状态,采用库仑定律重点分析研究IEC62305推荐的避雷针最大保护角法的雷电防护效果.结果表明:IEC62305推荐的避雷针最大保护角,其保护域内不仅可免遭雷电正击,还可免遭雷电侧击;而GBJ57推荐的最大保护角保护域内仅可免遭雷电正击.基于此,为GB50057采用IEC62305推荐最大保护角而不继续采用GBJ57推荐最大保护角提供了理论支撑和科学依据.%Aiming at the instantaneous state of the cloud-ground lightning and using the Coulomb's law, we analyze the lightning protection effect in this study based on the lightning rod maximum protection an gle in IEC 62305. The result shows that the lightning rod maximum protection angle recommended by IEC 62305 can not only protect direct-strike lightning but also flank striking lightning, while the maximum protection angle recommended by GBJ57 can only protect direct-strike lightning, thus providing a theoreti- cal support and a scientific basis for the adoption of the maximum protection angle recommended by IEC 62305 instead of that by GBJ57 in GB50057.

  18. 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)


    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.

  19. Transient state of polarization in optical ground wire caused by lightning and impulse current (United States)

    Kurono, Masahiro; Isawa, K.; Kuribara, Masayuki


    This paper describes a transient state of polarization in an optical ground wire (OPGW) theoretically, experimentally and with field measurements in lightning conditions, which is considered one of the fastest phenomena of polarization fluctuations in the natural environment. These characteristics will be required for optical coherent communication for utilities in future and for application to sensing of lightning with OPGW.

  20. Antenna structures and cloud-to-ground lightning location: 1995-2015 (United States)

    Kingfield, Darrel M.; Calhoun, Kristin M.; de Beurs, Kirsten M.


    Spatial analyses of cloud-to-ground (CG) lightning occurrence due to a rapid expansion in the number of antenna towers across the United States are explored by gridding 20 years of National Lightning Detection Network data at 500 m spatial resolution. The 99.8% of grid cells with ≥100 CGs were within 1 km of an antenna tower registered with the Federal Communications Commission. Tower height is positively correlated with CG occurrence; towers taller than 400 m above ground level experience a median increase of 150% in CG lightning density compared to a region 2 km to 5 km away. In the northern Great Plains, the cumulative CG lightning density near the tower was around 138% (117%) higher than a region 2 to 5 km away in the September-February (March-August) months. Higher CG frequencies typically also occur in the first full year following new tower construction, creating new lightning hot spots.

  1. Synthesis and testing of a conducting polymeric composite material for lightning strike protection applications (United States)

    Katunin, A.; Krukiewicz, K.; Turczyn, R.; Sul, P.; Łasica, A.; Catalanotti, G.; Bilewicz, M.


    Lightning strike protection is one of the important issues in the modern maintenance problems of aircraft. This is due to a fact that the most of exterior elements of modern aircraft is manufactured from polymeric composites which are characterized by isolating electrical properties, and thus cannot carry the giant electrical charge when the lightning strikes. This causes serious damage of an aircraft structure and necessity of repairs and tests before returning a vehicle to operation. In order to overcome this problem, usually metallic meshes are immersed in the polymeric elements. This approach is quite effective, but increases a mass of an aircraft and significantly complicates the manufacturing process. The approach proposed by the authors is based on a mixture of conducting and dielectric polymers. Numerous modeling studies which are based on percolation clustering using kinetic Monte Carlo methods, finite element modeling of electrical and mechanical properties, and preliminary experimental studies, allow achieving an optimal content of conducting particles in a dielectric matrix in order to achieve possibly the best electrical conductivity and mechanical properties, simultaneously. After manufacturing the samples with optimal content of a conducting polymer, mechanical and electrical characterization as well as high-voltage testing was performed. The application of such a material simplifies manufacturing process and ensures unique properties of aircraft structures, which allows for minimizing damage after lightning strike, as well as provide electrical bounding and grounding, interference shielding, etc. The proposed solution can minimize costs of repair, testing and certification of aircraft structures damaged by lightning strikes.

  2. 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;


    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...

  3. Designing an Optimal Lightning Protection Scheme for Substations Using Shielding Wires

    Directory of Open Access Journals (Sweden)

    A. Khodadadi


    Full Text Available An optimal lightning protection scheme for a substation using shielding wires is investigated in this paper through computer software analysis. An economic approach is utilized by choosing a reasonable trade-off between protection, the number of shielding wires and the heights of them from the ground. This study is initially applied to a simple two-wire system and then extended to a sample substation. The solution for each problem is executed in MATLAB and 3-D realization is shown.

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

    Institute of Scientific and Technical Information of China (English)


    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

  5. Lightning (United States)

    Pampe, William R.


    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)

  6. Lightning Protection System for HE Facilities at LLNL - Certification Template

    Energy Technology Data Exchange (ETDEWEB)

    Clancy, T J; Ong, M M; Brown, C G


    This document is meant as a template to assist in the development of your own lighting certification process. Aside from this introduction and the mock representative name of the building (Building A), this document is nearly identical to a lightning certification report issued by the Engineering Directorate at Lawrence Livermore National Laboratory. At the date of this release, we have certified over 70 HE processing and storage cells at our Site 300 facilities. In Chapters 1 and 2 respectively, we address the need and methods of lightning certification for HE processing and storage facilities at LLNL. We present the preferred method of lightning protection in Chapter 3, as well as the likely building modifications that are needed to comply with this method. In Chapter 4, we present the threat assessment and resulting safe work areas within a cell. After certification, there may be changes to operations during a lightning alert, and this is discussed in Chapter 5. Chapter 6 lists the maintenance requirements for the continuation of lighting certification status. Appendices of this document are meant as an aid in developing your own certification process, and they include a bonding list, an inventory of measurement equipment, surge suppressors in use at LLNL, an Integrated Work and Safety form (IWS), and a template certification sign-off sheet. The lightning certification process involves more that what is spelled out in this document. The first steps involve considerable planning, the securing of funds, and management and explosives safety buy-in. Permits must be obtained, measurement equipment must be assembled and tested, and engineers and technicians must be trained in their use. Cursory building inspections are also recommended, and surge suppression for power systems must be addressed. Upon completion of a certification report and its sign-off by management, additional work is required. Training will be needed in order to educate workers and facility managers

  7. Coincident Observation of Lightning using Spaceborne Spectrophotometer and Ground-Level Electromagnetic Sensors (United States)

    Adachi, Toru; Cohen, Morris; Li, Jingbo; Cummer, Steve; Blakeslee, Richard; Marshall, THomas; Stolzenberg, Maribeth; Karunarathne, Sumedhe; Hsu, Rue-Ron; Su, Han-Tzong; Chen, Alfred; Takahashi, Yukihiro; Frey, Harald; Mende, Stephen


    The present study aims at assessing a possible new way to reveal the properties of lightning flash, using spectrophotometric data obtained by FORMOSAT-2/ISUAL which is the first spaceborne multicolor lightning detector. The ISUAL data was analyzed in conjunction with ground ]based electromagnetic data obtained by Duke magnetic field sensors, NLDN, North Alabama Lightning Mapping Array (LMA), and Kennedy Space Center (KSC) electric field antennas. We first classified the observed events into cloud ]to ]ground (CG) and intra ]cloud (IC) lightning based on the Duke and NLDN measurements and analyzed ISUAL data to clarify their optical characteristics. It was found that the ISUAL optical waveform of CG lightning was strongly correlated with the current moment waveform, suggesting that it is possible to evaluate the electrical properties of lightning from satellite optical measurement to some extent. The ISUAL data also indicated that the color of CG lightning turned to red at the time of return stroke while the color of IC pulses remained unchanged. Furthermore, in one CG event which was simultaneously detected by ISUAL and LMA, the observed optical emissions slowly turned red as the altitude of optical source gradually decreased. All of these results indicate that the color of lightning flash depends on the source altitude and suggest that spaceborne optical measurement could be a new tool to discriminate CG and IC lightning. In the presentation, we will also show results on the comparison between the ISUAL and KSC electric field data to clarify characteristics of each lightning process such as preliminary breakdown, return stroke, and subsequent upward illumination.

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


    Hermoso Alameda, Blas; Montañá Puig, Juan


    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...

  9. 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


    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.

  10. 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)


    In the early development of wind turbine generators (WTG) in the United States, wind farms were primarily located in California where lightning activity is the lowest in the United States. As such, lightning protection for wind turbines was not considered to be a major issue for designers or wind farm operators. However, wind turbine installations are expanding into the Midwest, Southwest and other regions of the United States where lightning activity is significantly more intense and lightning damage to wind turbines is more common. There is a growing need, therefore, to better understand lightning activity on wind farms and to improve wind turbine lightning protection systems. In support of the U.S. Department of Energy/Electric Power Research Institute (DOE/EPRI) Utility Wind Turbine Verification Program (TVP), the National Renewable Energy Laboratory (NREL) has recently begun to take steps to determine the extent of damage due to lightning and the effectiveness of various lightning protection techniques for wind power plants. Working through the TVP program, NREL will also perform outreach and education to (1) help manufacturers to provide equipment that is adequately designed to survive lightning, (2) make sure that operators are aware of effective safety procedures, and (3) help site designers and wind farm developers take the risk of lightning into account as effectively as possible.

  11. Operational Cloud-to-Ground Lightning Initiation Forecasting Utilizing S-Band Dual-Polarization Radar (United States)


    cells exhibit considerably more complexity in their charge distributions, the tripole model is adequate to explain lightning formation. Although...application of dual-polarization weather radar. Part II: Warm- and cold- season applications. J. Operational Meteor., 1 (20), 243-264. Kumjian, M. R...Res., 94, 13151–13167. 60 Wolf, P., 2006: Anticipating the initiation, cessation , and frequency of cloud-to-ground lightning, utilizing WSR

  12. 14 CFR 23.867 - Electrical bonding and protection against lightning and static electricity. (United States)


    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Electrical bonding and protection against lightning and static electricity. 23.867 Section 23.867 Aeronautics and Space FEDERAL AVIATION... Electrical bonding and protection against lightning and static electricity. (a) The airplane must be...

  13. Lightning rod ionizing natural ionca - Ionic electrode active trimetallictriac of grounding - Definitive and total solution against 'blackouts' and electrical faults generated by atmospheric charges (lightning)

    Energy Technology Data Exchange (ETDEWEB)

    Cabareda, Luis


    The Natural Ionizing System of Electrical Protection conformed by: Lightning Rod Ionizing Natural Ionca and Ionic Electrode Active Trimetallic Triac of Grounding offers Total Protection, Maximum Security and Zero Risk to Clinics, Hospitals, Integral Diagnostic Center, avoiding ''the burning'' of Electronics Cards; Refineries, Tanks and Stations of Fuel Provision; Electrical Substations, Towers and Transmission Lines with transformer protection, motors, elevators, A/C, mechanicals stairs, portable and cooling equipment, electrical plants, others. This New High Technology is the solution to the paradigm of Benjamin Franklin and it's the mechanism to end the 'Blackouts' that produces so many damages and losses throughout the world.

  14. Using Cloud-to-Ground Lightning Climatologies to Initialize Gridded Lightning Threat Forecasts for East Central Florida (United States)

    Lambert, Winnie; Sharp, David; Spratt, Scott; Volkmer, Matthew


    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 ( . 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

  15. Analytic Perturbation Method for Estimating Ground Flash Fraction from Satellite Lightning Observations (United States)

    Koshak, William; Solakiewicz, Richard


    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. Building the International Testing and Certification Service for Lightning Protection Products

    Institute of Scientific and Technical Information of China (English)


    Lightning Protective Devices Testing Center affiliated to Shanghai Lightning Protection Center (hereinafter referred to as “Testing Center”) is a third-party technical institution specialized in the testing of lightning protection equipment,which has passed the qualification certification and metrology accreditation of Certification and Accreditation Administratin of the People's Republic of China and is approved by China National Accreditation Service for Conformity Assessment Meanwhile,it is also a lightning products quality inspection institution authorized by Shanghai Municipal Bureau of Quality and Technical Superwsion and the only lightning products testing laboratory authorized by China Quality Certification Center.The Center has always attached great importance to the standardization work,and accumulated rich successful experiences in enhancing the testing capability and technical service level by means of standardization.

  17. Comparing distinct ground-based lightning location networks covering the Netherlands (United States)

    de Vos, Lotte; Leijnse, Hidde; Schmeits, Maurice; Beekhuis, Hans; Poelman, Dieter; Evers, Läslo; Smets, Pieter


    Lightning can be detected using a ground-based sensor network. The Royal Netherlands Meteorological Institute (KNMI) monitors lightning activity in the Netherlands with the so-called FLITS-system; a network combining SAFIR-type sensors. This makes use of Very High Frequency (VHF) as well as Low Frequency (LF) sensors. KNMI has recently decided to replace FLITS by data from a sub-continental network operated by Météorage which makes use of LF sensors only (KNMI Lightning Detection Network, or KLDN). KLDN is compared to the FLITS system, as well as Met Office's long-range Arrival Time Difference (ATDnet), which measures Very Low Frequency (VLF). Special focus lies on the ability to detect Cloud to Ground (CG) and Cloud to Cloud (CC) lightning in the Netherlands. Relative detection efficiency of individual flashes and lightning activity in a more general sense are calculated over a period of almost 5 years. Additionally, the detection efficiency of each system is compared to a ground-truth that is constructed from flashes that are detected by both of the other datasets. Finally, infrasound data is used as a fourth lightning data source for several case studies. Relative performance is found to vary strongly with location and time. As expected, it is found that FLITS detects significantly more CC lightning (because of the strong aptitude of VHF antennas to detect CC), though KLDN and ATDnet detect more CG lightning. We analyze statistics computed over the entire 5-year period, where we look at CG as well as total lightning (CC and CG combined). Statistics that are considered are the Probability of Detection (POD) and the so-called Lightning Activity Detection (LAD). POD is defined as the percentage of reference flashes the system detects compared to the total detections in the reference. LAD is defined as the fraction of system recordings of one or more flashes in predefined area boxes over a certain time period given the fact that the reference detects at least one

  18. Cyclic hygrothermal aging of aircraft lightning protections: Phenomenological overview

    KAUST Repository

    Lubineau, Gilles


    The recent transition to full composite fuselages is a major breakthrough in aeronautical design. To ensure satisfactory lightning protection, the electrical properties of the primary composite structure need to be improved and a design solution lies on bonding a metallic fishnet to the fuselage. An important issue is the prediction of the aging behavior of this top layer when exposed to severe aging conditions representative of flight environment. Multiple aging mechanisms affect this top layer made of thermoset resin and metallic fishnet with complex geometry and a first modeling strategy is a necessary starting point to better understand its evolution. This paper describes the overall phenomenology and the different mechanisms that can be expected in such a structure.

  19. Heavy precipitation retrieval from combined satellite observations and ground-based lightning measurements (United States)

    Mugnai, A.; Dietrich, S.; Casella, D.; di Paola, F.; Formenton, M.; Sanò, P.


    We have developed a series of algorithms for the retrieval of precipitation (especially, heavy precipitation) over the Mediterranean area using satellite observations from the available microwave (MW) radiometers onboard low Earth orbit (LEO) satellites and from the visible-infrared (VIS-IR) SEVIRI radiometer onboard the European geosynchronous (GEO) satellite Meteosat Second Generation (MSG), in conjunction with lightning data from ground-based networks - such as ZEUS and LINET. These are: • A new approach for precipitation retrieval from space (which we call the Cloud Dynamics and Radiation Database approach, CDRD) that incorporates lightning and environmental/dynamical information in addition to the upwelling microwave brightness temperatures (TB’s) so as to reduce the retrieval uncertainty and improve the retrieval performance; • A new combined MW-IR technique for producing frequent precipitation retrievals from space (which we call PM-GCD technique), that uses passive-microwave (PM) retrievals in conjunction with lightning information and the Global Convection Detection (GCD) technique to discriminate deep convective clouds within the GEO observations; • A new morphing approach (which we call the Lightning-based Precipitation Evolving Technique, L-PET) that uses the available lightning measurements for propagating the rainfall estimates from satellite-borne MW radiometers to a much higher time resolution than the MW observations. We will present and discuss our combined MW/IR/lightning precipitation algorithms and analyses with special reference to some case studies over the western Mediterranean.

  20. Observation of cloud-to-ground lightning channels with high-speed video camera

    CERN Document Server

    Buguet, M; Blanchet, P; Pédeboy, S; Barnéoud, P; Laroche, P


    Between May and October 2013 (period of sustained thunderstorm activity in France), several cloud-to-ground lightning flashes have been observed in Paris area with a high-speed video camera (14000 frames per second). The localization and the polarity of the recorded cloud-to-ground flashes have been obtained from the French lightning detection network M{\\'e}t{\\'e}orage which is equipped with the same low frequency sensors used by the US NLDN. In this paper we focused on 7 events (3 positive cloud-to-ground lightning flashes and 4 negative cloud-to-ground lightning flashes). The propagation velocity of the leaders and its temporal evolution have been estimated; the evolution of branching of the negative leaders have been observed during the propagation of the channel which get connected to ground and initiate the first return stroke. One aim of this preliminary study is to emphasize the differences between the characteristics of the positive and of the negative leaders.

  1. Lightning protection for the process canyons at the Savannah River site

    Energy Technology Data Exchange (ETDEWEB)

    McAfee, D.E.


    Westinghouse Savannah River Company (WSRC) has performed Lightning Studies for the existing Process Canyons at the Savannah River Site (SRS). These studies were initiated to verify the lightning protection systems for the facilities and to compare the installations to the National Fire Protection (NFPA) Standard 780, Lighting Protection Code, 1992. The original study of the F-Canyon was initiated to develop answers to concerns raised by the Defense Nuclear Facility Safety Board (DNFSB). Once this study was completed it was determined that a similar study for H-Canyon would be prudent; followed by an evaluation of the Defense Waste Processing Facility (DWPF) Vitrification Building (S-Canyon). This paper will provide an overview of the nature of lightning and the principals of lightning protection. This will provide the reader with a basic understanding of the phenomena of lighting and its potential for damaging structures, components, and injuring personnel in or near the structure.

  2. Seminar for National Lightning Protection and Standardization Held in Chengdu,Sichuan

    Institute of Scientific and Technical Information of China (English)


    @@ Seminar for National Lightning Protection and Standardization was held in Chengdu of Sichuan province in China on July 30-31. It was sponsored by the Chinese National Technical Committee for Lightning Protection Standardization and was organized by ZhongGuang High-tech Industrial Development Co.,Ltd. About 70 participants engaged in R&D, management and education of lightning protection technology and in design, manufacturing, test of lightning protection products from different industries, such as railway, telecommunication, meteorology, traffic, construction etc, attended the seminar. Prof. LuChonghui, Mr. Wang Deyan and Prof. He Jinliang presided it respectively, who are the chairman and vice chairmen of the committee. Mr. Ma Lincong,secretary-general of China Association for Standardization, made the opening address.

  3. Design of Lightning Arresters for Electrical Power Systems Protection

    Directory of Open Access Journals (Sweden)

    Shehab Abdulwadood


    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.

  4. Cloud-to-ground lightning activity over Greece: Spatio-temporal analysis and impacts (United States)

    Matsangouras, I. T.; Nastos, P. T.; Kapsomenakis, J.


    Cloud-to-ground (CG) lightning activity recorded by the Hellenic National Meteorological Service (HNMS) Precision Lightning Network (PLN) is analysed over the wider area of Greece. In addition, the spatial and temporal relationships between TRMM 3B42 (Tropical Rainfall Measuring Mission) datasets and lightning are presented. The analyses concern the period from January 14, 2008 to December 31, 2012. The Laboratory of Climatology and Atmospheric Environment, University of Athens, has established a detailed dataset of lightning impacts over Greece from 1895 to 2013, based on digitized archive editions of newspapers. The mean seasonal variability of CG lightning activity revealed autumn as the most dominant season with 303 LD, while the mean monthly variability of CG indicated October as the most lightning active month and May as the month with a mean of 27 LD. The mean annual spatial distribution of CG lightning per km2, depicted the maximum frequency over Pindus mountain range (> 7 CG/km2). During the autumn season, the northern Ionian Sea experienced a mean frequency of more than 5 CG/km2, compared to the southern Ionian Sea and NW Peloponnesus, where values of more than 7 CG/km2 are depicted. During the summer season, the maximum frequency appeared along Pindus mountain range, around Attica, Thessaly and central Macedonia highlands. The spatial distribution of seasonal correlations between the number of CG flashes/day and gridded (TRMM 3B42) daily rainfall totals for the period 2008-2012 over Greece, indicated that correlations were mainly positive all over the under study area, within all seasons, and especially during summer and autumn. Regarding the lightning impacts in Greece, based on the 1895-2013 study period, more than 343 fatalities and at least 224 injured people have been recorded. The spatial analysis of lightning impacts, showed that the majority of events has been recorded over Greek mainland and only few scattered events have been reported over

  5. Charge structure analysis of a severe hailstorm with predominantly positive cloud-to-ground lightning (United States)

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


    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.

  6. Small Negative Cloud-to-Ground Lightning Reports at the KSC-ER (United States)

    Wilson, Jennifer G.; Cummins, Kenneth L.; Krider, E. Philip


    '1he NASA Kennedy Space Center (KSC) and Air Force Eastern Range (ER) use data from two cloud-to-ground (CG) lightning detection networks, the CGLSS and the NLDN, and a volumetric lightning mapping array, LDAR, to monitor and characterize lightning that is potentially hazardous to ground or launch operations. Data obtained from these systems during June-August 2006 have been examined to check the classification of small, negative CGLSS reports that have an estimated peak current, [I(sup p)] less than 7 kA, and to determine the smallest values of I(sup p), that are produced by first strokes, by subsequent strokes that create a new ground contact (NGC), and by subsequent strokes that remain in a pre-existing channel (PEC). The results show that within 20 km of the KSC-ER, 21% of the low-amplitude negative CGLSS reports were produced by first strokes, with a minimum I(sup p) of-2.9 kA; 31% were by NGCs, with a minimum I(sup p) of-2.0 kA; and 14% were by PECs, with a minimum I(sup p) of -2.2 kA. The remaining 34% were produced by cloud pulses or lightning events that we were not able to classify.

  7. Observations on the leader-return stroke of cloud-to-ground lightning with the broadband interferometer

    Institute of Scientific and Technical Information of China (English)

    董万胜; 刘欣生; 张义军; 张广庶


    Radio frequency observations of cloud-to-ground lightning (CG) were made in 1999 in Guangdong Province with the broadband lightning interferometer. In this paper, radiation source locations and electric field waveforms are analyzed for different types of breakdown events, including the preliminary breakdown of in-cloud activities, the stepped leaders of initial strokes to ground and activities during and following return strokes. It is shown that the structure and development of lightning discharges and associated breakdown processes can be reconstructed by using this new type of lightning radiation source location system. The detectable radiation of lightning was primarily produced by the negative breakdown process. The channel was concentrated with few branches during the preliminary breakdown stage of CG lightning flashes. The radiation sources appeared generally at the tip of the channel. During the late period of the stepped leader, the radiation sources were dispersed with branches extended away from the main channel. The radiation sources were in a certain length segment of the channel and the altitude of the segment descended along with the propagation of the leader to the ground. During the preliminary breakdown and the stepped leader of initial strokes to the ground, a sequence of fast negative streamers were observed to start continually from or farther away the lightning-initiated region and propagate along the developed leader channel, which may supply negative charge that assisted the leader's development. The progression speed of fast negative streamers was about ten times faster than the average speed of lightning channel.

  8. Cloud-to-ground lightning characteristics over Houston, Texas: 1989-2000 (United States)

    Steiger, Scott M.; Orville, Richard E.; Huffines, Gary


    Cloud-to-ground (CG) lightning detected by the National Lightning Detection Network (NLDN) indicates a relatively high flash density over Houston, Texas, for the 12-year period 1989-2000. A significant enhancement of 45% in the flash density is observed compared to the nearby surrounding areas. The strength of the enhancement varies on the basis of season and time of day, with the greatest increases occurring during the summer (58%) and during the 0900-1800 LT time periods in each season. Observations indicate that large lightning events (defined as days with >100 flashes in a geographic region that includes Houston and nearby rural areas) were responsible for the climatological lightning anomaly and that increased thunderstorm initiation was not the most significant cause of the enhancement. A decrease (-12%) in the percentage of positive flashes is observed over the city. Higher negative median peak currents along the coast and well into the Gulf of Mexico were also discovered. Several explanations for our observations are suggested. The urban heat island and increased cloud condensation nuclei concentrations, especially from industrial pollution, are speculated to be significant factors in creating lightning enhancement. Pollution effects are speculated to cause a change in a thunderstorm's charge distribution, which can affect the polarity of CG flashes. The potential effect of the nearby coastal Gulf salt water on the calculated peak current is examined. Variations in multiplicity values across the region are observed but not explained.

  9. Cloud-to-Ground Lightning Characteristics Over Houston, TX: 1989-2000 (United States)

    Steiger, S. M.; Orville, R. E.


    Cloud-to-Ground (CG) lightning detected by the National Lightning Detection Network (NLDN) indicates a relatively high flash density over Houston, Texas for the twelve-year period 1989-2000. A significant enhancement of 45% in the flash density is observed compared to the nearby surrounding areas. The strength of the enhancement varies based on season and time-of-day, with the greatest increases occurring during the summer (58%), and during the 0900-1800 LST time periods in each season. Observations indicate that large lightning events (defined as days with > 1,000 flashes in a geographic region that includes Houston and nearby rural areas) were responsible for the climatological lightning anomaly, and that increased thunderstorm initiation was not the most significant cause of the enhancement. A decrease (-12%) in the percentage of positive flashes is observed over the city. Higher negative median peak currents along the coast and well into the Gulf of Mexico were also discovered. Several explanations for our observations are suggested. The urban heat island and increased cloud condensation nuclei (CCN) concentrations, especially from industrial pollution, are shown to be significant factors in creating lightning enhancement. Pollution effects are speculated to cause a change in a thunderstorm's charge distribution, which can affect the polarity of CG flashes. The potential effect of the nearby coastal Gulf salt water on the measured peak current is examined.

  10. Development of lightning resistant overhead ground wire and characteristics against lightning current triggered by rocket; Tai rai kaku chisen no kaihatsu to rokketo yurai no jitsuraigeki denryu ni yoru tai rai seino no kensho

    Energy Technology Data Exchange (ETDEWEB)

    Shimizu, M.; Yokoya, M.; Kawashima, T. [Chubu Electric Power Co. Inc., Nagoya (Japan); Omi, H. [Sumitomo Electric Industries Ltd., Osaka (Japan); Asano, Y. [Fujikura Ltd., Tokyo (Japan); Goda, Y. [Central Research Inst. of Electric Power Industry, Tokyo (Japan); Nakamura, K. [Nagoya Inst. of Technology, Nagoya (Japan)


    It has been important to maintain high reliability for supplying electric power in recent high-intelligent society. Overhead ground wires (GW) are installed at upper positions of overhead transmission lines in order to prevent lightning attack on conductors. As the sacrifice, GW sometimes gets certain damages including strand-breakage by a severe lightning attack. Recently, optical fiber composite ground wire(OPGW), which has arisen for development of strong GW against lightning attack, in particular for transmission lines passing through areas where `winter lightning` with enormous electric charge occurs, or areas where frequent lightning occurs. We investigated materials and strand structures to get high lightning-resistant properties and verified by rocket-triggered lightning experiments and DC arc tests. As the results, we have developed excellent lightning-resistant OPGW that has fundamental properties equivalent to conventional GW. 12 refs., 12 figs., 4 tabs.

  11. Protection characteristics of a Faraday cage compromised by lightning burnthrough.

    Energy Technology Data Exchange (ETDEWEB)

    Warne, Larry Kevin; Bystrom, Edward; Jorgenson, Roy Eberhardt; Montoya, Sandra L.; Merewether, Kimball O.; Coats, Rebecca Sue; Martinez, Leonard E.; Jojola, John M.


    A lightning flash consists of multiple, high-amplitude but short duration return strokes. Between the return strokes is a lower amplitude, continuing current which flows for longer duration. If the walls of a Faraday cage are made of thin enough metal, the continuing current can melt a hole through the metal in a process called burnthrough. A subsequent return stroke can couple energy through this newly-formed hole. This LDRD is a study of the protection provided by a Faraday cage when it has been compromised by burnthrough. We initially repeated some previous experiments and expanded on them in terms of scope and diagnostics to form a knowledge baseline of the coupling phenomena. We then used a combination of experiment, analysis and numerical modeling to study four coupling mechanisms: indirect electric field coupling, indirect magnetic field coupling, conduction through plasma and breakdown through the hole. We discovered voltages higher than those encountered in the previous set of experiments (on the order of several hundreds of volts).

  12. 采用架空接闪线的防直击雷设计%Direct Lightning Protection Design of Overhead Lightning Line

    Institute of Scientific and Technical Information of China (English)

    黄旭; 李红旭


    Based on an example of a building,this paper introduced the lightning protection design of a certain first-class direct lighting protection buildings.The different layouts of adopting single lightning rod and single overhead lightning conductor were calculated and contrasted,and ultimately a plan which uses several overhead lightning conductors was confirmed.During the comparison,the protective range and its difference between dual overhead lightning conductors and designed specifications of lightning protection were analyzed.Finally,the rolling ball method was adopted to do the checking computation of the final plan,which confirms that it can play a role in direct lightning protection.%以某厂房为例,介绍了一类防雷建筑物的防直击雷设计。计算比较了独立接闪杆、架空接闪线的几种不同布置方式,并确定一种数根架空接闪线的方案。在方案比较中,着重分析了双架空接闪线的保护范围及其与防雷设计规范中的不同。采用滚球法对最终方案进行了防雷验算,确认其能起到防直击雷的作用。

  13. Objective Lightning Forecasting at Kennedy Space Center/Cape Canaveral Air Force Station using Cloud-to-Ground Lightning Surveillance System Data (United States)

    Lambert, Winifred; Wheeler, Mark


    The 45th Weather Squadron (45 WS) forecasters at Cape Canaveral Air Force Station (CCAFS) in Florida include a probability of thunderstorm occurrence in their daily morning briefings. This information is used by personnel involved in determining the possibility of violating Launch Commit Criteria, evaluating Flight Rules for the Space Shuttle, and daily planning for ground operation activities on Kennedy Space Center (KSC)/CCAFS. Much of the current lightning probability forecast is based on a subjective analysis of model and observational data. The forecasters requested that a lightning probability forecast tool based on statistical analysis of historical warm-season (May - September) data be developed in order to increase the objectivity of the daily thunderstorm probability forecast. The tool is a set of statistical lightning forecast equations that provide a lightning occurrence probability for the day by 1100 UTC (0700 EDT) during the warm season. This study used 15 years (1989-2003) of warm season data to develop the objective forecast equations. The local CCAFS 1000 UTC sounding was used to calculate stability parameters for equation predictors. The Cloud-to-Ground Lightning Surveillance System (CGLSS) data were used to determine lightning occurrence for each day. The CGLSS data have been found to be more reliable indicators of lightning in the area than surface observations through local informal analyses. This work was based on the results from two earlier research projects. Everitt (1999) used surface observations and rawinsonde data to develop logistic regression equations that forecast the daily thunderstorm probability at CCAFS. The Everitt (1999) equations showed an improvement in skill over the Neumann-Pfeffer thunderstorm index (Neumann 1971), which uses multiple linear regression, and also persistence and climatology forecasts. Lericos et al. (2002) developed lightning distributions over the Florida peninsula based on specific flow regimes. The

  14. Electrically conductive carbon fibre-reinforced composite for aircraft lightning strike protection (United States)

    Katunin, Andrzej; Krukiewicz, Katarzyna; Turczyn, Roman; Sul, Przemysław; Bilewicz, Marcin


    Aircraft elements, especially elements of exterior fuselage, are subjected to damage caused by lightning strikes. Due to the fact that these elements are manufactured from polymeric composites in modern aircraft, and thus, they cannot conduct electrical charges, the lightning strikes cause burnouts in composite structures. Therefore, the effective lightning strike protection for such structures is highly desired. The solution presented in this paper is based on application of organic conductive fillers in the form of intrinsically conducting polymers and carbon fabric in order to ensure electrical conductivity of whole composite and simultaneously retain superior mechanical properties. The presented studies cover synthesis and manufacturing of the electrically conductive composite as well as its characterization with respect to mechanical and electrical properties. The performed studies indicate that the proposed material can be potentially considered as a constructional material for aircraft industry, which characterizes by good operational properties and low cost of manufacturing with respect to current lightning strike protection materials solutions.

  15. Lightning, surge and transient protection. Citations from the NTIS data base (United States)

    Reed, W. E.


    Techniques and devices for the protection of electronic and electrical equipment are presented in these Federally sponsored research reports. The citations include research on suppressors, limiters, lightning arresters, electromagnetic pulse protection devices, and overvoltage protection networks. Electromagnetic shielding is excluded. This updated bibliography contains 106 abstracts, 44 of which are new entries to the previous edition.

  16. Positive Charge Region in Lower Part of Thunderstorm and Preliminary Breakdown Process of Negative Cloud-to-Ground Lightning

    Institute of Scientific and Technical Information of China (English)

    ZHANG Yijun; MENG Qing; LU Weitao; MA Ming; ZHENG Dong; Pau R. Krehbiel


    A new lightning locating technology, called Lightning Mapping Array (LMA), has been developed. The system takes advantage of GPS technology to measure the times of arrival (TOA) of lightning impulsive very high frequency (VHF) radiation events at each remote location. The spatiotemporal development processes of lightning are described in three-dimension by measurement of the system with high time resolution (50 ns) and space precision (50-100 m). The charge structures in thunderstorm and their relationship with lightning discharge processes are revealed. The temporal and spatial characteristics of preliminary breakdown process involved in negative cloud-to-ground (CG) lightning discharges are analyzed based on the data of lightning VHF radiation events. The effect of positive charge region in lower part of thunderstorm on the occurrence of negative CG lightning discharge is discussed. The results indicate that the preliminary breakdown process with longer duration in negative CG lightning discharges is an intracloud discharge process. It occurs between negative and positive charge regions located in middle and lower parts of thunderstorm respectively.It initiates from the negative charge region and propagates downward. After propagating into the positive charge region, the lightning channel develops horizontally. The characteristics of the preliminary breakdown process are consistent with that of intracloud lightning discharges. The stepped leaders are initiated by the K type breakdown which occurs in the last stage of the preliminary breakdown process and develops downward through the positive charge region. The existence of positive charge region in lower part of thunderstorm results in the occurrence of preliminary breakdown process with longer duration before the return stroke of negative CG lightning discharges.

  17. Effect of cloud-to-ground lightning and meteorological conditions on surface NOx and O3 in Hong Kong (United States)

    Fei, Leilei; Chan, L. Y.; Bi, Xinhui; Guo, Hai; Liu, Yonglin; Lin, Qinhao; Wang, Xinming; Peng, Ping'an; Sheng, Guoying


    Cloud-to-ground (CG) lightning, meteorological conditions and corresponding surface nitrogen oxides (NOx) and ozone (O3) variations in relation to thunderstorm and lightning activities over Hong Kong at Kwai Chung (urban), Tung Chung (new town) and Tap Mun (background) during active lightning seasons from 2009 to 2013 were studied by analyzing respective air quality monitoring station data along with CG lightning and meteorological data. We observed NOx enhancement and significant O3 decline on lightning days. Influences of land use types, lightning activities and meteorological conditions on surface NOx and O3 were examined. NOx and O3 concentrations shifted towards higher and lower levels, respectively, during lightning days especially in the dominant wind directions. Principal component analysis/absolute principal component scores (PCA/APCS) method and stepwise multiple linear regression (MLR) analysis were employed to examine the influence of thunderstorm related lightning and meteorological parameters on surface NOx and O3. Wind speed was supposed to be the most important meteorological parameter affecting the concentration of NOx, and lightning activities were observed to make a positive contribution to NOx. Negative contribution of hot, cloudy and wet weather and positive contribution of wind speed were found to affect the concentration of O3. Lightning parameters were also found to make a small positive contribution to O3 concentration at Tap Mun and Tung Chung, but the net effect of lightning activities and corresponding meteorological conditions was the decrease of O3 on lightning days. Reasonably good agreement between the predicted and observed NOx and O3 values indicates that PCA/APCS-MLR is a valuable method to study the thunderstorm induced NOx and O3 variations.

  18. Forcing factors of cloud-to-ground lightning over Iberia: regional-scale assessments

    Directory of Open Access Journals (Sweden)

    J. A. Santos


    Full Text Available Cloud-to-ground lightning in a sector covering the Iberian Peninsula, the Balearic Islands and nearby seas (36–44° N, 10° W–5° E is analysed in the period from 2003 to 2009 (7 yr. Two Iberian lightning detection networks, composed of 18 sensors over Portugal and Spain, are combined for the first time in the present study. The selected characteristics are cloud-to-ground flashes (CGFs, first stroke peak current, polarity and multiplicity (number of strokes in a given flash. This study examines the temporal (on hourly, monthly and seasonal timescales and spatial variability of CGFs. The influence of five forcing factors on lightning (elevation, lifted index, convective available potential energy and daily minimum and maximum near-surface air temperatures over the Iberian sector is also assessed. For regional-scale assessments, six subsectors with different climatic conditions were analysed separately. Despite important regional differences, the strongest lightning activity occurs from late spring to early autumn, and mostly in the afternoon. Furthermore, CGFs are mainly located over high-elevation areas in late spring to summer, while they tend to occur over the sea in autumn. The results suggest that (1 orographically forced thunderstorms over mountainous areas, mostly from May to September, (2 tropospheric buoyancy forcing over western-central and northern regions in summer and over the Mediterranean regions in autumn, and (3 near-surface thermal contrasts from October to February largely control the location of lightning in Iberia. There is no evidence of different forcings by polarity. A clear correspondence between summertime precipitation patterns and CGFs is also found.

  19. Lightning protection design and testing of an all composite wet wing for the Egrett (United States)

    Burrows, B. J. C.; Haigh, S. J.; Chessum, C.; Dunkley, V. P.


    The Egrett aircraft has an all composite wing comprising CFC(carbon fiber composite)/Nomex sandwich skins, full length CFC main spar caps, and GFRP (glass fiber reinforced plastics) main and auxiliary spar webs. It also has short inboard CFC auxiliary spar caps. It has fine aluminum wires woven into the surface for protection. It has an integral fuel tank using the CFC/Nomex skins as the upper and lower tank walls, and lies between the forward auxiliary spar and the forward of the two main spar webs. The fuel tank is not bagged, i.e., it is in effect a wet wing tank. It has conventional capacitive type fuel gauging. The aircraft was cleared to IFR standards and so required full lightning protection and demonstration that it would survive the lightning environment. The lightning protection was designed for the wing (and also for the remainder of the aircraft). An inner wing test samples (which included a part of the fuel tank) were tested as part of the proving program. The protection design and the testing process are described. The intrinsic structural features are indicated that improve lightning protection design and which therefore minimize the weight and cost of any added lightning protection components.

  20. Research and Application on Lightning Protection Grounding Technology for Large Scale Photovol-taic Power Generation System in Mountainous Areas%山区大型光伏发电系统防雷接地技术探究与应用

    Institute of Scientific and Technical Information of China (English)



    Photovoltaic power generation system is based on a film area of solar panels. In order to avoid the waste of land resources,generally large-scale solar photovoltaic generation stations are built on the hillside far away from the town,where is empty,without high-buildings,in high risk area of lightning.It is especially important to make sure the quality of lightning protection earthing electrodes for the electrical resistivity of mountains soil is very high ,fur-thermore it with largescope of radiation,much electrical equipment in power station.In this article,explored the pho-tovoltaic power generation system on the slope of the high resistance of grounding technology theory method by twen-ty MW ground actual problems in the first phase of the photovoltaic powers station project in Xuanyang village Xieji town Yongqiao district. Make the photovoltaic power grounding system in accordance with the requirements of the drawings design basis.Achieve"adjust measures to local conditions,economic and reasonable". Finally the popular-ization and application of the conclution can be maken.%光伏发电系统需要成片区的太阳能电池板作为基础,为了尽量减小对土地的浪费,大型太阳能光伏发电站往往都建设在偏离城镇的山坡上,环境空旷,周边没有高大建筑物防护,其本身就处于雷击高风险区域,而且山区土壤电阻率较高,辐射范围大,电站内电气设备较多,因而确保防雷接地质量尤为重要.该文通过分析埇桥区谢集乡宣杨村20MW地面光伏电站项目一期工程遇到的实际问题,探究在高阻区的山坡上完成光伏发电系统防雷接地技术的方法,使光伏发电接地系统在符合图纸设计要求的基础上,做到"因地制宜、经济合理"并加以推广运用.

  1. Influence of the Canton Tower on the cloud-to-ground lightning in its vicinity (United States)

    Zhang, Changxiu; Lu, Weitao; Chen, Luwen; Qi, Qi; Ma, Ying; Yao, Wen; Zhang, Yijun


    This paper analyzed the influence of the Canton Tower on cloud-to-ground lightning in its vicinity based on the data obtained by Lightning Location System (LLS) of the Guangdong Power Grid Corporation from 1999 to 2015. The LLS data obtained before (1999-2005) and after (2010-2015) the erection of the Canton Tower were compared. The flash/stroke density showed a significant increase in the immediate vicinity around the Canton Tower within a radius of 1 km and a clear decrease in the annular vicinity with a radius from 1 km to 4 km. The arithmetic mean and median LLS-inferred peak current of strokes that occurred in 1 km radius area around the Canton Tower exhibited a significant increase, while that of the strokes that occurred beyond 1 km did not show a clear change. The percentage of negative flashes (ratio of negative flashes to total flashes) showed a slight increase in the immediate vicinity around the Canton Tower, which could be caused by the upward lightning (often negative) initiated from the tower. Due to the existence of the Canton Tower, the lightning multiplicity presented a decreasing trend to some extent within 4 km radius around the tower compared with the arithmetic mean value within 10 km radius. It is speculated that the Canton Tower induced lots of upward flashes and attracted some downward flashes around it within several kilometers radius to itself.

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

    Directory of Open Access Journals (Sweden)

    Reynaldo Zoro


    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.

  3. 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


    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.

  4. Manual for lightning protection and earthing. Electrical- and facility engineering. 5. tot. new rev. and enl. ed.; Handbuch fuer Blitzschutz und Erdung. Elektro- und Gebaeudetechnik

    Energy Technology Data Exchange (ETDEWEB)

    Hasse, P.; Wiesinger, J.; Zischank, W.


    Recent research and international lightning protection conferences (ICLP) and standardisation committees (IEC) brought about new findings on lightning protection which are considered in this 5th edition. The book outlines the history of lightning research and protection, the development of storm cells and lightning discharges, the incidence of lightning and warning, the electricity characteristics of earthborne lightnings, magnetic lightning fields, the electromagnetic field of the lightning path, the principles and types of lightning protectors, potential equalisation in lightning protection, lightning protection of electric and computer systems, magnetic shields, test methods and generators for lightning protection components and protectors, lightning protection of persons, and legal regulations on lightning protection in Germany. (orig./GL) [German] Aus aktuellen Forschungsergebnissen haben sich ebenso wie aus den internationalen Blitzschutzkonferenzen (ICLP) und Normungsgremien (IEC) neue, weiterfuehrende Aspekte der Blitzschutztechnik ergeben, die in der 5. Auflage dieses Buch ihren Niederschlag gefunden haben. Es befasst sich eingehend mit der Historie der Blitzforschung und des Blitzschutzes, der Entstehung von Gewitterzellen und Blitzentladungen, der Blitzhaufigkeit und Gewitterwarnung, den Stromkennwerten von Erdblitzen, den magnetischen Blitzfeldern, dem elektromagnetischen Feld des Blitzkanals, den Prinzipien des Blitzschutzes, den Fangeinrichtungen, Ableitungen und Erdungen, dem Blitzschutz-Potentialausgleich, dem Blitzschutz elektrischer und informationstechnischer Anlagen, den magnetischen Schirmen, den Pruefverfahren und -generatoren fuer Blitzschutz-Komponenten und -Schutzgeraete, dem Blitzschutz fuer Personen, den Blitzschutzbestimmungen in der Bundesrepublik Deutschland. (orig./GL)

  5. Grounding, Bonding, Shielding, and Lightning Bibliography 1972 to 1979 (United States)


    frequency are given. -58- - - I. Marongiu, " Metodo di Calcolo Semplificato della Resistenza di Terra di un Sistema di Dispersori Moiteplici Parallelo...grounding problems presented by swimming pools , antenna masts and aircraft stands are included. J. Brettle and M. W. Baskerville, "Electrical Bonding

  6. A study of the relationship between cloud-to-ground lightning and precipitation in the convective weather system in China

    Directory of Open Access Journals (Sweden)

    Y. Zhou

    Full Text Available In this paper, the correlation between cloud-to-ground (CG lightning and precipitation has been studied by making use of the data from weather radar, meteorological soundings, and a lightning location system that includes three direction finders about 40 km apart from each other in the Pingliang area of east Gansu province in P. R. China. We have studied the convective systems that developed during two cold front processes passing over the observation area, and found that the CG lightning can be an important factor in the precipitation estimation. The regression equation between the average precipitation intensity (R and the number of CG lightning flashes (L in the main precipitation period is R = 1.69 ln (L - 0.27, and the correlation coefficient r is 0.86. The CG lightning flash rate can be used as an indicator of the formation and development of the convective weather system. Another more exhaustive precipitation estimation method has been developed by analyzing the temporal and spatial distributions of the precipitation relative to the location of the CG lightning flashes. Precipitation calculated from the CG lightning flashes is very useful, especially in regions with inadequate radar cover.

    Key words. Meteorology and atmospheric dynamics (atmospheric electricity; lightning; precipitation

  7. Protecting electronic equipment in composite structures against lightning

    NARCIS (Netherlands)

    Blaj, Mihai Alexandru


    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

  8. Lightning protection of ships in maritime and costal environment

    NARCIS (Netherlands)

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


    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

  9. Lightning flash detection in Venus and Jupiter with spacecraft and ground-based telescope (United States)

    Takahashi, Yukihiro; Watanabe, Shigeto; Yamashita, Kozo; Sato, Mitsuteru


    In these decades lightning process was found to be an excellent tool to explore the Earth's atmosphere based on the knowledge of the relationship between the atmospheric dynamics and electrical charge. This relationship may be applicable to the atmospheric exploration in other planets, too. Even though extensive investigations using data obtained with spacecraft and ground-based telescopes have been carried out, we don't reach consensus on the existence of lightning in Venus. Indeed there exist some strong indications of electrical discharge both in optical and radio wave measurements. But these "evidences" are sometimes not accepted in the majority of researcher community. An infrared sensor, VIRTIS of Venus Express, doesn't find the positive indication of lightning flash at this moment. LAC on board Akatsuki is the first sensor designed for the lightning detection in Venus so that it can identify the optical flash 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. Unique performance of LAC compared to other equipments is the high-speed sampling rate at 32 us interval for all 32 pixels of APD matrix, enabling us to distinguish the optical lightning flash from other pulsing noises. We selected OI 777 nm line, the most expected emissions in CO2 atmosphere based on the laboratory experiment. Though, unfortunately, the first attempt of the insertion of Akatsuki into the orbit around Venus was failure in December 2010, the second one carried out in December 7 in 2015 was quite successful. We checked out the sound condition of high voltage system of LAC on January 20, 2016 for the first time after the launch. 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 after April 2016. Here we would report the preliminary observational results of LAC. Also we are also considering the

  10. Cloud-to-ground lightning over Mexico and adjacent oceanic regions: a preliminary climatology using the WWLLN dataset (United States)

    Kucieńska, B.; Raga, G. B.; Rodríguez, O.


    This work constitutes the first climatological study of lightning over Mexico and adjacent oceanic areas for the period 2005-2009. Spatial and temporal distributions of cloud to ground lightning are presented and the processes that contribute to the lightning variability are analysed. The data are retrieved from the World Wide Lightning Location Network (WWLLN) dataset. The current WWLL network includes 40 stations which cover much of the globe and detect very low frequency radiation ("spherics") associated with lightning. The spatial distribution of the average yearly lightning over the continental region of Mexico shows the influence of orographic forcing in producing convective clouds with high lightning activity. However, a very high number of strikes is also observed in the States of Tabasco and Campeche, which are low-lying areas. This maximum is related to the climatological maximum of precipitation for the country and it may be associated with a region of persistent low-level convergence and convection in the southern portion of the Gulf of Mexico. The maps of correlation between rainfall and lightning provide insight into the microphysical processes occurring within the clouds. The maritime clouds close to the coastline exhibit similar properties to continental clouds as they produce very high lightning activity. The seasonal cycle of lightning registered by WWLLN is consistent with the LIS/OTD dataset for the selected regions. In terms of the annual distribution of cloud-to-ground strikes, July, August and September exhibit the highest number of strikes over continental Mexico. The diurnal cycle indicates that the maximum number of strikes over the continent is observed between 6 and 9 p.m. LT. The surrounding oceanic regions were subdivided into four distinct sectors: Gulf of Mexico, Caribbean, Sub-tropical Pacific and Tropical Pacific. The Gulf of Mexico has the broadest seasonal distribution, since during winter lightning associated with mid

  11. Studying the Formation Mechanism of New Ground Strike Points in Natural Negative Cloud-to-Ground Lightning (United States)

    Campos, L. Z. D. S.; Cummins, K. L.; Pinto, O., Jr.


    Data from three-dimensional VHF mapping, high-speed video and slow electric field antenna of multiple ground contact flashes (MGCFs) have been analyzed in an attempt to characterize the process through which new ground terminations in natural lightning are formed. The three-dimensional VHF mapping data (obtained by a Lightning Mapping Array, LMA) provided valuable information on the processes that occurred inside the cloud during the interval between strokes. Detailed case studies of over 30 MGCFs observed in the vicinity of a wind farm in Kansas, USA, have allowed the identification and qualitative description of three mechanisms through which a given flash may touch ground at different locations. In events of Type I, the dart leader that initiates the subsequent stroke starts in the original channel and then diverges from the original path of the first stroke, ionizing a new channel and reaching ground at a different location. In high-speed video records, these events eventually have their "diverging" point visible below cloud base and their strike locations are separated by a few hundreds of meters. Type II, on the other hand, comprises flashes in which the subsequent stroke is initiated in an in-cloud branch that is farther from the inception region of the first return stroke, moving in another direction and touching ground at farther distances (up to more than 10 km from the initial strike location). Finally, Type III flashes typically gave rise to several return strokes, each with different ground strike points. Stepped leaders initiated in the same general region in the cloud give rise to these strokes with typical interstroke intervals below 100 milliseconds but no common channel branches among them could be conclusively identified. Representative events of each type are discussed in detail.

  12. Lightning protection for roof-mounted solar cell using two masts

    Directory of Open Access Journals (Sweden)

    N. Petcharaks


    Full Text Available Houses invested in roof-mounted solar cell need protection from direct lightning. This paper presents the application of numerical method in designing the height and location of masts based on protection angle method according to international standard IEC 62305. An isolated external lightning protection system using two isolated masts is designed. The protected zone which is in the volume according to the protection angle method, depends on the protection level, the rolling sphere radius and the height of the masts which must be less than the rolling sphere radius defined in IEC standard. Furthermore, separation distance between the protected house and mast depends on the height of the mast. This paper develops a program using heuristic numerical method to design masts to protect a house with roof-mounted solar cell. Input data such as the house dimensions and the lightning protection class should be provided. This program is tested on houses with different dimensions. The height and location of two masts are obtained. The numerical results show that this program can be used effectively and correctly.

  13. 30 CFR 57.12069 - Lightning protection for telephone wires and ungrounded conductors. (United States)


    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Lightning protection for telephone wires and ungrounded conductors. 57.12069 Section 57.12069 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION... ungrounded conductors. Each ungrounded conductor or telephone wire that leads underground and is...

  14. 30 CFR 56.12069 - Lightning protection for telephone wires and ungrounded conductors. (United States)


    ... ungrounded conductors. 56.12069 Section 56.12069 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION... NONMETAL MINES Electricity § 56.12069 Lightning protection for telephone wires and ungrounded conductors. Each ungrounded power conductor or telephone wire that leads underground and is directly exposed...

  15. 76 FR 33129 - Airworthiness Standards; Electrical and Electronic System Lightning Protection (United States)


    ...). Under that section, the FAA is charged with prescribing regulations to promote safe flight of civil... History Existing regulations for the lightning protection of electrical and electronic systems installed...-by- case evaluation based on engineering and flight crew assessment of the specific function and...

  16. 75 FR 16676 - Airworthiness Standards; Electrical and Electronic System Lightning Protection (United States)


    ... concepts, terminology, and practices. Parts 23, 27 and 29 regulations for lightning protection are less... Transportation Order DOT 2100.5 prescribes policies and procedures for simplification, analysis, and review of... recommendations of the ARAC are available at the following Web address:

  17. Evaluation of the protection of rural lines transformers against lightning discharges

    Energy Technology Data Exchange (ETDEWEB)

    Mello, Darcy Ramalho de; Oliveira, Ana Angelica da Silva; Medeiros, Carmem Polycarpo; Rodrigues, Jose Antonio P. [Centro de Pesquisas de Energia Eletrica (CEPEL), Nova Iguacu, RJ (Brazil)], Emails:,,,


    This article describe the tests made in order to evaluate the efficacy and the limitations of several methods used to protect 15 kV and 34.5 kV rural lines transformers against lightning discharges. The results obtained showed that the equipment used in the H V side of the transformers offer a good protection against lightning but, high values of the reflected voltage at the secondary side of the transformers were measured and the use of low voltage arresters, from several manufacturers, do not present a good result for the consumer. Due to the results obtained with the protections, an evaluation of the response frequency curve of the transformer was made. The results showed that is necessary to develop a new project for the transformers or a new protection for the low voltage side of the actual transformers to protect the consumer. (author)

  18. Lightning Phenomenology (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.

  19. Studying energy evolution in the discharge chamber of a multichamber lightning protection system (United States)

    Pinchuk, M. E.; Budin, A. V.; Kumkova, I. I.; Chusov, A. N.


    We present experimental data on the distribution of energy deposition along the discharge chamber of a multichamber lightning protection system at the initial stage of a discharge process modeling a lightning current pulse with 10 kA amplitude. The multichamber system comprised serially connected gas-discharge chambers. The breakdown between electrodes situated on the bottom of a channel in each chamber induces the formation of a shock wave. Subsequent energy evolution during the development of discharge proceeds in the entire volume bounded by the shock wave.

  20. Lightning Science: Five Ways Lightning Strikes People (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 ...

  1. Interception efficiency of CVM-based lightning protection systems for buildings and the fractional Poisson model

    CERN Document Server

    Haller, Harold S


    The purpose of this paper is to resolve a question regarding efficiency of a lightning protection system (LPS) for buildings based on the collection volume method (CVM) . The paper has two components. The first, following suggestions of other authors [Abidin and Ibrahim 2004], takes advantage of count data from installed devices, and independent installation-site inspections to develop our statistical analysis. The second component investigates the validity of the underlying theory by introducing a novel methodology of fractional Poisson processes, which are able to reproduce the burstiness of lightning strikes, an essential feature of stochastic time dependence of incidence of lightning strikes. The standard Poisson processes used in the past efforts in this area cannot do that.

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

  3. Concept of a Conducting Composite Material for Lightning Strike Protection

    Directory of Open Access Journals (Sweden)

    Katunin A.


    Full Text Available The paper focuses on development of a multifunctional material which allows conducting of electrical current and simultaneously holds mechanical properties of a polymeric composite. Such material could be applied for exterior fuselage elements of an aircraft in order to minimize damage occurring during lightning strikes. The concept introduced in this paper is presented from the points of view of various scientific disciplines including materials science, chemistry, structural physics and mechanical engineering with a discussion on results achieved to-date and further plans of research.

  4. Protection against lightning and surges in photovoltaic installations; Protecao contra descargas atmosfericas e surtos em instalacoes fotovoltaicas

    Energy Technology Data Exchange (ETDEWEB)

    Schultz, Brigitte [Siemens AG (Germany); Wettingfeld, Juergen [W. Wettingfeld GmbH (Germany)


    Besides damaging in the photovoltaic panels, lightning can also involve electronic equipment through cables that penetrate in buildings. A supplement for photovoltaic systems located on the roof of buildings was published by the German standardization committees in order to integrate them into lightning protection. In this paper, it is analyzed the requirements of the standards and application case studies.

  5. Research on Protection against Lightning for Roof Fixture%屋顶固定物防雷击研究

    Institute of Scientific and Technical Information of China (English)



    I n th is paper, the incorrect design of connecting roof fixture to lightning protection device without considering any lightning protection premise is analyzed and corrected; the standard IEC 62305 - 3:2010 Edition 2. 0 Protection against Lightning -Part 3:Physical Damage to Structures and Life Hazard has been studied so as to understand whether or not the roof fixture needs to be protected against lightning or connected to lightning protection device, as well as the basis part terms of GB 50057-2010 Code for Design Protection of Structures against Lightning.%针对屋顶固定物不考虑任何防雷击前提而与防雷装置相连的错误设计进行剖析和纠正,研读 IEC 62305-3:2010 Edition 2.0《Protection against Lightning -Part 3: Physical Damage to Struc-tures and Life Hazard》标准,理解屋顶固定物要不要防雷击、要不要与防雷装置连接及其原因,以及GB 50057-2010《建筑物防雷设计规范》部分条款的依据所在。

  6. Demonstration project of rural lightning protection%浅淡农村防雷示范工程工作

    Institute of Scientific and Technical Information of China (English)

    韦翔; 姚志东; 王春丽


    Demonstra and lightning safety lightning protection lightning shelter for tion project of rual lightning protection includes:installation of electroni warning signs to transfer meteorological information, lightning approac knowledge; installation of lightning protection tower villager; improvement of lightning protection facilities as village committee, houses and factories efficiency antenna, of lightning school, farm produce market; installation of lightnin easily attacked protection line and solar water heater by lightning; installation E; taking lightning protec c display hing and and gloriette to provide of public buildings, such g protection facilities for SPD for great value of interception tion measures on TV antenna, satellite%农村(示范村)防雷工程主要包括:安装电子显示屏和防雷击安全警示牌,为村民传递气象信息、预警雷电临近、宣传防雷知识;安装避雷铁塔、避雷亭,为村民提供避雷场所;完善村委会、学校、农贸市场等公共建筑物的防雷设施;雷电灾害风险值大的民房、厂房的防雷装置安装;对防雷装置拦截效率E值大的线路安装SPD;对电视天线、卫星天线、太阳能热水器采取防雷措施等。

  7. Lightning current test of power ground wires with optical fibres (OPGW); Blitzstromfestigkeitspruefung von Erdseilen mit integrierten Lichtwellenleitern

    Energy Technology Data Exchange (ETDEWEB)

    Boehme, M. [VEW EuroTest GmbH, Dortmund (Germany); Moeller, K. [Technische Hochschule Aachen (Germany). Inst. fuer Allgemeine Elektrotechnik und Hochspannungstechnik; Nolden, W. [Felten und Guilleaume Energietechnik AG, Koeln (Germany)


    The area-wide application of ground wires with integrated optical fibers establishes a basis to use the existing overhead lines in addition to power supply also as communication networks. Taking in account the particular lightning stroke endangering of overhead lines a basic study of the thermal stress and damage progression of this ground wire type during a lightning stroke is necessary. (orig.) [Deutsch] Der Einsatz von Erdseilen mit integrierten Lichtwellenleitern schafft die Voraussetzung, bestehende Freileitungstrassen nicht nur zur Energieversorgung zu nutzen, sondern auch als Kommunikationsnetze zu betreiben. Unter Beruecksichtigung der besonderen Blitzeinschlagsgefaehrdung von Freileitungstrassen ist eine grundlegende Untersuchung der thermischen Beanspruchung und der Schadensentwicklung dieses Erdseiltyps waehrend eines Blitzeinschlags notwendig. (orig.)

  8. Hydro-Quebec TransEnergie's perspective on overhead transmission line protection against lightning

    Energy Technology Data Exchange (ETDEWEB)

    Dutil, A. [Hydro-Quebec, Montreal, PQ (Canada). TransEnergie Div.


    Hydro-Quebec TransEnergie's interest in transmission line surge arresters (TLSA) was discussed. The utility conducted studies regarding the use of TLSAs to reduce outages caused by lightning in overhead transmission lines having voltages of 52 to 330 kV. It was determined that in some cases, TLSA is the only solution to reducing flashover initiated by lightning. This paper presented the results of 4 different TLSA configurations in which the impact of grounding resistance on TLSA performance was examined in an effort to determine the most effective configuration. The study revealed that lightning flashovers could be reduced by 70 per cent by installing 1 TLSA on every 2 poles of a 52 kV transmission line. The TLSA should be mounted on one pole structure and the earth wire on the unprotected poles should be removed. According to several tests conducted at Hydro-Quebec's Institut de Recherche en Electricite du Quebec (IREQ), the energy absorption capability of arresters from 4 different manufacturers proved to be at least 6 kJ/kv. The arresters failure rate was estimated to 3 per cent every time a lightning strike occurred on a transmission line. It was suggested that a 100 km long line with one pole every 60 meters should not have more than one arrester failure per year. The arresters must be installed with a mechanical device that could disconnect a failed unit from the transmission system to avoid a permanent fault on the network. It was concluded that TLSAs are useful in reducing lightning flashovers caused by lightning. However, Hydro-Quebec TransEnergie still has concerns regarding their cost, reliability, impact on line maintenance, testing difficulties in the field, mechanical stress on the conductors, and their ability to withstand dielectric behaviour under ice. tabs., figs.

  9. Statistical analysis of lightning electric field measured under Malaysian condition (United States)

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


    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.

  10. Lightning protection design for hydrological automatic measurement system of for middle and small rivers%中小河流水文自动测报系统防雷工程设计

    Institute of Scientific and Technical Information of China (English)



    In the consideration of environmental factors and lightning activity in the surrounding area of the central station of hydrological automatic measurement system for middle and small rivers in Wenshan Prefecture of Yunnan Province, the approach of artificial-triggered lightning for the system is systematically analyzed, and based on the principles of safety, economy, practi-cability and compliance with national standards, the feasible lightning protection schemes of external and internal structures are put forward. The external lightning protection is mainly realized by lightning rod (belt, network), down lead, grounding grid while the inner lightning protection is mainly realized by electromagnetic shielding, equipotential connection, lightning arrester ( SPD) . In addition, a common grounding body scheme shared with lightning protection body, work exchange ground body, static electricity ground, shielding ground, insulating ground is put forward, which not only safeguard the safety of lightning protection device, but also save the investment.%结合云南省文山州中小河流水文监测系统中心站周围的环境因素、雷电活动规律等,系统分析了水文自动测报系统的引雷途径,本着安全、经济、实用的原则,在遵循国家有关防雷标准的基础上,提出了切实可行的建筑物外部防雷和内部防雷设计方案。水文自动测报系统外部防雷设计侧重考虑避雷针(带、网)、引下线、接地网等方面,内部防雷设计则主要考虑电磁屏蔽、等电位连接、避雷器(SPD)3部分。并且,参考IEC国际电工委员会的有关防雷技术标准,提出了水文自动测报系统设备防雷地、工作交流地(N线)、静电地、屏蔽地、绝缘地等共用一个接地体的方案,既保证了防雷设备的安全性,又节约了工程投资。

  11. Relativistic-microwave theory of ball lightning (United States)

    Wu, H.-C.


    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.

  12. Relativistic-microwave theory of ball lightning. (United States)

    Wu, H-C


    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.

  13. How to verify lightning protection efficiency for electrical systems? Testing procedures and practical applications

    Energy Technology Data Exchange (ETDEWEB)

    Birkl, Josef; Zahlmann, Peter [DEHN and SOEHNE, Neumarkt (Germany)], Emails:,


    There are increasing numbers of applications, installing Surge Protective Devices (SPDs), through which partial lightning currents flow, and highly sensitive, electronic devices to be protected closely next to each other due to the design of electric distribution systems and switchgear installations which is getting more and more compact. In these cases, the protective function of the SPDs has to be co-ordinated with the individual immunity of the equipment against energetic, conductive impulse voltages and impulse currents. In order to verify the immunity against partial lightning currents of the complete system laboratory tests on a system level are a suitable approach. The proposed test schemes for complete systems have been successfully performed on various applications. Examples will be presented. (author)

  14. A Case Study of Cloud-to-Ground Lightning Activities in Hailstorms under Cold Eddy Synoptic Situation

    Institute of Scientific and Technical Information of China (English)

    FENG Guili; QIE Xiushu; YUAN Tie; ZHOU Yunjun


    There were three hailstorms in Shandong Province, caused by a same northeast cold eddy situation on 1 June 2002. Cloud-to-ground (CG) flashes occurring in the weather event were observed by Shandong Lightning Detection Network (SLDN), which consists of 10 sensors covering all over Shandong Province. The temporal and spatial distributions of CG lightning are nvestigated for the three hailstorms by using the data from SLDN, Doppler radar and satellite. The results show that different thunderstorms present different lightning features even if under the same synoptic situation. The percentage of positive CG lightning is very high during the period of hail falling. CG flashes mainly occurred in the region with a cloud top brightness temperature lower than -50℃. Negative CG flashes usually clustered in the lower temperature region and tended to occur in the region with maximum temperature gradient, while the positive ones usually spread discretely. Negative CG flashes usually occurred in intense echo regions with reflectivity greater than 50dBz, while the positive CG flashes often occurred in weak and stable echo regions (10-30 dBz) or cloud anvils, although they can be observed in strong convective regions sometimes. Almost all hail falling took place in the stage with active positive flashes, and the peak positive flash rate is a little prior to the hail events. The thunderstorm could lead to disastrous weather when positive CG lightning activities occur in cluster. Severe thunderstorms sometimes present a low flash rate at its vigorous stage, which is probably caused by the "mechanism of chargeregion lift" through investigating the reflectivity evolution. Combined with the total lightning (intracloud and CG) data obtained by LIS onboard TRMM, the phenomenon of high ratio of intracloud flash to CG flash in severe hailstorm has been discussed. The competition of the same charge sources between different lightning types can also be helpful for explaining the cause of

  15. Lightning attachment process to common buildings (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.


    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

  16. Characteristics of cloud-to-ground lightning activity over Seoul, South Korea in relation to an urban effect

    Directory of Open Access Journals (Sweden)

    S. K. Kar


    Full Text Available Cloud-to-ground (CG lightning flash data collected by the lightning detection network installed at the Korean Meteorological Administration (KMA have been used to study the urban effect on lightning activity over and around Seoul, the largest metropolitan city of South Korea, for the period of 1989–1999. Negative and positive flash density and the percentage of positive flashes have been calculated. Calculation reveals that an enhancement of approximately 60% and 42% are observed, respectively, for negative and positive flash density over and downwind of the city. The percentage decrease of positive flashes occurs over and downwind of Seoul and the amount of decrease is nearly 20% compared to upwind values. The results are in good agreement with those obtained by Steiger et al. (2002 and Westcott (1995. CG lightning activities have also been considered in relation to annual averages of PM10 (particulate matter with an aerodynamic diameter smaller than 10 μm and sulphur dioxide (SO2 concentrations. Interesting results are found, indicating that the higher concentration of SO2 contributes to the enhancement of CG lightning flashes. On the other hand, the contribution from PM10 concentration has not appeared in this study to be as significant as SO2 in the enhancement of CG lightning flashes. Correlation coefficients of 0.33 and 0.64 are found between the change in CG lightning flashes and the PM10 and SO2, respectively, for upwind to downwind areas, suggesting a significant influence of the increased concentration of SO2 on the enhancement of CG flashes.

  17. Studying Convective Events Over Southern Arizona by Using Ground GPS Receivers and Cloud to Ground Lightning (United States)

    Orduño, A. M.; Sosa, C. M.; Jacobo, R. A.


    Over the last decades, Global Position System (GPS) satellites have been used for in various fields of the Earth Sciences. In particular, "GPS Meteorology" was born in the attempt to retrieve water vapor, specifically column-integrated water vapor or, precipitable water vapor (PWV), that results from the noise induced by the atmosphere in the GPS signal. Monitoring PWV with GPS is relatively inexpensive, works under all weather conditions, and has a high time resolution which complements traditional techniques such as radiosondes and satellite-based retrievals. The North American Monsoon (NAM) is a seasonal system that affects the southwestern of United States and northwestern Mexico. Atmospheric Water Vapor is transported from the Gulf of California, Pacific Ocean and the Gulf of Mexico to the continental areas and this contribute to the genesis of convective systems that develop over this region. In many cases, these systems are characterized by relatively short lifetimes, a great amount of precipitation accompanied with lightning making it difficult to study with radiosondes, given their limited time resolution (operationally twice a day). On the other hand, GOES satellite has better time resolution (one hour), but does not provide water vapor in cloudy conditions, precisely when the data are needed. This makes GPS a great tool to study deep atmospheric convection over during the NAM. During the monsoon season 2002 and 2003, we noted that local GPS and the radiosondes launched in Tucson, Arizona showed, for some cases, a significant discrepancy in their PWV estimation. In determining the causes of these discrepancies we discovered that the GPS was detecting convective events in its vicinity that the radiosondes could not detect, a strength that had not considered before. Convective activity in Southern Arizona often produces gust fronts that result in dramatic changes of temperature and humidity. These gust fronts also generate a shift in wind direction and

  18. The Distribution of Cloud to Ground Lightning Strike Intensities and Associated Magnetic Inductance Fields Near the Kennedy Space Center (United States)

    Burns, Lee; Decker, Ryan


    Lightning strike location and peak current are monitored operationally in the Kennedy Space Center (KSC) Cape Canaveral Air Force Station (CCAFS) area by the Cloud to Ground Lightning Surveillance System (CGLSS). The present study compiles ten years worth of CGLSS data into a database of near strikes. Using shuffle launch platform LP39A as a convenient central point, all strikes recorded within a 20-mile radius for the period of record O R ) from January 1, 1993 to December 31,2002 were included in the subset database. Histograms and cumulative probability curves are produced for both strike intensity (peak current, in kA) and the corresponding magnetic inductance fields (in A/m). Results for the full POR have application to launch operations lightning monitoring and post-strike test procedures.

  19. Lightning protection of mobile phone stations in high voltage towers; Blitzschutz bei Mobilfunkstationen auf Mittel- und Hochspannungsmasten. Schutz vor Ueberspannungen

    Energy Technology Data Exchange (ETDEWEB)

    Balzer, G. [TU Darmstadt (Germany); Richter, B. [ABB Hochpannungstechnik, Baden (Switzerland); Schmitt, O. [RWE Net AG, Siegen (Germany)


    Transmitter units for mobile phone networks are often installed in existing high voltage towers. In these cases a strict separation of the grounding systems is essential to avoid interferences between the high voltage area and the low voltage energy supply for the mobile phone transmitter station. In order to protect the safety transformer of the mobile phone installation against lightning surges a metall-oxide (MO-) surge arrester is necessary, which furthermore has to withstand the power frequency voltage in case of a single-phase fault in the high voltage power line. For a 110 kV system the power frequency voltage in case of a single-phase short circuit as well as the lightning current stress for a MO-surge arrester is calculated. (orig.) [German] Der weltweit zunehmende Ausbau der Mobilfunknetze erfordert eine grosse Anzahl von Standorten fuer Sende- und Empfangsanlagen. Dabei werden neben neuen Mobilfunkmasten auch Mittel- und Hochspannungsmaste genutzt. Zum Schutz der in den Mobilfunkanlagen eingesetzten Trenntransformatoren gegen moegliche Blitzeinwirkungen werden Metalloxid-Ueberspannungsableiter (MO-Ableiter) eingesetzt. Die Verfasser erlaeutern die geeignete Dimensionierung anhand praktischer Anwendungsbeispiele. (orig.)

  20. Cloud-to-ground lightning over Mexico and adjacent oceanic regions. A preliminary climatology using the WWLLN dataset

    Energy Technology Data Exchange (ETDEWEB)

    Kucienska, B.; Raga, G.B. [Universidad Nacional Autonoma de Mexico (Mexico). Centro de Ciencias de la Atmosfera; Rodriguez, O. [Instituto Mexicano de Tecnologia del Agua, Morelos (Mexico)


    This work constitutes the first climatological study of lightning over Mexico and adjacent oceanic areas for the period 2005-2009. Spatial and temporal distributions of cloud to ground lightning are presented and the processes that contribute to the lightning variability are analysed. The data are retrieved from theWorldWide Lightning Location Network (WWLLN) dataset. The current WWLL network includes 40 stations which cover much of the globe and detect very low frequency radiation (''spherics'') associated with lightning. The spatial distribution of the average yearly lightning over the continental region of Mexico shows the influence of orographic forcing in producing convective clouds with high lightning activity. However, a very high number of strikes is also observed in the States of Tabasco and Campeche, which are low-lying areas. This maximum is related to the climatological maximum of precipitation for the country and it may be associated with a region of persistent low-level convergence and convection in the southern portion of the Gulf of Mexico. The maps of correlation between rainfall and lightning provide insight into the microphysical processes occurring within the clouds. The maritime clouds close to the coastline exhibit similar properties to continental clouds as they produce very high lightning activity. The seasonal cycle of lightning registered by WWLLN is consistent with the LIS/OTD dataset for the selected regions. In terms of the annual distribution of cloud-to-ground strikes, July, August and September exhibit the highest number of strikes over continental Mexico. The diurnal cycle indicates that the maximum number of strikes over the continent is observed between 6 and 9 p.m. LT. The surrounding oceanic regions were subdivided into four distinct sectors: Gulf of Mexico, Caribbean, Subtropical Pacific and Tropical Pacific. The Gulf of Mexico has the broadest seasonal distribution, since during winter lightning associated

  1. 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


    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.

  2. 机场空管设备雷电防护%Lightning Protection of Airport Electronic Facilities

    Institute of Scientific and Technical Information of China (English)

    黄裕文; 钟秉武


    绵阳南郊机场2004年以来多普勒全向信标/测距仪(DVOR/DME)、仪表着陆系统(ILS)、无向信标机(NDB)、卫星站(TES)、航空气象自动观测系统(AWOS)、甚高频对空电台(VHF)等空管系统设备先后多次发生雷电灾害事故,不同程度地造成了设备故障和工作中断现象,对该机场的飞行保障造成了较为严重的影响.通过对雷灾案例的分析,介绍多级SPD保护,逐级消除雷电残压,同一建筑内设备联合接地和等电位处理,规范综合布线及建立定期维护检测制度,及时排查防雷安全隐患等措施,总结了切实有效解决通信导航设施发生雷电灾害事故的经验和方法.%Since 2004, there occurred lightning accidents many times to airport facilities at Mianyang Airport,such as the Doppler VHF Omnidirectional Radio/Distance Measurement Equipment, Instrument Landing System, No-Directional Beacon, Transportable Earth Stations, Aviation Automated Weather Observing Systems, Very High Frequency radio and so on, which caused equipment failure and work interruptions in different degrees. Through analyzing the lightning cases, some countermeasures are introduced, such as multi-level SPD protection, eliminating lightning residual voltage step by step, integrated grounding and equipotential bonding for all the equipments within the same building, standardizing the generic cabling and establishing the regular maintenance and detection system, checking potential safety hazard timely, etc. Some experiences and effective means to clear up faults in communication and navigation facilities induced by lightning accidents are summarized.

  3. A study of National Lightning Detection Network responses to natural lightning based on ground truth data acquired at LOG with emphasis on cloud discharge activity (United States)

    Zhu, Y.; Rakov, V. A.; Tran, M. D.; Nag, A.


    The U.S. National Lightning Detection Network (NLDN) detection efficiency (DE) and classification accuracy (CA) for cloud discharge (IC) activity (identified here by a sequence of non-return-stroke-type electric field pulses not accompanied by channels to ground) were evaluated using optical and electric field data acquired at the LOG (Lightning Observatory in Gainesville), Florida. Our ground truth "IC events" include 26 "isolated IC events" (complete IC flashes), 58 "IC events before first return stroke," and 69 "IC events after first return stroke." For the total of 153 IC events, 33% were detected by the NLDN, and the classification accuracy was 86%. For complete IC flashes, the detection efficiency and classification accuracy were 73% and 95%, respectively, and the average number of NLDN-reported cloud pulses was 2.9 per detected event. For 24 preliminary breakdown pulse trains in CG flashes, the detection efficiency and classification accuracy were 46% and 82%, respectively. We have additionally estimated the DE and CA for return strokes in CG flashes. Irrespective of stroke order and polarity, the DE was 92% (339/367), and the CA was also 92% (312/339). The DEs for negative first and subsequent strokes were 98% and 90%, respectively.

  4. Ground-based and spacecraft observations of lightning activity on Saturn (United States)

    Zakharenko, V.; Mylostna, C.; Konovalenko, A.; Zarka, P.; Fischer, G.; Grießmeier, J.-M.; Litvinenko, G.; Rucker, H.; Sidorchuk, M.; Ryabov, B.; Vavriv, D.; Ryabov, V.; Cecconi, B.; Coffre, A.; Denis, L.; Fabrice, C.; Pallier, L.; Schneider, J.; Kozhyn, R.; Vinogradov, V.; Mukha, D.; Weber, R.; Shevchenko, V.; Nikolaenko, V.


    In late 2007, Saturn electrostatic discharges (SED) were simultaneously observed at the radio telescope UTR-2 and with the Cassini spacecraft. Observations at UTR-2 were performed with a multichannel receiver in the frequency range 12-33 MHz, and those performed on Cassini-with a swept frequency receiver that is part of the RPWS (Radio and Plasma Wave Science) instrument in the frequency band 1.8-16 MHz. We got a very good coincidence between data of UTR-2 and Cassini. It is shown for the first time that ground-based radio astronomy lets us detect Saturn's lightning with a high degree of reliability despite terrestrial interferences. This is the necessary basis for further detailed study of the temporal and spectral characteristics of the SEDs with ground based radio telescopes. Based on six observation sessions, several parameters of SEDs were determined, in particularly a correlation of 0.77±0.15 between the average intensity of storms and the e-folding time.

  5. Lightning Protection and Structural Bonding for the B2 Test Stand (United States)

    Kinard, Brandon


    With the privatization of the space industry, NASA has entered a new era. To explore deeper parts of the solar system, NASA is developing a new spacecraft, the Space Launch System (SLS), capable of reaching these destinations, such as an asteroid or Mars. However, the test stand that is capable of testing the stage has been unused for many years. In addition to the updating/repair of the stand, more steel is being added to fully support the SLS. With all these modifications, the lightning protection system must be brought up to code to assure the protection of all personnel and assets. Structural bonding is a part of the lightning protection system. The focus of this project was to assure proper structural bonding. To begin, all relevant technical standards and the construction specifications were reviewed. This included both the specifications for the lightning protection and for general construction. The drawings were reviewed as well. From the drawings, bolted structural joints were reviewed to determine whether bonding was necessary. Several bolted joints were determined to need bonding according to the notes in the drawings. This exceeds the industry standards. The bolted joints are an electrically continuous joint. During tests, the stand experiences heavy vibration that may weaken the continuity of the bolted joint. Therefore, the secondary bonding is implemented to ensure that the structural joint has low resistance. If the structural joint has a high resistance because of corrosion, a potential gradient can occur that can cause a side flash. Damage, injury, or death can occur from a side flash so they are to be prevented. A list of the identified structural joints was compiled and sent to the contractor to be bonded. That covers the scope of this project.

  6. Corona discharges from a windmill and its lightning protection tower in winter thunderstorms (United States)

    Wu, Ting; Wang, Daohong; Rison, William; Thomas, Ronald J.; Edens, Harald E.; Takagi, Nobuyuki; Krehbiel, Paul R.


    This paper presents lightning mapping array (LMA) observations of corona discharges from a windmill and its lightning protection tower in winter thunderstorms in Japan. Corona discharges from the windmill, called windmill coronas, and those from the tower, called tower coronas, are distinctly different. Windmill coronas occur with periodic bursts, generally radiate larger power, and possibly develop to higher altitudes than tower coronas do. A strong negative electric field is necessary for the frequent production of tower coronas but is not apparently related with windmill coronas. These differences are due to the periodic rotation of the windmill and the moving blades which can escape space charges produced by corona discharges and sustain a large local electric field. The production period of windmill coronas is related with the rotation period of the windmill. Surprisingly, for one rotation of the windmill, only two out of the three blades produce detectable discharges and source powers of discharges from these two blades are different. The reason for this phenomenon is still unclear. For tower coronas, the source rate can get very high only when there is a strong negative electric field, and the source power can get very high only when the source rate is very low. The relationship between corona discharges and lightning flashes is investigated. There is no direct evidence that corona discharges can increase the chance of upward leader initiation, but nearby lightning flashes can increase the source rate of corona discharges right after the flashes. The peak of the source height distribution of corona discharges is about 100 m higher than the top of the windmill and the top of the tower. Possible reasons for this result are discussed.

  7. Hanford site ground water protection management plan

    Energy Technology Data Exchange (ETDEWEB)


    Ground water protection at the Hanford Site consists of preventative and remedial measures that are implemented in compliance with a variety of environmental regulations at local, state, and federal levels. These measures seek to ensure that the resource can sustain a broad range of beneficial uses. To effectively coordinate and ensure compliance with applicable regulations, the U.S. Department of Energy has issued DOE Order 5400.1 (DOE 1988a). This order requires all U.S. Department of Energy facilities to prepare separate ground water protection program descriptions and plans. This document describes the Ground Water Protection Management Plan (GPMP) for the Hanford Site located in the state of Washington. DOE Order 5400.1 specifies that the GPMP covers the following general topical areas: (1) documentation of the ground water regime; (2) design and implementation of a ground water monitoring program to support resource management and comply with applicable laws and regulations; (3) a management program for ground water protection and remediation; (4) a summary and identification of areas that may be contaminated with hazardous waste; (5) strategies for controlling hazardous waste sources; (6) a remedial action program; and (7) decontamination, decommissioning, and related remedial action requirements. Many of the above elements are currently covered by existing programs at the Hanford Site; thus, one of the primary purposes of this document is to provide a framework for coordination of existing ground water protection activities. The GPMP provides the ground water protection policy and strategies for ground water protection/management at the Hanford Site, as well as an implementation plan to improve coordination of site ground water activities.

  8. Lightning Protection Design of Ammunition Warehouse%某弹药库房防雷设计方案

    Institute of Scientific and Technical Information of China (English)

    张宝华; 刘振宇; 严凤斌; 林义


    Direct lightning stroke, lightning, lightning invasion wave, electrostatic and other protective measures were designed scientifically through field investigation and reasonable terms against high risk for the treasury vulnerable to lightning. The specific implementation plan was developed. The purpose was to provide technical guidance and reference for safety of the warehouse.%针对弹药库房危险性高、易受雷击等特点,笔者通过实地勘测,合理计算,科学地设计了直击雷、感应雷、雷电波侵入、静电等防护措施,并制定了具体的实施方案,对仓库的安全工作有一定的技术指导和借鉴作用.

  9. Reduction of the visual impact of overhead transmission line systems through utilisation of line surge arresters as lightning protection

    DEFF Research Database (Denmark)

    Sørensen, Thomas Kjærsgaard; Holbøll, Joachim


    in line performance and lightning protection of the nearest substations requires thorough modelling of the new line including all electrical parameters necessary for performance evaluation under all conditions. In this paper, explicit use of line surge arresters as lightning protection on the line...... of the line and the required protection level in substations. The use of line surge arresters gives the possibility to decrease the height of towers thereby improving the visual impression of the overhead line transmission systems. However the usage of line surge arresters will, dependent upon line surge...

  10. Geotechnics - the key to ground water protection

    DEFF Research Database (Denmark)

    Baumann, Jens; Foged, Niels; Jørgensen, Peter


    During the past 5 to 10 years research into ground water protection has proved that fractures in clay till may increase the hydraulic conductivity and herby the vulnerability of the ground water considerably. However, research has not identified a non-expensive and efficient method to map...

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

  12. Ground-Water Protection and Monitoring Program

    Energy Technology Data Exchange (ETDEWEB)

    Dresel, P.E.


    This section of the 1994 Hanford Site Environmental Report summarizes the ground-water protection and monitoring program strategy for the Hanford Site in 1994. Two of the key elements of this strategy are to (1) protect the unconfined aquifer from further contamination, and (2) conduct a monitoring program to provide early warning when contamination of ground water does occur. The monitoring program at Hanford is designed to document the distribution and movement of existing ground-water contamination and provides a historical baseline for evaluating current and future risk from exposure to the contamination and for deciding on remedial action options.

  13. Cloud-to-ground lightning flash characteristics from June 1984 through May 1985 (United States)

    Orville, Richard E.; Weisman, Robert A.; Pyle, Richard B.; Henderson, Ronald W.; Orville, Richard E., Jr.


    A magnetic direction-finding network for the detection of lightning cloud-to-ground strikes has been installed along the east coast of the United States. Time, location, flash polarity, stroke count, and peak signal amplitude are recorded in real time. The data were recorded from Maine to North Carolina and as far west as Ohio; analyses were restricted to flashes within 300 km of a direction finder. Measurements of peak signal strength have been obtained from 720,284 first return strokes lowering negative charge. The resulting distribution indicates that few negative strokes have peak currents exceeding 100 kA. Measurements have also been obtained of peak signal strength from 17,694 first return strokes lowering positive charge. These strokes have a median peak current of 45 kA, with some peak currents reaching 300-400 kA. The median peak signal strength and the peak current, double from summer to winter for both negative and positive first return strokes. The polarity of ground flashes is observed to be less than 5 percent positive throughout the summer and early fall, then increases to over 50 percent during the winter, and returns to less than 10 percent in early spring. The percent of positive flashes with one stroke is observed to be approximately 90 percent throughout the year. The percent of negative flashes with one stroke is observed to increase from 40 percent in the summer to approximately 80 percent in January, returning to less than 50 percent in the spring.

  14. Lightning return stroke current radiation in presence of a conducting ground: 1. Theory and numerical evaluation of the electromagnetic fields (United States)

    Delfino, Federico; Procopio, Renato; Rossi, Mansueto


    The general theory describing the electromagnetic field radiated by a lightning stroke over a conducting ground is presented in this paper. The derivation of the Green functions necessary to solve the problem is discussed in detail, and the determination of the expressions for the electromagnetic field components is carried out in a form that minimizes the final computational costs. A method for the numerical evaluation of the electromagnetic field is then proposed, and it is shown that it can be used starting from any "engineering model" representation for the lightning current distribution along the channel. Such method is based on a new efficient evaluation of the so-called Sommerfeld's integrals appearing in the electromagnetic field expressions, without resorting to any kind of approximated formulas for them. The numerical treatment of the Sommerfeld's integrals is characterized by a proper subdivision of the integration domain, the use of the Romberg technique and the determination of a suitable upper bound for the error due to the integral truncation. In the second part of this work it will be shown how the results provided by the developed theory can be used in order to assess the validity of the most common simplified approach for the calculation of the lightning radiation over a lossy ground plane.

  15. TVA's experience with the SUNYA lightning detection network

    Energy Technology Data Exchange (ETDEWEB)

    Whitehead, J.; Driggans, R. (Tennessee Valley Authority, Chattanooga, TN (USA))


    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.

  16. Modeling the spatial differentiation in cloud-to-ground lightning: A case study in Atlanta, Georgia, USA (United States)

    Strikas, Ona

    Urban cloud-to-ground (CG) lightning enhancement has been well documented for Atlanta, Georgia. This study builds on those investigations using modeling techniques. Numerous styles of analyses and regressions were conducted to establish patterns of CG lightning over the North Georgia region. CG lightning demonstrated clustering for all years of data: 1995--2008. However, the first strike of each day with lightning was randomly distributed according to a Poisson distribution, demonstrating the clustering is not due to permanent features. Attempts were unsuccessful to model CG lightning clusters as either a Matern or Thomas Poisson point process. Regressions of CG lightning with built environment covariates---FAA aviation obstacle locations and heights, population density, road length density, distance to the center of Atlanta, PM10 emissions data, distance to highways, and coal plant locations---as well as natural variables such as projected coordinate easting, northing, and NWS severe thunderstorm status were executed at resolutions of 1km, 2km, 4km, and 8km. Analyses demonstrated significantly higher flash frequency near FAA aviation obstacles. With an R2 value of 0.22, taller obstacles are struck more frequently than shorter obstacles. Regressions with road length density revealed little explanatory power (maximum R2=0.19), but demonstrated a positive correlation independent of scale. A multi-level visualization technique demonstrates the road length density correlation loses accuracy within dense urban corridors. Distance from Atlanta shows a negative correlation, but only at larger scales. Subsetting both regressions by direction reveals a significant difference on the Eastern and Western sides of Atlanta. Subsetting both regressions only to Gwinnett County, Georgia illustrates road length density has no correlation with flash frequency, and distance to Atlanta is still a scale dependent process. PM10 emissions analysis suggests that CG amplification is most

  17. 暂态电流和电位抬升对雷电风险参数Pc的影响%Impact of Transient Current and Ground Potential Rising on Pc inLightning Risk Assessment

    Institute of Scientific and Technical Information of China (English)

    杨仲江; 余蜀豫; 程斌


    IEC 62305 proposed by the International Electrotechnical Commission is most commonly used. In IEC 6230S, parameter Pc is defined as follows: the probability of system failure is due to buildings stroking by the lighting. The parameter depends on the protection level of Surge Protective Device (SPD). However, when lightning strokes buildings, the lightning current in steel will produce electromagnetic interference on the internal system. And when the current runs into the earth, there is a high ground potential increase. In this case, SPD will not work well. Therefore, the definition of Pc 's no longer appropriate. Transient calculation models when lightning strokes metal frame of buildings have been proposed. However, no one has applied them to the study of lightning risk assessment. Here, a transient calculation model with Matlab is established to figure out transient current distribution in steels of the buildings when they are stroked by lightning and to calculate the back voltage due to ground potential rise. Under a certain approximate conditions, the effect due to lightning strokes buildings and the current goes into the earth on internal system is analyzed. Using the previous data, a clear physical model is set to show what factors affect the internal system most when lightning strokes buildings or the current goes into the earth. It is able to find that wiring mode and the installation of metal tube are the important parameters having the effect on the value of Pc. Finally, by means of determining the factor that affects the parameter of Pc and improving the parameter value, the value of lightning risk is accurately calculated with this method. The design of lightning protection and the planning of lightning protection are scientifically guided by the method.%雷电防护标准IEC 62305中定义参数Pc为雷击建筑物导致内部系统故障的概率,Pc完全取决于浪涌保护器(Surge Protective Device,SPD)的保护等级.SPD在很多情况下并不

  18. Discussion on the Lightning Protection Construction Technology and Announcements in Building Electrical Installation%关于建筑电气安装中防雷接地施工技术与注意事项的探讨

    Institute of Scientific and Technical Information of China (English)



    现代建筑电气安装中防雷接地施工是比较关键的环节,其施工质量的好坏直接影响着电气安装的安全性。因防雷接地施工是一项系统的工程,在施工过程中要严格把控各个技术环节,做好相关的管理工作与注意事项。%Lightning protection and grounding construction in modern building electrical instal ation is the key link, its cons-truction quality directly affects the safety of electrical instal a-tion. Because of the lightning protection and grounding constr-uction is a systematic project, it needs to strictly control the various links in the construction process, do a good job in the relevant administrations and announcements.

  19. Lightning protection guidelines and test data for adhesively bonded aircraft structures (United States)

    Pryzby, J. E.; Plumer, J. A.


    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.

  20. Production of Ionospheric Perturbations by Cloud-to-Ground Lightning and the Recovery of the Lower Ionosphere (United States)

    Liu, Ningyu; Dwyer, Joseph; Rassoul, Hamid


    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

  1. Initiation and propagation of cloud-to-ground lightning observed with a high-speed video camera (United States)

    Tran, M. D.; Rakov, V. A.


    Complete evolution of a lightning discharge, from its initiation at an altitude of about 4 km to its ground attachment, was optically observed for the first time at the Lightning Observatory in Gainesville, Florida. The discharge developed during the late stage of a cloud flash and was initiated in a decayed branch of the latter. The initial channel section was intermittently illuminated for over 100 ms, until a bidirectionally extending channel (leader) was formed. During the bidirectional leader extension, the negative end exhibited optical and radio-frequency electromagnetic features expected for negative cloud-to-ground strokes developing in virgin air, while the positive end most of the time appeared to be inactive or showed intermittent channel luminosity enhancements. The development of positive end involved an abrupt creation of a 1-km long, relatively straight branch with a streamer corona burst at its far end. This 1-km jump appeared to occur in virgin air at a remarkably high effective speed of the order of 106 m/s. The positive end of the bidirectional leader connected to another bidirectional leader to form a larger bidirectional leader, whose negative end attached to the ground and produced a 36-kA return stroke.

  2. Frequency domain model for transient analysis of lightning protection systems of buildings. (United States)

    Gómez, Pablo


    A frequency domain modeling approach for lightning protection systems (LPS) of buildings is described and validated in this paper. The model is based on a 2-port transmission line representation of each conductor, and the further assembling of a network representing the complete structure. Horizontal and vertical conductors are modeled using formulas based on the complex images method, in order to take into account frequency dependence. Variation of electrical parameters with height is also considered for vertical conductors. This is accomplished by means of a non-uniform modeling approach based on conductor subdivision and cascaded connection of chain matrices computed for each segment. The results from the model are validated by means of comparisons with measurements reported elsewhere, as well as simulations using PSCAD/EMTDC.

  3. 水质自动监测站综合防雷技术研究%Research on Integrated Lightning Protection Technology of Automatic Water Quality Monitoring Station

    Institute of Scientific and Technical Information of China (English)

    樊希彬; 于淼; 梁铁军


    基于建筑物雷击风险评估方法,得出本地可能遭受到的雷击形式和雷电破坏电子设备途径.以鸭绿江丹东江桥水质自动监测站综合防雷系统工程设计与施工为基础,对水质自动监测站外部、内部综合防雷技术体系进行阐述,通过现代防雷技术方法,有效降低监测设备因雷击而产生的故障率、最大限度预防和减少雷击所发生的人身伤亡和国家财产损失.%According to the method of building lightning risk assessment, ways of local lightning and means that lightning damages to electronic devices are obtained. Based on the design and construction of integrated lightning protection system of Yalu River automatic water quality monitoring stations in Dandong, external and internal integrated lightning protection system of automatic water quality monitoring stations is illustrated. Through methods of modern lightning protection technology, the failure rate generated from monitoring equipment stuck by lightning can be effectively reduced, the body injuries, deaths and the loss of state property led by lightning can be maximally prevented and reduced.

  4. Why do oceanic negative cloud-to-ground lightning exhibit larger peak current values? (United States)

    Chronis, T.; Koshak, W.; McCaul, E.


    This study examines the temporal (monthly) and spatial climatology (2004-2010) of the first return stroke of the cloud-to-ground (CG) lightning flash peak current (Ip) across various land/water boundaries over the contiguous United States. Four regions are examined: the Gulf of Mexico (region 1), the Florida peninsula (region 2), Lake Michigan (region 3), and part of the U.S. Mid-Atlantic (region 4). The crosss across the coastlines of regions 1, 2, and 4 show a gradual oceanward increase in the mean negative polarity CG peak current values (-Ip). This transition along the respective land/ocean boundaries is not sharp but gradual. In direct contrast with ocean, there is no consistent behavior in -Ip values as we move from land out across the fresh water of Lake Michigan (region 3). Meanwhile, the positive CG flash peak current (+Ip) values do not exhibit a consistent variation across any coastal boundary. For region 1, the -Ip values increase as we move toward the coast (southwards) especially during the wet season (June-October). This finding is in direct contrast with studies that documented winter as the season of maximum -Ip values. The zonal and seasonal variations of -Ip values across region 4 are not quite as pronounced, but the oceanic -Ip values are still larger than over the adjoining landmass. We explore in turn which up to date hypotheses pertinent to the oceanic -Ip enhancement are supported or refuted by our findings. It is concluded that the oceanic -Ip enhancement is not an artifact related to CG detection or Ip retrieval methods, nor is it likely related to the cloud top heights or CG activity. The study cannot refute the role of electrical conductivity and its contribution to CG leader attachment processes. However, given the observed "blurred transition" of the Ip values across the coastlines this paper suggests that likely the main physical mechanism is acting on the thundercloud potential. The recently suggested role of sodium chloride (Na

  5. 高速铁路避雷器与防雷线技术综合应用研究%Integrated Research on Application of Technology of Lightning Arrester and Lightning Protection Rod in High-speed Railway System

    Institute of Scientific and Technical Information of China (English)



    In China,high-speed railways,in most cases,are to take path through diverse landform,topography where differed geography,climate and operational conditions at varied areas would make lightning protection even tougher for the development of high-speed railways,but what even more challenging is that the technology of lightning arrester and lightning protection rod are still self-deficient.Thus,any separate use of certain lightning protection technology can hardly help to achieve technological promotion of lightning arrestment and lightning protection in high-speed railways, optimally.It is constructively rendered a conformation in this article that at all the sections where high-speed railways are to travel through,lightning arrester and lightning protection rod as a set of comprehensive engineering system can be applied to high-speed railway catenary,which designed to make the entire lines subject to overall protection and control under a system of lightning arrestment and lightning protection and therefore,to form an organic combination and reciprocal advantage between these two mature technologies.As attested by certain researches,at the geographic locations where are allocated with mountainous areas,areas with a varied topography and specially distributed landform, catenary onto high-speed railways is primarily being furnished with lightning arrester meanwhile at the geographic locations where intense lightning/thunderstorm being likely distributed,topography flat and main electrical equipment installed,erection of lightning arrestment rod would be empirical.These two afore said means would have to account for differed topographic areas,intended to form full coverage of lightning arrestment and lightning protection,and thus,to effectively secure safety of high-speed railway lines and facilities.%我国高速铁路线路大多要经过多种地形、地貌,不同区域地理、气候、运行条件的差异增加了高速铁路防范雷击的难度,且避雷

  6. A Ground-Based Campaign in Search of Terrestrial Gamma-ray Flashes Associated with Thunderclouds and Lightning (United States)

    Schaal, M.; Dwyer, J. R.; Saleh, Z. H.; Rassoul, H.; Lazarus, S. M.; Splitt, M. E.; Ulrich, W.; Cramer, E.; Smith, D. M.; Hazelton, B. J.; Grefenstette, B.


    Terrestrial Gamma-ray Flashes (TGFs) are intense bursts of gamma-rays first observed from space using the BATSE instrument onboard the Compton Gamma Ray Observatory. Recent measurements from the RHESSI spacecraft, along with modeling, show that these flashes most likely originate from altitudes between 15 and 21 km, making it difficult to detect such events on the ground due to atmospheric attenuation. However, in 2004, Dwyer et al. reported a gamma-ray burst at ground level during the initial stage of a rocket-triggered lightning that had a similar energy spectrum and time duration to TGFs. These results suggest that the processes that produce TGFs may also occur at lower altitudes within thunderclouds, beamed downwards instead of upwards like TGFs observed from space, making it possible to observe such events on the ground. In 2009, we launched a ground campaign to search for such TGF-like gamma-ray events during thunderstorms in coordination with ADELE (Airborne Detector for Energetic Lightning Emissions) which flew onboard the NSF/NCAR GV and was later used in the ground observation. A flat plate antenna to measure dE/dt along with scintillator/PMT detectors to measure gamma-ray emissions were mounted in a SUV, which was then driven into the active regions of thunderstorms. Radiosonde measurements to study the atmospheric conditions during the campaign were also performed . A high-speed Photron camera was used to capture any optical phenomena that might be observed. In this presentation, we report initial results from the September 2009 campaign.

  7. A review of advances in lightning observations during the past decade in Guangdong, China (United States)

    Zhang, Yijun; Lü, Weitao; Chen, Shaodong; Zheng, Dong; Zhang, Yang; Yan, Xu; Chen, Lüwen; Dong, Wansheng; Dan, Jianru; Pan, Hanbo


    This paper reviews recent advances in understanding the physical processes of artificially triggered lightning and natural lightning as well as the progress in testing lightning protection technologies, based on a series of lightning field campaigns jointly conducted by the Chinese Academy of Meteorological Sciences and Guangdong Meteorological Bureau since 2006. During the decade-long series of lightning field experiments, the technology of rocket-wire artificially triggered lightning has been improved, and has successfully triggered 94 lightning flashes. Through direct lightning current waveform measurements, an average return stroke peak current of 16 kA was obtained. The phenomenon that the downward leader connects to the lateral surface of the upward leader in the attachment process was discovered, and the speed of the upward leader during the connection process being significantly greater than that of the downward leader was revealed. The characteristics of several return strokes in cloud-to-ground lighting have also been unveiled, and the mechanism causing damage to lightning protection devices (i.e., ground potential rise within the rated current) was established. The performance of three lightning monitoring systems in Guangdong Province has also been quantitatively assessed.

  8. Objective Lightning Forecasting at Kennedy Space Center and Cape Canaveral Air Force Station using Cloud-to-Ground Lightning Surveillance System Data (United States)

    Lambert, Winfred; Wheeler, Mark; Roeder, William


    The 45th Weather Squadron (45 WS) at Cape Canaveral Air-Force Station (CCAFS)ln Florida issues a probability of lightning occurrence in their daily 24-hour and weekly planning forecasts. This information is used for general planning of operations at CCAFS and Kennedy Space Center (KSC). These facilities are located in east-central Florida at the east end of a corridor known as 'Lightning Alley', an indication that lightning has a large impact on space-lift operations. Much of the current lightning probability forecast is based on a subjective analysis of model and observational data and an objective forecast tool developed over 30 years ago. The 45 WS requested that a new lightning probability forecast tool based on statistical analysis of more recent historical warm season (May-September) data be developed in order to increase the objectivity of the daily thunderstorm probability forecast. The resulting tool is a set of statistical lightning forecast equations, one for each month of the warm season, that provide a lightning occurrence probability for the day by 1100 UTC (0700 EDT) during the warm season.

  9. Lightning hazards overview: Aviation requirements and interests (United States)

    Corn, P. B.


    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.

  10. Predicting Warm Season Nocturnal Cloud-To-Ground Lightning Near Cape Canaveral, Florida (United States)


    rendered the standard t-test inappropriate. However, Mielke et al. (1976, 1981) has 12 developed a non-parametric test for investigating univariate...higher confidence level. A detailed description of the procedure can be found in Mielke et al. (1981). In assessing the statistical significance of...1984: Average diurnal variation of summer lightning over the Florida peninsula. Mon. Wea. Rev., 112, 1134-1140. Mielke , P. W., K. J. Berry, and E. S

  11. 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. (United States)


    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

  12. Fine Selection of Lightning Protection Method of Distributed Photovoltaic Power Station%分布式光伏发电防雷措施的精细化选择

    Institute of Scientific and Technical Information of China (English)

    邓海利; 郭业才; 宋兆俊


    利用闪电监测系统确定光伏电站所在地的雷击大地密度,从而计算电站的年预计雷击次数,并划分防雷类别。提出用雷电统计资料来确定滚球半径,使直击雷保护范围计算更为精确。针对避雷针阴影对光伏电池板产生的热斑效应,提出使用太阳高度角及方位角来选择避雷针的安装位置,降低阴影对光伏电池板的影响。为降低热斑效应,建议大型光伏电站使用避雷线防护。提出利用雷电流幅值选取浪涌保护器(SPD )的冲击放电电流,降低SPD的钳制电压,优化SPD保护效果。提议控制机房结构内筋兼做屏蔽层,并根据雷电统计数据确定内筋的网格尺寸。最后提出根据光伏电池阵列的布局,结合当地土壤电阻率,分区域建设环形接地系统。%The lightning density around photovoltaic (PV ) power station is determined based on lightning location system . This density is used to calculate and predict the number of lightning at a year on average of the power station and divide lightning protection categories .Lightning statistical data is used to determine the ball radius ,making the lightning protection range calculation more accurate .The lightning rod shadow will produce hot spot effect on the PV cell panel ,so the average height and azimuth angle of sun is used to choose the installation location of lightning rod ,so as to reduce the effect of shadow for the PV cell panel .In order to reduce the hot spot effect it is suggested that the lightning line should be used in large-scale PV power station .It is proposed that the lightning current amplitude is applied to select Surge Protection Device (SPD ) ,reduce the max clamping voltage of SPD and to optimize the protection effect of SPD .The reinforced room is controlled to be shielding layer and according to the lightning statistical data ,the reinforced grid size is determined .At the end ,the regional constructed ring

  13. Comparing lightning polarity and cloud microphysical properties over regions of high ground flash density in South Africa

    CSIR Research Space (South Africa)

    Simpson, LA


    Full Text Available This study aims to find a correlation between lightning polarity and microphysical properties of a storm cloud, for events where large amounts of lightning damage have occured and/or there has been a reported lightning-related fatality....

  14. Unmanned ground vehicles for integrated force protection (United States)

    Carroll, Daniel M.; Mikell, Kenneth; Denewiler, Thomas


    The combination of Command and Control (C2) systems with Unmanned Ground Vehicles (UGVs) provides Integrated Force Protection from the Robotic Operation Command Center. Autonomous UGVs are directed as Force Projection units. UGV payloads and fixed sensors provide situational awareness while unattended munitions provide a less-than-lethal response capability. Remote resources serve as automated interfaces to legacy physical devices such as manned response vehicles, barrier gates, fence openings, garage doors, and remote power on/off capability for unmanned systems. The Robotic Operations Command Center executes the Multiple Resource Host Architecture (MRHA) to simultaneously control heterogeneous unmanned systems. The MRHA graphically displays video, map, and status for each resource using wireless digital communications for integrated data, video, and audio. Events are prioritized and the user is prompted with audio alerts and text instructions for alarms and warnings. A control hierarchy of missions and duty rosters support autonomous operations. This paper provides an overview of the key technology enablers for Integrated Force Protection with details on a force-on-force scenario to test and demonstrate concept of operations using Unmanned Ground Vehicles. Special attention is given to development and applications for the Remote Detection Challenge and Response (REDCAR) initiative for Integrated Base Defense.

  15. Observation and study on the whole process of cloud-to-ground lightning using narrowband radio interferometer

    Institute of Scientific and Technical Information of China (English)


    A narrowband radio interferometer has been developed and used to locate the entire sources of VHF radiations from a negative cloud-to-ground (CG) lightning discharge which contains 19 strokes. This system uses five antennas to form an array consisting of short- and long-baselines along two or- thogonal directions. The system error which comes from frequency conversion is reduced by phase detection through direct high frequency amplifying. An interactive graphic analysis procedure is used to remove the fringe ambiguities which exist inherently in interferometry and to determine the direction of lightning radiation sources in two dimensions (azimuth and elevation) as a function of time at a time resolution of microsecond orders. With the developed system, the whole progression process in time and space of a lightning flash can be reconstructed. In this paper, combining the synchronous data of electric filed change and VHF radiation, the whole processes of an example negative CG flash have been studied in detail. It is found that the preliminary breakdown event of the CG flash started from negative charge region and exhibited firstly a downward pregression and then an upward propagation. There were very intense and continuous radiations during stepped leaders which became much stronger when the first return stroke began. In contrast, there were less and only discrete radiations during dart leaders. Stepped leader and dart leader may transform to each other depending on the state of the ionization of the path. The progression speed of initial stepped leaders was about 105 ms?1, while that was about 4.1×106 and 6.0×106 ms?1 for dart leaders and dart-stepped leaders, respectively. M events produced hook-shaped field changes accompanied by active burst of radiations at their begin- nings. Followed these active radiation processes, M events appeared to contact finally into conducting main discharge channels. The mean progression speed of M events was about 7×107 ms?1

  16. Observation and study on the whole process of cloud-to-ground lightning using narrowband radio interferometer

    Institute of Scientific and Technical Information of China (English)

    ZHANG GuangShu; ZHAO YuXiang; QIE XiuShu; ZHANG Tong; WANG YanHui; CHEN ChengPin


    A narrowband radio interferometer has been developed and used to locate the entire sources of VHF radiations from a negative cloud-to-ground (CG) lightning ischarge which contains 19 strokes. This system uses five antennas to form an array consisting of short- and long-baselines along two or-thogonal directions. The system error which comes from frequency conversion is reduced by phase detection through direct high frequency amplifying. An interactive graphic analysis procedure is used to remove the fringe ambiguities which exist inherently in interferometry and to determine the direction of lightning radiation sources in two dimensions (azimuth and elevation) as a function of time at a time resolution of microsecond orders. With the developed system, the whole progression process in time and space of a lightning flash can be reconstructed, in this paper, combining the synchronous data of electric filed change and VHF radiation, the whole processes of an example negative CG flash have been studied in detail. It is found that the preliminary breakdown event of the CG flash started from negative charge region and exhibited firstly a downward pregression and then an upward propagation. There were very intense and continuous radiations during stepped leaders which became much stronger when the first return stroke began. In contrast, there were less and only discrete radiations during dart leaders. Stepped leader and dart leader may transform to each other depending on the state of the ionization of the path. The progression speed of initial stepped leaders was about 105 ms-1, while that was about 4.1×106 and 6.0×106 ms-1 for dart leaders and dart-stepped leaders, respectively. M events produced hook-shaped field changes accompanied by active burst of radiations at their begin-nings. Followed these active radiation processes, M events appeared to contact finally into conducting main discharge channels. The mean progression speed of M events was about 7×107 ms-1

  17. 现代智能建筑电子系统防雷技术浅析%The modern intelligent building electrical system lightning protection technology is analysed

    Institute of Scientific and Technical Information of China (English)

    徐国栋; 窦坤; 董东; 董永红


    现代智能建筑电子系统防雷包括直击雷和雷电感应防护,既要考虑雷电来自电路的侵入又要考虑来自磁场的干扰,既要拦截来自带电线路的雷电危害又要考虑非带电金属体的反击,为此综合提出屋面直击雷、电源、信号线缆防护等全方位防雷方案,供同行参考.%Lightning protection of modern electronic systems, inteligent buildings including direct lightning and thunder and lightning induction protection, should not only consider the thunder from the invasion of the circuit and to consider from the interference of magnetic field, both to intercept from live line lightning harm and to consider the charged metal body, this paper provides comprehensive roof lightning, power supply, signal cable protection, such as comprehensive lightning protection scheme, for the coleague reference.

  18. Application of Soil Resistivity Test in Airport Lightning Protection Design%土壤电阻率检测分析在机场防雷设计中的应用

    Institute of Scientific and Technical Information of China (English)

    李衣长; 王婷婷; 龚成龙; 龚伟; 巫圣灿


    对某民用机场开展雷电灾害风险评估,采用温纳四极法测试土壤电阻率,对检测数据进行水平分布和垂直分布分析,利用土壤结构反演方法,得到一个等效的均匀土壤电阻率,为机场防雷接地装置设计提供了科学化、精细化的依据。%Lightning disaster risk assessment is conducted for a civil airport; Wenner quadrupole method is adopted to test the soil resistivity. An equivalent and uniform soil resistivity, which is obtained through horizontal and vertical distribution analysis on tested data and by soil structure inversion method, provides a scientific and precise basis for grounding device design for airport lightning protection.

  19. Analysis on Lightning Surge Propagation in Wind Farm (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.

  20. Analysis and Assessment of Peak Lightning Current Probabilities at the NASA Kennedy Space Center (United States)

    Johnson, D. L.; Vaughan, W. W.


    This technical memorandum presents a summary by the Electromagnetics and Aerospace Environments Branch at the Marshall Space Flight Center of lightning characteristics and lightning criteria for the protection of aerospace vehicles. Probability estimates are included for certain lightning strikes (peak currents of 200, 100, and 50 kA) applicable to the National Aeronautics and Space Administration Space Shuttle at the Kennedy Space Center, Florida, during rollout, on-pad, and boost/launch phases. Results of an extensive literature search to compile information on this subject are presented in order to answer key questions posed by the Space Shuttle Program Office at the Johnson Space Center concerning peak lightning current probabilities if a vehicle is hit by a lightning cloud-to-ground stroke. Vehicle-triggered lightning probability estimates for the aforementioned peak currents are still being worked. Section 4.5, however, does provide some insight on estimating these same peaks.

  1. 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: [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)


    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.

  2. 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


    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.

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

    Institute of Scientific and Technical Information of China (English)


    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.

  4. Research on Winter Lightning in Japan (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.

  5. The Power of the Point: Benjamin Franklin, the Lightning Rod and Two Misconceptions That Have Plagued Us to This Day (United States)

    Aulich, G. D.; Moore, C. B.; Rison, W.


    Most people know that Ben Franklin invented the lightning rod and that his rods have successfully protected structures for over 250 years. What people don't know is that he invented them on the basis of two misconceptions. The first, that an elevated pointed conductor would discharge a thunderstorm, thereby preventing lightning. The second, that, should the first process fail, the elevated conductor, by virtue of its pointed tip, would serve as a preferred receptor for any lightning strokes that did occur. It has long been known that grounded, elevated, pointed conductors can not discharge thunderstorms and experiments conducted at the Langmuir Laboratory during the 1990s have shown that moderately blunt, rather than pointed, rods are the best receptors for lightning strokes. Nevertheless, Franklin's incorrect ideas about lightning rods persist in many minds, even among some people in the lightning protection business.

  6. Protection of ± 500 kV HVDC Double-circuit Converter Station from Lightning Induced Overvoltage

    Institute of Scientific and Technical Information of China (English)

    DONG Manling; YUAN Zhiyong; LI Tianwei; ZHAO Xiangen; ZHANG Jiaxin; HE Junjia


    In order to obtain reasonable schemes of arrester in converter stations,the arrester scheme of"Xiluodu-Guangdong HVDC ±500 kV double circuit transmission" project against lighting induced overvoltage,which was designed according to the main principle of lightning protection in converter station,is discussed.A calculation of the lighting induced overvoltage in Zhaotong converter station under various operation modes is performed with ATP-EMTP software,then the surge arrester configuration of the converter station is decided,and the arrester protection schemes of smoothing reactor and neutral line are studied.It is concluded that additional protection is necessary because of the relatively large gap between protected disconnecting switch and arrester of metallic return transfer bus.Plus,the smoothing reactor (SR) arrester near the valve hall could be removed to improve the scheme's economic performance.

  7. 配电网线路防雷系统的保护研究%Protection Research of Line Lightning Protection System for Distribution Network

    Institute of Scientific and Technical Information of China (English)



    Since the complex network structure and low insulation levels for distribution networks. it is easy to lead to lightning accident. And further it will cause power outages and great economic losses. This paper analyzes the principle and the features of lightning protection technology for the powers and the technical program for discribution network is proposed.%由于配电网的网络结构复杂、绝缘水平较低,配电网很容易遭受雷害事故,引起停电事故,从而导致很大的经济损失.本文就电网防雷技术的原理及特点进行分析,并结合实际,提出适用于配电网防雷的技术方案.

  8. Phase Retrieval from Modulus Using Homeomorphic Signal Processing and the Complex Cepstrum: An Algorithm for Lightning Protection Systems

    Energy Technology Data Exchange (ETDEWEB)

    Clark, G A


    In general, the Phase Retrieval from Modulus problem is very difficult. In this report, we solve the difficult, but somewhat more tractable case in which we constrain the solution to a minimum phase reconstruction. We exploit the real-and imaginary part sufficiency properties of the Fourier and Hilbert Transforms of causal sequences to develop an algorithm for reconstructing spectral phase given only spectral modulus. The algorithm uses homeomorphic signal processing methods with the complex cepstrum. The formal problem of interest is: Given measurements of only the modulus {vert_bar}H(k){vert_bar} (no phase) of the Discrete Fourier Transform (DFT) of a real, finite-length, stable, causal time domain signal h(n), compute a minimum phase reconstruction {cflx h}(n) of the signal. Then compute the phase of {cflx h}(n) using a DFT, and exploit the result as an estimate of the phase of h(n). The development of the algorithm is quite involved, but the final algorithm and its implementation are very simple. This work was motivated by a Phase Retrieval from Modulus Problem that arose in LLNL Defense Sciences Engineering Division (DSED) projects in lightning protection for buildings. The measurements are limited to modulus-only spectra from a spectrum analyzer. However, it is desired to perform system identification on the building to compute impulse responses and transfer functions that describe the amount of lightning energy that will be transferred from the outside of the building to the inside. This calculation requires knowledge of the entire signals (both modulus and phase). The algorithm and software described in this report are proposed as an approach to phase retrieval that can be used for programmatic needs. This report presents a brief tutorial description of the mathematical problem and the derivation of the phase retrieval algorithm. The efficacy of the theory is demonstrated using simulated signals that meet the assumptions of the algorithm. We see that for

  9. Lightning Technology. (United States)


    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

  10. Lightning-produced NO2 observed by two ground-based UV-visible spectrometers at Vanscoy, Saskatchewan in August 2004

    Directory of Open Access Journals (Sweden)

    A. Fraser


    Full Text Available Ground-based measurements of ozone and NO2 differential slant columns by the SAOZ (Système d'Analyse par Observations Zénithales and UT-GBS (University of Toronto Ground-Based Spectrometer instruments during the MANTRA 2004 field campaign are presented herein. During the afternoon of 28 August, a thunderstorm passed over the instruments, which were installed at Vanscoy, Saskatchewan (52° N, 107° W. Enhanced differential slant columns of ozone and NO2 were observed by both instruments during the storm, with maximum values of two and 25 times the expected clear sky columns, respectively. The enhanced ozone differential slant columns are primarily due to the longer path traversed by the solar radiation caused by multiple scattering inside the thick cloud layer associated with the thunderstorm. The enhanced NO2 columns are partly attributed to NOx production by lightning. Two new methods are used to separate the NO2 enhancements into contributions from the longer path length and production by lightning. Combining the observed excess NO2 with lightning flash data from the Canadian Lightning Detection Network and Environment Canada Doppler radar measurements, the production of NO2 molecules per lightning flash is determined. Using these two methods, the best estimate of the production rate is found to be (7.88±2.52×1026 molecules NO2/flash from the UT-GBS and (6.81±2.17×1026 molecules NO2/flash from SAOZ. These results are consistent with the range of previous estimates reported in the literature.

  11. High-speed video of competing and cut-off leaders prior to "upward illumination-type" lightning ground strokes (United States)

    Stolzenburg, Maribeth; Marshall, Thomas; Karunarathne, Sumedhe; Karunarathna, Nadeeka; Warner, Tom; Orville, Richard


    This study presents evidence to test a hypothesis regarding the physical mechanism resulting in very weak "upward illumination" (UI) type ground strokes occurring within a few milliseconds after a normal return stroke (RS) of a negative lightning flash. As described in previous work [Stolzenburg et al., JGR D15203, 2012], these short duration (strokes form a new ground connection, without apparent connection to the main RS, over their relatively short (return path. From a dataset of 170 video flashes acquired in 2011 (captured at 50000 frames per second), we find 20 good UI examples in 18 flashes at 2.5-32.3 km distance from the camera. Average separation values are 1.26 ms and 1.9 km between the ground connections of the UI and main RS. Based on electric field change data for the flashes, the estimated peak current of the UI strokes averages -5.0 kA, about one-third the average value for the preceding RS. In 15 cases the video data show a distinct stepped leader to the UI which develops concurrently with the stepped leader to the main RS. Estimated altitude of the UI leader tip just before the main RS occurs ranges from 0 to 610 m, and in 7 cases steps are visible in the UI leader after the main RS. In most of the examples the RS and UI appear as separate channels for their entire visible portion, but in 5 cases there is a junction indicating the UI leader is a cut-off branch from the main leader. A generalized schematic of the seven main luminosity stages in a typical UI, along with video examples showing each of these stages and electric field change data, will be presented.

  12. Ground Level Observations of a Possible Downward-Beamed TGF during a Rocket-Triggered Lightning Flash at Camp Blanding, Florida in August 2014 (United States)

    Bozarth, A.; Dwyer, J. R.; Cramer, E. S.; Rassoul, H.; Uman, M. A.; Jordan, D.; Grove, J. E.


    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.

  13. A Method to Estimate the Probability that Any Individual Cloud-to-Ground Lightning Stroke was Within Any Radius of Any Point (United States)

    Huddleston, Lisa; Roeder, WIlliam P.; Merceret, Francis J.


    A new technique has been developed to estimate the probability that a nearby cloud-to-ground lightning stroke was within a specified radius of any point of interest. 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 within the location error ellipse. This technique is adapted from a method of calculating the probability of debris collision with 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.

  14. The start of lightning: Evidence of bidirectional lightning initiation (United States)

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


    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.

  15. On the diurnal cycle of deep moist convection in the southern side of the Alps analysed through cloud-to-ground lightning activity (United States)

    Gladich, I.; Gallai, I.; Giaiotti, D. B.; Stel, F.


    In this work, eight years of cloud-to-ground lightning data are used as a proxy observable to describe the hourly frequency of deep moist convection occurrence over an area characterized by complex geography in the southern side of the Alps (Friuli Venezia Giulia). The study area is divided in eight sub-zones, defined according to the climatic differences of the southern side of the Alps, in particular those related to the precipitation regime. In the eight sub-zones, the hourly frequency of cloud-to-ground lightning shows two different behaviours: bimodal and single-mode. Single-mode hourly frequencies, in turn, can be divided into two more classes: afternoon maximum and evening maximum. A conceptual model for the explanation of the observed features is proposed. This conceptual model takes into account the atmospheric instability, which has a maximum during afternoon, and the convection forcing represented by the switch in the breezes regime, which is stronger in the late morning and evening. The proposed conceptual model is coherent with the complementary meteorological parameters taken into account (hourly rain, temperature and wind distribution and speed) and it is capable to describe, at least qualitatively, the observed behaviours in cloud-to-ground lightning hourly distribution.

  16. 计算机网络系统的雷电防护研究%A study on lightning protection of computer network system

    Institute of Scientific and Technical Information of China (English)

    周中伟; 周中意; 陈海辉


    Taking lightning protection of computer network system as an object of study* the different channels of lightning invade of computer network system was analyzed. According to the characteristic of highly integrated den-sification of electronic components in computer network system! The design ideas about the internal protection and external protection were put forward. In the design, the importance of the internal protection was especially emphasized. Taking into account lightning electromagnetism impulse, the lightning induction and the physical characteristic of the computer network system, the requirements and techniques for lightning protection of the computer network system were emphatically elaborated, and then the lightning protection measures for the computer network system were presented, which have better reference value and maneuverability.%以计算机网络系统雷电防护为研究对象,分析了雷电入侵计算机网络系统的不同途径;针对计算机网络系统电子元件高度集成密集化的特点,提出了内部防雷和外部防雷的设计观点;强调计算机网络系统内部防雷设计的重要性,并结合雷电电磁脉冲、雷电感应及计算机网络系统物理原件组成特征,着重论述计算机网络系统雷电防护的技术性及实践性要求;进而提出了计算机网络系统雷电防护的措施,具有较好的操作性和参考价值.

  17. Disposition of Lightning Activity Due to Pollution Load during Dissimilar Seasons as Observed from Satellite and Ground-Based Data

    Directory of Open Access Journals (Sweden)

    Anirban Middey


    Full Text Available The precise role of air pollution on the climate and local weather has been an issue for quite a long time. Among the diverse issues, the effects of air pollution on lightning are of recent interest. Exploration over several years (2004 to 2011 has been made over Gangetic West Bengal of India using lightning flash data from TRMM-LIS (Tropical Rainfall Measuring Mission-Lightning Imaging Sensor, atmospheric pollutants, and rainfall data during pre-monsoon (April and May and monsoon (June, July, August and September seasons. Near-surface pollutants such as PM10 and SO2 have a good positive association with aerosol optical depth (AOD for both the pre-monsoon and monsoon months. High atmospheric aerosol loading correlates well with pre-monsoon and monsoon lightning flashes. However, rainfall has a dissimilar effect on lightning flashes. Flash count is positively associated with pre-monsoon rainfall (r = 0.64, but the reverse relation (r = −0.4 is observed for monsoon rainfall. Apart from meteorological factors, wet deposition of atmospheric pollutant may be considered a crucial factor for decreased lightning flash count in monsoon. The variation in the monthly average tropospheric column amount of NO2, from the Tropospheric Emission Monitoring Internet Service (TEMIS, is synchronic with average lightning flash rate. It has a good linear association with flash count for both pre-monsoon and monsoon seasons. The effect of lightning on tropospheric NO2 production is evident from the monthly average variation in NO2 on lightning and non-lightning days.

  18. Discussion on Lightning Protection Measures of Electrification Railway Catenary%电气化铁路接触网防雷措施的探讨

    Institute of Scientific and Technical Information of China (English)



      针对国内电气化铁道部分线路遭受雷击较频繁的现状,本文对接触网遭受雷击跳闸情况进行了统计分析,借鉴国外接触网防雷措施,结合我国电气化铁道防雷措施的现状,同时参考国内电气化铁路防雷措施的研究成果,提出了我国电气化铁路接触网系统的防雷措施原则及建议。%Aiming at the situation that the domestic electrified railway line often suffers from lightning, the paper makes a statistical analysis on lightning trip-out times of catenary; combined with foreign catenary lightning protection measures and domestic lightning protection measures of electrification railway, it puts forward the principle and suggestion on lightning protection measures of electrification railway catenary.

  19. The evolution of discharge current and channel radius in cloud-to-ground lightning return stroke process (United States)

    Fan, Tingting; Yuan, Ping; Wang, Xuejuan; Cen, Jianyong; Chang, Xuan; Zhao, Yanyan


    The spectra of two negative cloud-to-ground lightning discharge processes with multi-return strokes are obtained by a slit-less high-speed spectrograph, which the temporal resolution is 110 μs. Combined with the synchronous electrical observation data and theoretical calculation, the physical characteristics during return strokes process are analysed. A positive correlation between discharge current and intensity of ionic lines in the spectra is verified, and based on this feature, the current evolution characteristics during four return strokes are investigated. The results show that the time from peak current to the half-peak value estimated by multi point-fitting is about 101 μs-139 μs. The Joule heat in per unit length of four return strokes channel is in the order of 105J/m-106 J/m. The radius of arc discharge channel is positively related to the discharge current, and the more intense the current is, the greater the radius of channel is. Furthermore, the evolution for radius of arc core channel in the process of return stroke is consistent with the change trend of discharge current after the peak value. Compared with the decay of the current, the temperature decreases more slowly.

  20. Correlation between the spectral features and electric field changes of multiple return strokes in negative cloud-to-ground lightning (United States)

    Wang, Xuejuan; Yuan, Ping; Cen, Jianyong; Liu, Guorong


    Using high time-resolved spectra and simultaneous records of the electric field change of three negative cloud-to-ground (CG) lightning flashes with multiple return strokes, the correlations between the total intensity of ionic lines in the spectra and the corresponding amplitude of the initial electric field change, as well as between the total intensity of the spectra and the channel apparent diameter, have been analyzed. The analysis shows the following: (1) The amplitude of the initial electric field change is roughly proportional to the total intensity of ionic lines. (2) The total intensity of the spectra shows a significant linear correlation with the apparent diameter of the channel. (3) The total intensity of ionic lines for 17 analyzed return strokes decreases with increasing height along the channel, which is consistent with the current variation along the channel in the modified transmission line model; the Master, Uman, Lin, and Standler model; and the Diendorfer-Uman model. Meanwhile, the total intensity of ionic lines for other two analyzed return strokes along the channel without attenuation, this is consistent with the current variation along the channel in the Bruce-Golde model, the transmission line model, and the Traveling Current Source model.

  1. Lightning in aeronautics (United States)

    Lago, F.


    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.

  2. 古建筑群防雷安全隐患及其对策研究%Study on the Lightning-Protection of Ancient Buildings

    Institute of Scientific and Technical Information of China (English)

    樊希彬; 熊群峰; 夏志刚


    By reviewing ancient buildings that were destroyed by lightning strike or fire caused by lightning, lightning protection of ancient buildings was discussed, ancient architectural complex in Dagu Mountain, a provincial-level scenic area of Liaoning, was taken for an example to detect potential safety hazards in lightning-protection of those ancient buildings, 5 types of potential safety hazards were summarized. By studying the classification of ancient buildings'lightning-protection, protection level, lightning-protection measures, design basis of lightningprotection engineering, construction and new construction technology, relevant technical specifications were taken as references for proposing 4 countermeasures against those potential safety hazards from the perspectives of exterior and interior parts of ancient buildings, lightning -protection of ancient trees and so on. In view of actual conditions of the ancient architectural complex in Dagu Mountain, construction plan, personnel placement, labor planning, construction quality control system, acceptance of works, technical documentation and such matters were specifically discussed to give useful support to the future lightning-protection of ancient buildings.%回顾了古建筑被雷电击毁或因雷电引起火灾的历史事件,由此引发了对古建筑群防雷安全问题的探讨,以辽宁省级风景名胜区大孤山古建筑群为例,对古建筑群防雷安全隐患进行勘查和检测,总结出5种防雷安全隐患类型.从古建筑防雷类别划分、保护级别、防雷措施、防雷工程设计依据、工程施工、新施工工艺等6个方面进行研究,依据相应技术规范分别从古建筑物外部、内部和古树木防雷等方面提出4项防雷安全隐患应对措施,并具体针对大孤山古建筑群的实际情况,详细探讨了施工方案、人员安排、劳务计划和施工质量保证体系、工程验收、技术文档等问题,以期为切实做好古建筑

  3. 雷电电磁脉冲防护及 SPD 选择%Lightning Electromagnetic Impulse Protection and SPD Selection

    Institute of Scientific and Technical Information of China (English)



    Key points for the protection of lightning electromagnetic impulse are analyzed according to the component features of lightning current. According to relevant documents of various committees of IEC, SPD selection for power inlet of building is discussed and technical progress and work direction of IEC lightning protection committee (TC81 committee) are introduced.%根据雷电流的分量特征,分析雷电电磁脉冲的防护要点。结合IEC各委员会的相关文件,讨论建筑物电源引入处SPD的选择,并介绍IEC雷电防护委员会(TC81委员会)技术进展和工作方向。

  4. Applications of triggered lightning to space vehicle operations (United States)

    Jafferis, William; Sanicandro, Rocco; Rompalla, John; Wohlman, Richard


    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.

  5. Comparative Analysis of the Cloud-to-ground Lightning Data Between Two Lightning Location Systems%浙江省两套闪电定位系统地闪数据对比

    Institute of Scientific and Technical Information of China (English)

    赵伟; 姜瑜君; 童杭伟; 张斌


    Comparative analysis of the lightning location data from 2009 to 2013 is conducted by temporal and spatial distribution and detection efficiency,to explore the difference of data collected from two lightning location systems (LLS)of Zhejiang meteorological department and Zhejiang electric power department. Results show that the inter-annual cloud-to-ground (CG)lightning frequency observed by the LLS of Zhe-jiang meteorological department is stably lower than that observed by the LLS of Zhejiang electric power department.The number of positive CG lightning occupies 3.5% of total CG lightning observed by the LLS of Zhejiang meteorological department,which is also 2% less than that observed by the LLS of Zhe-jiang electric power department,and both of them are in a reasonable interval.From the viewpoint of spa-tial distribution,the CG lightning density of two datasets is nearly equal in coastal plain and the Jinhua-Quzhou Basin,but the CG lightning density obtained by Zhejiang electric power department is stably more than that of Zhejiang meteorological department in the other areas except in Chun’an which is located in the border of Hangzhou and Quzhou.It is also found that the occurrence of high CG lightning density re-gion in Chun’an observed by LLS of Zhejiang meteorological department is abnormal.Further analysis of the number of monthly mean thunderstorm days obtained by these two LLSs and manual observation indi-cates that the monthly mean thunderstorm days observed by the LLS of Zhejiang meteorological depart-ment is not more than that of manual observations except in summer,when the monthly mean thunder-storm days observed by LLS of Zhejiang electric power department is almost more than that of manual ob-servations every month.It suggests that the LLS of Zhejiang meteorological department does well in detec-ting strong thunderstorms while the weaker thunderstorms could be missed.Hence,the LLS detective a-bility of Zhejiang electric power department is

  6. Lightning Injuries (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 ...

  7. Lightning Protection of Monitored Control System in Oil Depot%油库监控系统的雷电防护

    Institute of Scientific and Technical Information of China (English)



    Analysis damage and aftermath of lightning strike to oil depot,and analysis prime cause and intrusion path of lightning strike.According to design code for protection of Structures against lightning(GB50057-2010),adopt method of subdivision protection,synthetically protect monitored control system of storage and transportation of oil,security surveillance system and oil control system,to avoid damage of lightning strike because of careless omission.%综合分析雷击对油库造成的损害和后果,以及雷击损害的主要原因和侵入途径,依据《建筑物防雷设计规范》GB50057-2010,采用"分单元防护思想",对油库的储油监控系统、现场安防监控系统、输油控制系统等进行了全面综合防护,防止了因疏漏带来的雷击危害。

  8. Low voltage lightning arresters. Components. Low voltage grids; Parafoudres basse tension. Composants. Reseaux basse tension

    Energy Technology Data Exchange (ETDEWEB)

    Rousseau, A. [Assistance Protection System SAS, 94 - Cachan (France)


    Electrical equipments used in domestic and industrial applications are more and more sensible to overvoltages because of the massive use of electronic components in these equipments and appliances. Overvoltages do not propagate only with power lines but also through phone lines, coaxial cables, data networks, and even through grounding circuits. The informations about low voltage grids, useful for the selection of lightning arresters are presented in this article. In the ideal case, each possible way of input for overvoltage currents must be protected. The components used in lightning arresters have improved for a better reliability, a better energy resistance and a better protection level. These components are also presented in this article: 1 - technical and standard evolution: improvement of the understanding of low voltage phenomena, standards evolution, recall of basic definitions and data about lightning protection; 2 - components: varistors, spark gaps, silicon-based solid components, aging and end of life, decoupling components (thermistors, resistors, inductors); 3 - low voltage grids: different types of energy networks, transmission of overvoltages on low voltage networks (overvoltages due to lightning, or power station actuating, temporary overvoltages), influence of lightning conductors and lightning strikes close to the building structure, statistical data about lightning overvoltages on low voltage grids, protection and risk analysis. (J.S.)

  9. Lightning and Gunpowder in the 18th Century (United States)

    Krider, E. P.


    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

  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


    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. 29 CFR 1926.954 - Grounding for protection of employees. (United States)


    ..., DEPARTMENT OF LABOR (CONTINUED) SAFETY AND HEALTH REGULATIONS FOR CONSTRUCTION Power Transmission and... the new lines or equipment. (c) Communication conductors. Bare wire communication conductors on power... operation of protective devices. (i) Grounding to tower. Grounding to tower shall be made with a tower...

  12. Earliest recorded ground-based decameter wavelength observations of Saturn's lightning during the giant E-storm detected by Cassini spacecraft in early 2006 (United States)

    Konovalenko, A. A.; Kalinichenko, N. N.; Rucker, H. O.; Lecacheux, A.; Fischer, G.; Zarka, P.; Zakharenko, V. V.; Mylostna, K. Y.; Grießmeier, J.-M.; Abranin, E. P.; Falkovich, I. S.; Sidorchuk, K. M.; Kurth, W. S.; Kaiser, M. L.; Gurnett, D. A.


    We report the history of the first recorded ground-based radio detection of Saturn's lightning using the Ukrainian UTR-2 radiotelescope at frequencies from 20 to 25 MHz. The observations were performed between 29 January and 3 February 2006, during which lighting activity (E-storm) on Saturn was detected by the radio experiment onboard Cassini spacecraft. The minimum detectable flux density (1σ-level) at UTR-2 reached 40 Jy (1Jy=10-26WmHz) for narrowband observations (Δf=10kHz) and 4 Jy for broadband observations (Δf=1MHz), for an effective telescope area of ≈100,000m and integration time of 20 ms. Selection criteria including comparison of simultaneous ON/OFF-source observations were applied to distinguish detection of lightning-associated radio pulses from interference. This allowed us to identify about 70 events with signal-to-noise ratio more than 5. Measured flux densities (between 50 and 700 Jy) and burst durations (between 60 and 220 ms) are in good agreement with extrapolation of previous Cassini measurements to a ground-based observer. This first detection demonstrates the possibility of Solar System planetary lightning studies using large, present and future ground-based radio instruments. The developed methods of observations and identification criteria are also implemented on the UTR-2 radio telescope for the investigation of the next Saturn's storms. Together with recently published UTR-2 measurements of activity measured after the 2006 storm reported here, the results have significant implications for detectable planetary radio emission in our Solar System and beyond.

  13. Protected Area Certificates: Gaining Ground for Better Ecosystem Protection? (United States)

    Segerstedt, Anna; Grote, Ulrike


    Protected areas are vital to sustain a number of ecosystem services. Yet, many protected areas are underfinanced and lack management effectiveness. Protected area certificates have been suggested as a way to resolve these problems. This instrument would allow land managers to certify an area if it meets certain conservation criteria. The certificates could then be sold on an international market, for example to companies and any consumers that are interested in environmental protection. Some pilot initiatives have been launched, yet little is known about future demand and features of protected area certificates. To fill this knowledge gap, we conduct a choice experiment with close to 400 long-distance tourists from Germany as a potential group of buyers. Our results indicate that the respondents have the highest willingness to pay for certificates that conserve sensitive ecosystems and in addition to this lead to poverty reduction and safeguard water resources. For other attributes such as a greenhouse gas reduction, the preferences are less significant. Overall, the results are rather homogenous irrespective of where the protected areas are located. These insights are important for the future design and marketing of protected area certificates.

  14. Lightning protection for electric utility and industrial applications; Blitzschutz fuer Stromversorgungs- und Industrieanlagen

    Energy Technology Data Exchange (ETDEWEB)

    Benda, S. [ABB EMC Certification AB, Vaesteraas (Sweden)


    Lightning strokes generate high interference voltages in industrial plants and high-voltage substations. The characteristics of the transients, the amplitudes of the voltages and their number vary considerably from one network to another. A sound understanding of the phenomena involved and of the implications of certain industry practices are necessary to ensure the safe and reliable operation of the installed electrotechnical equipment. (orig.) [Deutsch] Blitzeinschlaege verursachen in Industrieanlagen und Hochspannungsstationen hohe Stoerspannungen. Die Kennwerte der Ausgleichsspannungen, die Amplituden der Spannungen und deren Anzahl sind von Netz zu Netz verschieden. Um einen sicheren und zuverlaessigen Betrieb der installierten elektrischen Ausruestung sicherzustellen, ist es wichtig, die Phaenomene, die dabei eine Rolle spielen, und die Auswirkungen bestimmter Praktiken in der Industrie gut verstehen. (orig.)

  15. Lightning transient analysis in wind turbine blades

    DEFF Research Database (Denmark)

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


    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...

  16. High-Resolution Analysis Products to Support Severe Weather and Cloud-to-Ground Lightning Threat Assessments over Florida (United States)

    Case, Jonathan; Spratt, Scott; Sharp, David


    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

  17. Cathodic protection for the bottoms of above ground storage tanks

    Energy Technology Data Exchange (ETDEWEB)

    Mohr, John P. [Tyco Adhesives, Norwood, MA (United States)


    Impressed Current Cathodic Protection has been used for many years to protect the external bottoms of above ground storage tanks. The use of a vertical deep ground bed often treated several bare steel tank bottoms by broadcasting current over a wide area. Environmental concerns and, in some countries, government regulations, have introduced the use of dielectric secondary containment liners. The dielectric liner does not allow the protective cathodic protection current to pass and causes corrosion to continue on the newly placed tank bottom. In existing tank bottoms where inadequate protection has been provided, leaks can develop. In one method of remediation, an old bottom is covered with sand and a double bottom is welded above the leaking bottom. The new bottom is welded very close to the old bottom, thus shielding the traditional cathodic protection from protecting the new bottom. These double bottoms often employ the use of dielectric liner as well. Both the liner and the double bottom often minimize the distance from the external tank bottom. The minimized space between the liner, or double bottom, and the bottom to be protected places a challenge in providing current distribution in cathodic protection systems. This study examines the practical concerns for application of impressed current cathodic protection and the types of anode materials used in these specific applications. One unique approach for an economical treatment using a conductive polymer cathodic protection method is presented. (author)

  18. 昌北雷达站防雷改造工程浅析%Brief Analysis of Lightning Protection Engineering in Changbei Radar Station

    Institute of Scientific and Technical Information of China (English)



    Secondary radar is the air traffic controllers "clairvoyance",the normal operation of which is one of the keys to ensure the safety and ordered flight. The position of the secondary radar station is relatively high and isolated, which is very easy to be struck by lightning. Now the lightning accident has become an important factor in the failure of the radar station equipment,so a sound radar station lightning protection system is of great significance. This paper introduces some lightning accidents in Nanchang Changbei Radar Station in recent years,and discusses the problems and treatment methods in the lightning protection engineering.%航管二次雷达是空中交通管制员的“千里眼”,保障其正常运行是保证飞机安全、有序飞行的关键之一。由于二次雷达站所处的位置一般地势相对较高、且孤立,极易遭受雷击,已成为雷达站设备故障停机的一个重要因素,因此做好雷达站的防雷保护系统意义重大。本文介绍了近年来南昌昌北雷达站雷击案例,以及在防雷改造工程施工监督过程中出现的问题及处理方法。

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


    Shimoji, Nobuaki; Aoyama, Ryoma


    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...

  20. The Anthropogenic/Lightning Effects Around Houston: The Houston Environmental Aerosol Thunderstorm (HEAT) Project - 2005 (United States)

    Orville, R. E.


    A major field program will occur in summer 2005 to determine the sources and causes for the enhanced cloud-to-ground lightning over Houston, Texas. This program will be in association with simultaneous experiments supported by the Environmental Protection Agency (EPA) and the Texas Commission on Environmental Quality (TCEQ), formally the Texas Natural Resource Conservation Commission (TNRCC). Recent studies covering the period 1989-2002 document a 60 percent increase of cloud-to-ground lightning in the Houston area as compared to surrounding background values, which is second in flash density only to the Tampa Bay, Florida area. We suggest that the elevated flash densities could result from several factors, including 1) the convergence due to the urban heat island effect and complex sea breeze (thermal hypothesis), and 2) the increasing levels of air pollution from anthropogenic sources producing numerous small cloud droplets and thereby suppressing mean droplet size (aerosol hypothesis). The latter effect would enable more cloud water to reach the mixed phase region where it is involved in the formation of precipitation and the separation of electric charge, leading to an enhancement of lightning. The primary goals of HEAT are to examine the effects of (1) pollution, (2) the urban heat island, and (3) the complex coastline on storms and lightning characteristics in the Houston area. The transport of air pollutants by Houston thunderstorms will be investigated. In particular, the relative amounts of lightning-produced and convectively transported NOx into the upper troposphere will be determined, and a comparison of the different NOx sources in the urban area of Houston will be developed. The HEAT project is based on the observation that there is an enhancement in cloud-to-ground (CG) lightning. Total lightning (intracloud (IC) and CG) will be measured using a lightning mapping system (LDAR II) to observe if there is an enhancement in intracloud lightning as well.

  1. Research on Lightning Protection of 220 kV Power Supply Lines of Double-circuit Railway Traction Station on the Same Tower and Improvement Strategy%220 kV 同塔双回铁路牵引站供电线路防雷问题及改进策略研究

    Institute of Scientific and Technical Information of China (English)

    周华敏; 王锐; 周原; 彭向阳; 顾温国


    Aiming at the problem of frequent lightning tripping of 220 kV power supply lines of double-circuit railway trac-tion station on the same tower,reason for tripping was summarized and analyzed and pertinent improvement was made com-bining existing lightning protection measures.Idle conductors were transformed into coupling grounding wires and electro-magnetic transient simulation software ATP/EMTP was used for working out lightning back-flashover level of the tower so as to determine optimal way to transform the upper phase conductor.Differentiation lightning protection strategy was used, configuration way of line arresters was optimized and simultaneous tripping ability to prevent lightning of double-circuit lines were improved.Air gap distance between jumper wires and tower cross arm was adjusted to meet operational demand and jumper wire strings or windage protection insulators were increased considering of wind protection requirement.Grounding resistance of lines was generally surveyed and grounding devices of the tower in those areas with high earth resistivity and high ground flash density were preferentially transformed for reducing resistance.By means of using above comprehensive transformation measures for lightning protection and differentiation lightning protection,performance of lightning protec-tion of 220 kV power supply lines of double-circuit railway traction station on the same tower might be greatly improved.%针对220 kV 同塔双回铁路牵引站供电线路自投运以来频繁发生雷击跳闸问题,总结分析跳闸原因,结合线路已有防雷措施,进行有针对性的改进。将闲置导线改造为耦合地线,并利用电磁暂态仿真软件 ATP/EMTP计算杆塔反击耐雷水平,确定对上相导线进行改造的最佳方式;采取差异化防雷策略,优化线路避雷器配置方式,提高双回线路防雷击同时跳闸能力;调整跳线与铁塔横担空气间隙距离以满足运行要求,同时结合防风需要,

  2. EMC Practices focused in the mitigation of Lightning Electromagnetic Pulse (LEMP): Earthing and bonding approach of the IEC 62305


    Malagón-Carvajal, Gabriel; Giraldo-Picón, Wilson; Ordoñez-Plata, Gabriel; Chacón, Julio Cesar


    This paper presents the results obtained during the parameter identification of electromagnetic compatibility in lightning protection systems. It sets out a number of good engineering practices, aimed at mitigation of disturbances, transient type, created by an electromagnetic pulse, generated during the grounding of lightning. These disturbances are often reflected as overvoltage and / or overcurrent radiated and conducted or also called surges, the latter a strong impact on the operation of...

  3. International Aerospace and Ground Conference on Lightning and Static Electricity (ICOLSE) (10th) and the Congres International Aeronautiq (17th) Held in Paris (France) on 10-13 June 1985 (United States)


    MATHPAL and 3. RAI.- Ground electrostatic field changes due to lightning 89 1 XII 2B-3 Y. GOTO, K. NARITA, M. NAITO and R. FUNAYAMA.- Electric...t 8 3H2 M.W. Maier et al. Tabla 3. - DIrictlon flndar bearing arror (in dagraaa] for tin triggered flaahsa. I Direction Flndar Flaah 1 Flaah

  4. 关于特殊仓库易燃易爆场所雷电防护的探讨%Lightning Protection of Special Warehouse and Flammable and Explosive Places

    Institute of Scientific and Technical Information of China (English)

    廖严峰; 秦玉新


    Basing on the lightning protection design and the construction of the special warehouses, flammable and explosive places under the new norms, the construction program and the notes of direct lightning and induced lightning were analyzed.%介绍特殊仓库内易燃易爆场所在新规范下如何进行防雷工程的设计与施工,重点针对直击雷与感应雷防护措施的施工方案及施工要点进行分析。

  5. 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


    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.

  6. Probability, consequences, and mitigation for lightning strikes of Hanford high level waste tanks

    Energy Technology Data Exchange (ETDEWEB)

    Zach, J.J.


    The purpose of this report is to summarize selected lightning issues concerning the Hanford Waste Tanks. These issues include the probability of a lightning discharge striking the area immediately adjacent to a tank including a riser, the consequences of significant energy deposition from a lightning strike in a tank, and mitigating actions that have been or are being taken. The major conclusion of this report is that the probability of a lightning strike deposition sufficient energy in a tank to cause an effect on employees or the public is unlikely;but there are insufficient, quantitative data on the tanks and waste to prove that. Protection, such as grounding of risers and air terminals on existing light poles, is recommended.

  7. Probability, consequences, and mitigation for lightning strikes to Hanford site high-level waste tanks

    Energy Technology Data Exchange (ETDEWEB)

    Zach, J.J.


    The purpose of this report is to summarize selected lightning issues concerning the Hanford Waste Tanks. These issues include the probability of lightning discharge striking the area immediately adjacent to a tank including a riser, the consequences of significant energy deposition from a lightning strike in a tank, and mitigating actions that have been or are being taken. The major conclusion of this report is that the probability of a lightning strike depositing sufficient energy in a tank to cause an effect on employees or the public is unlikely;but there are insufficient, quantitative data on the tanks and waste to prove that. Protection, such as grounding of risers and air terminals on existing light poles, is recommended.

  8. Using Total Lightning Observations to Enhance Lightning Safety (United States)

    Stano, Geoffrey T.


    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

  9. The Quality Control Algorithms Used in the Creation of NASA Kennedy Space Center Lightning Protection System Towers Meteorological Database (United States)

    Orcutt, John M.; Brenton, James C.


    An accurate database of meteorological data is essential for designing any aerospace vehicle and for preparing launch commit criteria. Meteorological instrumentation were recently placed on the three Lightning Protection System (LPS) towers at Kennedy Space Center (KSC) launch complex 39B (LC-39B), which provide a unique meteorological dataset existing at the launch complex over an extensive altitude range. Data records of temperature, dew point, relative humidity, wind speed, and wind direction are produced at 40, 78, 116, and 139 m at each tower. The Marshall Space Flight Center Natural Environments Branch (EV44) received an archive that consists of one-minute averaged measurements for the period of record of January 2011 - April 2015. However, before the received database could be used EV44 needed to remove any erroneous data from within the database through a comprehensive quality control (QC) process. The QC process applied to the LPS towers' meteorological data is similar to other QC processes developed by EV44, which were used in the creation of meteorological databases for other towers at KSC. The QC process utilized in this study has been modified specifically for use with the LPS tower database. The QC process first includes a check of each individual sensor. This check includes removing any unrealistic data and checking the temporal consistency of each variable. Next, data from all three sensors at each height are checked against each other, checked against climatology, and checked for sensors that erroneously report a constant value. Then, a vertical consistency check of each variable at each tower is completed. Last, the upwind sensor at each level is selected to minimize the influence of the towers and other structures at LC-39B on the measurements. The selection process for the upwind sensor implemented a study of tower-induced turbulence. This paper describes in detail the QC process, QC results, and the attributes of the LPS towers meteorological

  10. Geological Effects on Lightning Strike Distributions

    KAUST Repository

    Berdahl, J. Scott


    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.

  11. 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


    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.

  12. The CHUVA Lightning Mapping Campaign (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


    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

  13. 中美外部雷电防护系统设计规范比较%Comparation of External Lightning Protection Systems Design Requirements between American Standards and Chinese Standards

    Institute of Scientific and Technical Information of China (English)

    傅剑锋; 杨凯; 徐定成


    The related technical requirements of external lightning protection in NFPA 780—2011,such as earthing electrode,downlead,air-termination system,materials of lightning protection system,risk assessment were introduced.NFPA 780—2011 was compared with the related Chinese lightning protection standard,regulations and standards.It could provide reference for more and more overseas project.%从风险评估、防雷系统的材料、接闪器、引下线、接地体等几个方面,介绍了NFPA780—2011外部防雷的相关技术要求,并与中国防雷设计规范的要求进行比较,为海外设计项目提供了设计参考。

  14. Infrasonic Observations from Triggered Lightning (United States)

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


    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.

  15. Analysis on Improvement of Lightning Protection of Nuclear Auxiliary Building Ventilation System of LING AO PhaseⅡ%岭澳二期核辅助厂房通风系统防雷改进分析

    Institute of Scientific and Technical Information of China (English)

    李明钢; 王耀刚; 李东; 关济实; 张立蕊


    Affected by climate, it is always raining in Guang Dong province and the Daya bay nuclear power plant always suffers from lightning. Therefore, it is very important to improve the lightning protection facilities. In order to solve the problems that lightning protection of nuclear auxiliary building ventilation system and other related component in Daya bay nuclear power plant reactor protection system, and improve the lightning protection level, a plan about improving the lightning protection facilities is proposed, and further analysis and demonstration are made as well, which are based on the actual situation. The plan of improving the lightning protection facilities is of great significance to the safe and stable operation of Daya bay nuclear power station.%受气候影响,广东大亚湾核电站多发雷雨,而雷击会严重威胁核电站的安全稳定运行。因此,提高防雷设施十分重要。针对大亚湾核电站反应堆保护系统相关的核辅助厂房通风系统的信号回路结构及容易受到雷电干扰部分的防雷保护问题,结合实际情况,对核辅助厂房通风系统的防雷设施进行改进及分析论证,提高防雷等级。该防雷设施改进方案对大亚湾核电站的安全稳定运行有着重要的意义。

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

    Directory of Open Access Journals (Sweden)

    Antropov I. M.


    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

  17. 太阳能光伏建筑雷电防护问题研究%Study of Lightning Protection for Solar Photovoltaic Building

    Institute of Scientific and Technical Information of China (English)

    郭福雁; 王宁


    Photovoltaic building is a combination of photovoltaic power generation technology and construction technology, which is not only a new trend of photovoltaic applications, but also a new development of green building. Because of the solar photovoltaic panels installed in the roof of buildings, the solar PV system is large and its installation height is high. Therefore, the probability of the lightning strike is apt to be higher than that of the common building. Moreover, the connect-ing wire between the components of the PV system is long, that is extremely vulnerable to the attack of lightning electromag-netic pulse, especially, the core parts of the system are vulnerable to be damaged. So, it is very important to design and install a set of safe, reliable and perfect lightning protection measures for photovoltaic building.%光伏建筑是光伏发电技术与建筑技术的结合,既是光伏应用的新趋势,也是绿色建筑的新发展。由于光伏发电系统的太阳能光伏板安装在建筑物的屋顶,占地面积大,安装高度高,因此,其遭受雷击的概率较一般建筑雷击概率高。而且,构成光伏系统的各部分组件间的连接线缆长,极易遭受雷击电磁脉冲的袭击,损坏系统中的核心部件。因此,设计、安装一套安全、可靠、完善的雷电防护措施对太阳能光伏建筑非常重要。

  18. Aircraft Lightning Protection Handbook (United States)


    ac generator tripoff (6 Instances of tripoff All of these effects will be considered indirect effects Autopilot I- in this discussion, even though...lines = 10’ kilolines (18.8) 0.Flux density: Flux density may be measured in teslas 00 (webers per square meter), gauss (or lines per square centimeter...e-’J (18.12) 1 tesla = 1 weber per meter2 = 1 tesla = 104 gauss the total volt-second product is 1 tesla = 1.550 x 10-5 lines/in 2 1 tesla


    Directory of Open Access Journals (Sweden)

    Abdul Syakur


    Full Text Available The aim of grounding system to protect of electrical equipment and instrumentation system and peopletogether. The lightning stroke near the strucutre of building can damage of equipment and instrumentationsystem. Therefore, it is very important to protect theese electrical and electronic equipment from lightningstrike uses lightning protection system and grounding system.This paper presents kind of grounding system at type of soil and place. The measurement of groundingresistance in soil and septictank have done. Types of soil for grounding resistance measuring aremarshland, clay and rockland.The measurement results of grounding resistance show that value of grounding resistance depend ondeepness of electrode and kind of soil and septictank. Grounding resistance value in septictank is morelower than soil.

  20. Study on Secondary Equipment Lightning Protection for Traction Power Supply System%牵引供电系统二次设备防雷保护研究

    Institute of Scientific and Technical Information of China (English)



    针对铁路牵引供电系统二次回路防雷问题进行研究和分析,提出在所用变压器、交直流电源回路、UPS电源回路、弱电回路等应采取分级防护方案以防过电压。%Study and analysis are made with respect of the problems of the secondary equipment lightning protection for the railway traction power supply system,the paper puts forward the graded protection plan for the auxiliary transformer circuit,AC or DC power circuit,UPS circuit and low voltage circuit so as to prevent the overvoltage.

  1. Lightning: Nature's Probe of Severe Weather for Research and Operations (United States)

    Blakeslee, R.J.


    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.

  2. Measured electric and magnetic fields from an unusual cloud-to-ground lightning flash containing two positive strokes followed by four negative strokes (United States)

    Jerauld, J. E.; Uman, M. A.; Rakov, V. A.; Rambo, K. J.; Jordan, D. M.; Schnetzer, G. H.


    We present electric and magnetic fields measured at multiple stations between about 300 and 800 m of a cloud-to-ground "bipolar" lightning flash containing two initial positive strokes, separated in time by 53 ms and striking ground at two locations separated by about 800 m, followed by four negative strokes that traversed the same path as the second positive stroke. The leader electric field durations for the positive first, positive second, and negative third strokes were about 120 ms, 35 ms, and 1 ms, respectively. The first-stroke leader electric field changes measured at five stations ranged from about +16 to +35 kV/m, the second stroke +8 to +13 kV/m, and the third stroke -0.9 to -1.8 kV/m (atmospheric electricity sign convention). The microsecond-scale return stroke waveforms of the first and second (positive) strokes exhibited a similar "slow-front/fast-transition" to those observed for close negative first strokes. The peak rate-of-change of the positive first stroke electric field normalized to 100 km was about 20 V m-1μs-1, similar to the values observed for close negative first strokes. The positive second stroke was followed by a long continuing current of duration at least 400 ms, while the positive first stroke had a total current duration of only about 1 ms. All four negative strokes were followed by long continuing current, with durations ranging from about 70 ms to about 230 ms. The overall flash duration was about 1.5 s.

  3. Where are the lightning hotspots on Earth? (United States)

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


    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

  4. 浅谈防雷装置对环境安全的影响%Discussion about Influence of Environment Safety Caused by Lightning Protection Equipment

    Institute of Scientific and Technical Information of China (English)

    吕许君; 钟国明; 王涪德


    The causes of waking wohage & touch voltage and their harms to people and livestock were analyzed to arouse the attention for the details of the grounding system construction. The measures to prevent the accident caused by waking voltage & touch voltage were summarized, to reduce the lightning strike injury as far as possible.%通过分析跨步电压和接触电压的成因及它们对人畜的危害。以此引起人们对接地装置施工细节的重视。最后总结出防止跨步电压和接触电压事故的措施。希望尽可能减少由此造成的雷击伤人事故。

  5. Classification of Small Negative Lightning Reports at the KSC-ER (United States)

    Ward, Jennifer G.; Cummins, Kenneth L.; Krider, Philip


    The NASA Kennedy Space Center (KSC) and Air Force Eastern Range (ER) operate an extensive suite of lightning sensors because Florida experiences the highest area density of ground strikes in the United States, with area densities approaching 16 fl/sq km/yr when accumulated in 10x10 km (100 sq km) grids. The KSC-ER use data derived from two cloud-to-ground (CG) lightning detection networks, the "Cloud-to-Ground Lightning Surveillance System" (CGLSS) and the U.S. National Lightning Detection Network (TradeMark) (NLDN) plus a 3-dimensional lightning mapping system, the Lightning Detection and Ranging (LDAR) system, to provide warnings for ground operations and to insure mission safety during space launches. For operational applications at the KSC-ER it is important to understand the performance of each lightning detection system in considerable detail. In this work we examine a specific subset of the CGLSS stroke reports that have low values of the negative inferred peak current, Ip, i.e. values between 0 and -7 kA, and were thought to produce a new ground contact (NGC). When possible, the NLDN and LDAR systems were used to validate the CGLSS classification and to determine how many of these reported strokes were first strokes, subsequent strokes in a pre-existing channel (PEC), or cloud pulses that the CGLSS misclassified as CG strokes. It is scientifically important to determine the smallest current that can reach the ground either in the form of a first stroke or by way of a subsequent stroke that creates a new ground contact. In Biagi et al (2007), 52 low amplitude, negative return strokes ([Ip] strokes) on the basis of video and waveform recordings. Low amplitude return strokes are interesting because they are usually difficult to detect, and they are thought to bypass conventional lightning protection that relies on a sufficient attractive radius to prevent "shielding failure" (Golde, 1977). They also have larger location errors compared to the larger current

  6. Positive lightning and severe weather (United States)

    Price, C.; Murphy, B.


    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.

  7. Grounding and fault protection of the SMUD PVI array (United States)

    Rosen, D.


    If large terrestrial photovoltaic (PV) power plants are to provide an economic source of generation, low-cost, reliable and easily maintainable systems must be developed. In addition, if the system is to be a central station powerplant owned and operated by an electric utility, the design must also be consistent with utility specifications and design standards. The particular solutions developed to address these issues, with regard to grounding and fault protection, for the first phase of the Sacramento Municipal Utility District's (SMUD) 100 mw(ac) PV powerplant are presented. This plant, known as PV1, is nominally rated at 1 mw(ac) and is scheduled to be in operation by the spring of 1984.

  8. Laboratory Investigation on Lightning Flashes to High Voltage Transmission Lines%Laboratory Investigation on Lightning Flashes to High Voltage Transmission Lines

    Institute of Scientific and Technical Information of China (English)

    Thongchai Disyadej; Stanislaw Grzybowski


    This paper presents an investigation on the attractive width of high voltage transmission lines to lightning strikes. In order to design the optimal lightning protection, the estimated number of lightning flashes on the line, which is based on its attractive width, needs to be determined. The investigation was performed using experiments with model tests at the Mississippi State University High Voltage Laboratory. For laboratory experiments, a total of 2,100 negative and positive switching impulse voltages were applied to transmission line models from a conducting rod, which represented a lightning downward leader. Different tested models of transmission lines on a scale of 1:100 were used. The effects of overhead ground wires, phase conductors, tower structures, and the magnitude and polarity of lightning strokes were also studied. The attractive width increased gradually with the height of overhead ground wires and towers as well as the magnitude of the lightning stroke current. Impulse polarity had an impact on the at- tractive width, and the attractive width for negative polarity was larger than that {or positive polarity. The taller tower had more effect on flash distribution to transmission lines than the shorter one. The experimental results agree with the actual transmission line observations published in literature. The new expressions for the attractive width of transmission lines, based on the experimental results, were established. The accurate estimation of the attractive width can help electric power utilities plan transmission systems reliably and economically. The detailed description of the back- ground problem, proposed method, experimental results, and analysis are presented in this paper.

  9. Process Analysis of Double Circuit Transmission Line Trip-out on the Same Tower Due to Lightning

    Institute of Scientific and Technical Information of China (English)

    DUAN Da-peng; REN Zhi-gang; WANG Peng; YE Kuan; CHANG Xiao-qi; LI Wei


    In recent years,several failures of double circuit transmission line on the same tower due to lightning were happened in Beijing power grid.Although it can be reclosed successful,the lightning strike caused a grave threat to the power grid security.The cause of the accident and the accident process were studied for the sake of further understanding of the impact of lightning on power grid.As an example,110 kV double circuit transmission line(Xilong-line) was analyzed.At first,the system topology was given.Through the analysis on relay protection actions and the fault recorder data,over voltageon the insulator strings was calculated.Based on the analysis and the calculation,accident cause and the process were presented respectively.Secondly,it comes to the conclusion that the lightning failure was caused by counterattack.The wave of the lightning over voltage would spread to the not grounded neutral point of the transformers,and make the neutral protective gap breakdown,then cause freewheeling with the frequency of 50 Hz.As results of the relay protection,the double circuit transmission line all tripped out.Finally,the causes of the accident were proposed that included terrain features,large corner towers,strong thunderstorm weather and poor grounded contact of the tower.

  10. A Generalised Fault Protection Structure Proposed for Uni-grounded Low-Voltage AC Microgrids (United States)

    Bui, Duong Minh; Chen, Shi-Lin; Lien, Keng-Yu; Jiang, Jheng-Lun


    This paper presents three main configurations of uni-grounded low-voltage AC microgrids. Transient situations of a uni-grounded low-voltage (LV) AC microgrid (MG) are simulated through various fault tests and operation transition tests between grid-connected and islanded modes. Based on transient simulation results, available fault protection methods are proposed for main and back-up protection of a uni-grounded AC microgrid. In addition, concept of a generalised fault protection structure of uni-grounded LVAC MGs is mentioned in the paper. As a result, main contributions of the paper are: (i) definition of different uni-grounded LVAC MG configurations; (ii) analysing transient responses of a uni-grounded LVAC microgrid through line-to-line faults, line-to-ground faults, three-phase faults and a microgrid operation transition test, (iii) proposing available fault protection methods for uni-grounded microgrids, such as: non-directional or directional overcurrent protection, under/over voltage protection, differential current protection, voltage-restrained overcurrent protection, and other fault protection principles not based on phase currents and voltages (e.g. total harmonic distortion detection of currents and voltages, using sequence components of current and voltage, 3I0 or 3V0 components), and (iv) developing a generalised fault protection structure with six individual protection zones to be suitable for different uni-grounded AC MG configurations.

  11. Study on Lightning Proof of a Vehicle Radar%某车载雷达的防雷研究

    Institute of Scientific and Technical Information of China (English)

    陈世荣; 常继根


    The vehicle radar is easy to get lightning strike when it works on dry and wide highland .The meth-od of protection against direct lightning strike and indirect lightning strike is introduced .The three-dimensional model of the protection range of single lightning rod is obtained via MATLAB programming .Changing soil , embedding electrode deeply , adding resistance-reducing agents are introduced for reducing grounding resist-ance of lightning rod on dry land .The lightning proof of vehicle radar in dry land is improved effectively .%针对车载雷达在高地势开阔、干燥地区容易受到雷击威胁的情况,分别介绍了直击雷和感应雷的车载雷达防雷措施,并通过MATLAB进行了单根避雷针保护范围的三维分析;采用更换土壤、深埋电极、添加降阻剂等多种措施降低干燥地区避雷针的接地电阻,有效地提高了干燥地区车载雷达的防雷效果。

  12. 官地矿6 kV送配电线路的防雷保护%Lightning protection for 6 kV power transmission and distribution lines of Guandi mine

    Institute of Scientific and Technical Information of China (English)



    6 kV送配电线路和雷击跳闸一直是困扰矿井安全供电的一个难题,雷击事故几乎占线路全部跳闸事故的一半以上。找到更好更有效的线路防雷保护措施是每个电力工作者关注的难题。通过对雷击线路的危害的分析,找出各种改善线路雷电性能的措施。%6 kV power transmission and distribution lines and lightning trip is always a problem in coal mine safety power supply lightning accident, accounting for almost half of the line all trip accident. In order to find a better line lightning protection meas-ures more effectively, is a problem to pay attention to each electricity workers. We analyzed the harm of lightning lines, find out all kinds of measures to improve the lightning performance of transmission lines.

  13. Protection against lightning surges provided by line arresters - Furnas' experience on 138 kV system

    Energy Technology Data Exchange (ETDEWEB)

    Camara, Alessandra S.B.; Esmeraldo, Paulo C.V.; Nigri, Armando [FURNAS Centrais Eletricas S.A., Rio de Janeiro, RJ (Brazil)


    Furnas is about to make use of the line surge arrester technology in its network, based on studies that have been developed regarding with line performance improvement. In association to such studies, Furnas has installed six line arresters units on a 138 kV line with an arrester manufacturer cooperation, in order to get some experience on installation and maintenance, besides lightning incidence monitoring and line arrester behavior analysis. This paper presents first results and conclusions related to this 138 kV experimental installation on Furnas system. (author)

  14. Breakdown tests of glass fibre reinforced polymers (GFRP) as part of improved lightning protection of wind turbine blades

    DEFF Research Database (Denmark)

    Madsen, Søren Find; Holbøll, Joachim; Henriksen, Mogens;


    This paper addresses a need for analysing the interaction between electrical discharges and GFRP. A test method for evaluating the breakdown and withstand voltages for materials used in wind turbine blades has been developed. The method is based on IEC 243-3, methods of test for electrical strength...... of solid insulating materials, and simulates the situation in a wind turbine blade, where a lightning discharge penetrates an insulating layer towards an inner earth conductor. Different GFRP materials supplied by Danish wind turbine blade manufacturers have been tested. In the subsequent experiments, both...

  15. Role of upward leaders in modifying the induced currents in solitary down-conductors during a nearby lightning strike to ground (United States)

    Kumar, Udaya


    Electromagnetic field produced by a lightning strike to ground causes significant induction to tall objects in the vicinity. The frequency of occurrence of such nearby ground strikes can be higher than the number of direct strikes. Therefore, a complete knowledge on these induced currents is of practical relevance. However, limited efforts towards the characterisation of such induced currents in tall down-conductors could be seen in the literature. Due to the intensification of the background field caused by the descending stepped leader, tall towers/down-conductors can launch upward leaders of significant length. The nonlinearity in the conductance of upward leader and the surrounding corona sheath can alter the characteristics of the induced currents. Preliminary aspects of this phenomenon have been studied by the author previously and the present work aims to perform a detailed investigation on the role of upward leaders in modifying the characteristics of the induced currents. A consistent model for the upward leader, which covers all the essential electrical aspects of the phenomena, is employed. A first order arc model for representing the conductance of upward leader and a field dependant quadratic conductivity model for the corona sheath is employed. The initial gradient in the upward leader and the field produced by the return stroke forms the excitation. The dynamic electromagnetic response is determined by solving the wave equation using thin-wire time-domain formulation. Simulations are carried out initially to ascertain the role of individual parameters, including the length of the upward leader. Based on the simulation results, it is shown that the upward leader enhances the induced current, and when significant in length, can alter the waveshape of induced current from bipolar oscillatory to unipolar. The duration of the induced current is governed by the length of upward leader, which in turn is dependant on the return stroke current and the

  16. Over-voltage surge arrester for lightning protection; Einsatz von Ueberspannungsableitern beim Blitzschutz. Notwendige Strombelastbarkeit von Varistoren in induktiv gekoppelten Schleifen

    Energy Technology Data Exchange (ETDEWEB)

    Haeberlin, H. [Berner Fachhochschule, Hochschule fuer Technik und Architektur (HTA), Burgdorf, (Switzerland)


    The article discusses the necessary loading characteristics of varistors that are used in inductively coupled loops to provide protection against over-voltages produced by lightning strikes. An overview of various types of commercially available surge arresters is presented; their function and their use in photovoltaic installations is discussed in detail. The calculation of the inductively induced currents is discussed in depth for loops with and without varistors. Diagrams with graphs of current against time and mathematical solutions for the representation of the induced currents are presented in detail. The article is supplemented by examples of the calculation of varistor current and a simplified procedure is presented for the definition of the varistor currents necessary for a particular application.

  17. Atmospheric circulation patterns, cloud-to-ground lightning, and locally intense convective rainfall associated with debris flow initiation in the Dolomite Alps of northeastern Italy (United States)

    Underwood, S. Jeffrey; Schultz, Michael D.; Berti, Metteo; Gregoretti, Carlo; Simoni, Alessandro; Mote, Thomas L.; Saylor, Anthony M.


    The Dolomite Alps of northeastern Italy experience debris flows with great frequency during the summer months. An ample supply of unconsolidated material on steep slopes and a summer season climate regime characterized by recurrent thunderstorms combine to produce an abundance of these destructive hydro-geologic events. In the past, debris flow events have been studied primarily in the context of their geologic and geomorphic characteristics. The atmospheric contribution to these mass-wasting events has been limited to recording rainfall and developing intensity thresholds for debris mobilization. This study aims to expand the examination of atmospheric processes that preceded both locally intense convective rainfall (LICR) and debris flows in the Dolomite region. 500 hPa pressure level plots of geopotential heights were constructed for a period of 3 days prior to debris flow events to gain insight into the synoptic-scale processes which provide an environment conducive to LICR in the Dolomites. Cloud-to-ground (CG) lightning flash data recorded at the meso-scale were incorporated to assess the convective environment proximal to debris flow source regions. Twelve events were analyzed and from this analysis three common synoptic-scale circulation patterns were identified. Evaluation of CG flashes at smaller spatial and temporal scales illustrated that convective processes vary in their production of CF flashes (total number) and the spatial distribution of flashes can also be quite different between events over longer periods. During the 60 min interval immediately preceding debris flow a majority of cases exhibited spatial and temporal colocation of LICR and CG flashes. Also a number of CG flash parameters were found to be significantly correlated to rainfall intensity prior to debris flow initiation.

  18. 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


    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.

  19. Fire Environment Mechanism of Lightning-groundfire for Daxing anling Mountains

    Institute of Scientific and Technical Information of China (English)


    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...

  20. Tropic lightning: myth or menace? (United States)

    McCarthy, John


    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.

  1. New Observations of the Attachment Process in Natural Lightning (United States)

    Tran, M. D.; Rakov, V. A.; Mallick, S.


    We examined the natural-lightning attachment process using high-speed (HS) video records in conjunction with electric field and electric field derivative measurements, all obtained at the Lightning Observatory in Gainesville (LOG), Florida. In different types of strokes (negative first, negative subsequent, and positive first), we observed faintly luminous formations (FLFs) connecting the downward leader to ground. The 2-D lengths of FLFs ranged from 51 to 200 m in negative first strokes (N = 11), from 130 to 908 m in negative subsequent strokes (N=5), and it was 177 m in 1 positive first stroke. The nature of FLFs in negative first strokes differs from that in negative subsequent strokes. We inferred that in first strokes FLFs are mostly composed of positive streamers that developed from the prospective strike point (without a significant upward connecting leader), tens of microseconds prior to the return-stroke onset, while in subsequent strokes they are manifestations of elevated conduction current (of the order of 1 A) in the weakly-conducting defunct channel, occurring in response to the increasing average electric field of the descending leader. The FLF in the positive stroke appeared to be similar to its counterparts in negative first strokes. The streamer connection of the first-stroke leader tip to ground constitutes the break-through phase of the attachment process. Establishment of this connection tens of microseconds prior to the lightning return-stroke onset has never been reported before. We found that the streamer connection did not significantly influence the propagation characteristics of descending leader (and the upward connecting leader, if any), except for always guiding it to the origin of streamers on the grounded object. Implications of the new observations for lightning protection will be discussed. AcknowledgementsThis research was supported in part by NSF and DARPA.

  2. 配电网雷电防护措施总结分析及其应用%The Summary of Lightning Protection Measures and Its Applications for the Distribution Network

    Institute of Scientific and Technical Information of China (English)

    李德峰; 陈述


    配电网很容易遭受雷害引起停电或跳闸事故,影响电网的安全稳定运行。总结了现行的配网防雷的主要措施,对每项措施的优缺点进行分析研究。把总结的防雷措施应用在实际的配电网中,通过2个成功提高配网雷电水平的应用案例,为配电网中心供电所防雷改造及10 kV配网线路防雷改造提供了借鉴。%Distribution network is vulnerable to lightning damage and caused power outages or tripping accidents,which affect the safe and stable operation of the power grid. This paper summarizes the main measures of the Lightning Protection Measures for distribution network. advantages and disadvantages of each of these measures were analyzed. The summary of of the lightning protection measures was applied in the actual distribu-tion network,This paper provides a reference for the Distribu-tion Network to Improve the ability to respond to lightning.

  3. Analysis of overvoltages in overhead ground wires of extra high voltage (EHV) power transmission line under single-phase-to-ground faults

    NARCIS (Netherlands)

    Dudurych, [No Value; Rosolowski, E


    Overhead ground wires (GW) of extra high voltage (EHV) power transmission lines, apart from lightning-induced overvoltage protection are frequently used for carrier-current communication. In this case the ground wires are suspended on insulators, the dielectric strength of which should be sufficient

  4. Lightning activity during the 1999 Superior derecho (United States)

    Price, Colin G.; Murphy, Brian P.


    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.

  5. The GOES-R Lightning Mapper Sensor (United States)

    Buechler, Dennis; Christian, Hugh; Goodman, Steve


    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

  6. Visual Analysis for Nowcasting of Multidimensional Lightning Data

    Directory of Open Access Journals (Sweden)

    Stefan Peters


    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. Lightning Sensors for Observing, Tracking and Nowcasting Severe Weather (United States)

    Price, Colin


    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

  8. Design and Implementation of the Lightning Protection in Jiaxiang GNSS Base Station of CMONOC%陆态网络嘉祥基准站防雷避雷的设计实施

    Institute of Scientific and Technical Information of China (English)

    刘作华; 冯志军


    According to the actual situation of Jiaxiang GNSS base station,This article has been given a detailed de-scription of lightning protection measures for base station. Especially lightning protection in mountain area ,what jiaxiang GNSS base station to do is relatively successful,which can be used for reference to other base stations and some similar geological conditions stations ,microwave radar stations,television stations and other stations.%本文对陆态网络嘉祥基准站的所采取的避雷措施进行了详细的说明。对有类似地质情况的基站、微波站、电视差转台等做好防雷避雷能够起到一定的借鉴作用。

  9. North Alabama Total Lightning Climatology in Support of Lightning Safety Operations (United States)

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


    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

  10. Characteristics of Lightning Discharges and Electric Structure of Thunderstorm

    Institute of Scientific and Technical Information of China (English)

    Qie Xiushu; Zhang Yijun; Zhang Qilin


    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.

  11. Lightning and Life on Exoplanets (United States)

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


    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

  12. Climatology of lightning activity in South China and its relationships to precipitation and convective available potential energy (United States)

    Zheng, Dong; Zhang, Yijun; Meng, Qing; Chen, Luwen; Dan, Jianru


    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.

  13. Theory of ball lightning

    CERN Document Server

    Wu, H -C


    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 ...

  14. The lightning flash

    CERN Document Server

    Cooray, Vernon


    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.

  15. Lightning safety of animals. (United States)

    Gomes, Chandima


    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.

  16. On the initiation of lightning in thunderclouds. (United States)

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


    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.

  17. Lightning phenomenology in the Tampa Bay Area (United States)

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


    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.

  18. Lightning activity and precipitation structure of hailstorms

    Institute of Scientific and Technical Information of China (English)

    FENG GuiLi; QIE XiuShu; YUAN Tie; NIU ShuZhen


    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.

  19. Lightning activity and precipitation structure of hailstorms

    Institute of Scientific and Technical Information of China (English)


    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.

  20. The Quality Control Algorithms Used in the Process of Creating the NASA Kennedy Space Center Lightning Protection System Towers Meteorological Database (United States)

    Orcutt, John M.; Brenton, James C.


    The methodology and the results of the quality control (QC) process of the meteorological data from the Lightning Protection System (LPS) towers located at Kennedy Space Center (KSC) launch complex 39B (LC-39B) are documented in this paper. Meteorological data are used to design a launch vehicle, determine operational constraints, and to apply defined constraints on day-of-launch (DOL). In order to properly accomplish these tasks, a representative climatological database of meteorological records is needed because the database needs to represent the climate the vehicle will encounter. Numerous meteorological measurement towers exist at KSC; however, the engineering tasks need measurements at specific heights, some of which can only be provided by a few towers. Other than the LPS towers, Tower 313 is the only tower that provides observations up to 150 m. This tower is located approximately 3.5 km from LC-39B. In addition, data need to be QC'ed to remove erroneous reports that could pollute the results of an engineering analysis, mislead the development of operational constraints, or provide a false image of the atmosphere at the tower's location.

  1. International Aerospace and Ground Conference on Lightning and Static Electricity (15th) Held in Atlantic City, New Jersey on October 6 - 8, 1992. Addendum (United States)


    Current Channel to a Uniaxially Anisotropic Composite Skin . 62-1 Poh H. Ng, Paul M. McKenna Study of Atmospheric Electrical Events Above Complex Terrain...Lightning by Launch V ehicles .................. ............................... ... 74-1" Rodney A. Perala, Terence H. Rudolph, Calvin C. Easterbrook...MacGorman, Donald R. 55* Rudolph, Terence H. 74 Maier, Matthew R. 28 Matsuura, K. 60, 61 Sanicandro, Rocco 7t Mauriello, A. J. 34 Sargent, Noel B. 36

  2. Fire and lightning: what are the risks and how to be protected?; Incendie et foudre: Quel sont les risques et comment se proteger?

    Energy Technology Data Exchange (ETDEWEB)

    Rigal, F.


    This article reviews the risks of fire and lightning on photovoltaic panels installed on roofs. It appears that the risk of lighting must be taken into account since the direct impact of lightning on photovoltaic panels can be disastrous. The installation of lightning rods or lightning protector is recommended. Concerning fire risks, technical failures or the presence of electric arcs can put fire on solar panels but their occurrence is very low (only about 20 cases reported in Europe for the last 10 years). Tests have shown that standard photovoltaic panels play a low part in the progressing of a fire. There is an electrocution hazard for firemen intervening on a roof bearing solar panels. A device cutting the continuous current generating by the panels is being studied. (A.C.)

  3. Exploring the middle ground between environmental protection and economic growth. (United States)

    Kaplowitz, Michael D; Lupi, Frank; Yeboah, Felix K; Thorp, Laurie G


    Public preference concerning the environment and the economy typically has been characterized as either pro-environmental protection or pro-economic development. Researchers and policymakers increasingly suggest that environmental protection and economic growth are not mutually exclusive. However, use of dichotomous-choice policy preference questions persists. This note empirically examines an alternative response format for the typical dichotomous-choice environmental/economic policy preference question and explores respondents' stated policy preferences in light of their support for recycling. We find that most respondents do not view environmental protection and economic development policy goals to be mutually exclusive. Most respondents view economic growth and environmental protection as compatible suggesting a more heterogeneous view of the environment-economic relationship than oft reported. Hence excluding a middle response choice to the standard environment/economic policy preference question may add measurement error, increase item nonresponse, and fail to account for the views of respondents who view these goals as complementary.

  4. Analysis on Lightning Protection Performance of Metal Oxide Surge Arresters for Transmission Lines%复合绝缘外套线路型ZnO避雷器防雷运行分析

    Institute of Scientific and Technical Information of China (English)

    李谦; 钟定珠; 彭向阳; 樊灵孟; 罗真海; 林火华


    According to analysis of the lightning protection practice of Metal Oxide Surge Arresters on the Guangdong 110 kV and 220 kV Transmission Lines in recent years, the positive effectiveness of Metal Oxide Surge Arresters on lowering the lightning stroke tripp efficiency has been preliminarily affirmed. The existing issues in the site-selection, installation and maintenance are discussed, the beneficial suggestions for popularizationis also presented.%总结了复合绝缘外套线路型ZnO避雷器近年在广东省110、220 kV输电线路的运行经验;肯定了线路避雷器降低线路雷击跳闸率的积极效果;讨论了在解决选点、安装和运行维护等方面存在的问题并提出了建议。

  5. 关中环线站场仪表系统防雷工程设计浅析%Analysis of Instrument System Lightning Surge Protection on Guanzhong Pipeline Station

    Institute of Scientific and Technical Information of China (English)

    李娇媚; 王贵波


    Natural gas station instrument system lightning current intrusion caused equipment damage and affected production in high frequency region. Taken Guanzhong natural gas storage peak shaving pipeline project for instance, in the sight of loop and system, integrated consideration of lightning surge protection, improved the security and the stability of system.%针对天然气站场仪表系统在高雷区受雷电流入侵,导致设备损坏,从而影响生产的问题。以关中环线天然气储气调峰管道工程为例,从回路和系统的角度,综合考虑防雷措施,使系统防雷的可靠性得到提升。

  6. MSFC shuttle lightning research (United States)

    Vaughan, Otha H., Jr.


    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.

  7. Experiments of Wind Turbine Blades with Rocket Triggered Lightning (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.

  8. Fault Characteristics and Protection Scheme of the MMC-UPFC under Different Grounding Design (United States)

    Zheng, Tao; Wang, Ketan; Wu, Dan; Qi, Huanhuan


    The Unified Power Flow Controller (UPFC) based on Modular Multilevel Converter (MMC) is more suitable for high-voltage and large-capacity transmission fields. According to the actual needs of demonstration project, 3 grounding proposals were brought out and the effect of different grounding proposals to the fault characteristics and protection schemes is analyzed in detail. The conclusion that only parallel valve side star connected large resistance grounding is more advantageous in MMC-UPFC was derived.

  9. 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


    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.

  10. Self-response multi-functional composite material base on carbon nanotube paper using deicing, flame retardancy, thermal insulation, and lightning-strike protection (United States)

    Chu, Hetao; Zhang, Zhichun; Liu, Yanju; Leng, Jinsong


    Carbon nanotube paper (CNP) based multi-functional composite material is an attractive candidate for deicing, flame retardancy, thermal insulation and lighting strike protection due to the excellent conductivity, light weight and thin dimensions. In this article, multi-functional carbon nanotube paper was fabricated successfully by using commercial carbon nanotube. As a deicing composite material, carbon nanotube was used directly without pretreatment in fabricating carbon nanotube paper. The conductivities of the carbon nanotube paper and deicing composite were 77.8S/cm and 64.9S/ respectively. Electrical heating and deicing performance were test by infrared camera with deicing time less than 220s and 450s to melt a certain amount of ice under different ambient condition. CNT was grafted by zirconium (IV) butoxide solution and dimethyl dichlorosilicane to form co-oligomers on the tube surface while oligomers decompose under a certain temperature to develop an inorganic layer of silicon zirconium oxide. The oxidizing temperature of carbon nanotube increases more than 20°C and the weight loss rate decreases 20% than the untreated carbon nanotube. Lightning protection material required high electro conductivity, due to the utmost high current in a short time. Therefore, silver nanoparticles were deposited on the surface of carbon nanotube with the diameter around 100nm. The conductivity increased sharply from 84s/cm to1756s/cm with the mount of 5.9wt% Ag of the modified carbon nanotube paper because the silver nanoparticles deposited on the surface. In addition, the silver modified also can be used as thermal insulation material decreasing the infrared radiation.

  11. 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


    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.

  12. Lightning frequency over the Italian peninsula (United States)

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


    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

  13. The verification of lightning location accuracy in Finland deduced from lightning strikes to trees (United States)

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


    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.

  14. Lightning-induced overvoltages in low-voltage systems

    Energy Technology Data Exchange (ETDEWEB)

    Hoeidalen, Hans Kristian


    Lightning-induced overvoltages (LIOs) are a main source of failures in low-voltage overhead line systems. This thesis deals mainly with calculations of LIOs aiming to enable the design of a proper voltage protection. Models for calculation of LIOs are adapted from the literature or developed based on measurements. The models used are believed to be fairly accurate for the first few microseconds, which is usually sufficient for predicting the maximum induced voltage in the system. The lightning channel is modelled by the Modified Transmission Line (MTL) model with the Transmission Line (TL) model as a special case. The coupling between the electrical fields from a lightning channel and an overhead line is modelled by Agrawal`s model. The attenuation of electrical fields over a lossy ground is modelled by Norton`s- or the Surface Impedance methods. The validity of all the applied models is analysed. In addition, measurements have been performed in order to develop models of distribution transformers and low-voltage power installation (LVPI) networks. Simple models of typical transformers and LVPIs are developed for calculations when specific data are unavailable. The practical range of values and its influence on the LIOs in a system is investigated. The main frequency range of interest related to LIOs is 10 kHz - 1 MHz in which all the models are accurate. The adapted or developed models are used to calculate LIOs in low-voltage systems. The influence of various key parameters in the system is investigated. Most important are the return stroke amplitude and rise time, the overhead line height and location, the termination of overhead line segments, neutral grounding, and the ground conductivity. 135 refs., 136 figs., 12 tabs.

  15. 电视转播台雷电防范及措施%Prevention and Measures for Alpine TV Station Lightning

    Institute of Scientific and Technical Information of China (English)



    Based on the fact that the mountain stations vulnerable to lightning,this paper demonstrates light-ning protection measures from the perspective of ground grid,equipotential connection and multilevel lightning protection respectively.After modification,the probability of accidents caused by lighting are greatly reduced, and has attained remarkable results.%针对高山台站易受雷击破坏的特点,分别从接地网、等电位连接和多级浪涌避雷防护等方面叙述了雷击的防范措施,通过防雷技术改造后,雷击造成设备事故的概率大大减少,取得了明显的成效。

  16. 30 CFR 77.508-1 - Lightning arresters; wires entering buildings. (United States)


    ... 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...

  17. 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


    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...

  18. An Integrated 0-1 Hour First-Flash Lightning Nowcasting, Lightning Amount and Lightning Jump Warning Capability (United States)

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


    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

  19. 30 CFR 77.802 - Protection of high-voltage circuits; neutral grounding resistors; disconnecting devices. (United States)


    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Protection of high-voltage circuits; neutral... AND SURFACE WORK AREAS OF UNDERGROUND COAL MINES Surface High-Voltage Distribution § 77.802 Protection of high-voltage circuits; neutral grounding resistors; disconnecting devices. High-voltage...

  20. A Fossilized Energy Distribution of Lightning (United States)

    Pasek, Matthew A.; Hurst, Marc


    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.

  1. Transition and verification of ground fault protection method in Hokuriku Shinkansen line

    Directory of Open Access Journals (Sweden)

    Michiteru Koyanagi


    Full Text Available The electrical discharge gaps called S type horn are applied to the ground fault detection and protection in AC traction power supply system for high speed railway called Shinkansen. In this method, the earth resistance of the steel pipe pillar is an important factor for the ground fault protection by the electrical discharge. In this study, the analyses of the transient characteristics of grounding fault are carried out by using EMTP, and the ground resistance value required to trigger discharge at S type horn was calculated. Moreover, the protection effect of a discharge gap called GP the substation equipment that is a discharge gap which is inserted between rails and substation mesh is evaluated.

  2. Discussion on Matters Involving Protection against Lightning Back Flashover for Trees and Nearby Civilian Houses%树木及邻近民居防雷电反击相关问题探讨

    Institute of Scientific and Technical Information of China (English)

    汝洪博; 马金福; 王海芳


    Based on the research on the mutual effect of protection against lightning measures adopted for trees and nearby civilian houses, the article analyzes the requirements on protection against lightning back flashover for trees and nearby civilian houses where air-termination system are provided, and comes to the following conclusions: requirements on protection against lightning back flashover can be understood as the constraints on the impulse earthing resistance ( Ri) and safe distance ( Sa1) of tree’s earthing electrode; the design value of Ri and Sa1 shall be set according to specification and such constraints; safe distance among underground earthing electrodes and metal pipelines shall be considered for trees and civilian houses adopting separate protection against lightning device; in case Ri and Sa1 in actual works cannot meet protection requirements, other protection measures shall be taken.%以树木及其邻近民居防雷措施的相互影响为研究对象,详细分析安装接闪装置的树木与邻近民居防雷电反击相关要求,得出:防雷电反击相关要求可以看作是树木接地体的冲击接地电阻Ri与安全距离Sa1二者的约束条件, Ri和Sa1的设计要求值除了依照规范设计外,还应结合该约束条件综合考虑;各自独立设计防雷装置的树木与民居建筑尚应考虑地下接地体间及与金属管道的安全距离;当实际工程中Ri和Sa1无法满足防反击要求时,应采取其他防护措施。

  3. Lightning Protection and Grounding Technology for Photoelectric Buildings%光电建筑的防雷及接地

    Institute of Scientific and Technical Information of China (English)

    吴小云; 李建泉; 翟文杰; 程宇旭



  4. Evaluation of the Performance Characteristics of CGLSS II and U.S. NLDN Using Ground-Truth Dalta from Launch Complex 398, Kennedy Space Center, Florida (United States)

    Mata, C. T.; Mata, A. G.; Rakov, V. A.; Nag, A.; Saul, J.


    A new comprehensive lightning instrumentation system has been designed for Launch Complex 39B (LC39B) at the Kennedy Space Center, Florida. This new instrumentation system includes seven synchronized high-speed video cameras, current sensors installed on the nine downconductors of the new lightning protection system (LPS) for LC39B; four dH/dt, 3-axis measurement stations; and five dE/dt stations composed of two antennas each. The LPS received 8 direct lightning strikes (a total of 19 strokes) from March 31 through December 31 2011. The measured peak currents and locations are compared to those reported by the Cloud-to-Ground Lightning Surveillance System (CGLSS II) and the National Lightning Detection Network (NLDN). Results of comparison are presented and analyzed in this paper.

  5. Research on the Lightning Indirect Effects Harm and Protection for Aircraft%飞行器雷电间接效应危害及其防护研究

    Institute of Scientific and Technical Information of China (English)

    滕向如; 刘光斌; 余志勇; 庄信武


    雷电对飞行器的损伤作用分为直接效应和间接效应,间接效应可能导致内部电子电气设备及系统功能紊乱或丧失。本文在分析雷电特性的基础上,应用理论分析和计算的方法,探究了飞行器雷电间接效应的作用机理,并结合GJB 1389A[1]、GJB 2639-1996[2]等标准对间接效应试验和雷电防护方案进行了设计。%The possible damage effects of lightning to aircraft can be divided into direct effects and indirect effects. The indirect effects may lead the function of the inner electrical/electronic equipments and systems to disorder or lose. Work mechanism of the lightning indirect effects is mainly analyzed by the method of theoretical analysis and calculating, which is on the basis of the characters of lightning, the indirect effects test and protection project are designed by referring to the standards GJB 1389A, GJB 2639-1996, etc.

  6. Installation rules for low-voltage lightning arresters; Regles d'installation des parafoudres basse tension

    Energy Technology Data Exchange (ETDEWEB)

    Mignardot, D. [Schneider Electric, 38 - Grenoble (France)


    Following assessment of lightning risk and selection of a suitable lightning arrester for the installation, knowledge of good practice in arrester installation is crucial in obtaining genuinely effective protection. Major concepts here include earthing diagrams, building equipotentiality, lightning arrester cascade arrangements, and device disconnection and coordination plans. Understanding of these concepts is important in ensuring effective protection against overvoltages of atmospheric origin. (authors)

  7. Ground-based astronomical instrument for planetary protection (United States)

    Kendrick, Richard L.; Bennett, Dave; Bold, Matthew


    Planetary protection consists of the measurement and characterization of near-earth objects including earth threatening asteroids and earth orbiting debris. The Lockheed Martin STAR Labs in Palo Alto California is developing new astronomical instruments for use in planetary protection. The observation of asteroids is standard for astronomical facilities and there are available instruments designed with this specific science mission in mind. Orbital debris observation and characterization has a somewhat different set of requirements and includes large fields of view with simultaneous spectro-polarimetric data on multiple closely spaced objects. Orbital debris is comprised of spent rocket bodies, rocket fairing covers, paint chips, various satellite components, debris from satellite collisions and explosions and nonoperational satellites. The debris is present in all orbital planes from Low Earth orbit out to the geosynchronous graveyard orbit. We concentrate our effort on the geosynchronous and nearby orbits. This is because typical groundbased astronomical telescopes are built to track at sidereal rates and not at the 1 degree per second rates that are required to track low earth orbiting objects. The orbital debris materials include aluminum, mylar, solar cell materials, composite matrix material and other materials that are used in the fabrication of satellites and launch vehicles. These materials typically have spectral features in different wavebands than asteroids which are mostly composed of materials with molecular absorption bands such as in H2O. This will drive an orbital debris material identification instrument to wavebands and resolutions that are typically not used in asteroid observations.

  8. 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


    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.

  9. Lightning characteristics of derecho producing mesoscale convective systems (United States)

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


    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.

  10. Lightning Sensors for Observing, Tracking and Nowcasting Severe Weather. (United States)

    Price, Colin


    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.

  11. Lightning Injury: A Review (United States)


    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

  12. Quantification and identification of lightning damage in tropical forests. (United States)

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


    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

  13. Nowcasting of Lightning-Related Accidents in Africa (United States)

    Ihrlich, Laura; Price, Colin


    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.

  14. A Lightning Detector Onboard Austrian Nanosatellite (LiNSAT) (United States)

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


    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

  15. 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....

  16. An Operational Perspective of Total Lightning Information (United States)

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


    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

  17. 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


    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

  18. Lightning injury: a review. (United States)

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


    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.

  19. The physics of lightning

    Energy Technology Data Exchange (ETDEWEB)

    Dwyer, Joseph R., E-mail: [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)


    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.

  20. Numerical modeling of initiation of lightning leaders from tall structures by sprite-producing lightning discharges (United States)

    Pasko, V. P.


    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

  1. 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


    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.

  2. Climate Change and Tropical Total Lightning (United States)

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


    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.

  3. Lightning location system supervising Swedish power transmission network (United States)

    Melin, Stefan A.


    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.

  4. How Australian Female Adolescents Prioritize Pregnancy Protection: A Grounded Theory Study of Contraceptive Histories (United States)

    Smith, Jennifer L.; Skinner, S. Rachel; Fenwick, Jennifer


    Grounded theory principles were systematically employed to reveal key differences in pregnancy risk and underlying disparities in contraceptive use in (a) never-pregnant (b) pregnant-terminated and (c) pregnant-continued teenagers. Analysis of 69 semistructured interviews revealed a bicausal model of pregnancy protection that accounted for…


    Directory of Open Access Journals (Sweden)

    P. V. Kriksin


    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

  6. 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;


    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...

  7. The spectra and temperature of cloud lightning discharge channel

    Institute of Scientific and Technical Information of China (English)


    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.

  8. 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


    facility, when the facility is struck by lightning. In the following examples we will use Dr. Merewether's calculations from a poor quality Faraday cage as the input for the RF coupling analysis. coupling of radio frequency (RF) energy to explosive components is an indirect effect of currents [1]. If HE is adequately separated from the walls of the facility that is struck by disassembled have been turned into Faraday-cage structures to protect against lightning is initiation of the HE. last couple of decades, DOE facilities where HE is manufactured, assembled, stored or lightning. The most sensitive component is typically a detonator, and the safety concern lightning, electrons discharged from the clouds should not reach the HE components. radio receiver, the metal cable of a detonator can extract energy from the EM fields. This to the earth will create electromagnetic (EM) fields in the facility. Like an antenna in a

  9. Thunderbolt in biogeochemistry: galvanic effects of lightning as another source for metal remobilization. (United States)

    Schaller, Jörg; Weiske, Arndt; Berger, Frank


    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.

  10. Lightning flash density in relation to aerosol over Nanjing (China) (United States)

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


    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.

  11. Infrasound Observations from Lightning (United States)

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


    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.

  12. Statistical Evolution of the Lightning Flash (United States)

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


    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

  13. Note on lightning temperature

    Energy Technology Data Exchange (ETDEWEB)

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


    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.

  14. Lightning hazards to aircraft (United States)

    Corn, P. B.


    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.

  15. Lightning and Radar Observations of the 29 May 2004 Tornadic HP Supercell during TELEX (United States)

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


    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.

  16. Lightning in hybrid cable-overhead lines and consequent transient overvoltages

    DEFF Research Database (Denmark)

    Silva, Filipe Miguel Faria da; Schultz Pedersen, Kasper; Bak, Claus Leth


    Whereas lines that consist entirely of underground cable are naturally protected from lightning, the phenomenon must be considered for lines that are a mix of overhead lines and underground cables. The difference between overhead lines and underground cables wave impedances may lead to transient...... overvoltages caused by reflections at the transitions points. This paper explains the phenomenon and analyses the influence of modelling Corona effect, the grounding of the towers and of the cable’s screen on the overvoltage magnitude. The analysis is made both for direct strokes on the overhead line phase......, Transient Overvoltages...

  17. On ULF Signatures of Lightning Discharges (United States)

    Bösinger, T.; Shalimov, S. L.


    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.

  18. Protection Measures for Buildings Based on Coordinating Action Theory of Ground, Foundation and Structure

    Institute of Scientific and Technical Information of China (English)


    Based on the theory of coordinating action of building ground, foundation and structure, this paper presents a modified method for calculating additional stresses on buildings in mining areas by considering the joint effect of curvature deformation and horizontal deformation on buildings. It points out that for buildings over the coal pillar, it is advisable to soften the intermediate ground of buildings when they are affected by mining. For buildings over the goaf, it is preferable to soften the ground at both ends of buildings. In order to enhance the ability of a building to resist tensile deformation, the key measure is to reinforce the bottom foundation of the building. In addition, the concept of "angle of break of building" is proposed. It is because of this angle that the protecting coal pillar is left, which is a better solution than prevailing solutions The findings provide a more scientific basis for mining under buildings.

  19. The effects of lightning on digital flight control systems (United States)

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


    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.


    Directory of Open Access Journals (Sweden)

    Sandra Franova


    Full Text Available We decided to focus our research on two of the basic forms of ground squirrel s behaviour in the semi natural conditions of zoological gardens general activity and protective behavior. Our main goal was to perform a complex analysis of the ground squirrel s behaviour living in captivity and to compare the various categories of behaviour on a set timeline. We performed our research throughout the span of two years 2011 2012, during which we observed two separate ground squirrel colonies A, B. We took our compiled information and subjected these to a thorough statistical analysis and main tools of comparison. Based on a long term observation and analysis of the results, we were able to gather very detailed information about the two categories of the ground squirrel s behavior as well as the various periods on the timeline, which were worked into the ethogram of the ground squirrels living in captivity. The results from 2011 confirmed that the behavior of the ground squirrel bred in captivity both observed categories in the same way as was observed in the wild reaches two peaks with raised frequencies in manifestation of given behavior, mostly in the daily time periods, the first from 9am to 11am and the second from 2.30pm to 5pm. We also noted a change in 2012, when there was a reconstruction nearby the aviaries. These reconstructive activities influenced the behavior significant decrease of activity of the ground squirrels in the presence of the assigned workers approximately until 3pm, from which time also in connection with the lessening of the worker s presence the ground squirrels activity in their aviaries begun to rapidly rise, which held on until 5pm. The peak of protective behavior in 2012 has reached higher levels than the peak in 2011, which we attribute to their vigilance after the previous presence of people. Our results may serve as a basis for improvement of the life conditions of the ground squirrels bred in captivity as well as

  1. Lightning Threat Analysis for the Space Shuttle Launch Pad and the Payload Changeout Room Using Finite Difference Methods (United States)

    Collier, Richard S.


    This report describes finite difference computer calculations for the Space Shuttle Launch Pad which predict lightning induced electric currents and electric and magnetic fields caused by a lightning strike to the Lightning Protection System caternary wire. Description of possible lightning threats to Shuttle Payload components together with specifications for protection of these components, result from the calculation of lightning induced electric and magnetic fields inside and outside the during a lightning event. These fields also induce currents and voltages on cables and circuits which may be connected to, or a part of, shuttle payload components. These currents and voltages are also calculated. These threat levels are intended as a guide for designers of payload equipment to specify any shielding and/or lightning protection mitigation which may be required for payload components which are in the process of preparation or being transferred into the Shuttle Orbiter.

  2. An Assessment of Land Surface and Lightning Characteristics Associated with Lightning-Initiated Wildfires (United States)

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


    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.

  3. F-106 data summary and model results relative to threat criteria and protection design analysis (United States)

    Pitts, F. L.; Finelli, G. B.; Perala, R. A.; Rudolph, T. H.


    The NASA F-106 has acquired considerable data on the rates-of-change of electromagnetic parameters on the aircraft surface during 690 direct lightning strikes while penetrating thunderstorms at altitudes ranging from 15,000 to 40,000 feet. These in-situ measurements have provided the basis for the first statistical quantification of the lightning electromagnetic threat to aircrat appropriate for determining lightning indirect effects on aircraft. The data are presently being used in updating previous lightning criteria and standards developed over the years from ground-based measurements. The new lightning standards will, therefore, be the first which reflect actual aircraft responses measured at flight altitudes. The modeling technique developed to interpret and understand the direct strike electromagnetic data acquired on the F-106 provides a means to model the interaction of the lightning channel with the F-106. The reasonable results obtained with the model, compared to measured responses, yield confidence that the model may be credibly applied to other aircraft types and uses in the prediction of internal coupling effects in the design of lightning protection for new aircraft.

  4. Beijing Lightning Network (BLNET): Configuration, Function and Preliminary Results (United States)

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


    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.

  5. Lightning Radio Source Retrieval Using Advanced Lightning Direction Finder (ALDF) Networks (United States)

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


    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).

  6. Sub-Saharan African ground water protection-building on international experience. (United States)

    Kreamer, David K; Usher, Brent


    Sub-Saharan Africa faces significant challenges in dealing with ground water pollution. These countries can look to successes and missteps on other continents to help choose their own individual paths to ensuring reliable and clean supplies of ground water. In the large view, sub-Saharan Africa can define specific levels of acceptable risk in water quality that drive cleanup efforts and are amenable to acceptance across national and geographic boundaries. Ground water quality databases must be expanded, and data must be available in an electronic form that is flexible, expandable, and uniform, and that can be used over wide geographic areas. Guidance from other continents is available on well construction, sampling and monitoring, interim remediation, technical impracticability, monitored natural attenuation, and many specific issues such as how to deal with small waste generators and septic contamination of water supply wells. It is important to establish a common African view on the appropriateness of other nations' ground water quality guidance for African issues, economic conditions, and community circumstances. Establishing numerical, concentration-based, water quality action levels for pollutants in ground water, which many neighboring African nations could hold comparable, would set the stage for risk-based remediation of contaminated sites. Efforts to gain public, grass-roots understanding and support for stable and balanced enforcement of standards are also key. Finally, effective capacity building in the region could be an eventual solution to ground water quality problems; with increased numbers of trained environmental professionals, ground water throughout the region can be protected and contaminated sites cleaned up.

  7. Jet Stream Interrupter Gap Lightning Protection Device for 35 kV Overhead Transmission Lines%35kV架空输电线路间隙灭弧的研究

    Institute of Scientific and Technical Information of China (English)

    王巨丰; 黄维; 曲振旭; 刘儒


    To address the problem of lightning stroke on 35 kV overhead transmission lines, a jet stream interrupter gap lightning protection device (JSGLPD) for 35 kV overhead transmission lines was developed. When a lightning stroke on the transmission line causes AC flashover on insulator strings, the device is able to quickly cut off the power frequency freewheeling arc to effectively protect the insulator strings against ablation of the power frequency arc. The JSGLPD can achieve the function of limiting the external over-voltage on insulators and avoiding frequent tripping of circuit breaker. Moreover, the movement characteristics of electric arc in jet stream were investigated on the basis of an arc model, in which the arc is assumed to be a chain of small rigid cylindrical current elements, and the arc quenching process was discussed. In addition, a high speed camera system and an oscillograph were used to observe the changes in the current of arc, and the result shows that the arc can be cut off instantly by the high-speed air jet stream.%为解决35 kV架空输电线路的雷击问题,研制了在35 kV架空输电线路上的防雷保护间隙喷射气流灭弧装置.该装置运用了“瞬时疏导”的防雷理念,能够在线路发生雷击闪络时有效地保护绝缘子串免受工频电弧的灼烧,在疏导雷电能量后能够迅速切断工频续流电弧,实现既可以限制绝缘子的外部过电压又可以避免断路器频繁跳闸的功能.笔者在链式电弧模型的基础上结合激波理论研究喷射气流条件下电弧的运动,对电弧的熄灭过程进行了讨论.在高压试验中借助高速摄像机和数字示波器,获取了在高速气流作用下电弧被迅速熄灭的过程图像和数据.

  8. Analysis on Calculation and Characteristic of Ground Lightning Electromagnetic Field Based on Vertical Discharge Channel%基于垂直放电通道的地面雷电电磁场的计算与特征分析

    Institute of Scientific and Technical Information of China (English)



    In order to protect sensitive equipments from harms of lightning electromagnetic impulse field and select suitable safeguard procedures,field intensity and distribution regularity of lightning return-stroke electromagnetic field under vertical discharge channel is required to be analyzed. Therefore,impulse function was used for expressing bottom current of the channel,meanwhile,combining modified transmission line exponential model and according to dipole technique,Maxwell e-quation set was worked out as well as analytical expressions of electric field and electromagnetic field of vertical channel in space were deduced. By means of Cooray-Rubinstein formula,horizontal electric field component under the condition of considering conductivity of the earth was worked out and computation expressions of horizontal electric field component, vertical electric field component and lateral electromagnetic field component of random field points around the channel were obtained. Furthermore,transformation laws of electromagnetic field of random field points around lightning channel with different horizontal distance,height and conductivity of the earth were studied. The results indicate that waveforms and am-plitudes of electric field and electromagnetic field are obviously affected by horizontal distance,height and conductivity of the earth which might provide reliable basis for selecting suitable safeguard procedures.%为保护敏感设备免受雷电电磁脉冲场的危害并选择合适的防护措施,需分析垂直放电通道下雷电回击电磁场的场强及分布规律,为此,利用脉冲函数表示通道底部电流,结合回击电磁场的传输线回击电磁场的传输线(modified transmission line exponential model,MTLE)模型,根据偶极子法求解 Maxwell 方程组,推导垂直通道在空间产生电场与磁场的解析表达式,借助 Cooray-Rubinstein 公式计算在考虑大地电导率的情况下的水平电场分量,

  9. Explore the Technical and Maintenance of Transmission Lines Lightning Protection Measures%输电线路防雷技术及维护措施探讨

    Institute of Scientific and Technical Information of China (English)



    电力资源对社会的进步和发展起着非常大的促进作用。我国地域广阔,输电线路十分复杂,在对电力输电线路产生影响的诸多因素中,雷击是影响输电线路安全的关键。结合学习和工作实践经验,对输电线路防雷技术及其维护措施进行了分析,并提出了粗浅的建议。%Electric power resource of social progress and development plays a great role in promoting. China's vast, transmission lines is very complex, many factors have an impact on electricity transmission lines, and lightning is the key to safe power transmission line impact. Combining study and work experience, technology and transmission lines lightning maintenance measures were analyzed, and made superficial recommendations.

  10. Research on New Airworthiness Requirements of Lightning Protection for Civil Aircraft Fuel Tank Explosion Prevention%民机燃油箱防爆闪电防护新适航要求研究

    Institute of Scientific and Technical Information of China (English)

    张斌; 岳鹏; 薛勇; 周宇穗


    民用飞机燃油箱系统防爆设计是飞机设计的一个重要方面,其中适航对燃油箱系统闪电防护设计要求作为燃油箱防爆设计及验证的一个重要组成部分,历来受到航空工业界及美国联邦航空局( FAA )的普遍关注.通过研究FAA关于民用飞机燃油箱系统防爆方面闪电防护的最新适航要求,总结了相关条款的变化内容及相应的符合性验证方法,并预判了未来航空工业界由此产生的影响,对民用飞机适航验证有一定借鉴意义.%Fuel tank system explosion prevention of civil aircraft is an important part of aircraft design, and air-worthiness requirements lightning protection regulatory for fuel tank system as an important part of fuel tank explo-sion proof design and validation, has attracted widespread attention in the aviation industry and Federal Aviation Administration( FAA) . This paper studies the latest FAA lightning protection airworthiness requirements of civil aircraft fuel tank system, summarized the evolution of the corresponding provisions and compliance validation meth-od, and also predicted the future effect on aviation industry. The results show the method can provide useful refer-ence for the civil aircraft airworthiness certification.

  11. Lightning detection in planetary atmospheres

    CERN Document Server

    Aplin, Karen L


    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.

  12. Lightning medicine in South Africa. (United States)

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


    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.

  13. Lightning severity in Malaysia and some parameters of interest for engineering applications

    Directory of Open Access Journals (Sweden)

    Ab-Kadir Mohd Zainal Abidin


    Full Text Available To the electric utility engineer, the parameters of the flash that are of primary interest are the crest current for the first and subsequent strokes, the waveshape of these currents, correlation between the parameters, the number of strokes per flash and flash incidence rates where the ground flash density, denoted as flashes per square km-year and symbolized by Ng. The first three parameters, as we know them today, are to a very large extent based on the measurements of Berger. Berger's masts, 70 and 80 meters high, were mounted atop Mt. San Salvatore (Switzerland, which is 650 meters above Lake Lugano, where it can be readily noted that these 125 records represent one of the best and most extensive set of data available to the industry to date. This paper focuses on the lightning severity scenario in Malaysia, which could also applicable to other tropic countries, and some of the useful parameters for lightning protection system design and forensic study. Some specific engineering applications have also been summarised, taking into account various lightning parameters, available from past and current measurements available.

  14. Lightning and middle atmospheric discharges in the atmosphere (United States)

    Siingh, Devendraa; Singh, R. P.; Kumar, Sarvan; Dharmaraj, T.; Singh, Abhay K.; Singh, Ashok K.; Patil, M. N.; Singh, Shubha


    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.

  15. 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


    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.

  16. Lightning Return Stroke Current Analysis Using Electromagnetic Models and the 3D-FDTD Method

    Directory of Open Access Journals (Sweden)

    Kaddour Arzag


    Full Text Available The three dimensions finite difference time domain method (3D-FDTD is employed to calculate lightning return stoke current distributions in a vertical lightning channel. The latter is excited at its bottom by a lumped current source above a flat perfectly conducting ground. In this study four lightning return stroke electromagnetic models are used. The calculating approach, which is based on Taflove formulation of the 3D-FDTD method combined to the UPML boundary conditions, is implemented on Matlab environment. For validation needs, the obtained lightning return stroke space and time distributions are compared with others taken from specialized literature.

  17. Lightning incidents in Mongolia

    Directory of Open Access Journals (Sweden)

    Myagmar Doljinsuren


    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.

  18. Exploring Lightning Jump Characteristics (United States)

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


    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.

  19. Lightning Detection by LAC Onboard the Japanese Venus Climate Orbiter, Planet-C (United States)

    Takahashi, Y.; Yoshida, J.; Yair, Y.; Imamura, T.; Nakamura, M.


    Lightning activity in Venus has been a mystery for a long period, although many studies based on observations both by spacecraft and by ground-based telescope have been carried out. This situation may be attributed to the ambiguity of these evidential measurements. In order to conclude this controversial subject, we are developing a new type of lightning detector, LAC (Lightning and Airglow Camera), which will be onboard Planet-C (Venus Climate Orbiter: VCO). Planet-C will be launched in 2010 by JAXA. To distinguish an optical lightning flash from other pulsing noises, high-speed sampling at 50 kHz for each pixel, that enables us to investigate the time variation of each lightning flash phenomenon, is adopted. On the other hand, spatial resolution is not the first priority. For this purpose we developed a new type of APD (avalanche photo diode) array with a format of 8×8. A narrow band interference filter at wavelength of 777.4 nm (OI), which is the expected lightning color based on laboratory discharge experiment, is chosen for lightning measurement. LAC detects lightning flash with an optical intensity of average of Earth’s lightning or less at a distance of 3 Rv. In this paper, firstly we describe the background of the Venus lightning study to locate our spacecraft project, and then introduce the mission details.

  20. Location of lightning stroke on OPGW by use of distributed optical fiber sensor (United States)

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


    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.

  1. Climate change. Projected increase in lightning strikes in the United States due to global warming. (United States)

    Romps, David M; Seeley, Jacob T; Vollaro, David; Molinari, John


    Lightning plays an important role in atmospheric chemistry and in the initiation of wildfires, but the impact of global warming on lightning rates is poorly constrained. Here we propose that the lightning flash rate is proportional to the convective available potential energy (CAPE) times the precipitation rate. Using observations, the product of CAPE and precipitation explains 77% of the variance in the time series of total cloud-to-ground lightning flashes over the contiguous United States (CONUS). Storms convert CAPE times precipitated water mass to discharged lightning energy with an efficiency of 1%. When this proxy is applied to 11 climate models, CONUS lightning strikes are predicted to increase 12 ± 5% per degree Celsius of global warming and about 50% over this century.

  2. Lightning observation on 77 KV transmission lines and survey on their failure modes. 77kV sodensen no kaminari kansoku to kosho yoso no chosa

    Energy Technology Data Exchange (ETDEWEB)

    Katsuragi, Y.; Kato, K.; Yokotani, M. (Chubu Electric Power Co. Inc., Nagoya (Japan))


    It was intended to investigate comprehensively lightning arrestors to prevent two-line power failure due to lightning on a transmission line and the optical ground wire (OPGW), which was found lately problematical due to damages. Lightning observations were carried out for three years on lightning damages to the entire 77 kV transmission lines which carry both two items. This paper summarizes the discussions done by Chubu Electric Power Company of Japan on its 77kV Mizunami-Oi line in the Gifu prefectural district. The lightning observing equipment is an air-cored Rogowskii coil, consisted of a personal computer linked to series of processors and CPU buses including a lightning surge memory to catch lightning behaviors. The power supply is a lithium battery with a capacity of 90 AH which is light in weight and portable. The observation cost is as low as (1/20) of the conventional method. The use of the equipment clarified the lightning modes, and the data analyses elucidated the effects of the lightning arrestor, as well as reduced the power failures and determined the correlation of lightnings with lightning current waveforms which cause damages to the OPGW. The utilization of the developed lightning surge memory, the lightning arrestor operation annunciator, and the ground failure indicator resulted in a great deal of success. 5 refs., 20 figs., 15 tabs.

  3. Lightning not detected on Titan (United States)

    Tretkoff, Ernie


    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)

  4. Application Investigation on Parallel Gap Lightning Protection Device of Composite Insulators for 110 kV Transmission Line%110kV线路复合绝缘子防雷保护并联间隙的应用研究

    Institute of Scientific and Technical Information of China (English)

    陈锡阳; 尹创荣; 葛栋; 张翠霞; 王献丽; 贺子鸣; 杨挺; 王伟然


    笔者介绍东莞供电局110 kV线路复合绝缘子防雷保护并联间隙的应用研究成果,对安装并联间隙后线路雷电性能进行计算,对其引导雷电放电、转移疏导工频电弧、均匀工频电场3种功能加以试验验证,并介绍所研制的110 kV线路复合绝缘子防雷保护并联间隙的现场运行情况.研究结果表明,设计的110 kV输电线路复合绝缘子用并联间隙满足要求,现场运行情况良好,能够作为现有防雷措施的有利补充,具有广阔的应用前景.%The application investigation on parallel gap lightning protection device of composite insulators for the 110 kV overhead transmission line used in Dongguan Power Supply Company is present in this article. The lightning performance calculation after the installation of parallel gap device is carried out. The functions of its guiding lightning discharge,transferring power frequency arc,uniforming power frequency electric field are verified by tests. The operation situation of the 110 kV line parallel gap lightning protection of composite insulator is introduced. The results show that the designs of the parallel gap for 110 kV transmission line composite insulators meet the requirements. The parallel gap is in good on-site operation condition, which can be used as the positive complement the existing lightning protection measures, and has broad application prospects.

  5. Analysis and application of lightning characteristics in Jiangsu from 2006 to 2009%2006-2009年江苏省地闪特征分析及应用

    Institute of Scientific and Technical Information of China (English)

    焦雪; 冯民学; 钟颖颖


    根据2006-2009年江苏省气象部门闪电定位系统资料,对江苏省地闪的总体特征、雷电流强度和地闪的时空分布特征进行了分析,并利用江苏13市雷暴日观测记录,统计了各市地闪密度公式.结果表明,江苏省以负地闪为主,正地闪的平均雷电流强度大干负地闪;地闪随时间变化明显,空间分布和地形密切相关,地闪密集区域应相应加强防雷工作;装设接闪器的建筑物也有遭受雷击的可能,江苏97.75%的地闪的雷电流强度都集中在100 kA以下;各市使用本地化的地闪密度计算公式比IEC公式计算得出的结果更符合实际.%Based on the cloud-to-ground(CG) lightning data of Jiangsu from 2006 to 2009, a study was made of the general characteristics, lightning intensity and temporal-spatial distribution of CG lightning in Jiangsu. According to the thunderstorm days in 13 cities of Jiangsu, equations for calculating density of ground lightning are given. It shows that most of CG flashes are negative, the mean intensity of positive CG flashes are bigger than the negative ones, the CG lightning varies a lot daily and monthly,meanwhile the spatial distribution differs from place to place, we should pay more attention to some dense areas. The structures which are protected by lightning rods still have probabilities to be damaged by lightning. 97. 75% of lightning in Jiangsu is below 100 kA. The calculation result based on local density of ground lightning is more accurate than that calculated by IEC formula.

  6. Airborne Laser Scanning Quantification of Disturbances from Hurricanes and Lightning Strikes to Mangrove Forests in Everglades National Park, USA

    Directory of Open Access Journals (Sweden)

    Kevin Whelan


    Full Text Available Airborne light detection and ranging (LIDAR measurements derived before and after Hurricanes Katrina and Wilma (2005 were used to quantify the impact of hurricanes and lightning strikes on the mangrove forest at two sites in Everglades National Park (ENP. Analysis of LIDAR measurements covering 61 and 68 ha areas of mangrove forest at the Shark River and Broad River sites showed that the proportion of high tree canopy detected by the LIDAR after the 2005 hurricane season decreased significantly due to defoliation and breakage of branches and trunks, while the proportion of low canopy and the ground increased drastically. Tall mangrove forests distant from tidal creeks suffered more damage than lower mangrove forests adjacent to the tidal creeks. The hurricanes created numerous canopy gaps, and the number of gaps per square kilometer increased from about 400~500 to 4000 after Katrina and Wilma. The total area of gaps in the forest increased from about 1~2% of the total forest area to 12%. The relative contribution of hurricanes to mangrove forest disturbance in ENP is at least 2 times more than that from lightning strikes. However, hurricanes and lightning strikes disturb the mangrove forest in a related way. Most seedlings in lightning gaps survived the hurricane impact due to the protection of trees surrounding the gaps, and therefore provide an important resource for forest recovery after the hurricane. This research demonstrated that LIDAR is an effective remote sensing tool to quantify the effects of disturbances such as hurricanes and lightning strikes in the mangrove forest.

  7. Ground-water protection, low-level waste, and below regulatory concern: What`s the connection?

    Energy Technology Data Exchange (ETDEWEB)

    Gruhlke, J.M.; Galpin, F.L. [Environmental Protection Agency, Washington, DC (United States). Office of Radiation Programs


    The Environmental Protection Agency (EPA) has a responsibility to protect ground water and drinking water under a wide variety of statutes. Each statute establishes different but specific requirements for EPA and applies to diverse environmental contaminants. Radionuclides are but one of the many contaminants subject to this regulatory matrix. Low-level radioactive waste (LLW) and below regulatory concern (BRC) are but two of many activities falling into this regulatory structure. The nation`s ground water serves as a major source of drinking water, supports sensitive ecosystems, and supplies the needs of agriculture and industry. Ground water can prove enormously expensive to clean up. EPA policy for protecting ground water has evolved considerably over the last ten years. The overall goal is to prevent adverse effects to human health, both now and in the future, and to protect the integrity of the nation`s ground-water resources. The Agency uses the Maximum Contaminant Levels (MCLs) under the Safe Drinking Water Act as reference points for protection in both prevention and remediation activities. What`s the connection? Both low-level waste management and disposal activities and the implementation of below regulatory concern related to low-level waste disposal have the potential for contaminating ground water. EPA is proposing to use the MCLs as reference points for low-level waste disposal and BRC disposal in order to define limits to the environmental contamination of ground water that is, or may be, used for drinking water.

  8. Holonomic quantum computing in ground states of spin chains with symmetry-protected topological order

    CERN Document Server

    Renes, Joseph M; Brennen, Gavin K; Bartlett, Stephen D


    While solid-state devices offer naturally reliable hardware for modern classical computers, thus far quantum information processors resemble vacuum tube computers in being neither reliable nor scalable. Strongly correlated many body states stabilized in topologically ordered matter offer the possibility of naturally fault tolerant computing, but are both challenging to engineer and coherently control and cannot be easily adapted to different physical platforms. We propose an architecture which achieves some of the robustness properties of topological models but with a drastically simpler construction. Quantum information is stored in the degenerate ground states of spin-1 chains exhibiting symmetry-protected topological order (SPTO), while quantum gates are performed by adiabatic non-Abelian holonomies using only single-site fields and nearest-neighbor couplings. Gate operations respect the SPTO symmetry, inheriting some protection from noise and disorder from the SPTO robustness to local perturbation. A pote...

  9. High-altitude electrical discharges associated with thunderstorms and lightning (United States)

    Liu, Ningyu; McHarg, Matthew G.; Stenbaek-Nielsen, Hans C.


    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.

  10. Comprehensive Analysis of Lightning Performance of Overhead Power Distribution Line with Varied Ground Obliquity%不同地形条件下架空配电线路的防雷分析

    Institute of Scientific and Technical Information of China (English)

    刘靖; 刘明光; 屈志坚; 刘铁


    In order to take lightning problem into consideration comprehensively, we introduced a new model for calculating the lightning outage rate of overhead power distribution line due to direct and indirect lightning strokes. By establishing an improved EGM model of overhead distribution line based on striking distance theory, combining with probability density function of lightning current, we solved the attract range of overhead line, which possesses a nonlinear relationship with line height for different district. Taking the Rusck's formula into consideration, basing on Generalized Integral method, we put forward a new arithmetic for calculating the lightning outage rate which includes indirect lightning. By calculation of two real 10 kV power distribution line, the new method is practical and accurate. The results show that indirect strokes are the main cause of lightning trip out, and for analyzing the lightning performance of overhead power distribution lines, the indirect lightning must be taken into consideration.%雷电活动直接影响到架空电力线路的安全稳定运行,为全面分析架空配电线路的雷害问题,提出了一种计入地形条件影响的分析新方法.先基于雷电的击距理论建立架空配电线路的引雷模型,结合雷电流的概率密度函数,求出了线路在不同高度和不同地形条件下的引雷范围与线路高度呈非线性关系;在确定线路引雷范围的基础上,分别计算了我国不同地域的架空线路直接雷击跳闸率;在对Rusck感应雷过电压研究成果分析的基础上,利用广义积分法得出了不同地形和地域的感应雷击跳闸率计算公式,而且架空配电线路中感应雷击跳闸次数占总雷击跳闸次数能达到83%,在架空线路的防雷分析中应该计入感应雷击的影响.2条10 kV架空线路算例与实际运行情况的对比验证了该计算方法的正确性.

  11. Recreational Trails Reduce the Density of Ground-Dwelling Birds in Protected Areas (United States)

    Thompson, Bill


    Recreational disturbance associated with trails has been identified as one of the major factors causing a decline of native biodiversity within protected areas. However, despite the negative impacts that recreation can have on biodiversity, providing public access to nature is critical for the future of the conservation of biodiversity. As such, many protected area managers are looking for tools to help maintain a balance between public access and biodiversity conservation. The objectives of this study were to examine the impacts of recreational trails on forest-dwelling bird communities in eastern North America, identify functional guilds which are particularly sensitive to recreational trails, and derive guidelines for trail design to assist in managing the impacts of recreational trails on forest-dwelling birds. Trails within 24 publicly owned natural areas were mapped, and breeding bird communities were described with the use of point count surveys. The density of forest birds, particularly of those species which nest or forage on the ground, were significantly positively influenced by the amount of trail-free refuge habitat. Although management options to control trail use in non-staffed protected areas are limited, this study suggests that protected area managers could design and maintain a trail network that would minimize impacts on resident wildlife, while providing recreational opportunities for visitors, by designing their trail network to maximize the area of trail-free habitat.

  12. Numerical Simulation of the Lightning Return Stroke. (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.

  13. Runaway breakdown and hydrometeors in lightning initiation. (United States)

    Gurevich, A V; Karashtin, A N


    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.

  14. Lightning Imaging with LOFAR

    Directory of Open Access Journals (Sweden)

    Scholten Olaf


    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. (United States)

    Weewish Tree, 1979


    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. 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 (United States)

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


    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.

  17. On peculiarities of the method for determining the probability of lightning striking terrestrial explosive objects (United States)

    Gundareva, S. V.; Kalugina, I. E.; Temnikov, A. G.


    We have described a new probabilistic method for calculating and assessing lightning striking terrestrial explosive objects using a combined criterion for the emergence of upward streamer and leader discharges from the elements of the object being protected and lightning rods taking into account the probabilistic nature of the avalanche-streamer and streamer-leader transitions, the trajectories of a downward stepped lightning leader and lightning current. It has been shown that the disregard of possible formation of uncompleted streamer discharges from the elements of the object in the electric field of a downward lightning leader, which can ignite explosive emission, decreases the rated probability of the object being damaged by a lightning stroke by several times.

  18. Areal studies aid protection of ground-water quality in Illinois, Indiana, and Wisconsin (United States)

    Mills, Patrick C.; Kay, Robert T.; Brown, Timothy A.; Yeskis, Douglas J.


    In 1991, the U.S. Geological Survey, in cooperation with the U.S. Environmental Protection Agency, initiated studies designed to characterize the ground-water quality and hydrogeology in northern Illinois, and southern and eastern Wisconsin (with a focus on the north-central Illinois cities of Belvidere and Rockford, and the Calumet region of northeastern Illinois and northwestern Indiana). These areas are considered especially susceptible to ground-water contamination because of the high density of industrial and waste-disposal sites and the shallow depth to the unconsolidated sand and gravel aquifers and the fractured, carbonate bedrock aquifers that underlie the areas. The data and conceptual models of ground-water flow and contaminant distribution and movement developed as part of the studies have allowed Federal, State, and local agencies to better manage, protect, and restore the water supplies of the areas. Water-quality, hydrologic, geologic, and geophysical data collected as part of these areal studies indicate that industrial contaminants are present locally in the aquifers underlying the areas. Most of the contaminants, particularly those at concentrations that exceeded regulatory water-quality levels, were detected in the sand and gravel aquifers near industrial or waste-disposal sites. In water from water-supply wells, the contaminants that were present generally were at concentrations below regulatory levels. The organic compounds detected most frequently at concentrations near or above regulatory levels varied by area. Trichloroethene, tetrachloroethene, and 1,1,1-trichloroethane (volatile chlorinated compounds) were most prevalent in north-central Illinois; benzene (a petroleum-related compound) was most prevalent in the Calumet region. Differences in the type of organic compounds that were detected in each area likely reflect differences in the types of industrial sites that predominate in the areas. Nickel and aluminum were the trace metals

  19. A Study on the technology of the Protective Device Application for the power Telecommunication Facilities

    Energy Technology Data Exchange (ETDEWEB)

    Lee, B.K.; Lee, S.J.; Choi, H.Y. [Korea Electric Power Research Insitute, Taejeon (Korea, Republic of); Lee, B.H.; Jeon, D.K.; Lee, K.O.; Ahn, C.H.; Kim, S.O.; Kim, J.S. [Electrical Engineering and Science Research Center, Seoul (Korea, Republic of)


    In order to protect the power telecommunication system from surge by lightning or switching and ground potential rise, characteristics of surge are analyzed when surge strikes communication system. Surge generator which meets international standard was made and test of protective devices was carried out by using it. Counter measures against surge is established through the analysis of ground potential which varies with transient ground impedance. Also specification for installing protective devices was recommended, which is proper to apply to the field system. (author). 186 refs., 203 figs., 21 tabs.

  20. Challenge of lightning detection with LAC on board Akatsuki spacecraft (United States)

    Takahashi, Yukihiro; Sato, Mitsutero; Imai, Masataka; Yair, Yoav; Fischer, Georg; Aplin, Karen


    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.

  1. Science of Ball Lightning (Fire Ball) (United States)

    Ohtsuki, Yoshi-Hiko


    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

  2. Attempts to Create Ball Lightning with Triggered Lightning (United States)


    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

  3. A statistical scheme to forecast the daily lightning threat over southern Africa using the Unified Model (United States)

    Gijben, Morné; Dyson, Liesl L.; Loots, Mattheus T.


    Cloud-to-ground lightning data from the Southern Africa Lightning Detection Network and numerical weather prediction model parameters from the Unified Model are used to develop a lightning threat index (LTI) for South Africa. The aim is to predict lightning for austral summer days (September to February) by means of a statistical approach. The austral summer months are divided into spring and summer seasons and analysed separately. Stepwise logistic regression techniques are used to select the most appropriate model parameters to predict lightning. These parameters are then utilized in a rare-event logistic regression analysis to produce equations for the LTI that predicts the probability of the occurrence of lightning. Results show that LTI forecasts have a high sensitivity and specificity for spring and summer. The LTI is less reliable during spring, since it over-forecasts the occurrence of lightning. However, during summer, the LTI forecast is reliable, only slightly over-forecasting lightning activity. The LTI produces sharp forecasts during spring and summer. These results show that the LTI will be useful early in the morning in areas where lightning can be expected during the day.

  4. Comparison of Two Algorithms for the Reduction of Noise Events in Orbital Optical Lightning Data (United States)

    Mach, D. M.; Bateman, M. G.


    The Geostationary Lightning Mapper (GLM) will be launched as part of the GOES-R satellite. The GLM on-board software is designed to allow a large amount of non-lightning data (noise) to be transmitted to the ground. This is done so that the ground software can remove the noise while at the same time preserving the weak lightning events in the data stream. The ground software has a noise filter that removes events that do not meet certain coherency requirements. The filter utilizes the location, time, and amplitude of the event, along with the background level to determine the likelihood that the event is actually due to lightning and not noise. Due to various constraints, the technique does not use all relevant information to determine the likelihood that the event is actually due to lightning. A more complete filter that uses the full extent of the information available, including clustering results, should produce better results. However, the extra coding and complexity needed to implement the full clustering based filter may not justify the slightly better results. To test the various filter options, this study uses GLM proxy data generated from numerous ground based and orbital sources that mimic the expected characteristics of the GLM lightning event data. These proxy data sets have noise data added, again based on the expected characteristics of GLM noise data. The full proxy data sets (noise and lightning) are filtered by the two methods and the results compared.

  5. The 13 years of TRMM Lightning Imaging Sensor: From Individual Flash Characteristics to Decadal Tendencies (United States)

    Albrecht, R. I.; Goodman, S. J.; Petersen, W. A.; Buechler, D. E.; Bruning, E. C.; Blakeslee, R. J.; Christian, H. J.


    How often lightning strikes the Earth has been the object of interest and research for decades. Several authors estimated different global flash rates using ground-based instruments, but it has been the satellite era that enabled us to monitor lightning thunderstorm activity on the time and place that lightning exactly occurs. Launched into space as a component of NASA s Tropical Rainfall Measuring Mission (TRMM) satellite, in November 1997, the Lighting Imaging Sensor (LIS) is still operating. LIS detects total lightning (i.e., intracloud and cloud-to-ground) from space in a low-earth orbit (35deg orbit). LIS has collected lightning measurements for 13 years (1998-2010) and here we present a fully revised and current total lightning climatology over the tropics. Our analysis includes the individual flash characteristics (number of events and groups, total radiance, area footprint, etc.), composite climatological maps, and trends for the observed total lightning during these 13 years. We have identified differences in the energetics of the flashes and/or the optical scattering properties of the storms cells due to cell-relative variations in microphysics and kinematics (i.e., convective or stratiform rainfall). On the climatological total lightning maps we found a dependency on the scale of analysis (resolution) in identifying the lightning maximums in the tropics. The analysis of total lightning trends observed by LIS from 1998 to 2010 in different temporal (annual and seasonal) and spatial (large and regional) scales, showed no systematic trends in the median to lower-end of the distributions, but most places in the tropics presented a decrease in the highest total lightning flash rates (higher-end of the distributions).

  6. Industrial accidents triggered by lightning. (United States)

    Renni, Elisabetta; Krausmann, Elisabeth; Cozzani, Valerio


    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.

  7. Lightning location system for power transmission lines; Sodensen rakurai chiten no tanchi system

    Energy Technology Data Exchange (ETDEWEB)

    Kurihara, M. [Central Research Institute of Electric Power Industry, Tokyo (Japan)


    A novel Lightning Location System (LLS) for power transmission lines has been developed. In this system, an optical loop is constituted, wherein a light signal is reflected by an Optical Fiber Composite Ground Wire (OPGW) end, positioned opposite to the incident end, and returns to the incident end. When a lightning lands on an OPGW, the lightning current travels through the steel tower serving as the grounding route and, because the OPGW is a strand of aluminum-clad wires, produces a magnetic field in the OPGW along its longitudinal direction, which causes fluctuations in polarization simultaneously in the light signals traveling, up or down in the opposite directions, through the lightning-struck spot. When the fluctuations are observed at the receiving end, two fluctuations are detected with a certain time difference between the two, and the time difference is the required information because the time difference is equivalent to the time that is twice the time that a light signal requires to travel from the lightning-struck spot to the light-reflecting end. Accordingly, the distance from the lightning-struck spot can be calculated using the observed time difference. In actual observation in a lightning-abundant period of approximately two months and half, fluctuations in polarization were observed 51 times, and there was agreement on the order of second with the LLS lightning detecting time in 43 out of the 51. 5 refs., 3 figs.

  8. Learning from concurrent Lightning Imaging Sensor and Lightning Mapping Array observations in preparation for the MTG-LI mission (United States)

    Defer, Eric; Bovalo, Christophe; Coquillat, Sylvain; Pinty, Jean-Pierre; Farges, Thomas; Krehbiel, Paul; Rison, William


    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

  9. The effects of lightning and high altitude electromagnetic pulse on power distribution lines

    Energy Technology Data Exchange (ETDEWEB)

    Uman, M.A.; Rubinstein, M.; Yacoub, Z. [Florida Univ., Gainesville, FL (United States)


    We simultaneously recorded the voltages induced by lightning on both ends of an unenergized 448-meter long unenergized electric power line and the lightning vertical electric and horizontal magnetic fields at ground level near the line. The lightning data studied and presented here were due both to cloud lightning and to very close (about 20 m from the line) artificially initiated lightning. For cloud sources, a frequency-domain computer program called EMPLIN was used to calculate induced line voltages as a function of source elevation, angle of incidence, and wave polarization of the radiated cloud discharge pulses in order to compare with the measurements. For very-close lightning, the measured line voltages could be grouped into two categories, those in which multiple, similarly shaped, evenly spaced pulses were observed, which we call oscillatory, and those dominated by a principal pulse with subsidiary oscillations of much smaller amplitude, which we call impulsive. The amplitude of the induced voltage ranged from tens of kilovolts for oscillatory voltages to hundreds of kilovolts for impulsive voltages. A new technique is derived for the calculation of the electromagnetic fields from nearby lightning to ground above an imperfectly conducting ground. This technique was used in conjunction with an existing time domain coupling theory and lightning return stroke model to calculate voltages at either end of the line. The results show fair agreement with the measured oscillatory voltage waveforms if corona is ignored and improved results when corona effects are modeled. The modeling of the impulsive voltage, for which local flashover probably successful. In an attempt to understand better the sources of the line voltages for very close lightning, measurements of the horizontal and vertical electric fields 30 m from triggered lightning were obtained.

  10. Acoustic vs Interferometric Measurements of Lightning (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.


    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.

  11. Lightning flash multiplicity in eastern Mediterranean thunderstorms (United States)

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


    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.

  12. Lightning Initiation and Propagation (United States)


    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

  13. TRIP illumines lightning (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.

  14. Lightning position detecting system using OPGW; OPGW wo mochiita rakurai ichi tanchi system

    Energy Technology Data Exchange (ETDEWEB)

    Kurihara, M. [Central Research Institute of Electric Power Industry, Tokyo (Japan)


    Discussions were given to utilize an optical fiber composite aerial ground wire (OPGW) not only as an information transmission path, but also for lightning detection. Power transmission lines are installed with aerial ground wires for lightning shielding, into which optical fibers were assembled to make the system an OPGW. An optical loop is constructed, in which optical signals admitted to an incidence end is turned back at an OPGW end opposing the incidence end so that the optical signals return back to the incidence end. If an OPGW is hit by lightning, a lightning current flows through steel towers as the grounding path. This current flow generates a magnetic field inside the OPGW, causing simultaneously polarized rotation (a Faraday effect) in the same direction in the optical signals going back and forth in the optical loop. When this is observed at the incidence end, polarizing variation is observed twice with a certain time difference, which corresponds to two times of the distance between the lightning point and the turn-back point. Thus a distance to the lightning point can be derived. As compared with other identification systems, this method is characterized by capability of collecting lightning information along power transmission lines at one point, no necessity of a device to be connected to a transmission line, and no necessity of comparative information or clock synchronization. 4 refs.

  15. TT系统接地和防电击简析%Analysis of TT System Grounding and Electric Shock Protection

    Institute of Scientific and Technical Information of China (English)



    阐述IEC 60364-4-41:2005《Low-voltage electrical installations-Part 4-41: Protection for safety-Protection against electric shock》标准规定TT系统内由同一保护电器所保护的所有电气设备必须采用共用接地防电击的原由,举例说明户外农电装置、施工场地、路灯等TT系统应用中的接地和防电击实施方案。着重叙述路灯TT系统共用接地并采用过电流防护电器兼防电击在我国的特殊现实意义。%To elaborate the reason why all electrical equipments protected by the same protective device must adopt common grounding to prevent electric shock as set up in Low-voltage Electrical Installations-Part 4-41:Protection for Safety-Protection against Electric Shock ( IEC 60364 - 4 - 41: 2005) , and to illustrate the implementation plan of grounding and electric shock prevention for outdoor rural power devices, construction sites and street lamps etc. with examples, in particular the special practical significance of TT system of street lamps with common grounding, adopting overcurrent protective devices to prevent against electric shock in China.

  16. 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...

  17. Direct satellite observation of lightning-produced NOx

    Directory of Open Access Journals (Sweden)

    T. Wagner


    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

  18. Lightning Detection Efficiency Analysis Process: Modeling Based on Empirical Data (United States)

    Rompala, John T.


    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.

  19. A Lightning Channel Retrieval Algorithm for the North Alabama Lightning Mapping Array (LMA) (United States)

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


    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

  20. Lightning-based propagation of convective rain fields

    Directory of Open Access Journals (Sweden)

    S. Dietrich


    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.

  1. [Lightning-caused fire, its affecting factors and prediction: a review]. (United States)

    Zhang, Ji-Li; Bi, Wu; Wang, Xiao-Hong; Wang, Zi-Bo; Li, Di-Fei


    Lightning-caused fire is the most important natural fire source. Its induced forest fire brings enormous losses to human beings and ecological environment. Many countries have paid great attention to the prediction of lightning-caused fire. From the viewpoint of the main factors affecting the formation of lightning-caused fire, this paper emphatically analyzed the effects and action mechanisms of cloud-to-ground lightning, fuel, meteorology, and terrain on the formation and development process of lightning-caused fire, and, on the basis of this, summarized and reviewed the logistic model, K-function, and other mathematical methods widely used in prediction research of lightning-caused fire. The prediction methods and processes of lightning-caused fire in America and Canada were also introduced. The insufficiencies and their possible solutions for the present researches as well as the directions of further studies were proposed, aimed to provide necessary theoretical basis and literature reference for the prediction of lightning-caused fire in China.

  2. Analyses of Forming Mechanism in Experiential Method of Protective Angle Based on the Coulomb's Law%基于库仑定律的经验保护角法形成机理分析

    Institute of Scientific and Technical Information of China (English)

    李家启; 江孟蜀; 王代新


    保护角法是一种确定避雷针有效保护范围的计算方法.基于闪电发生前瞬间可视为静电场,提出雷电流库仑引力比理论(①视雷电流为运动点电荷;②该电荷与避雷针尖及地面点间作用遵守库仑定律;③雷电流运动走向由其所受引力比决定),据此分析得到的避雷针保护半径理论式与IEC提供的经验公式一致,为避雷针经验保护角法形成机理提供了理论依据.%The method of protection angle is used for calculating the effective scope of lightning-rod protection. Based on the premise that the instantaneous state of lightning is regarded as electrostatic field, the theory of the lightning current Coulomb force ratio has been presented in this paper. Firstly, the lightning current is treated as a moving point charge. Secondly, the action among the charge and the top of lightning rod and the ground agrees with the Coulomb's law. Thirdly, the path of lightning current moving is decided by the the lightning current Coulomb force ratio. According to the above three assumptions the following is acquired that the theory of the protective radius of lightning rod conforms to the experiential method recommend by IEC. Thus, the result provides a theoretical support for the forming mechanism of the experiential method of protection angle.

  3. Lightning and thermal injuries. (United States)

    Sanford, Arthur; Gamelli, Richard L


    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

  4. Lightning Magnetic Field Measurements around Langmuir Laboratory (United States)

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


    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.

  5. The effects of Sao Paulo urban heat island on lightning activity: Decadal analysis (1999-2009) (United States)

    Bourscheidt, Vandoir; Pinto, Osmar; Naccarato, Kleber P.


    Eleven years of lightning data from the Brazilian Integrated National Lightning Detection Network were used to analyze the effects of the urban heat island (UHI) of Sao Paulo on lightning activity, extending the investigation of previous works. Cloud-to-ground lightning data were analyzed in both spatial and temporal perspectives, using different approaches: flash density, flash rate, thunderstorm hours (TH), and the cell initiation technique (CIT), which aims to identify the onset of thunderstorms. Land surface temperature (LST) from MODIS (Moderate Resolution Imaging Spectroradiometer) was used to analyze the UHI evolution over the years. MODIS data were validated using ground stations, distributed within the urban area. Different time intervals (seasonal and intraday) were used in an attempt to separate local convective systems from synoptic-scale events. The results indicate significant effects of the UHI (using LST) on THs and CIT. The CIT showed a nearly ring pattern, especially during the afternoon (14:00-18:00 LT) of summer months, reinforcing temperature contrast as a condition for storm initiation. The results also suggest an amplification of the UHI effects on thunderstorm activity by local factors (sea and country breeze, synoptic events, and terrain). Higher flash rates were also observed throughout the urban region, which influences the lightning density. Temporal analysis indicates that minimum temperature and lightning activity increase in wintertime. In summary, the results agree with previous studies about the UHI and indicate its importance on lightning occurrence, especially by increasing the temperature contrast and the instability in these regions.

  6. 2000~2007年输电线路雷击闪络统计分析%Statistics and Analysis of Lightning Flashovers of Transmission Lines During 2000~2007

    Institute of Scientific and Technical Information of China (English)

    李晓岚; 陈家宏; 谷山强


    Lightning stroke is one of the important causes of the accidents that occur on transmission lines. With the development of power system, the proportion of outages on transmission lines because of lightning stroke also increases. And according to the lightning accidents results, the lightning stroke characteristics is related to the time factors tightly. In order to analyze the correlativity between the lightning flashover amount and the time factors, about 425 times lightning flashover on 187 lines in l0 power supply companies of 220 kV and 500 kV transmission lines during 2000~2007 are investigated in this paper. The correlativity between the lightning flashover amount and the time factors is analyzed. According to the lightning stroke accidents investigation records, the lightning flashover amount of transmission line increases from the year of 2000 to 2007. In each year lightning flashovers mostly happen in the month of June, July and August. Similarly in each day the flashover amount also varies with the time of day obviously. These lightning flashovers mainly occur during 14:00~21:00 in the afternoon. The analysis results in this paper have a good agreement with the meteorological observations and lightning detection data of lightning location system (LLS). And these results provide good reference for the lightning protection work in power system.

  7. Influence of Towering Complex on Lightning Flash-over Rate for 10 kV Distribution Lines%高耸建筑群对附近10 kV架空线路雷击跳闸率的影响

    Institute of Scientific and Technical Information of China (English)

    谢化安; 谭进; 刘刚


    针对高耸建筑群的存在会降低周边10 kV架空线路雷击跳闸率的问题,根据线路雷击跳闸率的计算公式分析了建筑物的存在对附近10 kV架空线路雷击跳闸率的影响,并结合电气几何模型的击距理论分析了引入高耸建筑物后导线暴露弧与大地暴露弧交点的变化及建筑物相对介电常数、高度、距离、面积对雷电先导阶段导线附近电场、感应过电压和感应雷跳闸率变化的影响,为城区10 kV架空线路防雷水平的评估提供一条新途径.%Aiming at the problem that high-rise buildings will reduce lightning trip-out rate nearby 10 kV overhead lines, this paper analyzes the influence of existence of buildings on the lightning trip-out rate nearby 10 kV overhead lines based on the formula of line lightning trip-out rate. Combining the lightning distance theory of electro-geometrical model, it analyzes the impact of variations of intersection point of the lines exposure arc and the ground exposure arc and its dielectric constant, height, distance, area on the electric field around the lines, induced overvoltage and the rate of induced lightning trip-out at the time of lightning leader. Thus, it provides a new method for assessment of lightning protection a-bility of 10kV transmission lines in urban areas.

  8. Lightning Observations with the Upgraded Lanmguir Lab Lightning Mapping Array (United States)

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


    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.

  9. Variation in Regional and Global Lightning (United States)

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


    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.

  10. a Time-Resolved Photographic Study of Lightning in the Thunderstorm Research International Program (United States)

    Idone, Vincent Peter

    Time-resolved recordings of 118 strokes in both natural and artificially triggered lightning flashes obtained during participation in the Thunderstorm Research International Program (TRIP) have allowed the measurement of leader and return stroke propagation speeds, providing the largest single body of such data to date. The mean two-dimensional return stroke propagation speed found for 63 natural lightning strokes is 11 x 10('7) m/s. The distribution of measured propagation speeds peaks strongly at (TURN)9 x 10('7) m/s and extends from 2.9 to 24 x 10('7) m/s. Propagation speed reductions in upper channel segments are observed in both first and subsequent strokes. Those results are compared with the earlier work of Schonland and McEachron; substantial disparities are found and examined. The return stroke propagation speeds of the triggered lightning strokes are evaluated in three dimensions via stereo photography of the lightning. A mean of 11 x 10('7) m/s is found for 55 strokes, with a range of 6.4 to 16 x 10('7) m/s. Return stroke propagation speed reductions during propagation along the channel are also observed for these triggered lightning strokes. Propagation speeds are determined for 21 natural and 32 triggered lightning dart leaders, with means of 11 x 10('6) m/s and 18 x 10('6) m/s, respectively. Dart leader propagation speed increases near ground are reported for the first time. Variations in the propagation speed and luminous characteristics of four natural lightning dart-stepped leaders, two triggered lightning dart-stepped leaders, and three natural lightning stepped leaders are examined. The analysis reveals a positive correlation between the dart length and the dart leader propagation speed, this being observed in both natural and triggered lightning. Also, a correlation is found between the dart leader and return stroke propagation speed for the triggered lightning data; no such correlation is found for natural lightning. For one stroke of the

  11. Characteristics of the two active stages of lightning activity in two hailstorms (United States)

    Xu, Shuang; Zheng, Dong; Wang, Yongqing; Hu, Pengyu


    Two hailstorms that occurred in Beijing and Tianjin, respectively, are investigated, based mainly on the total lightning data observed by the System d'Alerte Fondre par Interferometric Radioelecctrique (SAFIR3000), the cloud-to-ground (CG) lightning data of a CG lightning location system, and the echo data of a Doppler radar. Both hailstorms exhibited two lightning frequency peaks: the first was before the hailfall and the second was after the hailfall, with the second peak greater than the first. The dominant polarity of the CG lightning was positive in the stage around the first frequency peak, but changed to negative in the stage around the second frequency peak. The evolution of radar echoes and the height distribution of lightning radiation sources are explored, revealing that both hailstorms had stronger convection and the main positive charge occurred at mid levels during the stage around the first frequency peak. However, whilst the Beijing hailstorm experienced the enhancement of convection, with the main positive charge at upper levels around the second frequency peak, the Tianjin hailstorm generated its second frequency peak during the period when the convection kept weakening and the main positive charge dropped to mid-lower levels. Through evaluation of the radar parameters, we investigate the mechanisms responsible for the second stage of active lightning discharge. Furthermore, the lightning activity exhibited a close relationship with radar echo parameters and hailfall. Lightning jump signals were found before the hailfall and were associated with the change ratio of the 40-dBZ echo volume above the -15°C level, which demonstrates the application value of lightning data in severe weather warning.

  12. Characteristics of the Two Active Stages of Lightning Activity in Two Hailstorms

    Institute of Scientific and Technical Information of China (English)

    徐爽; 郑栋; 王咏青; 胡鹏宇


    Two hailstorms that occurred in Beijing and Tianjin, respectively, are investigated, based mainly on the total lightning data observed by the System d’Alerte Fondre par Interferometric Radioelecctrique (SAFIR3000), the cloud-to-ground (CG) lightning data of a CG lightning location system, and the echo data of a Doppler radar. Both hailstorms exhibited two lightning frequency peaks: the first was before the hailfall and the second was after the hailfall, with the second peak greater than the first. The dominant po-larity of the CG lightning was positive in the stage around the first frequency peak, but changed to negative in the stage around the second frequency peak. The evolution of radar echoes and the height distribution of lightning radiation sources are explored, revealing that both hailstorms had stronger convection and the main positive charge occurred at mid levels during the stage around the first frequency peak. However, whilst the Beijing hailstorm experienced the enhancement of convection, with the main positive charge at upper levels around the second frequency peak, the Tianjin hailstorm generated its second frequency peak during the period when the convection kept weakening and the main positive charge dropped to mid–lower levels. Through evaluation of the radar parameters, we investigate the mechanisms responsible for the second stage of active lightning discharge. Furthermore, the lightning activity exhibited a close relationship with radar echo parameters and hailfall. Lightning jump signals were found before the hailfall and were associated with the change ratio of the 40-dBZ echo volume above the–15℃level, which demonstrates the application value of lightning data in severe weather warning.

  13. Lightning climatology over Jakarta, Indonesia, based on long-term surface operational, satellite, and campaign observations (United States)

    Mori, Shuichi; Wu, Peiming; Yamanaka, Manabu D.; Hattori, Miki; Hamada, Jun-Ichi; Arbain, Ardhi A.; Lestari, Sopia; Sulistyowati, Reni; Syamsudin, Fadli


    Lightning frequency over Indonesian Maritime Continent (MC) is quite high (Petersen and Rutledge 2001, Christian et al. 2003, Takayabu 2006, etc). In particular, Bogor (south of Jakarta, west Jawa) had 322 days of lightning in one year (Guinness Book in 1988). Lightning causes serious damage on nature and society over the MC; forest fore, power outage, inrush/surge currents on many kinds of electronics. Lightning climatology and meso-scale characteristics of thunderstorm over the MC, in particular over Jakarta, where social damage is quite serious, were examined. We made Statistical analysis of lightning and thunderstorm based on TRMM Lightning Image Sensor (LIS) and Global Satellite Mapping of Precipitation (GSMaP) together with long-term operational surface observation data (SYNOP) in terms of diurnal, intraseasonal, monsoonal, and interannual variations. In addition, we carried out a campaign observation in February 2015 in Bogor to obtain meso-scale structure and dynamics of thunderstorm over Jakarta to focus on graupel and other ice phase particles inside by using an X-band dual-polarimetric (DP) radar. Recently, Virts et al. (2013a, b) showed comprehensive lightning climatology based on the World Wide Lightning Location Network (WWLLN). However, they also reported problems with its detection efficiency (< 10%) and small sampling frequency (< 0.1% of the time fly over tropics) by satellites. Therefore, we firstly examine in situ lightning data based on SYNOP observed by the Indonesian Agency for Meteorology, Climatology, and Geophysics (BMKG) because lightning is quite local and sporadic phenomena. We've started to analyze lightning characteristics over Jakarta region based on SYNOP as the ground truth data and GSMaP. Variability of lightning frequency around Jakarta was affected much by local conditions, e.g., topography (elevation) and proximity to the coastline. We confirmed the lightning frequency and its diurnal variation around Jakarta were much

  14. Physical properties of volcanic lightning: Constraints from magnetotelluric and video observations at Sakurajima volcano, Japan (United States)

    Aizawa, Koki; Cimarelli, Corrado; Alatorre-Ibargüengoitia, Miguel A.; Yokoo, Akihiko; Dingwell, Donald B.; Iguchi, Masato


    The lightning generated by explosive volcanic eruptions is of interest not only as a promising technique for monitoring volcanic activity, but also for its broader implications and possible role in the origin of life on Earth, and its impact on the atmosphere and biosphere of the planet. However, at present the genetic mechanisms and physical properties of volcanic lightning remain poorly understood, as compared to our understanding of thundercloud lightning. Here, we present joint magnetotelluric (MT) data and video imagery that were used to investigate the physical properties of electrical discharges generated during explosive activity at Sakurajima volcano, Japan, and we compare these data with the characteristics of thundercloud lightning. Using two weeks of high-sensitivity, high-sample-rate MT data recorded in 2013, we detected weak electromagnetic signals radiated by volcanic lightning close to the crater. By carefully inspecting all MT waveforms that synchronized with visible flashes, and comparing with high-speed (3000 frame/s) and normal-speed (30 frame/s) videos, we identified two types of discharges. The first type consists of impulses (Type A) and is interpreted as cloud-to-ground (CG) lightning. The second type is characterized by weak electromagnetic variations with multiple peaks (Type B), and is interpreted as intra-cloud (IC) lightning. In addition, we observed a hybrid MT event wherein a continuous weak current accompanied Type A discharge. The observed features of volcanic lightning are similar to thunderstorm lightning, and the physical characteristics show that volcanic lightning can be treated as a miniature version of thunderstorm lightning in many respects. The overall duration, length, inter-stroke interval, peak current, and charge transfer all exhibit values 1-2 orders of magnitude smaller than those of thunderstorm lightning, thus suggesting a scaling relation between volcanic and thunderstorm lightning parameters that is independent of

  15. Calculations of lightning-induced voltages in medium voltage distribution lines

    Energy Technology Data Exchange (ETDEWEB)

    Munhoz Rojas, Patricio E. [Instituto de Tecnologia para o Desenvolvimento (LACTEC/UFPR), Curitiba, PR (Brazil)], E-mail:; Pinto, Cleverson Luiz da Silva [Companhia Paranaense de Energia (COPEL), Curitiba, PR (Brazil)], E-mail:


    The objective of this paper is to show the results of a new computer program, written in Mat Lab environment, that is intended to calculate the lightning induced voltages in multi-conductor non-homogeneous lines, in order to be able to evaluate the impact of the usual protective measures implemented against lightning-induced disturbances. The main new features of this program are: a coupling model in terms of the scalar potentials referred to a remote ground was adopted; the coupling to the vertical conductors was considered in a manner similar to rest of the line; the describing equations were converted into a system of coupled ordinary differential equations, by a discretization only in space, which was subsequently solved using the powerful ODE solvers existing in Mat Lab. The validation of the new program has been performed by comparing its predicted results with other theoretical and computational results available in the literature and also with other experimental results published in the literature. It is shown that the agreement with other well established theoretical results is very good and, also, that the agreement between the newly calculated results and some published experimental results is better than previously obtained results. (author)

  16. 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


    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).

  17. Lightning Caused Fires and Acres (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...

  18. Lightning related fatalities in livestock: veterinary expertise and the added value of lightning location data. (United States)

    Vanneste, E; Weyens, P; Poelman, D R; Chiers, K; Deprez, P; Pardon, B


    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.

  19. Relationship between lightning activity and vertical airflow characteristics in thunderstorms (United States)

    Wang, Chenxi; Zheng, Dong; Zhang, Yijun; Liu, Liping


    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.

  20. Full scale lightning test technique (United States)

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


    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.


    Directory of Open Access Journals (Sweden)

    Jan Mikeš


    Full Text Available Automated heating, lighting and irrigation systems are nowadays standard features of industrial and commercial buildings, and are also increasingly found in ordinary housing. In addition to the benefits of user comfort, automated technology for buildings saves energy and, above all, it provides enhanced protection against leakage of water and hazardous gases, and against fire hazards. Lightning strikes are a natural phenomenon that poses a significant threat to the safety of buildings. The statistics of the Fire and Rescue Service of the Czech Republic show that buildings are in many cases inadequately protected against lightning strikes, or that systems have been damaged by previous strikes. A subsequent strike can occur within the period between regular inspections, which are normally made at intervals of 2–4 years. Over the whole of Europe, thousands of buildings are subjected to the effects of direct lightning strikes each year. This paper presents ways to carry out wireless monitoring of lightning strikes on buildings and to deal with their impact on lightning conductors. By intervening promptly (disconnecting the power supply, disconnecting the gas supply, sending an engineer to inspect the structure, submitting a report to ARC, etc. we can prevent many downstream effects of direct lightning strikes on buildings (fires, electric shocks, etc. This paper introduces a way to enhance contemporary home automation systems for monitoring lightning strikes based on wireless sensor networks technology.

  2. Lightning in superconductors. (United States)

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


    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.

  3. Lightning Imaging via VHF Emission (United States)

    Kawasaki, Z.


    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.

  4. 车载通信系统电源对感应雷击的防护研究%Indirect Lightning Protection on Power of Vehicle Communication System

    Institute of Scientific and Technical Information of China (English)



    首先建立了雷电流的模型,并对雷电流的时域和频域特征进行分析,通过计算典型雷电流对车载通信系统电源线上的感应电压,进而确定了带有天线的车载通信系统防雷区域以及相应的浪涌保护器(SPD-Surge Protective Device)的通流量、残压等相关技术指标,并对SPD的电路以及安装进行了相应的设计.

  5. Location accuracy evaluation of lightning location systems using natural lightning flashes recorded by a network of high-speed cameras (United States)

    Alves, J.; Saraiva, A. C. V.; Campos, L. Z. D. S.; Pinto, O., Jr.; Antunes, L.


    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.


    Directory of Open Access Journals (Sweden)

    Yu.E. Lapin


    Full Text Available Scientific center of children's health, Russian academy of medical sciences the presented article is dedicated to the urgent issue — formation of the legal grounds of the state policy in children's healthcare protection. Based on the logical and scicentometric analysis of the main international documents on the children's rights there have been pointed out the key provisions, which should be taken into account during the development of measures for the state regulation of public relations in the interests of the children under modern conditions of the Russian federation.Key words: children's rights, children's healthcare protection, state policy, international documents.

  7. Future Expansion of the Lightning Surveillance System at the Kennedy Space Center and the Cape Canaveral Air Force Station, Florida, USA (United States)

    Mata, C. T.; Wilson, J. G.


    The NASA Kennedy Space Center (KSC) and the Air Force Eastern Range (ER) use data from two cloud-to-ground (CG) lightning detection networks, the Cloud-to-Ground Lightning Surveillance System (CGLSS) and the U.S. National Lightning Detection Network (NLDN), and a volumetric mapping array, the lightning detection and ranging II (LDAR II) system: These systems are used to monitor and characterize lightning that is potentially hazardous to launch or ground operations and hardware. These systems are not perfect and both have documented missed lightning events when compared to the existing lightning surveillance system at Launch Complex 39B (LC39B). Because of this finding it is NASA's plan to install a lightning surveillance system around each of the active launch pads sharing site locations and triggering capabilities when possible. This paper shows how the existing lightning surveillance system at LC39B has performed in 2011 as well as the plan for the expansion around all active pads.

  8. Study of High-Energy Particles Correlated with Lightning at Utah's Telescope Array Cosmic Ray Observatory (United States)

    Belz, John


    It is known that x-ray and gamma radiation is emitted by lightning. This phenomenon has been observed by both ground-based and spaced-based detectors. Recently, cosmic ray physicists studying data collected by the 700 square-kilometer Telescope Array Surface Detector (TASD) have observed energetic elementary particles in coincidence with lightning strikes. A subset of these events contain reconstructable ``showers'' which point back to the particles' origin in the Earth's atmosphere. This implies that the energetic radiation may for the first time be traced to its source within the lightning strike. The Lightning Mapping Array (LMA) pioneered at Langmuir Laboratories is the ideal instrument to couple with the TASD in order to perform these studies. These LMA's consist of roughly ten VHF detectors spread over hundreds of square kilometers, and detect impulsive radiation from lightning. The sources of these impulses may be reconstructed and used to create a 3-dimensional GPS-timed reconstruction of a lightning strike. The merger of TA and LMA is also the ideal instrument to search for evidence of a more speculative - but more profound - connection between particle astrophysics and climate: The seeding of lightning strikes by cosmic ray air showers.

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

  10. 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


    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.

  11. Geometrical Effects on the Electromagnetic Radiation from Lightning Return Strokes (United States)

    Willett, J. C.; Smith, D. A.; LeVine, D. M.; Zukor, Dorothy J. (Technical Monitor)


    The morphological difference between the electromagnetic radiation-field waveforms of "first" and "subsequent" return strokes in cloud-to-ground lightning flashes is well known and can be used to identify the formation of new channels to ground. This difference is generally believed due to the existence of branches on first-stroke channels, whereas subsequent strokes re-illuminate only the main channel of a previous stroke; but experimental evidence for this hypothesis is relatively weak. It has been argued for the influence of channel geometry on the fine structure of radiation from subsequent return strokes by comparing the field-change waveforms recorded at the same station from strokes within the same flash and between different flashes of both natural and triggered lightning. The present paper introduces new evidence for both of these hypotheses from a comparison of waveforms between sensors in different directions from the same stroke.

  12. 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


    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.

  13. Measuring Method for Lightning Channel Temperature (United States)

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


    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

  14. Measuring Method for Lightning Channel Temperature (United States)

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


    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.

  15. Lightning NOx and Impacts on Air Quality (United States)

    Murray, Lee T.


    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.

  16. Measuring Method for Lightning Channel Temperature. (United States)

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


    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.

  17. Multivariate Statistical Inference of Lightning Occurrence, and Using Lightning Observations (United States)

    Boccippio, Dennis


    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.

  18. Diagnosis of a tank fire due to a lightning strike in a petroleum facility

    Energy Technology Data Exchange (ETDEWEB)

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


    The aim of this paper is to present ana analysis of the cause of fire in a crude storage tank, which was strike by a lightning discharge in a Petroleum facility located in Colombia, South America. In order to avoid accidents in futures, necessary modifications for the improvement of lightning protection system in crude storage tanks are suggested. Additionally, as pertinent description of the electrical pointy of view, diagnosis and recommendations are presented. (author)

  19. Lightning-induced overvoltages in medium voltage distribution systems and customer experienced voltage spikes

    Energy Technology Data Exchange (ETDEWEB)

    Sabiha, N. A.


    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

  20. Objective Lightning Probability Forecasts for East-Central Florida Airports (United States)

    Crawford, Winfred C.


    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.

  1. High Impact Weather Forecasts and Warnings with the GOES-R Geostationary Lightning Mapper (GLM) (United States)

    Goodman, Steven; Blakeslee, Richard; Koshak, William; Mach, Douglas


    The Geostationary Operational Environmental Satellite (GOES-R) is the next series to follow the existing GOES system currently operating over the Western Hemisphere. A major advancement over the current GOES include a new capability for total lightning detection (cloud and cloud-to-ground flashes) from the Geostationary Lightning Mapper (GLM). The GLM will operate continuously day and night with near-uniform spatial resolution of 8 km with a product refresh rate of less than 20 sec over the Americas and adjacent oceanic regions. This will aid in forecasting severe storms and tornado activity, and convective weather impacts on aviation safety and efficiency. In parallel with the instrument development, a GOES-R Risk Reduction Science Team and Algorithm Working Group Lightning Applications Team have begun to develop cal/val performance monitoring tools and new applications using the GLM alone, in conjunction with other instruments, and merged or blended integrated observing system products combining satellite, radar, in-situ and numerical models. Proxy total lightning data from the NASA Lightning Imaging Sensor (LIS) on the Tropical Rainfall Measuring Mission (TRMM) satellite and regional ground-based lightning networks are being used to develop the pre-launch algorithms, test data sets, and applications, as well as improve our knowledge of thunderstorm initiation and evolution. In this presentation we review the planned implementation of the instrument and suite of operational algorithms.

  2. Arrester installations for improving the lightning performance of double circuits distribution lines

    Energy Technology Data Exchange (ETDEWEB)

    Thanasaksiri, T. [ChiangMai Univ., ChianMai (Thailand). Dept. of Electrical Engineering


    The Provincial Electricity Authority (PEA) of Thailand serves 99 per cent of the the country's power customers. The main power distribution lines used by PEA consist of 22 and 33 kV high voltage distribution systems and a 400/230 V low voltage system. In order to supply more energy and for economic reasons, distribution lines for industrial and commercial loads consist of double circuits. Lightning strikes on either circuit can affect the other. There are different methods that can be used to reduce the number of flashovers on lines and improve the lightning performance of lines. This paper presented a method for improving the lightning performance of 22 kV double circuit overhead distribution lines by means of arrester installations. The study focused both on partial and full arrester installations and considered arrester energy discharge. The paper discussed the electromagnetic transients program (EMTP) model of systems studied, including a pole and footing impedance model; a line model; an arrester model; an insulator model; a flashover model; and a lightning source model. The studied configurations included pole structure types; phase and ground wire conductors; lightning arresters; insulators; and ground rods. It was concluded that full installation provides better lightning performance compared to partial installation. 7 refs., 8 tabs.

  3. Ground-based investigation of atomic oxygen effects on naked Ag and Ag with protective organic coatings

    Institute of Scientific and Technical Information of China (English)

    张蕾; 严川伟; 屈庆; 孙刚; 童靖宇; 曹楚南


    Protective behavior of organic coatings of alkyd, epoxy, urethane and siloxane applied to silver solar cell interconnects and erosion of Ag were investigated by exposure experiments to ground simulation atomic oxygen (AO). Evaluations of their protective properties were made through assessing their mass change characteristics, chemical and physical changes to AO attack. The specimens after exposure were analyzed with SEM/EDAX and XPS. The results indicated that the silver is heavily etched, some coatings such as epoxy, alkyd, urethane are seriously degraded or removed as volatile oxides and the morphology of coatings changed. It is evident that siloxane coatings have excellent properties for anti-AO attack. The erosion product consists of silicon dioxide layer of compact texture and is left on the surface to provide adequate protection from further attack by the energetic AO.

  4. Lightning jump as a nowcast predictor: Application to severe weather events in Catalonia (United States)

    Farnell, C.; Rigo, T.; Pineda, N.


    Several studies reported sudden increases in the total lightning flash rate (intra-cloud+cloud-to-ground) preceding the occurrence of severe weather (large hail, wind gusts associated to thunderstorms and/or tornadoes). Named ;Lightning Jump;, this pattern has demonstrated to be of operational applicability in the forecasting of severe weather phenomena. The present study introduces the application of a lightning jump algorithm, with an identification of cells based solely on total lightning data, revealing that there is no need of radar data to trigger severe weather warnings. The algorithm was validated by means of a dataset severe weather events occurred in Catalonia in the period 2009-2014. Results obtained revealed very promising.

  5. Lightning electromagnetic radiation field spectra in the interval from 0.2 to 20 MHz (United States)

    Willett, J. C.; Bailey, J. C.; Leteinturier, C.; Krider, E. P.


    New Fourier transforms of wideband time-domain electric fields (E) produced by lightning (recorded at the Kennedy Space Center during the summers of 1985 and 1987) were recorded in such a way that several different events in each lightning flash could be captured. Average HF spectral amplitudes for first return strokes, stepped-leader steps, and 'characteristic pulses' are given for significantly more events, at closer ranges, and with better spectral resolution than in previous literature reports. The method of recording gives less bias toward the first large event in the flash and thus yields a large sample of a wide variety of lightning processes. As a result, reliable composite spectral amplitudes are obtained for a number of different processes in cloud-to-ground lightning over the frequency interval from 0.2 to 20 MHz.

  6. A Novel Protection Method for Single Line-to-Ground Faults in Ungrounded Low-Inertia Microgrids

    Directory of Open Access Journals (Sweden)

    Liuming Jing


    Full Text Available This paper proposes a novel protection method for single line-to-ground (SLG faults in ungrounded low-inertia microgrids. The proposed method includes microgrid interface protection and unit protection. The microgrid interface protection is based on the difference between the zero-sequence voltage angle and the zero-sequence current angle at the microgrid interconnection transformer for fast selection of the faulty feeder. The microgrid unit protection is based on a comparison of the three zero-sequence current phase directions at each junction point of load or distributed energy resources. Methods are also included to locate the minimum fault section. The fault section location technology operates according to the coordination of microgrid unit protection. The proposed method responds to SLG faults that may occur in both the grid and the microgrid. Simulations of an ungrounded low-inertia microgrid with a relay model were carried out using Power System Computer Aided Design (PSCAD/Electromagnetic Transients including DC (EMTDC.

  7. Volcanic Lightning in the Laboratory: The Effect of Ultra-Rapid Melting on Ash Particles (United States)

    Mueller, S.; Keller, F.; Helo, C.; Buhre, S.; Castro, J. M.


    Lightning discharge is a common process occurring at explosive volcanic eruptions. During the formation of ash plumes, the dynamical interaction of ash particles creates charges which can, given a sufficiently large charge gradient, cause lightning discharges within the plume (`plume lightning') or from ground to plume (`near-vent lightning'), respectively. Given the extreme heat release during the short duration of a discharge (potentially > 30.000 K), it is likely that the ash particles suspended in a plume are, in any form, affected by volcanic lightning. Genareau et al. (2015) found evidence of glass spherules and glass aggregates in ash deposits of two explosive eruptions (Eyjafjallajökull, Mt. Redoubt), and linked them to short-term melting processes induced by volcanic lightning (analogue to fulgurites). In order to systematically investigate the potential impact of lightning on air-suspended ash we have designed a new experimental setup. An electric arc between two electrodes is generated by a 400 Amp arc welding device. Ash-sized sample material is then blown into the established lightning arc, and a certain proportion of the injected silicate glasses and/or minerals is melted due to the high temperatures in and around the plasma channel. In a first set of experiments, we have used natural volcanic ash from Laacher See Tephra (Eifel, Germany) in distinct size fractions between 36 and 250 microns, in order to qualitatively investigate melting and amalgamation features. Spherule and aggregate textures similar to those reported by Genareau et al. (2015) were successfully reproduced during these experiments. In a second set of experiments, homogenized phonolitic glass fragments, in different size fractions, were subjected to the electric arc and subsequently analyzed under the EMP, in order to investigate effects of "flash melting" on major element glass chemistry. Genareau K, Wardman JB, Wilson TM, McNutt SR, Izbekov P (2015): Lightning-induced volcanic

  8. Experimental generation of volcanic lightning (United States)

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


    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

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

    Institute of Scientific and Technical Information of China (English)


    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...

  10. Activities of the Commission for Ground Surface Protection against Mining Damage in the first quarter of 1985. [Poland

    Energy Technology Data Exchange (ETDEWEB)

    Chroszcz, A.


    Five meetings of the Commission held from January to March 1985 are reported. Underground coal mining in the safety pillar of Bytom was discussed in the light of rock bursts and fatal accidents in the Dymitrow mine. Three coal mines remove the safety pillar: Dymitrow, Szombierki and Rozbark. The Commission discussed: replacing longwall mining with caving by longwall mining with hydraulic stowing, using packings with reduced settling, reducing concentration of mining operations in the area of Bytom center, coordination of underground mining by 3 mines (coordination of mining order, thickness of coal slices or coal seams, concentration of longwall mining in seams with reduced hazards of rock bursts, methods for protection of buildings and industrial plants at the ground surface against ground deformation. The Commission also discussed program of coal mining with hydraulic stowing in the safety pillar of the Batory Steelworks, the Hajduki chemical plant and Chorzow (order of mining, schemes for slice mining, forecasting ground subsidence, methods for protection against mining damage), underground mining with caving or stowing in safety pillars of the Miechowice and Karb mines under Bytom, new regulations on geodetic surveys in underground coal mines.


    Directory of Open Access Journals (Sweden)

    M. I. Fursanov


    Full Text Available The article presents the results of studies of the effects of lightning on low voltage systems of high voltage electrical substations with outdoor switchgears of 110 kV. The topicality of research is associated with a wide spreading of such substations as well as with a high reliability requirements of their work and, also, with their widespread distribution and high probability of lightning strikes to the substation or around it. The highest probable and the most dangerous effects of lightning on low voltage systems of a substation are determined on the basis of critical review and special literature analysis and, also, of systematization of practical information that had been collected during the survey of operating substations. Adequate physical models were developed for the list of hazardous effects based on physical processes of lightning. A model of each effect was studied on the basis of the sensitivity theory. The accuracy and adequacy of the models were verified by means of comparison of calculation results for the models under investigation with the results of calculations fulfilled in accordance with specialized programs, as well as from practical or theoretical data obtained by other authors. The factors that had been included in the models were studied and were defined in accordance with their nature (natural or artificial, the range of possible values in a substation was determined; the coefficients of elasticity were calculated. The obtained results enable to ascertain the contribution of the factor in the effect of lightning and the ability to control the factor. The relationship between the factors and the effects of lightning are shown as graphs. For practical application the information, obtained as the result of the research, was organized in the form of checklists that can be applied when collecting baseline information to develop the lightning protection of the substation, to examine the existing lightning protection, to

  12. Sprites, Elves and Intense Lightning Discharges

    CERN Document Server

    Füllekrug, Martin; Rycroft, Michael J


    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.

  13. A Study on EMTP-Analysis Model for Switch-Board SPD with Gap and Propagation Characteristics of Lightning Surge on Simple Indoor Distribution Line (United States)

    Sakamoto, Yoshiki; Miyazaki, Teru; Okabe, Shigemitsu

    The numbers of damages of home electric appliances due to lightning surges have recently increased. Installing Surge Protective Devices (SPDs) for indoor distribution line is one of countermeasures against the damages, and is also spreading after an amendment of the regulation on indoor wires in 2005. Past studies have showed that the SPDs installed on the switchboard are effective for protecting all the equipment supplied by indoor distribution lines against lightning strokes. However, it is difficult to evaluate the protective effects of the SPDs against lightning strikes when considering complex indoor wires in houses. Thus, a high-precision analysis method is required to clarify the lightning performance of the SPDs for interior wiring. In this research, experiments were conducted to grasp the protective effects of the SPDs installed on a switchboard against lightning surges invading into a house, and an analysis model by the EMTP was proposed. The calculated results relatively agreed with the experimental results.

  14. Lightning current parameters according to IEC 62305. Background, experience and outlook; Blitzstromparameter nach IEC 62305. Hintergrund, Erfahrung und Ausblick

    Energy Technology Data Exchange (ETDEWEB)

    Heidler, Fridolin [Universitaet der Bundeswehr Muenchen, Neubiberg (Germany). Inst. fuer Elektrische Energieversorgung


    Lightning protection measures are specified in the international standard series IEC 62305, which were integrated in European and German standards immediately upon publication in early 2006. The German version is the DIN EN 62 305 (VDE 0185-305). Investigations have shown that lightning currents present the biggest hazard. It is therefore the main danger at which all protective measures of the IEC 62305 standard series are aimed. The lightning current parameters to which the standards refer are based on long-term measurements carried out by Prof. Karl Berger on two telecommunication towers on San Salvatore mountain, Switzerland. (orig.)

  15. Results of Rocket-Triggered Lightning Studies at Camp Blanding, Florida: An Update (United States)

    Rakov, V. A.


    In this review, we present selected results of triggered-lightning experiments at the International Center for Lightning Research and Testing (ICLRT) at Camp Blanding, Florida. After a general update, the following three topics will be covered in more detail. (1)Mechanism of cutoff and re-establishment of current in rocket-triggered lightning. We will present evidence (electric and magnetic fields, channel-base current, time-resolved optical records) that the gap resulting from the vaporization of the triggering wire by the upward positive leader current is bridged by a leader/return-stroke type process (Rakov et al., 2003). Characterization of the attempted interruption and following re-establishment of current to ground in rocket-triggered lightning may have important implications for the understanding of channel current cutoff in natural lightning flashes and may provide new insights into the formation of strokes occurring in the same channel within a millisecond or less. (2)Estimation of input energy in rocket-triggered lightning. In 2000, the electric fields in the immediate vicinity (within 0.1 to 1.6 m) of the triggered lightning channel were measured with Pockels sensors (Miki et al., 2002). We used these fields and associated currents measured at the base of a 2-m strike object to compute power and energy, each per unit channel length and as a function of time (up to 10 ms), associated with return strokes in rocket-triggered lightning. In doing so, we assumed that the vertical component of the electric field at horizontal distances of 0.1 to 1.6 m from the lightning attachment point is not much different from the longitudinal electric field inside the channel (Borovsky, 1995). The estimated mean input energy over the first 50 μs or so is between 1 and 10 kJ/m, consistent with predictions of gas dynamic models. (3)Multiple-station measurements of electric and magnetic fields and their time derivatives produced by close natural lightning discharges. In 2002

  16. Modeling Lightning Impact Thermo-Mechanical Damage on Composite Materials (United States)

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


    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.

  17. Artificially triggered lightning and its characteristic discharge parameters in two severe thunderstorms

    Institute of Scientific and Technical Information of China (English)


    The lightning-induced-damages in the mid-latitude regions are usually caused during severe thunder-storms. But the discharge parameters of natural lightning are difficult to be measured. Five lightning flashes have been artificially triggered with the rocket-wire technique during the passage of two severe thunderstorms. The discharge current and close electric field of return stroke in artificially triggered lightning have been obtained in microsecond time resolution by using current measuring systems and electric field change sensors. The results show that the five triggered lightning flashes include 1 to 10 return strokes, and the average return stroke current is 11.9 kA with a maximum of 21.0 kA and a mini-mum of 6.6 kA, similar to the subsequent return strokes in natural lightning. The half peak width of the current waveform is 39 μs, which is much larger than the usual result. The peak current of stroke Ip (kA) and the neutralized charge Q(C) has a relationship of Ip = 18.5Q0.65. The radiation field of return stroke is 5.9 kV·m-1 and 0.39 kV·m-1 at 60 m and 550 m, respectively. The radiation field decreases as r -1.119 with increase of horizontal distance r from the discharge channel. Based on the well-accepted transmission line model, the speed of return stroke is estimated to be about 1.4×108 m·s-1, with a variation range of (1.1―1.6)×108 m·s-1. Because of the similarities of the triggered lightning and natural lightning, the results in this article can be used in the protection design of natural lightning.

  18. Using Flow Regime Lightning and Sounding Climatologies to Initialize Gridded Lightning Threat Forecasts for East Central Florida (United States)

    Lambert, Winifred; Short, David; Volkmer, Matthew; Sharp, David; Spratt, Scott


    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:// . 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

  19. Lightning hazard reduction at wind farms

    Energy Technology Data Exchange (ETDEWEB)

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


    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.

  20. A Study of Lightning Protection Systems (United States)


    cording systems extended from agnetic field systems from 1 ic and magnetic fields, the about 0.3 microsecond, ly at two Florida stations th the result...voltages can occur, it is often necessary to utilize one or more voltage limiting devices to hold or clamp these transients to a harmless level...channels triggered by Apollo 12 at an altitude of about 2 km struck the high-pressure gas facility within 30 m of the base of the 160 m launch umbilical

  1. 14 CFR 420.71 - Lightning protection. (United States)


    ... metallic power, communication, and instrumentation lines entering an explosive hazard facility. (3... tests, including any action taken to correct deficiencies noted. (b) Electrical power lines. A licensee shall ensure that electric power lines at its launch site meet the following requirements: (1)...

  2. Variable phase propagation velocity for long-range lightning location system (United States)

    Liu, Zhongjian; Koh, Kuang Liang; Mezentsev, Andrew; Enno, Sven-Erik; Sugier, Jacqueline; Füllekrug, Martin


    The electromagnetic wave propagation velocity at low radio frequencies is an important input parameter for lightning location systems that use time of arrival (TOA) method. This velocity is normally fixed at or near the speed of light. However, this study finds that the radio waves from two submarine communication transmitters at 20.9 kHz and 23.4 kHz exhibit phase propagation velocities that are 0.51% slower and 0.64% faster than the speed of light as a result of sky wave contributions and ground effects. Therefore, a novel technique with a variable phase propagation velocity is implemented for the first time in the TOA method and applied to electric field recordings with a long-baseline lightning location system that consists of four radio receivers in western Europe. The lightning locations inferred from variable velocities improve the accuracy of locations inferred from a fixed velocity by 0.89-1.06 km when compared to the lightning locations reported by the UK MetOffice. The normal distributions of the observed phase propagation velocities in small geographic areas are not centered at the speed of light. Consequently, representative velocities can be calculated for many small geographic areas to produce a velocity map over central France where numerous lightning discharges occurred. This map reflects the impact of sky waves and ground effects on the calculation of lightning locations as a result of the network configuration. It is concluded that the use of variable phase propagation velocities mitigates the influence of sky waves and ground effects in long-range lightning location networks.

  3. Impact and Improvement Method of the Biological Effects during the Transmission Tower Being Lightning Struck (United States)

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


    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.

  4. A Methodology to Reduce the Computational Effort in the Evaluation of the Lightning Performance of Distribution Networks

    Directory of Open Access Journals (Sweden)

    Ilaria Bendato


    Full Text Available The estimation of the lightning performance of a power distribution network is of great importance to design its protection system against lightning. An accurate evaluation of the number of lightning events that can create dangerous overvoltages requires a huge computational effort, as it implies the adoption of a Monte Carlo procedure. Such a procedure consists of generating many different random lightning events and calculating the corresponding overvoltages. The paper proposes a methodology to deal with the problem in two computationally efficient ways: (i finding out the minimum number of Monte Carlo runs that lead to reliable results; and (ii setting up a procedure that bypasses the lightning field-to-line coupling problem for each Monte Carlo run. The proposed approach is shown to provide results consistent with existing approaches while exhibiting superior Central Processing Unit (CPU time performances.

  5. Upward Lightning in Rapid City, SD and the First Season of the Upward Lightning Triggering Study (UPLIGHTS) (United States)

    Redmond, C. A.; Warner, T. A.; Helsdon, J. H.; Schumann, C.; Alves, J.; Saba, M. M.; Cummins, K. L.; Orville, R. E.


    For the past three years, upward lightning from ten towers located along the front range of the Black Hills have been observed using both standard- and high-speed cameras and electric field measurements. Multiple towers arranged in close proximity to each other combined with high cloud bases common during the warm season allow Rapid City, South Dakota to be an ideal location to observe upward lightning. The UPward LIGHtning Triggering Study (UPLIGHTS) was developed at South Dakota School of Mines and Technology in cooperation with the National Institute for Space Research in Brazil, to expand the instrumentation available for observation and analysis of the triggering flash type, component, and mechanism along with weather conditions that are favorable for upward lightning development. This project combines local weather observations, multiple electric field meters and field change sensors, and two interferometers with the previously used cameras. UPLIGHTS main goal is to use these resources to better understand the triggering/initiation of upward lightning from tall objects. Based on the analysis of previous years' observations, we proposed that the primary triggering flash type is a positive cloud-to-ground (+CG) in the vicinity of the towers. UPLIGHTS will attempt to determine if upward positive leaders are triggered from these towers by either 1) the approach of horizontally propagating negative stepped leaders associated with either intracloud development or following a +CG return stroke and/or 2) a +CG return stroke as it propagates through a previously formed leader network that is near the towers. The study will also examine the mechanism behind the initiation of upward leaders from multiple tall objects during same flash. This talk will touch on some concepts of previous work along with a summary of summer 2012, the first of three UPLIGHTS seasons.

  6. Identifying eastern Baltic cod nursery grounds using hydrodynamic modelling: knowledge for the design of Marine Protected Areas

    DEFF Research Database (Denmark)

    Hinrichsen, Hans-Harald; Kraus, Gerd; Böttcher, Uwe


    Knowledge of the spatial and temporal distribution of juvenile cod is essential to closing the life cycle in population dynamic models, and it is a prerequisite for the design of Marine Protected Areas (MPAs) aiming at the protection of juveniles. In this study, we use a hydrodynamic model...... evidence that the final destinations of juvenile cod drift routes are affected by decadal climate variability. Application of the methodology to MPA design is discussed, e.g. identifying the overlap of areas with a high probability of successful juvenile cod settlement and regions of high fishing effort...... to examine the spatial distribution of eastern Baltic cod larvae and early juveniles. The transport patterns of the larvae spawned at the three major spawning grounds in the central Baltic Sea were investigated by drift model simulations for the period 1979–2004. We analysed potential habitats...

  7. Economic impact and effectiveness of radiation protection measures in aviation during a ground level enhancement

    Directory of Open Access Journals (Sweden)

    Matthiä Daniel


    Full Text Available In addition to the omnipresent irradiation from galactic cosmic rays (GCR and their secondary products, passengers and aircraft crew may be exposed to radiation from solar cosmic rays during ground level enhancements (GLE. In general, lowering the flight altitude and changing the flight route to lower latitudes are procedures applicable to immediately reduce the radiation exposure at aviation altitudes. In practice, however, taking such action necessarily leads to modifications in the flight plan and the consequential, additional fuel consumption constrains the mitigating measures. In this work we investigate in a case study of the ground level event of December 13th 2006 how potential mitigation procedures affect the total radiation exposure during a transatlantic flight from Seattle to Cologne taking into account constraints concerning fuel consumption and range.

  8. Lightning Location System Data from Wind Power Plants Compared to Meteorological Conditions of Warm- and Cold Thunderstorm Events

    DEFF Research Database (Denmark)

    Vogel, Stephan; Lopez, Javier; Garolera, Anna Candela


    Five years of Lightning Location System (LLS) data from five different wind turbine sites in Europe are analysed. The sites are located in Croatia, Italy, Spain, France and one offshore wind power plant in the North sea. Each location exhibits individual characteristic properties in terms...... of topography, height above mean sea level (AMSL), and average ground flash density. For three sites, the most severe lightning events have been identified during the warm and cold months whereas the other two locations exhibit severe lightning detections mainly during the warm months. In this work severity...

  9. Description and Status of the DC Lightning Mapping Array (United States)

    Blakeslee, Richard; Rudlosky, Scott D.; Bailey, Jeffrey C.; Hall, John M.; Goodman, Steven J.; Zubrick, Steven; Krehbiel, Paul


    The DC Lightning Mapping Array (DC LMA) centered on the Washington, DC metro region has been in operation since 2006. During that time the DC LMA has provided real time data to regional National Weather Service (NSF) Sterling, VA forecast office for operations support and the NOAA Meteorological Development Laboratory (MDL) for new product development and assessment. Data from this network (as well as other from other LMA systems) are now being used to create proxy Geostationary Lightning Mapper (GLM) data sets for GOES-R risk reduction and algorithm development activities. In addition, since spring 2009 data are provided to the Storm Prediction Center in support of Hazardous Weather Testbed and GOES-R Proving Ground activities during the Spring Program. Description, status and plans will be discussed.

  10. Aircraft Lightning Electromagnetic Environment Measurement (United States)

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


    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.

  11. A Conjecture Concerning Ball Lightning

    CERN Document Server

    Sturrock, P A


    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.

  12. Characteristics of the Radiation Field Waveforms Produced by Lightning Return Strokes (United States)

    Lee, Bok-Hee; Eom, Ju-Hong; Kang, Sung-Man; Paek, Seung-Kwon; Kawamura, Tatsuo


    Some features of the radiation field waveforms produced by cloud-to-ground lightning return strokes were investigated. A transient analyzer was used together with electric and magnetic field measuring devices with frequency bandwidths of 200 Hz to 1.6 MHz and 270 Hz to 2.3 MHz, respectively. The initial peak of the first lightning return stroke fields is followed by several large subsidiary peaks, whose amplitudes are a fraction of that of the initial peak and decrease with time. The subsidiary peaks of the first lightning return stroke fields may be caused by the effect of branches of leader channels. The mean amplitude ratios of the subsidiary peaks to the first return stroke field peak were widely distributed over the ranges of 0.25-0.8, and the mean time interval between the subsidiary peaks ranged from 5 to 15 μs. Detailed statistical analysis showed that the time interval between the subsidiary peaks and the ratio of the subsidiary peaks to the first lightning return stroke field peak in the present work are less than those obtained in subtropical and tropical regions. The parameters characterizing the wave tail of lightning return stroke fields are closely related to the propagation velocity and length of return stroke throughout the entire leader channel, and the subsidiary large pulses in the wave tail of return stroke fields seem to be associated with the resonance in major branches of lightning return stroke channels.

  13. A Comparative Study on the Positive Lightning Return Stroke Electric Fields in Different Meteorological Conditions

    Directory of Open Access Journals (Sweden)

    Chin-Leong Wooi


    Full Text Available Positive cloud-ground lightning is considerably more complex and less studied compared to the negative lightning. This paper aims to measure and characterize the significant parameters of positive return strokes electric field, namely, the zero-to-peak rise time, 10–90% rise time, slow front duration, fast transition rise time (10–90%, zero-crossing time, and opposite polarity overshoot relative to peak. To the best of the authors’ knowledge, this is the first time such detailed characteristics of positive lightning in Malaysia are thoroughly analyzed. A total of 41 positive lightning flashes containing 48 return strokes were analyzed. The average multiplicity is 1.2 strokes per flash. The majority of positive lightning was initiated from the primary positive charge rather than as a byproduct of in-cloud discharges. The cumulative probability distribution of rise time parameters, opposite polarity overshoot relative to peak, and slow front amplitude relative to peak are presented. A comparison between studies in four countries representing tropic, subtropic, and temperate regions was also carried out. Measured parameters in Florida, Sweden, and Japan are generally lower than those in Malaysia. Positive lightning occurrences in tropical regions should be further studied and analyzed to improve our current understanding on positive return strokes.

  14. 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:,; 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)


    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)

  15. The kinematic and microphysical control of lightning rate, extent, and NOX production (United States)

    Carey, Lawrence D.; Koshak, William; Peterson, Harold; Mecikalski, Retha M.


    This study investigates the kinematic and microphysical control of lightning properties, particularly those that may govern the production of nitrogen oxides (NOX = NO + NO2) via lightning (LNOX), such as flash rate, type, and extent. The NASA Lightning Nitrogen Oxides Model (LNOM) is applied to lightning observations following multicell thunderstorms through their lifecycle in a Lagrangian sense over Northern Alabama on 21 May 2012 during the Deep Convective Clouds and Chemistry (DC3) experiment. LNOM provides estimates of flash rate, type, channel length distributions, channel segment altitude distributions (SADs), and LNOX production profiles. The LNOM-derived lightning characteristics and LNOX production are compared to the evolution of radar-inferred updraft and precipitation properties. Intercloud, intracloud (IC) flash SAD comprises a significant fraction of the total (IC + cloud-to-ground [CG]) SAD, while increased CG flash SAD at altitudes >6 km occurs after the simultaneous peaks in several thunderstorm properties (i.e., total [IC + CG] and IC flash rate, graupel volume/mass, convective updraft volume, and maximum updraft speed). At heights 6 km. Graupel volume/mass, updraft volume, and maximum updraft speed are all well correlated to the total flash rate (correlation coefficient, ρ ≥ 0.8) but are less correlated to total flash extent (ρ ≥ 0.6) and total LNOX production (ρ ≥ 0.5). Although LNOM transforms lightning observations into LNOX production values, these values are estimates and are subject to further independent validation.

  16. Jovian Lightning and Moonlit Clouds (United States)


    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

  17. The Colorado Lightning Mapping Array (United States)

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


    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 (, 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

  18. Lightning Reporting at 45th Weather Squadron: Recent Improvements (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.


    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 to calculate the probability of any nearby lightning stroke. being within any radius of any point of interest was developed and is being implemented. This may supersede the use of location error ellipses. The 45 WS is pursuing adding data from nine NLDN sensors into 4DLSS in

  19. Implementing planetary protection on the Atlas V fairing and ground systems used to launch the Mars Science Laboratory. (United States)

    Benardini, James N; La Duc, Myron T; Ballou, David; Koukol, Robert


    On November 26, 2011, the Mars Science Laboratory (MSL) launched from Florida's Cape Canaveral Air Force Station aboard an Atlas V 541 rocket, taking its first step toward exploring the past habitability of Mars' Gale Crater. Because microbial contamination could profoundly impact the integrity of the mission, and compliance with international treaty was a necessity, planetary protection measures were implemented on all MSL hardware to verify that bioburden levels complied with NASA regulations. The cleanliness of the Atlas V payload fairing (PLF) and associated ground support systems used to launch MSL were also evaluated. By applying proper recontamination countermeasures early and often in the encapsulation process, the PLF was kept extremely clean and was shown to pose little threat of recontaminating the enclosed MSL flight system upon launch. Contrary to prelaunch estimates that assumed that the interior PLF spore burden ranged from 500 to 1000 spores/m², the interior surfaces of the Atlas V PLF were extremely clean, housing a mere 4.65 spores/m². Reported here are the practices and results of the campaign to implement and verify planetary protection measures on the Atlas V launch vehicle and associated ground support systems used to launch MSL. All these facilities and systems were very well kept and exceeded the levels of cleanliness and rigor required in launching the MSL payload.

  20. FDTD Electromagnetic Analysis of a Wind Turbine Generator Tower Struck by Lightning (United States)

    Nagao, Mitsuhiro; Nagaoka, Naoto; Baba, Yoshihiro; Ametani, Akihiro

    Transient current distributions within the grounding systems of a wind-turbine-generator (WTG) tower struck by lightning and its neighboring WTG tower, and transient electric field inside these towers have been calculated using the finite-difference time-domain (FDTD) method. The grounding terminal for the generator inside the lightning-struck WTG tower is connected to that inside the neighboring WTG tower through a long insulated wire. About 40% of the lightning current flows in the grounding grid of the neighboring tower at 30μ s. Inside the towers, the radial component of electric field is most significant. Its peak value is about 1kV/m near the base of each tower when a lightning current having a magnitude of 30kA and a 10-to-90% risetime of 2.5μ s is injected. The electric field decreases with increasing the height of the observation point in the towers. When the grounding terminals are buried below the substructure (the grounding grids are connected via an underground insulated wire), the electric field inside the tower is significantly reduced.

  1. Lightning location with variable radio wave propagation velocity (United States)

    Liu, Zhongjian; Koh, Kuang Liang; Mezentsev, Andrew; Sugier, Jacqueline; Fullekrug, Martin


    Lightning discharges can be located by triangulation of their broadband electromagnetic pulses in long-baseline (~500 km) radio receiver networks. Here we apply the time of arrival difference (TOA) method to electric field recordings with a low frequency radio receiver array consisting of four stations in western Europe. The electromagnetic wave propagation velocity at low radio frequencies is an important input parameter for the TOA calculation and it is normally assumed to be equal to the speed of light. However, the radio wave propagation depends for example on the frequency, ground conductivity and the ionospheric height and small variations can cause location differences from hundreds to thousands of meters, as demonstrated in this study. The radio wave propagation from two VLF transmissions at 20.9 kHz and 23.4 kHz are compared. The results show that the apparent phase velocities are 0.6% slower and 0.5% faster than the speed of light respectively. As a result, a variable velocity is implemented in the TOA method using continuously recorded data on the 8th August 2014, when a mesoscale convective system developed over central France. The lightning locations inferred with a variable wave propagation velocity are more clustered than those using a fixed velocity. The distribution of the lightning velocities in a given geographic area fits a normal distribution that is not centred at the speed of light. As a result, representative velocities can be calculated for smaller regions to generate a velocity map over a larger area of enhanced lightning activity. These results suggest a connection with the ground elevation and/or surface conductivity that might have an impact on the observed wave propagation velocities.

  2. Observations of Stratiform Lightning Flashes and Their Microphysical and Kinematic Environments (United States)

    Lang, Timothy J.; Williams, Earle


    During the Midlatitude Continental Convective Clouds Experiment (MC3E), combined observations of clouds and precipitation were made from airborne and ground-based in situ and remote sensing platforms. These observations were coordinated for multiple mesoscale convective systems (MCSs) that passed over the MC3E domain in northern Oklahoma. Notably, during a storm on 20 May 2011 in situ and remote sensing airborne observations were made near the times and locations of stratiform positive cloud-to-ground (+CG) lightning flashes. These +CGs resulted from extremely large stratiform lightning flashes that were hundreds of km in length and lasted several seconds. This dataset provides an unprecedented look at kinematic and microphysical environments in the vicinity of large, powerful, and long-lived stratiform lightning flashes. We will use this dataset to understand the influence of low liquid water contents (LWCs) in the electrical charging of MCS stratiform regions.

  3. On the Relationship between Observed NLDN Lightning ... (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

  4. The saptio-temporal distribution of lightning over the southern Levant and its relation to the regional synoptic systems (United States)

    Shalev, S.; Izsak, T.; Saaroni, H.; Yair, Y.; Ziv, B.


    associated with lightning, indicating the instability associated with these cyclones over the region. During the RST, even though it is characterized by different weather conditions, 60% of the days were associated with lightning. The spatial distribution of lightning is further studied for positive and negative cloud-to-ground flashes separately. Positive lightning, being <10% of their total number, are concentrated eastward over the coast and inland compared to the negative flashes. This may be explained by the enhanced inclination of the thunder-cloud due to their encounter with the coastline, leading to a "tilted dipole" which is manifested in a larger percentage of positive flashes. Similar results are found in the west coast of Japan in the winter season.

  5. Hybrid onboard and ground based digital channelizer beam-forming for SATCOM interference mitigation and protection (United States)

    Xiong, Wenhao; Wang, Gang; Tian, Xin; Pham, Khanh; Blasch, Erik; Chen, Genshe


    In this work, we propose a novel beam-forming power allocation method for a satellite communication (SATCOM) multiple-input multiple-output (MIMO) system to mitigate the co-channel interference (CCI) as well as limiting the signal leakage to the adversary users. In SATCOM systems, the beam-forming technique is a conventional way of avoiding interference, controlling the antenna beams, and mitigating undesired signals. We propose to use an advanced beam-forming technique which considers the number of independent channels used and transmitting power deployed to reduce and mitigate the unintentional interference effect. With certain quality of service (QoS) for the SATCOM system, independent channels components will be selected. It is desired to use less and stronger channel components when possible. On the other hand, considering that SATCOM systems often face the problem that adversary receiver detects the signal, a proposed power allocation method can efficiently reduce the received power at the adversary receiver. To reduce the computational burden on the transponder in order to minimize the size, mass, power consumption and delay for the satellite, we apply a hybrid onboard and ground based beam-forming design to distribute the calculation between the transponder and ground terminals. Also the digital channelizer beam-forming (DCB) technique is employed to achieve dynamic spatial control.

  6. Aerothermal Ground Testing of Flexible Thermal Protection Systems for Hypersonic Inflatable Aerodynamic Decelerators (United States)

    Bruce, Walter E., III; Mesick, Nathaniel J.; Ferlemann, Paul G.; Siemers, Paul M., III; DelCorso, Joseph A.; Hughes, Stephen J.; Tobin, Steven A.; Kardell, Matthew P.


    Flexible TPS development involves ground testing and analysis necessary to characterize performance of the FTPS candidates prior to flight testing. This paper provides an overview of the analysis and ground testing efforts performed over the last year at the NASA Langley Research Center and in the Boeing Large-Core Arc Tunnel (LCAT). In the LCAT test series, material layups were subjected to aerothermal loads commensurate with peak re-entry conditions enveloping a range of HIAD mission trajectories. The FTPS layups were tested over a heat flux range from 20 to 50 W/cm with associated surface pressures of 3 to 8 kPa. To support the testing effort a significant redesign of the existing shear (wedge) model holder from previous testing efforts was undertaken to develop a new test technique for supporting and evaluating the FTPS in the high-temperature, arc jet flow. Since the FTPS test samples typically experience a geometry change during testing, computational fluid dynamic (CFD) models of the arc jet flow field and test model were developed to support the testing effort. The CFD results were used to help determine the test conditions experienced by the test samples as the surface geometry changes. This paper includes an overview of the Boeing LCAT facility, the general approach for testing FTPS, CFD analysis methodology and results, model holder design and test methodology, and selected thermal results of several FTPS layups.

  7. 地闪近地面形态特征的数值模拟%A Numerical Study on Cjaracteristics of Cloud-to-ground Ligjtning Near Surface Configuration

    Institute of Scientific and Technical Information of China (English)

    谭涌波; 张冬冬; 周博文; 师正; 陈之禄; 陈超


    As a common phenomenon in nature,lightning can influence living environment and production ex-tremely.With continuous field lightning observation tests and model experiments,the understanding of lightning process is making a great progress,especially for cloud-to-