WorldWideScience

Sample records for wiring grounding lightning

  1. Development of Lightning-Resistant Overhead Ground Wire for Large-size Transmission Lines

    Science.gov (United States)

    Taniguchi, Sakae; Nagaraki, Yoshimi; Takami, Jun; Okabe, Shigemitsu; Saito, Toshiyuki; Nagano, Koji; Goda, Yutaka

    The overhead ground wire of AC 150mm2 is applied for the large-size transmission lines. According to inspections of transmission lines, melted component wires of AC 150mm2 have been found in some parts of 500kV transmission lines and it is obvious that the damages have been caused by lightning. Hence, the authors have developed lightning-resistant overhead ground wires as well as being evaluated lightning-resistant performance of the conventional AC 150mm2. In the paper, firstly, it is reported on the lightning performance of the conventional AC 150mm2 resulting from a DC arc test which is considered the polarity of currents and injected current waveforms for summer and winter lightning. As a result, the least amount of electric charges which can melt the components of the conventional wire was 180C. Then, the paper outlines the improvement of lightning performance of the overhead ground wire. Some kinds of developed ground wires as a trial piece have been proposed and tested, and here presented the characteristics of two typical developed wires among them. One is coated with conductive ceramic on the outer components and the another is enlarged a diameter of outer components. Both types of the wires show the excellent lightning performance from the DC arc test, comparing with the conventional ground wire of AC 150mm2.

  2. Ground Optical Lightning Detector (GOLD)

    Science.gov (United States)

    Jackson, John, Jr.; Simmons, David

    A photometer developed to characterize lightning from the ground is discussed. The detector and the electronic signal processing and data storage systems are presented along with field data measured by the system. The discussion will include improvements that will be incorporated to enhance the measurement of lightning and the data storage capability to record for many days without human involvement. Finally, the calibration of the GOLD system is presented.

  3. Lightning effects on the NASA F-8 digital-fly-by-wire airplane

    Science.gov (United States)

    Plumer, J. A.; Fisher, F. A.; Walko, L. C.

    1975-01-01

    The effects of lightning on a Digital Fly-By-Wire (DFBW)aircraft control system were investigated. The aircraft was a NASA operated F-8 fitted with a modified Apollo guidance computer. Current pulses similar in waveshape to natural lightning, but lower in amplitude, were injected into the aircraft. Measurements were made of the voltages induced on the DFBW circuits, the total current induced on the bundles of wires, the magnetic field intensity inside the aircraft, and the current density on the skin of the aircraft. Voltage measurements were made in both the line-to-ground and line-to-line modes. Voltages measured at the non-destructive test level were then scaled upward to determine how much would be produced by actual lightning. A 200,000 ampere severe lightning flash would produce between 40 and 2000 volts in DFBW circuits. Some system components are expected to be vulnerable to these voltages.

  4. 30 CFR 57.12069 - Lightning protection for telephone wires and ungrounded conductors.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Lightning protection for telephone wires and... AND NONMETAL MINES Electricity Surface Only § 57.12069 Lightning protection for telephone wires and... exposed to lightning shall be equipped with suitable lightning arrestors of approved type within 100 feet...

  5. 30 CFR 56.12069 - Lightning protection for telephone wires and ungrounded conductors.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Lightning protection for telephone wires and... NONMETAL MINES Electricity § 56.12069 Lightning protection for telephone wires and ungrounded conductors... lightning shall be equipped with suitable lightning arrestors of approved type within 100 feet of the point...

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

    Directory of Open Access Journals (Sweden)

    A. Khodadadi

    2017-06-01

    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.

  7. Modeling of Service-Drop Wires and Interior-Wiring Cables for Lightning Overvoltage Studies

    Science.gov (United States)

    Matsuura, Susumu; Noda, Taku; Nakamura, Masatoshi; Sakai, Hiroshi

    As the information society progresses, a variety of electronic appliances have come into wide use in common houses. If a lightning stroke causes faults or incorrect operations of these electronic appliances, a social economic loss is considered to be large. For this reason, the focus of lightning protection measures for distribution lines in Japan has expanded to include the low-voltage side of the distribution line in addition to the high-voltage side. In order to calculate lightning overvoltages at the low-voltage side, the surge characteristics of service-drop wires and interior-wiring cables have to be modeled accurately. First, this paper describes test results of the surge characteristics of service-drop wires and interior-wiring cables. The modal surge impedances and the propagation velocities of various service-drop wires and interior-wiring cables are obtained by the test. Based on the test results obtained, this paper proposes a modeling methodology of these wires and cables for accurate EMTP (Electro-Magnetic Transients Program) lightning overvoltage simulations. The proposed model is validated by comparing EMTP simulation results with field test results.

  8. 30 CFR 77.508-1 - Lightning arresters; wires entering buildings.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Lightning arresters; wires entering buildings... buildings. Lightning arresters protecting exposed telephone wires entering buildings shall be provided at the point where each such telephone wire enters the building. ...

  9. Estimate Of Positive Ground Lightning Flashes In Ibadan, Nigeria ...

    African Journals Online (AJOL)

    Positive ground lightning flashes have been monitored for a period of one year in Ibadan, Nigeria. The instrument used was lightning flash counter designed to isolate only positive lightning discharges at average radiation field change of 5.0 v/m and peak frequency response of 17.0kHz with 3dB attenuation and effective ...

  10. 30 CFR 77.508 - Lightning arresters, ungrounded and exposed power conductors and telephone wires.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Lightning arresters, ungrounded and exposed... AND SURFACE WORK AREAS OF UNDERGROUND COAL MINES Electrical Equipment-General § 77.508 Lightning... conductors and telephone wires shall be equipped with suitable lightning arresters which are adequately...

  11. 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

    2000-01-01

    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

  12. GAI LIGHTNING GROUND STRIKES V1

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set is restricted to EOS affiliated researchers. The U.S. National Lightning Detection Network is a commercial lightning detection network operated by...

  13. 30 CFR 75.701-4 - Grounding wires; capacity of wires.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Grounding wires; capacity of wires. 75.701-4... SAFETY AND HEALTH MANDATORY SAFETY STANDARDS-UNDERGROUND COAL MINES Grounding § 75.701-4 Grounding wires; capacity of wires. Where grounding wires are used to ground metallic sheaths, armors, conduits, frames...

  14. Effect of Overhead Ground Wire Installing under Distribution Lines on Surge Arrester Failures

    Science.gov (United States)

    Sugimoto, Hitoshi

    Distribution surge arresters are often damaged by lightning strokes, in particular, winter lightning. An overhead ground wire (OGW) is one of effective measures against surge arrester failures. However, adding the conventional OGW to existing overhead power distribution lines needs the power interruption for construction as well as high costs because of installing them above phase conductors. Experimental results show that a covered conductor for distribution lines is more difficult to attract lightning than a bare conductor. Moreover, lightning strokes to distribution pole heads occupied over 90% of all lightning strokes in the observation result of lightning strokes to actual distribution lines without the conventional OGW, and lightning strokes to power lines were hardly observed. These results indicate that the pole heads shield the power lines from direct lightning strokes. Therefore the author studies the application of an OGW under the distribution lines (UGW) for reducing surge arrester failures. The lightning performance of the UGW is estimated by the Electro-Magnetic Transients Program (EMTP) and its effectiveness is demonstrated. The measure is expected to cut costs of construction and maintenance for lightning protection.

  15. 30 CFR 77.701-3 - Grounding wires; capacity.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Grounding wires; capacity. 77.701-3 Section 77... MINES Grounding § 77.701-3 Grounding wires; capacity. Where grounding wires are used to ground metallic sheaths, armors, conduits, frames, casings, and other metallic enclosures, such grounding wires will be...

  16. Influence of Grounding Resistance Connecting to Surge Arresters on Effectiveness of Lightning Protection Caused by Direct Hit for Power Distribution Lines

    Science.gov (United States)

    Takahashi, Akihisa; Hidaka, Tetsuya; Ishimoto, Kazuyuki; Asakawa, Akira

    The grounding resistance of surge arresters (Arrs) for the lightning protection of power distribution lines is generally maintained below 30Ω in Japan. Therefore, electric power companies have been spending a large amount of money on the construction and maintenance of low grounding resistances. In this paper, the influence of grounding resistance on lightning protection measures is clarified for power distribution lines with both a ground wire (GW) and Arrs by EMTP analysis and experiments. These results showed that even if the grounding resistance of Arrs becomes high, effectiveness of lightning protection is hardly decreased. Moreover, the results indicated that it is more important for constructing a rational lightning protection system to install a lot of lightning devices on power distribution lines than to lower the grounding resistance of Arrs.

  17. Extensive air showers, lightnings and thunderstorm ground enhancements

    International Nuclear Information System (INIS)

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

    2016-01-01

    For the lightning research, we monitor the particle fluxes from thunderclouds, the so called Thunderstorm Ground Enhancements (TGEs) initiated by the runaway electrons, and Extensive Air Showers (EASs) originated from high energy protons or fully stripped nuclei that enter the Earth’s atmosphere. Besides, we monitor the near-surface electric field and the atmospheric discharges with the help of a network of electric field mills. The Aragats “electron accelerator” produced plenty of TGE and lightning events in spring 2015. Using 1-sec time series, we investigated the relation of lightnings and particle fluxes. Lightning flashes often terminated the particle flux; during some of TGEs the lightning would terminate the particle flux 3 times after successive recovery. It was postulated that a lightning terminates a particle flux mostly in the beginning of TGE or on the decay phase of it; however, we observed two events (19 October 2013 and 20 April 2015) when the huge particle flux was terminated just on a maximum of its development. We discuss the possibility that a huge EAS facilitates lightning leader to find its path to the ground. (author)

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

    DEFF Research Database (Denmark)

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

    2015-01-01

    -triggering video cameras were correlated with data from the U.S. National Lighting Detection Network. In all five events, the correlation showed that a cloud-to-ground (CG) lightning stroke with high peak current struck the ground within 10 km of the affected turbines at the time of the currents in the wind...

  19. First Cloud-to-Ground Lightning Timing Study

    Science.gov (United States)

    Huddleston, Lisa L.

    2013-01-01

    NASA's LSP, GSDO and other programs use the probability of cloud-to-ground (CG) lightning occurrence issued by the 45th Weather Squadron (45 WS) in their daily and weekly lightning probability forecasts. These organizations use this information when planning potentially hazardous outdoor activities, such as working with fuels, or rolling a vehicle to a launch pad, or whenever personnel will work outside and would be at-risk from lightning. These organizations would benefit greatly if the 45 WS could provide more accurate timing of the first CG lightning strike of the day. The Applied Meteorology Unit (AMU) has made significant improvements in forecasting the probability of lightning for the day, but forecasting the time of the first CG lightning with confidence has remained a challenge. To address this issue, the 45 WS requested the AMU to determine if flow regimes, wind speed categories, or a combination of the two could be used to forecast the timing of the first strike of the day in the Kennedy Space Center (KSC)/Cape Canaveral Air Force Station (CCAFS) lightning warning circles. The data was stratified by various sea breeze flow regimes and speed categories in the surface to 5,000-ft layer. The surface to 5,000-ft layer was selected since that is the layer the 45 WS uses to predict the behavior of sea breeze fronts, which are the dominant influence on the occurrence of first lightning in Florida during the warm season. Due to small data sample sizes after stratification, the AMU could not determine a statistical relationship between flow regimes or speed categories and the time of the first CG strike.. As expected, although the amount and timing of lightning activity varies by time of day based on the flow regimes and speed categories, there are extended tails of low lightning activity making it difficult to specify times when the threat of the first lightning flash can be avoided. However, the AMU developed a graphical user interface with input from the 45 WS

  20. Lightning effects on the NASA F-8 digital fly-by-wire airplane

    Science.gov (United States)

    Plumer, J. A.

    1975-01-01

    An investigation was conducted to evaluate the possible electromagnetic effects of lightning on a fly-by-wire flight control system which had been developed for an F8 aircraft. A brief description is presented of the flight control system. The test and measurement technique used in the investigation is discussed. The results of the investigation are considered, taking into account the vulnerability of individual system components to lightning induced voltages.

  1. Time-synchronized high-speed video images, electric fields, and currents of rocket-and-wire triggered lightning

    Science.gov (United States)

    Biagi, C. J.; Hill, J. D.; Jordan, D. M.; Uman, M. A.; Rakov, V. A.

    2009-12-01

    We present novel observations of 20 classically-triggered lightning flashes from the 2009 summer season at the International Center for Lightning Research and Testing (ICLRT) in north-central Florida. We focus on: (1) upward positive leaders (UPL), (2) current decreases and current reflections associated with the destruction of the triggering wire, and (3) dart-stepped leader propagation involving space stems or space leaders ahead of the leader tip. High-speed video data were acquired 440 m from the triggered lightning using a Phantom v7.1 operating at frame rates of up to 10 kfps (90 µs frame time) with a field of view from ground to an altitude of 325 m and a Photron SA1.1 operating at frame rates of up to 300 kfps (3.3 µs frame time) that viewed from ground to an altitude of 120 m. These data were acquired along with time-synchronized measurements of electric field (dc to 3 MHz) and channel-base current (dc to 8 MHz). The sustained UPLs developed when the rockets were between altitudes of 100 m and 200 m, and accelerated from about 104 to 105 m s-1 from the top of the triggering wire to an altitude of 325 m. In each successive 10 kfps high-speed video image, the newly formed UPL channels were brighter than the previously established channel and the new channel segments were longer. The UPLs in two flashes were imaged at a frame rate of 300 kfps from the top of the wire to about 10 m above the wire (110 m to 120 m above ground). In these images the UPL developed in a stepped manner with luminosity waves traveling from the channel tip back toward the wire during a time of 2 to 3 frames (6.6 µs to 9.9 µs). The new channel segments were on average 1 m in length and the average interstep interval was 23 µs. During 13 of the 20 initial continuous currents, an abrupt current decrease and the beginning of the wire illumination (due to its melting) occurred simultaneously to within 1 high-speed video frame (between 3.3 µs and 10 µs). For two of the triggered

  2. Cloud-to-ground lightning in Hurricane Andrew

    Science.gov (United States)

    Molinari, John; Moore, Paul K.; Idone, Vincent P.; Henderson, Ronald W.; Saljoughy, Arsalan B.

    1994-08-01

    The spatial and temporal distribution of cloud-to-ground lightning was examined in Hurricane Andrew of 1992. Lightning locations available from the National Lightning Detection Network were superimposed on infrared satellite images to relate lightning activity to hurricane cloud structure. A distinct radial variation occurred in time-averaged flash density, with a weak maximum in the eye wall, a region of near-zero flash density 40 to 100 km from the center, and a steady increase to a large maximum in the outer rainbands 190 km from the center. This radial distribution is consistent with the convective structure of mature hurricanes. Eye wall lightning tended to be episodic, occurring almost exclusively prior to and during periods of intensification of the storm. During these periods, negative flashes occurred several kilometers inward from the highest eye wall cloud tops, in the region of the largest radar reflectivity. Positive eye wall flashes, while small in number, tended to occur directly under the highest cloud tops. The results are suggestive of a normal dipole in sign but outwardly tilted along the sloping eye wall. In general, hurricane flash characteristics resembled those for a background data set of nonhurricane flashes from the same area. The exception occurred for negative flashes in the eye wall, which had a much smaller mean peak current than the background (25.3 kA versus 44.9 kA).

  3. 30 CFR 77.705 - Guy wires; grounding.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Guy wires; grounding. 77.705 Section 77.705... MANDATORY SAFETY STANDARDS, SURFACE COAL MINES AND SURFACE WORK AREAS OF UNDERGROUND COAL MINES Grounding § 77.705 Guy wires; grounding. Guy wires from poles supporting high-voltage transmission lines shall be...

  4. Combining satellite-based fire observations and ground-based lightning detections to identify lightning fires across the conterminous USA

    Science.gov (United States)

    Bar-Massada, A.; Hawbaker, T.J.; Stewart, S.I.; Radeloff, V.C.

    2012-01-01

    Lightning fires are a common natural disturbance in North America, and account for the largest proportion of the area burned by wildfires each year. Yet, the spatiotemporal patterns of lightning fires in the conterminous US are not well understood due to limitations of existing fire databases. Our goal here was to develop and test an algorithm that combined MODIS fire detections with lightning detections from the National Lightning Detection Network to identify lightning fires across the conterminous US from 2000 to 2008. The algorithm searches for spatiotemporal conjunctions of MODIS fire clusters and NLDN detected lightning strikes, given a spatiotemporal lag between lightning strike and fire ignition. The algorithm revealed distinctive spatial patterns of lightning fires in the conterminous US While a sensitivity analysis revealed that the algorithm is highly sensitive to the two thresholds that are used to determine conjunction, the density of fires it detected was moderately correlated with ground based fire records. When only fires larger than 0.4 km2 were considered, correlations were higher and the root-mean-square error between datasets was less than five fires per 625 km2 for the entire study period. Our algorithm is thus suitable for detecting broad scale spatial patterns of lightning fire occurrence, and especially lightning fire hotspots, but has limited detection capability of smaller fires because these cannot be consistently detected by MODIS. These results may enhance our understanding of large scale patterns of lightning fire activity, and can be used to identify the broad scale factors controlling fire occurrence.

  5. GPM GROUND VALIDATION EARTH NETWORKS TOTAL LIGHTNING NETWORK (ENTLN) MC3E V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The Earth Networks Total Lightning Network (ENTLN) is an integrated in-cloud (IC) lightning and cloud-to-ground (CG) detection network deployed on a global basis...

  6. Evaluation of Grounding Impedance of a Complex Lightning Protective System Using Earth Ground Clamp Measurements and ATP Modeling

    Science.gov (United States)

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

    2010-01-01

    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.

  7. A Lightning Surge Analysis for the Rationalization of the Grounding System in Power Distribution Lines

    Science.gov (United States)

    Miyazaki, Teru; Okabe, Shigemitsu; Aiba, Kiyoshi; Hirai, Takao; Yoshinaga, Jun

    The grounding system is one of the most important lightning-protection features of power distribution lines. Based on the statistical distribution of surge currents through lightning arrestors caused by indirect lightning strokes and electrical surges in customers, a rated value of the grounding resistance for lightning arrestors on distribution lines was specified in the 1960's. TEPCO had conducted field research to measure the waveforms of surge voltage and current in order to rationalize the lightning protection design of distribution lines. And the authors proposed a lightning-surges analysis model based on the observation data. In this study, a lightning surge analysis for the rationalization of the grounding system was carried out by means of the EMTP. The calculation conditions were set based on the observation data. The calculated results suggest that a simple grounding design is possible. That can be useful for the Electric Power Companies to manage grounding systems.

  8. Thunderstorm ground enhancements (TGEs) abruptly terminated by negative cloud-to-ground lightnings

    International Nuclear Information System (INIS)

    Chilingarian, A.; Hovsepyan, G.; Khanikyanc, G.; Pokhsraryan, D.; Soghomonyan, S.

    2016-01-01

    The relationship of lightnings and particle fluxes in the thunderclouds is not fully understood to date. Using the particle beams (the so-called Thunderstorm Ground Enhancements – TGEs) generated in the lower part of clouds by the strong electric fields as a probe, we investigate the characteristics of the related atmospheric discharges. The well-known effect of the TGE dynamics is the abrupt termination of the particle flux. We demonstrate that among 12 atmospheric discharges that abruptly terminated TGE all are the negative cloud-to-ground lightnings. The flux termination and lightning occurred at one and the same second. With new precise electronics on millisecond time scales we can see that particle flux decline occurred simultaneously with abrupt increase of electrostatic field after the return stroke of the lightning. Therefore, the declining of particle flux is connected with rearranging of charge centers in the cloud involving removal of the Lower Positive Charged Region (LPCR). (author)

  9. Calculating the Lightning Protection System Downconductors' Grounding Resistance at Launch Complex 39B, Kennedy Space Center, Florida

    Science.gov (United States)

    Mata, Carlos; Mata, Angel

    2011-01-01

    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 insulation installed atop three towers in a triangular configuration. Nine downconductors (each about 250 meters long) are connected to the catenary wire system. Each downconductor is connected to a 7.62-meter-radius circular counterpoise conductor with six equally spaced. 6-meter-1ong 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. counterpoise, to be bonded to the counterpoise, which results in a complex interconnected grounding system, given the many metallic piping, raceways and cable trays that run in multiple directions around LC39B.

  10. Characteristics of downward leaders in a cloud-to-ground lightning strike on a lightning rod

    Science.gov (United States)

    Wang, Caixia; Sun, Zhuling; Jiang, Rubin; Tian, Yangmeng; Qie, Xiushu

    2018-05-01

    A natural downward negative cloud-to-ground (CG) lightning was observed at a close distance of 370 m by using electric field change measurements and a high-speed camera at 5400 frames per second (fps). Two subsequent leader-return strokes of the lightning hit a lightning rod installed on the top of a seven-story building in Beijing city, while the grounding point for the stepped leader-first return stroke was 12 m away, on the roof of the building. The 2-D average speed of the downward stepped leader (L1) before the first return stroke (R1) was approximately 5.1 × 104 m/s during its propagation over the 306 m above the building, and those before the subsequent strokes (R2 and R3) ranged from 1.1 × 106 m/s to 2.2 × 106 m/s. An attempted leader (AL) occurred 201 ms after R1 and 10 ms before R2 reached approximately 99 m above the roof and failed to connect to the ground. The 2-D average speed of the AL was approximately 7.4 × 104 m/s. The luminosity at tip of the leader was brighter than the channel behind it. The leader inducing the R2 with an alteration of terminating point was a dart-stepped leader (DSL), which propagated through the channel of AL and continued to develop downward with new branches at about 17 m above the roof. The 2-D speed of the DSL at the bottom 99 m was 6.6 × 105 m/s. The average time interval between the stepped pulses of the DSL was approximately 10 μs, smaller than that of L1 with value of about 17 μs. The average step lengths of the DSL were approximately 6.6 m. The study shows that the stepped leader-first return stroke of lightning will not always hit the tip of a tall metal rod due to the significant branching property of the leader. However, under certain conditions, the subsequent return strokes may alter the grounding point to the tip of a tall metal rod. For the lightning rod, the protection against subsequent return strokes may be better than that against the first return stroke.

  11. Characteristics of cloud-to-ground lightning flashes over Sweden

    International Nuclear Information System (INIS)

    Sonnadara, Upul; Cooray, Vernon; Goetschl, Thomas

    2006-01-01

    A detailed study of the characteristics of cloud-to-ground (CG) lightning flashes over Sweden was carried out for the period 1987-2000 using data obtained from the Swedish lightning-locating network. Results are presented by analysing over half a million lightning ground flashes. The average variation of the annual mean of the total number of flashes was found to be 37%. About 12% of the CG flashes were positive flashes and their average variation about the annual mean was 26%. The average peak currents were fairly constant over the years with variations as little as 4% for negative flashes and 5% for positive flashes. The average peak current values for negative and positive flashes were -29.90 and +63.97 kA respectively. A correlation between the mean monthly flash count and percentage of positive flashes was seen. A similar relationship is seen with the mean monthly flash count and the peak currents for both polarities. In general, high flash density and high peak currents were observed in the southern part of Sweden where most of the major cities are located. Flash densities exceeding 0.4 flashes km -2 were observed for several large cities. The maximum flash rate of 32 flashes h -1 within a 10 km radius was seen in Joenkoeping (14.18 0 E, 57.78 0 N) in the province of Smaaland

  12. Calculating the Lightning Protection System Downconductors' Grounding Resistance at Launch Complex 39B, Kennedy Space Center

    Science.gov (United States)

    Mata, Carlos T.; Mata, Angel G.

    2012-01-01

    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. Nine downconductors (each about 250 meters long) are connected to the catenary wire system. Each downconductor 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 aboveground metallic piping, enclosures, raceways, and cable trays, within 7.62 meters of the counterpoise, to be bonded to the counterpoise, which results in a complex interconnected grounding system, given the many metallic piping, raceways, and cable trays that run in multiple directions 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 grounding impedance of the downconductors, an Earth Ground Clamp (EGC) (a stakeless device for measuring grounding impedance) and an Alternative Transient Program (ATP) model of the LPS are used. The EGC 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 resistance of the downconductors is then calculated by subtracting the ATP calculated loop impedances from the EGC measurements.

  13. Developing a Forecast Tool for Cloud-to-Ground Lightning in the North Central and Northeastern United States

    National Research Council Canada - National Science Library

    Folsom, Manuel

    2004-01-01

    Cloud-to-ground (CG) lightning is a hazard to the Air Force for both air and ground operations Forecasting CG lightning is a necessary and extremely important requirement for Air Force meteorologists and forecasters...

  14. Influence of strike object grounding on close lightning electric fields

    Science.gov (United States)

    Baba, Yoshihiro; Rakov, Vladimir A.

    2008-06-01

    Using the finite difference time domain (FDTD) method, we have calculated vertical electric field Ez, horizontal (radial) electric field Eh, and azimuthal magnetic field Hϕ produced on the ground surface by lightning strikes to 160-m- and a 553-m-high conical strike objects representing the Peissenberg tower (Germany) and the CN Tower (Canada), respectively. The fields were computed for a typical subsequent stroke at distances d' from the bottom of the object ranging from 5 to 100 m for the 160-m tower and from 10 to 300 m for the 553-m tower. Grounding of the 160-m object was assumed to be accomplished by its underground basement represented by a 10-m-radius and 8-m-long perfectly conducting cylinder with or without a reference ground plane located 2 m below. The reference ground plane simulates, to some extent, a higher-conducting ground layer that is expected to exist below the water table. The configuration without reference ground plane actually means that this plane is present, but is located at an infinitely large depth. Grounding of the 553-m object was modeled in a similar manner but in the absence of reference ground plane only. In all cases considered, waveforms of Eh and Hϕ are not much influenced by the presence of strike object, while waveforms of Ez are. Waveforms of Ez are essentially unipolar (as they are in the absence of strike object) when the ground conductivity σ is 10 mS/m (the equivalent transient grounding impedance is several ohms) or greater. Thus, for the CN Tower, for which σ ≥ 10 mS/m, the occurrence of Ez polarity change is highly unlikely. For the 160-m tower and for σ = 1 and 0.1 mS/m, waveforms of Ez become bipolar (exhibit polarity change) at d' ≤ 10 m and d' ≤ 50 m, respectively, regardless of the presence of the reference ground plane. The corresponding equivalent transient grounding impedances are about 30 and 50 Ω in the absence of the reference ground plane and smaller than 10 Ω in the presence of the reference

  15. Grounding, Bonding, Shielding, and Lightning Bibliography 1972 to 1979

    Science.gov (United States)

    1981-02-01

    channel. The interaction of lightning and aircraft is included. A discussion of ball lightning is included. H. H. Hoshiko, "Helical Channel Multiplier...project Telsa which produced artificial ball lightning with potentials as large as 20 million volts and provides a brief explanation of the hazards of... ball lightning . S. Stoller, "In-Plant Generation-Design Considerations for Industrial Facilities," IEEE Transactions on Industry Applications, vol. IA-12

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

    Directory of Open Access Journals (Sweden)

    Reynaldo Zoro

    2009-11-01

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

  17. Characteristics of negative lightning leaders to ground observed by TVLS

    Science.gov (United States)

    Qiu, Shi; Jiang, Zhidong; Shi, Lihua; Niu, Zhencong; Zhang, Peng

    2015-12-01

    The Thunder and VHF lightning Locating System (termed TVLS) is established and utilized to observe leader behaviors of negative cloud to ground (CG) flashes. This system takes advantages of VHF broadband interferometer and thunder imaging technique, which could provide the temporal and quasi-3D spatial evolution of lightning discharges. In conjunction with synchronized electric field changes (E-changes) and electric field derivatives (dE/dt) records, 10 leaders from two CG flashes are presented and analyzed. Based on the characteristic evolution of leader velocities, E-changes, dE/dt waveforms and VHF intervals, three stepped leaders, five dart leaders and two dart-stepped leaders are identified. The stepped leaders behave impulsive while approaching ground, with average speed (1.3∼3.9)×105 m/s. All normal dart leaders presented here exhibit irregular (or termed "chaotic") fluctuations in E-change and dE/dt waveforms, with the similar speeds ((1.0∼2.9)×107 m/s) and durations ((300∼700) μs) of the "chaotic" leaders observed by other investigators. The irregular fluctuations would be weak if the channels keep conductive until the leader enters the less conductive branches, coinciding with VHF radiations in time sequence. The dart-stepped leader could be divided into the dart stage and the stepped stage by a transition region, which usually lies around the branch junctions of previous active channel. The dart stage resembles the normal dart leader, and the stepped stage usually associates with regular pulse trains in E-change and dE/dt waveforms.

  18. Cloud-to-ground lightning activity in Colombia: A 14-year study using lightning location system data

    Science.gov (United States)

    Herrera, J.; Younes, C.; Porras, L.

    2018-05-01

    This paper presents the analysis of 14 years of cloud-to-ground lightning activity observation in Colombia using lightning location systems (LLS) data. The first Colombian LLS operated from 1997 to 2001. After a few years, this system was upgraded and a new LLS has been operating since 2007. Data obtained from these two systems was analyzed in order to obtain lightning parameters used in designing lightning protection systems. The flash detection efficiency was estimated using average peak current maps and some theoretical results previously published. Lightning flash multiplicity was evaluated using a stroke grouping algorithm resulting in average values of about 1.0 and 1.6 for positive and negative flashes respectively and for both LLS. The time variation of this parameter changes slightly for the years considered in this study. The first stroke peak current for negative and positive flashes shows median values close to 29 kA and 17 kA respectively for both networks showing a great dependence on the flash detection efficiency. The average percentage of negative and positive flashes shows a 74.04% and 25.95% of occurrence respectively. The daily variation shows a peak between 23 and 02 h. The monthly variation of this parameter exhibits a bimodal behavior typical of the regions located near The Equator. The lightning flash density was obtained dividing the study area in 3 × 3 km cells and resulting in maximum average values of 25 and 35 flashes km- 2 year- 1 for each network respectively. A comparison of these results with global lightning activity hotspots was performed showing good correlation. Besides, the lightning flash density variation with altitude shows an inverse relation between these two variables.

  19. Energy Absorption of Distribution Line Arresters due to Lightning Back Flow Current and Ground Potential Rise for Lightning Hit to Wind Turbine Generator System

    Science.gov (United States)

    Okamoto, Hiroshi; Sekioka, Shozo; Ebinuma, Yasumitsu; Yamamoto, Kazuo; Yasuda, Yoh; Funabashi, Toshihisa; Yokoyama, Shigeru

    In the coast of the Japan Sea which has many good places for wind turbine generator system, winter lightning occurs frequently. Many results of investigation have been reported not only damages of wind turbine generator system itself but also failures of distribution line arresters caused by part of the lightning current which flows into distribution lines when the customer's structure is struck by lightning. The lightning back flow current and ground potential rise are also important factors for a lightning protection design of distribution line arresters, which are connected to the wind turbine generator system struck by lightning. This paper describes simulation results of the energy absorption to estimate the lightning damages in the arresters considering the back flow current and the ground potential rise using the EMTP.

  20. Storm-based Cloud-to-Ground Lightning Probabilities and Warnings

    Science.gov (United States)

    Calhoun, K. M.; Meyer, T.; Kingfield, D.

    2017-12-01

    A new cloud-to-ground (CG) lightning probability algorithm has been developed using machine-learning methods. With storm-based inputs of Earth Networks' in-cloud lightning, Vaisala's CG lightning, multi-radar/multi-sensor (MRMS) radar derived products including the Maximum Expected Size of Hail (MESH) and Vertically Integrated Liquid (VIL), and near storm environmental data including lapse rate and CAPE, a random forest algorithm was trained to produce probabilities of CG lightning up to one-hour in advance. As part of the Prototype Probabilistic Hazard Information experiment in the Hazardous Weather Testbed in 2016 and 2017, National Weather Service forecasters were asked to use this CG lightning probability guidance to create rapidly updating probability grids and warnings for the threat of CG lightning for 0-60 minutes. The output from forecasters was shared with end-users, including emergency managers and broadcast meteorologists, as part of an integrated warning team.

  1. Investigation of Overvoltage Phenomena due to Lightning Surge in Low Voltage Wiring

    Science.gov (United States)

    Tan, Akiyoshi; Koga, Soichi; Vasa, Nilesh J.; Yokoyama, Shigeru; Hosokawa, Takeshi; Sawabe, Kimihide; Yoshioka, Tetsuo; Soeda, Masahiro

    In order to understand overvoltage phenomena due to the lightning surge in a low voltage wiring on a scale model of a structure, the load circuit of electrical appliances at the end of cable with circuit elements, such as resistors, capacitors and inductors, was simulated and the response at the end of cable was studied. Furthermore experimental results were compared with those of the digital simulation using EMTP (Electro-Magnetic Transients Program). The variation in the voltage waveform generated at the end of cable according to the state of the load of an electrical equipment was confirmed based on experiments and simulations. However, when a varistor (Surge Protective Device) was inserted at the end of cable, the voltage amplitude was clamped by the varistor irrespective of the load circuit.

  2. Lightning

    Science.gov (United States)

    Pampe, William R.

    1970-01-01

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

  3. Coincident Observation of Lightning using Spaceborne Spectrophotometer and Ground-Level Electromagnetic Sensors

    Science.gov (United States)

    Adachi, Toru; Cohen, Morris; Li, Jingbo; Cummer, Steve; Blakeslee, Richard; Marshall, THomas; Stolzenberg, Maribeth; Karunarathne, Sumedhe; Hsu, Rue-Ron; Su, Han-Tzong; hide

    2012-01-01

    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.

  4. Initial observations of cloud-to-ground lightning activity in microburst producing storms

    Science.gov (United States)

    Buechler, Dennis E.; Goodman, Steven J.

    1988-01-01

    Preliminary observations of cloud-to-ground lightning activity associated with wet microburst producing storms observed during the summer of 1986 near Huntsville, AL are presented. Reflectivity and velocity measurements obtained from two 10 cm Doppler radars are used to identify and characterize the microburst windshears and their parent clouds. A four-station lightning location network is used to characterize the ground discharges produced by these storms. Results show cloud-to-ground flashes preceding the microburst onset by 0 - 28 minutes and suggest that any storm in a microburst environment that produces a discharge to ground has the potential to generate an intense downdraft.

  5. Recent Lightning Experiments at the International Center for Lightning Research and Testing: From Ball Lightning to Gamma Rays

    Science.gov (United States)

    Uman, M. A.

    2008-12-01

    Recent lightning data and the instrumentation used to acquire it at the UF-FIT International Center for Lightning Research and Testing, located on about 1 square kilometer of flat ground at the Camp Blanding Army National Guard Base in north-central Florida, are discussed. The progress of several on-going studies is reviewed: (1) understanding the physics of the "classical" rocket-and-wire triggering of lightning from natural overhead thunderclouds, (2) attempting to generate ball lightning by allowing triggered-lightning to strike various materials and objects (e.g., tree-trunk sections, pools of salt water, silicon powder), (3) measuring the very close (100 m to 1 km) electric and magnetic fields of natural cloud-to-ground lightning, and (4) probing the relationship between lightning processes and the x-rays and gamma-rays associated with them.

  6. Cloud-to-Ground Lightning Estimates Derived from SSMI Microwave Remote Sensing and NLDN

    Science.gov (United States)

    Winesett, Thomas; Magi, Brian; Cecil, Daniel

    2015-01-01

    Lightning observations are collected using ground-based and satellite-based sensors. The National Lightning Detection Network (NLDN) in the United States uses multiple ground sensors to triangulate the electromagnetic signals created when lightning strikes the Earth's surface. Satellite-based lightning observations have been made from 1998 to present using the Lightning Imaging Sensor (LIS) on the NASA Tropical Rainfall Measuring Mission (TRMM) satellite, and from 1995 to 2000 using the Optical Transient Detector (OTD) on the Microlab-1 satellite. Both LIS and OTD are staring imagers that detect lightning as momentary changes in an optical scene. Passive microwave remote sensing (85 and 37 GHz brightness temperatures) from the TRMM Microwave Imager (TMI) has also been used to quantify characteristics of thunderstorms related to lightning. Each lightning detection system has fundamental limitations. TRMM satellite coverage is limited to the tropics and subtropics between 38 deg N and 38 deg S, so lightning at the higher latitudes of the northern and southern hemispheres is not observed. The detection efficiency of NLDN sensors exceeds 95%, but the sensors are only located in the USA. Even if data from other ground-based lightning sensors (World Wide Lightning Location Network, the European Cooperation for Lightning Detection, and Canadian Lightning Detection Network) were combined with TRMM and NLDN, there would be enormous spatial gaps in present-day coverage of lightning. In addition, a globally-complete time history of observed lightning activity is currently not available either, with network coverage and detection efficiencies varying through the years. Previous research using the TRMM LIS and Microwave Imager (TMI) showed that there is a statistically significant correlation between lightning flash rates and passive microwave brightness temperatures. The physical basis for this correlation emerges because lightning in a thunderstorm occurs where ice is first

  7. About Geometry and Initial Phase of Cloud-to-Ground Lightning

    OpenAIRE

    Berkopec, Aleš

    2016-01-01

    Cloud-to-ground lightning is the most common among atmospheric discharges. Since electric fields in the vicinity of a thunder-cloud do not exceed 250 kV/m the physical process that triggers the lightning remains unexplained. [1, 2, 3] Recent measurements established a weak correlation between solar wind and incidence of lightning. [4] Here we show, that if an ionized path created by cosmic rays provides a trigger, the distribution of lengths between two successive forking points in a lightnin...

  8. The Physics of Lightning

    Science.gov (United States)

    Rakov, V. A.

    2013-11-01

    An overview of the physics of cloud-to-ground lightning is given, including its initiation, propagation, and attachment to ground. Discharges artificially initiated (triggered) from natural thunderclouds using the rocket-and-wire technique are discussed with a view toward studying properties of natural lightning. Both conventional and runaway breakdown mechanisms of lightning initiation in thunderclouds are reviewed, as is the role of the lower positive charge region in facilitating different types of lightning. New observations of negative-leader stepping and its attachment to ground are compared to similar processes in long laboratory sparks. The mechanism and parameters of compact intracloud lightning discharges that are thought to be the most intense natural producers of HF-VHF (3-300 MHz) radiation on Earth are reviewed. The M-component mode of charge transfer to ground and its difference from the leader/return-stroke mode are discussed. Lightning interaction with the ionosphere and the production of energetic radiation (X-rays and gamma radiation) by cloud-to-ground leaders are considered.

  9. Radar characteristics of cloud-to-ground lightning producing storms in Florida

    Science.gov (United States)

    Buechler, D. E.; Goodman, S. J.

    1991-01-01

    The interrelation between cloud-to-ground lightning, convective rainfall, and the environment in Central Florida storms is examined. The rain flux, storm area, and ground discharge rates are computed within the outlined area. Time-height cross sections of maximum dBZ values at each level for two storms are shown. The multicellular nature of these storms is readily apparent. The cloud-to-ground lightning activity occurs mainly where high reflectivity values (30-40 dBZ) extend above 7 km.

  10. Using Cloud-to-Ground Lightning Climatologies to Initialize Gridded Lightning Threat Forecasts for East Central Florida

    Science.gov (United States)

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

    2005-01-01

    Each morning, the forecasters at the National Weather Service in Melbourn, FL (NWS MLB) produce an experimental cloud-to-ground (CG) lightning threat index map for their county warning area (CWA) that is posted to their web site (http://www.srh.weather.gov/mlb/ghwo/lightning.shtml) . Given the hazardous nature of lightning in central Florida, especially during the warm season months of May-September, these maps help users factor the threat of lightning, relative to their location, into their daily plans. The maps are color-coded in five levels from Very Low to Extreme, with threat level definitions based on the probability of lightning occurrence and the expected amount of CG activity. On a day in which thunderstorms are expected, there are typically two or more threat levels depicted spatially across the CWA. The locations of relative lightning threat maxima and minima often depend on the position and orientation of the low-level ridge axis, forecast propagation and interaction of sea/lake/outflow boundaries, expected evolution of moisture and stability fields, and other factors that can influence the spatial distribution of thunderstorms over the CWA. The lightning threat index maps are issued for the 24-hour period beginning at 1200 UTC (0700 AM EST) each day with a grid resolution of 5 km x 5 km. Product preparation is performed on the AWIPS Graphical Forecast Editor (GFE), which is the standard NWS platform for graphical editing. Currently, the forecasters create each map manually, starting with a blank map. To improve efficiency of the forecast process, NWS MLB requested that the Applied Meteorology Unit (AMU) create gridded warm season lightning climatologies that could be used as first-guess inputs to initialize lightning threat index maps. The gridded values requested included CG strike densities and frequency of occurrence stratified by synoptic-scale flow regime. The intent is to increase consistency between forecasters while enabling them to focus on

  11. Lightning Often Strikes Twice

    Science.gov (United States)

    2005-01-01

    Contrary to popular misconception, lightning often strikes the same place twice. Certain conditions are just ripe for a bolt of electricity to come zapping down; and a lightning strike is powerful enough to do a lot of damage wherever it hits. NASA created the Accurate Location of Lightning Strikes technology to determine the ground strike point of lightning and prevent electrical damage in the immediate vicinity of the Space Shuttle launch pads at Kennedy Space Center. The area surrounding the launch pads is enmeshed in a network of electrical wires and components, and electronic equipment is highly susceptible to lightning strike damage. The accurate knowledge of the striking point is important so that crews can determine which equipment or system needs to be retested following a strike. Accurate to within a few yards, this technology can locate a lightning strike in the perimeter of the launch pad. As an added bonus, the engineers, then knowing where the lightning struck, can adjust the variables that may be attracting the lightning, to create a zone that will be less susceptible to future strikes.

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

    Science.gov (United States)

    Koshak, William; Solakiewicz, Richard

    2013-01-01

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

  13. 30 CFR 75.521 - Lightning arresters; ungrounded and exposed power conductors and telephone wires.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Lightning arresters; ungrounded and exposed... Electrical Equipment-General § 75.521 Lightning arresters; ungrounded and exposed power conductors and... leads underground shall be equipped with suitable lightning arresters of approved type within 100 feet...

  14. Cell Mergers and Their Impact on Cloud-to-Ground Lightning Over the Houston Area

    Science.gov (United States)

    Gauthier, Michael L.; Petersen, Walter A.; Carey, Lawrence D.

    2009-01-01

    A previous hypothesis advanced from observational studies such as METROMEX suggests that the intensity, frequency, and organization of cumulus convection may be impacted by the forcing of enhanced merger activity downstream of urban zones. A resulting corollary is that cities may exert an indirect anthropogenic forcing of parameters related to convection and associated phenomena such as lightning and precipitation. This paper investigates the urban merger hypothesis by examining the role of convective cell mergers on the existence and persistence of the Houston lightning "anomaly", a local maximum in cloud-to-ground (CG) lightning activity documented to exist over and east of Houston. Using eight summer seasons of peak columnar radar reflectivity, CG lightning data and a cell-tracking algorithm, a two-dimensional cell merger climatology is created for portions of eastern Texas and Louisiana. Results from the tracking and analysis of over 3.8 million cells indicate that merger-driven enhancements in convection induce a positive response (O 46%) in ground-flash densities throughout the domain, with areas of enhanced lightning typically being co-located with areas of enhanced merger activity. However, while mergers over the Houston area (relative to elsewhere in the domain) do result in more vigorous convective cells that produce larger CG flash densities, we find that CG lightning contributions due to mergers are distributed similarly throughout the domain. Hence while we demonstrate that cell mergers do greatly impact the production of lightning, the urban cell merger hypothesis does not uniquely explain the presence of a local lightning maximum near and downstream of Houston.

  15. Cloud-to-ground lightning in a tornadic storm on 8 May 1986

    Science.gov (United States)

    Macgorman, Donald R.; Nielsen, Kurt E.

    1991-01-01

    The National Severe Storms Laboratory (NSSL) gathered Doppler radar and lightning ground strike data on a supercell storm that produced three tornadoes, including an F3 tornado in Edmond, Oklahoma, approximately 40 km north of NSSL. The Edmond storm formed 30 km ahead of a storm complex and developed its first and most damaging tornado just as the storm complex started to overtake it from the west. Lightning strike locations tended to concentrate just north of the mesocyclone, close to and inside a 50 dBZ reflectivity core. Positive ground flashes began just prior to the storm becoming tornadic, and positive flash rates peaked during the tornadic stage of the storm.

  16. Evaluation and planning for lightning rod grounding of PSTA cyclotron building

    International Nuclear Information System (INIS)

    Suyamto; Taufik; Idrus Abdul Kudus

    2015-01-01

    Lightning rod connected with the ground resistance is an equipment protection against hazards of lightning strikes building. Lightning strike to the building may result in damage to the building and destroy all the equipment inside it. The need for a lightning rod of a building is regulated in PUIPP expressed with risk factors (FR). The amount of FR is the sum of the value of the index of five (5 ) components of the building i.e building functions, construction, the height and the situation of the building and and the number of yearly lightning days in that places. At this time 05 PSTA building has undergone changes in the function of the building's mechanical workshop into a cyclotron building so that safety criteria also change into vital building with lightning rods resistance have to < 1 Ω. From measurements of grounding resistant which exist at present known that average Rp is 1.26 Ω so it is necessary to install new additional grounding resistance to reduce being less than 1 Ω. To fulfil this and taking into consideration the cost and ease of installation, planned addition of a grounding using electrodes solid rods of copper, a diameter of 16 mm and a length of 4 m , planted the soil water depth of 12 m, as well as clay covering, with a water content of about 30 %. Under these conditions and taking into the cost and ease of installation are expected to obtain optimal results i.e. soil resistivity 18.35 Ω-m and its resistance of Rx 4.82 Ω. When coupled with existing grounding final resistant Rp 0.99 Ω obtained is thus fulfilling the requirements of PUIPP that is less than 1 Ω. (author)

  17. Ground to Cloud Lightning Flash Currents and Electric Fields: Interaction with Aircraft and Production of Ionosphere Sprites

    Directory of Open Access Journals (Sweden)

    P. R. P. Hoole

    2014-01-01

    Full Text Available This paper presents for the first time a case for the importance of ground to cloud (upward leader lightning flash parameters for safety testing of direct aircraft-lightning interaction and protection of wind turbines, as well as the importance of radiated electric fields for indirect lightning-aircraft interaction and generation of electric discharges called sprites and halos in the ionosphere. By using an electric circuit model of the transverse magnetic waves along the return stroke channel, electric currents at ground level as well as cloud level are determined for both the cloud to ground lightning flash and the ground to cloud lightning flash. We show that when an aircraft triggers lightning, the electric currents will be much more severe in current magnitude, rate of rise of currents, and frequency spectrum than otherwise and are more severe than the parameters observed for the usual and well monitored (and measured cloud to ground (downward leader flashes. The rate of rise of currents and the frequency spectrum of the ground to cloud lightning flash are also given here. The electric fields radiated by the lightning flashes that would appear in the ionosphere are presented for both the earth flash and the ground to cloud flash.

  18. A case study of lightning attachment to flat ground showing multiple unconnected upward leaders

    Science.gov (United States)

    Cummins, Kenneth L.; Krider, E. Philip; Olbinski, Mike; Holle, Ronald L.

    2018-04-01

    On 10 July 2015, a cloud-to-ground (CG) lightning flash that produced two ground terminations was photographed from inside the safety of a truck in southern New Mexico. An analysis of archived NLDN data verified that this was a two-stroke flash, and a close-up view of the first stroke shows that it also initiated at least 12 unconnected, upward leaders (or "streamers") near the ground termination. No unconnected upward leaders were seen near the second ground attachment. After combining an analysis of the photograph with information provided by the NLDN, we infer that the first stroke was of negative (normal) polarity, had modest peak current, and struck about 460 m (± 24%) from the camera. Attachment occurred when an upward-propagating positive leader reached an inferred height of about 21 m above local ground. The second stroke struck ground about 740 m from the camera, and the height of its attachment leader is estimated to be 15 m. The estimated lengths of the unconnected upward leaders in the two-dimensional (2-D) plane of the first stroke range from 2 to 8 m, and all appear to be located within 15 m (2-D) of the main ground termination, with 24% uncertainty. Many of the unconnected upward leaders (inferred to be positive) exhibit multiple upward branches, and most of those branches have upward-directed forks or splits at their ends. This is the first report showing such extensive branching for positive upward leaders in natural lightning strikes to ground. None of the upward leaders can be seen to emanate from the tops of tall, isolated, or pointed objects on the ground, but they likely begin on small plants and rocks, or flat ground. In terms of lightning safety, this photo demonstrates that numerous upward leaders can be produced near a lightning strike point and have the potential to damage or cause injury at more than one specific point on the ground.

  19. Assessing Lightning and Wildfire Hazard by Land Properties and Cloud to Ground Lightning Data with Association Rule Mining in Alberta, Canada.

    Science.gov (United States)

    Cha, DongHwan; Wang, Xin; Kim, Jeong Woo

    2017-10-23

    Hotspot analysis was implemented to find regions in the province of Alberta (Canada) with high frequency Cloud to Ground (CG) lightning strikes clustered together. Generally, hotspot regions are located in the central, central east, and south central regions of the study region. About 94% of annual lightning occurred during warm months (June to August) and the daily lightning frequency was influenced by the diurnal heating cycle. The association rule mining technique was used to investigate frequent CG lightning patterns, which were verified by similarity measurement to check the patterns' consistency. The similarity coefficient values indicated that there were high correlations throughout the entire study period. Most wildfires (about 93%) in Alberta occurred in forests, wetland forests, and wetland shrub areas. It was also found that lightning and wildfires occur in two distinct areas: frequent wildfire regions with a high frequency of lightning, and frequent wild-fire regions with a low frequency of lightning. Further, the preference index (PI) revealed locations where the wildfires occurred more frequently than in other class regions. The wildfire hazard area was estimated with the CG lightning hazard map and specific land use types.

  20. Lightning Channels of Cloud-to-Ground Flashes Neutralizing Multiple Charge Regions Inside Winter Thunderclouds

    Science.gov (United States)

    Akita, Manabu; Yoshida, Satoru; Nakamura, Yoshitaka; Morimoto, Takeshi; Ushio, Tomoo; Kawasaki, Zen-Ichiro; Wang, Daohong

    Lightning Research Group of Osaka University (LRG-OU) has been developing and improving the VHF broadband digital interferometer (DITF) for thunderstorm observations. It enables us to locate the impulsive VHF radiation sources caused by lightning discharges with extremely high resolutions. As a result of the VHF observations during the 2007-2008 winter season in the Japan Sea coastal area, cloud-to-ground (CG) flashes that neutralize multiple charge regions inside thunderclouds are visualized by the VHF broadband DITF. The first flash is the positive CG flash that neutralizes multiple positive charge regions in a flash. The second flash is the bipolar lightning flash that neutralizes both positive and negative charge inside thunderclouds. In the case of bipolar lightning flashes, some tens millisecond after the return strokes, the subsequent negative breakdowns initiate from the proximities of the initiation points of the preceding negative stepped leaders. It was also found that the altitudes of negative charge regions are lower than 2km. The bipolar lightning flashes observed in this campaign neutralize positive charge after lowering the negative charge to the ground.

  1. Energized overhead ground wires - OHGWs the pioneer Brazilian application

    Energy Technology Data Exchange (ETDEWEB)

    D`Ajuz, Ary; Martinez, Manuel L.B.; Araujo, Ana Maria R.; Takai, Mario Noboru; Sganzerla, Flavio [ELETRONORTE, Brasilia, DF (Brazil); O. Junior, Helio P.; Fonseca, Claudio S. [Marte Engenharia (Brazil); Guimaraes, R.P.; Mendes, Eloisa R.

    1994-12-31

    This paper introduces an economical solution for close HV lines small villages and farms load supply. The needed modifications to adapt a planned transmission system to supply loads located along the lines routes are presented. The paper describes the two overhead ground wires scheme planned for implementation in the 230 kV transmission line under construction by ELETRONORTE in Mato Grosso and Rondonia supplying loads each one totaling roughly 8 MW. (author) 4 refs., 4 figs., 2 tabs.

  2. On the Distribution of Lightning Current among Interconnected Grounding Systems in Medium Voltage Grids

    Directory of Open Access Journals (Sweden)

    Guido Ala

    2018-03-01

    Full Text Available This paper presents the results of a first investigation on the effects of lightning stroke on medium voltage installations’ grounding systems, interconnected with the metal shields of the Medium Voltage (MV distribution grid cables or with bare buried copper ropes. The study enables us to evaluate the distribution of the lightning current among interconnected ground electrodes in order to estimate if the interconnection, usually created to reduce ground potential rise during a single-line-to-ground fault, can give place to dangerous situations far from the installation hit by the lightning stroke. Four different case studies of direct lightning stroke are presented and discussed: (1 two secondary substations interconnected by the cables’ shields; (2 two secondary substations interconnected by a bare buried conductor; (3 a high voltage/medium voltage station connected with a secondary substation by the medium voltage cables’ shields; (4 a high voltage/medium voltage station connected with a secondary substation by a bare buried conductor. The results of the simulations show that a higher peak-lowering action on the lighting-stroke current occurs due to the use of bare conductors as interconnection elements in comparison to the cables’ shields.

  3. Physical and observable characteristics of cloud-to-ground lightning over the Pearl River Delta region of South China

    Science.gov (United States)

    Liu, Yonglin; Chan, L. Y.; Lin, Qinhao; Feng, Wanxing; Bi, Xinhui; Chen, Jiahong; Tao, Hantao; Wang, Xinming; Chen, Duohong; Sheng, Guoying; Fu, Jiamo

    2014-05-01

    Cloud-to-ground (CG) lightning characteristic parameters deduced from the lightning location system (LLS) for five differing microenvironmental areas relative to megacity, city, municipal town, hilly suburban area, and mountainous rural area conditions were examined in our 2009-2011 Pearl River Delta (PRD) study. Our LLS data analysis showed that there were high variation of lightning characteristics and phenomenal changes among these areas. As a supplement to the usual study of physical characteristics, an observation-based methodology had been developed to study the lightning behavior, while the respective thunderstorms were traversing through these observation areas. Special features and phenomenal changes related to the lightning characteristic parameters, such as observable lightning stroke days (OLSDs) and observable lightning stroke frequency and density for an OLSD, were also addressed. Microenvironmental variation due to change in topography, degree of urbanization, urban effect, and thunderstorm strength was found to affect the spatial distribution of lightning stroke and the severity of lightning activities over the observation areas. This approach increases our understanding of lightning in subtropical China. It also tells us more about the behavior of lightning while the thunderstorm traverses through an observation area. This information is lacking in previous studies.

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

    OpenAIRE

    S. K. Kar; Y.-A. Liou; K.-J. Ha

    2007-01-01

    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,...

  5. Characteristics of cloud-to-ground lightning flashes along the east coast of the United States

    Science.gov (United States)

    Orville, R. E., Sr.; Pyle, R. B.; Henderson, R. W.; Orville, R. E., Jr.; Weisman, R. A.

    1985-01-01

    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. Most of the lightning occurring from Maine to Florida and as far west as Ohio is detected. Time, location, flash polarity, stroke count, and peak signal amplitude are recorded in real time. Flash locations, time, and polarity are displayed routinely for research and operational purposes. Flash density maps have been generated for the summers of 1983 and 1984, when the network only extended to North Carolina, and show density maxima in northern Virginia and Maryland.

  6. Enhancement of cloud-to-ground lightning activity over Taipei, Taiwan in relation to urbanization

    Science.gov (United States)

    Kar, S. K.; Liou, Y. A.

    2014-10-01

    Collecting the cloud-to-ground (CG) lightning flash data from Tai-Power Company of Taiwan, a long term study has been performed to investigate the enhancement of lightning activity in and around Taipei City, the largest metropolitan city of Taiwan, in relation to urbanization, for the period of 2005-2010. Results reveal that negative flash density is enhanced by approximately 64% while the positive flash density is enhanced by 48%, over and downwind of the city compared with other neighboring areas. On the other hand a decrease of nearly 24% in the percentage of positive flashes occurs over and downwind of Taipei compared to upwind values. We have also investigated the effect of urbanization on peak current of both polarities but no significant effect is noticed. Possible influence of urban particulate matter on the enhancement of CG lightning activity has been analyzed utilizing the annual averages of PM10 (particulate matter with aerodynamic diameter smaller than 10 μm) and SO2 (sulfur dioxide) concentrations data. Interesting results are found, indicating the higher concentrations of PM10 and SO2 contributes to the CG lightning enhancement. Both the concentrations exhibit a positive linear correlation with the percent change in CG flashes from the upwind to the urban area and from the upwind to the downwind area. However, the correlation coefficient for PM10 concentrations is comparatively much lower than SO2 concentrations. Positive correlations of 0.55 and 0.68 are found for the PM10 and SO2 concentrations, respectively, when compared separately with the percent change in CG flashes from the upwind to the downwind area, indicating the influence of aerosols on urban CG lightning enhancement. Hourly variation of lightning flashes show that the urban effects on CG lightning is prominent in the afternoon and early evening hours. The results obtained from the present analysis corroborate the results reported in the literature by other researchers.

  7. Lightning Surges on a Control Cable Incoming through a Grounding Lead

    Science.gov (United States)

    Ametani, Akihiro; Taki, Norikazu; Miyazaki, Daisuke; Nagaoka, Naoto; Okabe, Shigemitu

    The present paper has investigated the effect of sheath grounding on a control cable based on EMTP simulations, when a lightning current flows into counterpoises representing a part of a grounding mesh. Voltages and currents observed on the control cable are given as a superposition of an well-known induced voltage due to the lightning current on the counterpoise, of a voltage transferred from the counterpoise to which the cable metalic sheath is grounded, and of a lightning current circulating in a closed loop composed of the metalic sheath and the counterpoise when the cable both ends are grounded. The induced voltage from the counterpoise is not necessarily dominant even in a long cable because the current along the counterpoise decreases rapidly as the distance from the sending end increases. Although the sheath grounding decreases the node voltage due to the induced voltage, but at the same time increases a voltage transferred from the counterpoise. The inductance of a grounding lead reduces a current flowing into the cable sheath during a high frequency transient, and thus a more current flows through the counterpoise. This results in a higher induced voltage to the control cable from the counterpoise.

  8. Ground- and Space-based Observations of Horizontally-extensive Lightning Flashes

    Science.gov (United States)

    Zhang, D.; Cummins, K. L.; Bitzer, P. M.

    2017-12-01

    Horizontally-extensive lightning flashes occur frequently in association with mature and late phases of multicellular thunderstorms, both in trailing stratiform regions and horizontally-extensive anvils. The spatial relationship between these flashes and the parent cloud volume is of importance for space launch operational decision making, and is of broader scientific interest. Before this question can be accurately addressed, there is a need to understand the degree to which current lightning observation systems can depict the spatial extent of these long flashes. In this ongoing work, we will intercompare the depiction of horizontally-extensive flashes using several ground-based lightning locating systems (LLSs) located at Kennedy Space Center (KSC) with space-based observations observed by the recently-launched Geostationary Lightning Mapper (GLM) onboard the GOES-16 satellite. Ground-based datasets include the KSC Lightning Mapping Array (KSCLMA), the operational narrowband digital interferometer network MERLIN, and the combined cloud-to-ground and cloud lightning dataset produced by the U.S. National Lightning Detection Network (NLDN). The KSCLMA system is a network of VHF time-of-arrival sensors that preferentially report breakdown processes, and MERLIN is a network of VHF interferometers that point to the discharges in the horizontal plane. Observations to date indicate that MERLIN and the KSCSLMA provide similar overall descriptions of the spatial and temporal extent of these flashes, while the NLDN does not provide adequate spatial mapping of these flashes. The KSC LMA system has much better location accuracy, and provides excellent 3-dimensional representation within 100 km of KSC. It also has sufficient sensitivity to provide 2-dimensional flash mapping within 250 km of KSC. The MERLIN system provides a more-detailed representation of fast leader propagation (in 2 dimensions) with 100 km of KSC. Earlier work during the CHUVA campaign in Brazil with

  9. DC wiring system grounding and ground fault protection issues for central station photovoltaic power plants

    Science.gov (United States)

    Simburger, E. J.

    1983-01-01

    The DC wiring system for a photovoltaic power plant presents a number of unique challenges to be overcome by the plant designers. There are a number of different configurations that the grounding of the DC wiring system can take, and the choice will affect the number and type of protective devices required to ensure safety of personnel and protection of equipment. The major grounding and fault protection considerations that must be taken into account when selecting the basic overall circuit configuration are summarized. The inherent advantages and disadvantages of each type of circuit grounding (resistance or solid) along with the personnel safety and equipment protection issues for each of these grounding methods are presented.

  10. Objective Lightning Forecasting at Kennedy Space Center/Cape Canaveral Air Force Station using Cloud-to-Ground Lightning Surveillance System Data

    Science.gov (United States)

    Lambert, Winifred; Wheeler, Mark

    2004-01-01

    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

  11. Evaluation of Characteristics of Lightning Faults on 275kV Transmission Lines

    Science.gov (United States)

    Kawamura, Hironao; Itamoto, Naoki; Shinjo, Kazuo; Ishii, Masaru

    It is effective to design the lightning protection of transmission lines by employing simulation to be able to reproduce conditions of experienced lightning faults. As a result of the lightning faults on 275kV transmission lines in Hokuriku area, the frequency of only one-ground fault of upper or middle lines is higher. Especially, the frequency of one-ground faults of the middle lines in summer is the highest. It is thought that many one-ground faults in summer are caused by direct lightning strokes to phase conductors. Moreover, multi-ground faults caused by lightning strokes to tower tops or overhead ground wires also include many ground faults of the middle lines. In this paper, the experienced lightning faults on the 275kV transmission lines are reproduced by EMTP calculations and the characteristics of the ground-fault lines are examined.

  12. The physics of lightning

    Science.gov (United States)

    Dwyer, Joseph R.; Uman, Martin A.

    2014-01-01

    of upward connecting leaders from those objects or from the ground? What is the physics of compact intra-cloud discharges (CIDs) (that produce a narrow bipolar wideband electric field pulse, a narrow bipolar event or NBE, apparently multiple-reflecting propagating waves within 1 km height, and copious HF and VHF radiation)? How are CIDs related to other types of preliminary breakdown pulses? Are CIDs related to the Terrestrial Gamma-Ray Flashes (TGFs) observed on orbiting satellites or to the Transient Luminous Events (TLEs) photographed above cloud tops, particularly to so-called “gigantic jets”? By what physical mechanisms do lightning leaders emit pulses of X-rays? Do the X-rays play a role in lightning propagation? By what mechanism do thunderclouds generate relatively-steady internal X-rays? Do X-rays and other high energy radiation affect cloud electrification and play a role in lightning initiation? By what physical mechanisms are Terrestrial Gamma-Ray Flashes (TGFs) produced? Do TGFs pose a hazard to individuals in aircraft? How do cloud-to-ground and intra-cloud lightning affect the upper atmosphere and ionosphere? What are the physics of the Transient Luminous Events (TLEs), “Sprites”, “jets”, and “elves”? What is the energy input into the ionosphere/magnetosphere from lightning? How exactly does rocket-and-wire (“classical” with a grounded wire and “altitude” with a floating wire) triggering of lightning work? Are there other possible and practical triggering techniques such as laser triggering? Can triggering reduce or eliminate the local occurrence of natural lightning? What are the power and energy of the component processes of lightning flashes and how are they distributed among electromagnetic processes (DC to light), thermal processes, mechanical (acoustic) processes, and relativistic (high energy) processes (runaway electrons, runaway positrons, X-ray, and gamma rays)? What is the physics of ball lightning? Is there more than

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

    Directory of Open Access Journals (Sweden)

    J. A. Santos

    2013-07-01

    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.

  14. Relationships between thunderstorms and cloud-to-ground lightning in the United States

    Energy Technology Data Exchange (ETDEWEB)

    Changnon, S.A. (Changnon Climatologist, Mahomet, IL (United States))

    1993-01-01

    Climatic assessments of cloud-to-ground (CG) flashes, and of the relationship between CG flashes and thunder events, as reported at 62 first-order stations in the contiguous US, are performed on the basis of data from networks of lightning sensors operated during 1986-1989. The adequacy of thunder-event data for describing thunderstorm occurrences at a point is determined. The average and extreme frequencies of CG lightning is delineated. Thunder events are found to provide poor estimates of CG lightning incidences and durations. CG flash data reveal that 20 percent (far west) and 50 percent (southeast US) of all thunder events are missed at weather stations; 30-60 percent of all thunder events have durations too short; and 10 per cent (North and West), 40 percent (mountains), and 25 percent (southeast) of all CG flashes within 20 km of weather stations are not reported as thunderstorms. The use of historical thunder data, as a surrogate for lightning activity, is improper, and thunder values need to be adjusted with the relationships presented. 33 refs.

  15. Electrostatic protection of the solar power satellite and rectenna. Part 2: Lightning protection of the rectenna

    Science.gov (United States)

    1980-01-01

    Computer simulations and laboratory tests were used to evaluate the hazard posed by lightning flashes to ground on the Solar Power Satellite rectenna and to make recommendations on a lightning protection system for the rectenna. The distribution of lightning over the lower 48 of the continental United States was determined, as were the interactions of lightning with the rectenna and the modes in which those interactions could damage the rectenna. Lightning protection was both required and feasible. Several systems of lightning protection were considered and evaluated. These included two systems that employed lightning rods of different lengths and placed on top of the rectenna's billboards and a third, distribution companies; it consists of short lightning rods all along the length of each billboard that are connected by a horizontal wire above the billboard. The distributed lightning protection system afforded greater protection than the other systems considered and was easier to integrate into the rectenna's structural design.

  16. 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

  17. Synchronized observations of cloud-to-ground lightning using VHF broadband interferometer and acoustic arrays

    Science.gov (United States)

    Qiu, Shi; Zhou, Bi-Hua; Shi, Li-Hua

    2012-10-01

    A single-station-based lightning discharge channel reconstruction system by combining a two-dimensional (2D) VHF broadband interferometer and a three-dimensional (3D) acoustic lighting mapping system has been developed and used for lightning observations. Two cloud-to-ground (CG) flashes with highly branched leaders recorded by the system are analyzed and presented in this paper. VHF radiation could well delineate the development of simultaneous leader branches, while acoustic emissions mainly located on the main channel which was traversed by return stroke (RS) process. Localizations by VHF and acoustic emissions agree well with each other. The mapping results confirm that audible acoustic emission of lightning discharge is mainly associated with high current process like RS. Leaders could generate detectable acoustic signals, with amplitude at least an order weaker than ensuing RS, but they are hard to identify except in closer ranges than the main channel. As a significant phenomenon, this paper provides the first 3D locations associated with sources of tearing sounds, which are inferred to be generated by downward negative leaders when they approach ground. The synchronized observation enable VHF interferometer locate lightning development in spatially quasi 3D, and three stepped leaders, five dart leaders and two dart-stepped leaders are identified, with the 3D velocity (1.3-3.9) × 105 m/s, (1.0-2.9) × 107 m/s and from (1.0-1.3) × 107 m/s to (2.4-2.6) × 106 m/s, respectively. In addition, the application of this approach in improving the accuracy of thunder ranging is discussed.

  18. Positive cloud-to-ground lightning flashes in severe storms

    Science.gov (United States)

    Rust, W. D.; Macgorman, D. R.; Arnold, R. T.

    1981-01-01

    The occurrence of cloud-to-ground flashes that effectively lower positive charge to earth (+CG flash) over flat terrain has been documented in the mature stage of severe thunderstorms. Of the 31 documented +CG flashes, most had only one return stroke. Zero-to-peak rise times for the strokes averaged 7 microsec. The +CG flashes averaged 520 ms in duration, with 25 percent lasting more than 800 ms. Many of these had field changes suggestive of continuing current. Positive flashes have been observed to emanate from several regions of severe storms: high on the back of the main storm tower, through the wall cloud, and from the downshear anvil. Visually most of these positive flashes have emanated from high in the storm, and acoustic mapping of two shows thunder sources to a height of about 15 km.

  19. Multi-mode Observations of Cloud-to-Ground Lightning Strokes

    Science.gov (United States)

    Smith, M. W.; Smith, B. J.; Clemenson, M. D.; Zollweg, J. D.

    2015-12-01

    We present hyper-temporal and hyper-spectral data collected using a suite of three Phantom high-speed cameras configured to observe cloud-to-ground lightning strokes. The first camera functioned as a contextual imager to show the location and structure of the strokes. The other two cameras were operated as slit-less spectrometers, with resolutions of 0.2 to 1.0 nm. The imaging camera was operated at a readout rate of 48,000 frames per second and provided an image-based trigger mechanism for the spectrometers. Each spectrometer operated at a readout rate of 400,000 frames per second. The sensors were deployed on the southern edge of Albuquerque, New Mexico and collected data over a 4 week period during the thunderstorm season in the summer of 2015. Strikes observed by the sensor suite were correlated to specific strikes recorded by the National Lightning Data Network (NLDN) and thereby geo-located. Sensor calibration factors, distance to each strike, and calculated values of atmospheric transmission were used to estimate absolute radiometric intensities for the spectral-temporal data. The data that we present show the intensity and time evolution of broadband and line emission features for both leader and return strokes. We highlight several key features and overall statistics of the observations. A companion poster describes a lightning model that is being developed at Sandia National Laboratories.

  20. Doppler Radar and Cloud-to-Ground Lightning Observations of a Severe Outbreak of Tropical Cyclone Tornadoes

    Science.gov (United States)

    McCaul, Eugene W., Jr.; Buechler, Dennis; Cammarata, Michael; Arnold, James E. (Technical Monitor)

    2002-01-01

    Data from a single WSR-88D Doppler radar and the National Lightning Detection Network are used to examine the characteristics of the convective storms that produced a severe tornado outbreak within Tropical Storm Beryl's remnants on 16 August 1994. Comparison of the radar data with reports of tornadoes suggests that only 12 cells produced the 29 tornadoes that were documented in Georgia and the Carolinas on that date. Six of these cells spawned multiple tornadoes, and the radar data confirm the presence of miniature supercells. One of the cells was identifiable on radar for 11 hours, spawning tornadoes over a time period spanning approximately 6.5 hours. Time-height analyses of the three strongest supercells are presented in order to document storm kinematic structure and evolution. These Beryl mini-supercells were comparable in radar-observed intensity but much more persistent than other tropical cyclone-spawned tornadic cells documented thus far with Doppler radars. Cloud-to-ground lightning data are also examined for all the tornadic cells in this severe swarm-type tornado outbreak. These data show many of the characteristics of previously reported heavy-precipitation supercells. Lightning rates were weak to moderate, even in the more intense supercells, and in all the storms the lightning flashes were almost entirely negative in polarity. No lightning at all was detected in some of the single-tornado storms. In the stronger cells, there is some evidence that lightning rates can decrease during tornadogenesis, as has been documented before in some midlatitude tornadic storms. A number of the storms spawned tornadoes just after producing their final cloud-to-ground lightning flashes. These findings suggest possible benefits from implementation of observing systems capable of monitoring intracloud as well as cloud-to-ground lightning activity.

  1. Channel Base Current Model for Negative Multiple Cloud-to-ground Lightning

    Science.gov (United States)

    Ballarotti, M. G.; Saba, M. M.; Pinto, O.; Lacerda, M.; Williams, E.

    2012-12-01

    Approximately 50% of all negative cloud-to-ground lightning flashes have one single ground connection. For this type of flash, the current intensity at the channel base is modeled here as an electronic circuit with especial focus on the current cut-off process. The fundamental concept used is the current instability criteria proposed by Stan Heckman (1992). Considering the total channel resistance (R) and capacitance (C) and the thermodynamic (cooling) channel constant (tau), he hypothesizes that when RC > tau, the channel is unstable and the current cut-off (discrete stroke); and when RC Laboratory arc discharge data based on current measurements are used for R and tau as a function of current. In order to simulate this circuit, three processes were taken into account: (1) power source (lightning upper channel development inside the cloud), (2) electrical breakdown at the channel top (return-stroke initiation) and (3) channel base decay and cut-off (comparing tau, R and C). All processes have a correspondent circuit element/subsystem. The fundamental electronic elements are respectively: (1) a controlled current source as a function of charge density and cloud leader length and cross area; (2) a breakdown device (surge arrester) combined with a cut-off elapsed time-dependent resistance performing the resistive interrupted channel; and (3) a resistance in parallel with a capacitor in series with a switch controlled by a comparator RC versus tau. The primary objective of this modeling is to simulate the current waveform in time, representing the cut-off and transition to another subsequent return-stroke with realistic values for interstroke interval, continuing current and M-components amplitude and duration. Typical values for these parameters will be represented as well as distribution extreme values. These current waveforms will be compared with cloud-to-ground lightning current measurements in towers (e.g. San Salvatore, Gaisberg, Cachimbo).

  2. Evidence for the influence of land uses and soil types on cloud-to-ground lightning activity in Asturias (Spain)

    Science.gov (United States)

    Sisniega, David Prieto; García, Manuel Mora; Menéndez, Susana Fernández; Soriano, Luís Rivas; de Pablo Dávila, Fernando

    2018-05-01

    The present study analyses the impact of the different categories of land use and types of soils on cloud-to-ground (CG) lightning activity in the region of Asturias (Spain). Thirteen (fifteen) land uses (types of soils) and a range of fourteen years (2000 to 2013) of CG-lightning flash data were considered to complete the study. Some areas that have suffered the strong impact of human activity (urban, mining, and industrial) were associated with the increase of CG-lightning activity. When considering vegetated areas, areas with non-agricultural vegetation, arable land and permanent crops, it was showed a greater CG activity. With reference to the types of soils, Fluvisols, Regosols/Cambic-Arenosols, and Luvisols, these seemed to be associated to the increase of CG-lightning activity. The results found for the region of Asturias are different from those reported by Mora et al. (2015) for the region of Castilla y Leon (Spain).

  3. Ground-Based Observations of Terrestrial Gamma Ray Flashes Associated with Downward-Directed Lightning Leaders

    Science.gov (United States)

    Belz, J.; Abbasi, R.; Krehbiel, P. R.; LeVon, R.; Remington, J.; Rison, W.; Thomas, R. J.

    2017-12-01

    Terrestrial Gamma Flashes (TGFs) have been observed in satellite-borne gamma ray detectors for several decades, starting with the BATSE instrument on the Compton Gamma-Ray observatory in 1994. TGFs consist of bursts of upwards of 1018 primary gamma rays, with a duration of up to a few milliseconds, originating in the Earth's atmosphere. More recent observations have shown that satellite-observed TGFs are generated in upward-propagating negative leaders of intracloud lightning, suggesting that they may be sensitive to the processes responsible for the initial lightning breakdown. Here, we present the first evidence that TGFs are also produced at the beginning of negative cloud-to-ground flashes, and that they may provide a new window through which ground-based observatories may contribute to understanding the breakdown process. The Telescope Array Surface Detector (TASD) is a 700 square kilometer cosmic ray observatory, an array of 507 3m2 scintillators on a 1.2 km grid. The array is triggered and read out when at least three adjacent detectors observe activity within an 8 μs window. Following the observation of bursts of anomalous TASD triggers, lasting a few hundred microseconds and correlated with local lightning activity, a Lightning Mapping Array (LMA) and slow electric field antenna were installed at the TASD site in order to study the effect. From data obtained between 2014 and 2016, correlated observations were obtained for ten -CG flashes. In 9 out of 10 cases, bursts of up to five anomalous triggers were detected during the first ms of the flash, as negative breakdown was descending into lower positive storm charge. The triggers occurred when the LMA-detected VHF radiation sources were at altitudes between 1.5 to 4.5 km AGL. The tenth flash was initiated by an unusually energetic leader that reached the ground in 2.5 ms and produced increasingly powerful triggers down to about 500 m AGL. While the TASD is not optimized for individual gamma ray detection

  4. Evaluation of Fibre Lifetime in Optical Ground Wire Transmission Lines

    Science.gov (United States)

    Grunvalds, R.; Ciekurs, A.; Porins, J.; Supe, A.

    2017-06-01

    In the research, measurements of polarisation mode dispersion of two OPGWs (optical ground wire transmission lines), in total four fibres, have been carried out, and the expected lifetime of the infrastructure has been assessed on the basis of these measurements. The cables under consideration were installed in 1995 and 2011, respectively. Measurements have shown that polarisation mode dispersion values for cable installed in 1995 are four times higher than that for cable installed in 2011, which could mainly be explained by technological differences in fibre production and lower fibre polarisation mode dispersion requirements in 1995 due to lack of high-speed (over 10 Gbit/s) optical transmission systems. The calculation methodology of non-refusal work and refusal probabilities, using the measured polarisation mode dispersion parameters, is proposed in the paper. Based on reliability calculations, the expected lifetime is then predicted, showing that all measured fibres most likely will be operational within minimum theoretical service life of 25 years accepted by the industry.

  5. Scope of Jovian lightning observation by ground-based and spacecraft instruments

    Science.gov (United States)

    Fukuhara, T.; Takahashi, Y.; Sato, M.; Nakajima, K.

    2009-12-01

    It is suggested by recent observational and theoretical studies that the thunderstorms, i.e., strong moist convective clouds in Jupiter’s atmosphere are very important not only as an essential ingredient of meteorology of Jupiter but also as a potentially very useful “probe” of the water abundance of the deep atmosphere, which is crucial to constrain the behavior of volatiles in early solar system. We would propose the lightning observation with properly designed optical device onboard Jovian system orbiter and with the ground-based telescope. Based on detailed analysis of cloud motions by Galileo orbiter, Gierasch et al. proposed that the thunderstorms can produce the small scale eddies and ultimately drive the belt/zone structure. Moreover, the belt zone structure helps the development of thunderstorms in the belt region in accordance with observation; the belt/zone structure and thunderstorms may be in a symbiotic relation. This framework is a refined version of shallow origin theory, but, although it is a very fantastic idea, quantitative verification remains to be done. Most recent numerical modeling by our group calculated all three types of cloud, i.e., H2O, NH3, and, NH4SH. One of the most important findings is the existence of distinct, quasi-periodic temporal variation of the convective cloud activity; explosion of cloud activity extending all over the computational domain occurs separated by quiet period of order of 10 days. Another surprising finding is that the period of the active/break cycle is roughly proportional to the amount of condensable component in the sub-cloud layer. This strong correspondence between the deep volatile abundance and temporal variability of cloud convection implies a new method to probe the deep atmosphere. We believe JGO with other optical equipments especially for atmospheric spectral imaging is the ideal platform for the lightning detector. Comparing quantitative lightning activity with ambient cloud motion and

  6. Two-light circuit continuously monitors ac ground, phase, and neutral wires

    Science.gov (United States)

    Mee, R. W.

    1966-01-01

    Two-transformer, two-lamp circuit monitors the continuity of ac ground, neutral, and phase wires. The circuit gives different visual indications if any one of the three lines should become open circuited.

  7. GLM Proxy Data Generation: Methods for Stroke/Pulse Level Inter-Comparison of Ground-Based Lightning Reference Networks

    Science.gov (United States)

    Cummins, Kenneth L.; Carey, Lawrence D.; Schultz, Christopher J.; Bateman, Monte G.; Cecil, Daniel J.; Rudlosky, Scott D.; Petersen, Walter Arthur; Blakeslee, Richard J.; Goodman, Steven J.

    2011-01-01

    In order to produce useful proxy data for the GOES-R Geostationary Lightning Mapper (GLM) in regions not covered by VLF lightning mapping systems, we intend to employ data produced by ground-based (regional or global) VLF/LF lightning detection networks. Before using these data in GLM Risk Reduction tasks, it is necessary to have a quantitative understanding of the performance of these networks, in terms of CG flash/stroke DE, cloud flash/pulse DE, location accuracy, and CLD/CG classification error. This information is being obtained through inter-comparison with LMAs and well-quantified VLF/LF lightning networks. One of our approaches is to compare "bulk" counting statistics on the spatial scale of convective cells, in order to both quantify relative performance and observe variations in cell-based temporal trends provided by each network. In addition, we are using microsecond-level stroke/pulse time correlation to facilitate detailed inter-comparisons at a more-fundamental level. The current development status of our ground-based inter-comparison and evaluation tools will be presented, and performance metrics will be discussed through a comparison of Vaisala s Global Lightning Dataset (GLD360) with the NLDN at locations within and outside the U.S.

  8. GPM GROUND VALIDATION VAISALA US NLDN LIGHTNING FLASH DATA MC3E V3

    Data.gov (United States)

    National Aeronautics and Space Administration — The U.S. National Lightning Detection Network is a commercial lightning detection network operated by Vaisala. A network of over 100 antennae are connected to a...

  9. Insulator and Clerance Requirements in Overhead Line Transmission Systems without Shield Wires

    DEFF Research Database (Denmark)

    Sørensen, Thomas Kjærsgaard; Holbøll, Joachim

    2008-01-01

    This paper theoretically examines the required insulation lengths and clearances in 400 kV overhead line systems when not making use of ground wires as lightning protection. The influence of lightning strikes to the system is investigated based on dynamic transmission line simulations of a 400 kV...

  10. A Study on a Lightning-Surge Analysis Composite Model of a Reinforced Concrete Pole and a Grounding Electrode in Power Distribution Lines

    Science.gov (United States)

    Miyazaki, Teru; Okabe, Shigemitsu; Mori, Kenjirou; Aiba, Kiyoshi; Hirai, Takao; Yoshinaga, Jun; Sekioka, Shozo

    It has been well known for many years that grounding resistance has a current-dependent characteristic due to soil ionization. Moreover reinforced concrete poles should be treated as a kind of grounding electrode against lightning strokes. However, these characteristics were seldom taken into account for lightning-protection designs. If these characteristics are represented in EMTP models for lightning protection designs, the rationalization of the lightning protection designs for distribution lines is expected. In order to clarify transient behaviors of a system of a grounding electrode and a concrete pole, experiments were conducted with full-scale grounding systems. In this study, the paper described a composite model of a reinforced concrete pole and a grounding electrode for distribution lines and compared the calculated waveforms with measured waveforms of the experiments. The results show that it is necessary to take a current-dependent characteristic into account and treat concrete poles as a kind of grounding electrode.

  11. 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

    2007-11-01

    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.

  12. 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

    2007-11-01

    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.

  13. Design of power cable grounding wire anti-theft monitoring system

    Science.gov (United States)

    An, Xisheng; Lu, Peng; Wei, Niansheng; Hong, Gang

    2018-01-01

    In order to prevent the serious consequences of the power grid failure caused by the power cable grounding wire theft, this paper presents a GPRS based power cable grounding wire anti-theft monitoring device system, which includes a camera module, a sensor module, a micro processing system module, and a data monitoring center module, a mobile terminal module. Our design utilize two kinds of methods for detecting and reporting comprehensive image, it can effectively solve the problem of power and cable grounding wire box theft problem, timely follow-up grounded cable theft events, prevent the occurrence of electric field of high voltage transmission line fault, improve the reliability of the safe operation of power grid.

  14. Verification of the Lightning Protection Effect Produced by the Difference in the Grounding Systems at High Voltage Receipt Equipment

    Science.gov (United States)

    Sakamoto, Yoshiki; Miyazaki, Teru; Taki, Shoji; Okabe, Shigemitsu; Hashimoto, Takashi; Higano, Akira

    The integrated grounding system which bundles up all various grounding electrodes has been introduced as a new grounding system from the movement toward the formation of standard international adjustment in recent years, and the example adopted also in high voltage receipt equipment is increasing. However, there are very many differences between TN system in the West and TT system in our country and points to be checked since the grounding purpose is crossing variably as the account of the upper stated, when adopting an integrated grounding system, and there are few examples checked experimentally until now. In this research, the viewpoint was extracted to lightning protection in such a background, the grounding system and integrated grounding system which were used with high voltage receipt equipment until now were compared, and real experiment and EMTP analysis were carried out for the purpose of grasping the characteristic in an integrated grounding system. From the experiment result in high voltage receipt equipment, and an analysis result, the result verified about the usefulness of integrated grounding to lightning protection is reported.

  15. Preliminary Assessment of Detection Efficiency for the Geostationary Lightning Mapper Using Intercomparisons with Ground-Based Systems

    Science.gov (United States)

    Bateman, Monte; Mach, Douglas; Blakeslee, Richard J.; Koshak, William

    2018-01-01

    As part of the calibration/validation (cal/val) effort for the Geostationary Lightning Mapper (GLM) on GOES-16, we need to assess instrument performance (detection efficiency and accuracy). One major effort is to calculate the detection efficiency of GLM by comparing to multiple ground-based systems. These comparisons will be done pair-wise between GLM and each other source. A complication in this process is that the ground-based systems sense different properties of the lightning signal than does GLM (e.g., RF vs. optical). Also, each system has a different time and space resolution and accuracy. Preliminary results indicate that GLM is performing at or above its specification.

  16. Assessing Convective Influence by Utilizing Cloud to Ground Lightning Data and High Resolution Kinematic Trajectories

    Science.gov (United States)

    Porter, M. J.; Fuelberg, H.; Pickering, K.; Crawford, J.; Brune, W.; Cohen, R.; Heikes, B.; Sachse, G.; Singh, H.; Wennberg, P.

    2005-12-01

    One must understand the generation of NOx by lightning (LNOx) and its vertical redistribution by convection to quantify the atmospheric processing of reactive nitrogen species. This study addresses these themes by revisiting Jeker's concept of "lightning tracing" (Jeker et al., JGR, 2000) using INTEX-A data gathered from June to August 2004. Kinematic trajectories calculated with output from the National Weather Service's Rapid Update Cycle (RUC) model are initialized along several convectively influenced flights and then followed back to their most recent intersection with lightning flashes observed by the National Lightning Detection Network. Since the RUC data are hourly at a 20 km spacing, their resolution is much greater than usually available with global data. This procedure allows a meteorological assessment of the sample's age since convection, which then is compared to its observed chemistry. In addition, the influence of the most recent lightning encounter on the chemical data is contrasted to the influence of lightning accumulated along the entire back trajectory. Finally, an analysis of the number of flashes encountered along the trajectory provides a means to quantify LNOx production. Performing this "lightning tracing" over multiple flights spanning the entire troposphere allows the construction of a post-convective LNOx vertical profile for INTEX-A.

  17. Modeling transient luminous events produced by cloud to ground lightning and narrow bipolar pulses: detailed spectra and chemical impact

    Science.gov (United States)

    Perez-Invernon, F. J.; Luque, A.; Gordillo-Vazquez, F. J.

    2017-12-01

    The electromagnetic field generated by lightning discharges can produce Transient Luminous Events (TLEs) in the lower ionosphere, as previously investigated by many authors. Some recent studies suggest that narrow bipolar pulses (NBP), an impulsive and not well-established type of atmospheric electrical discharge, could also produce TLEs. The characterization and observation of such TLEs could be a source of information about the physics underlying NBP. In this work, we develop two different electrodynamical models to study the impact of lightning-driven electromagnetic fields in the lower ionosphere. The first model calculates the quasi-electrostatic field produced by a single cloud to ground lightning in the terrestrial atmosphere and its influence in the electron transport. This scheme allows us to study halos, a relatively frequent type of TLE. The second model solves the Maxwell equations for the electromagnetic field produced by a lightning discharge coupled with the Langevin's equation for the induced currents in the ionosphere. This model is useful to investigate elves, a fast TLE produced by lightning or by NBP. In addition, both models are coupled with a detailed chemistry of the electronically and vibrationally excited states of molecular nitrogen, allowing us to calculate synthetic spectra of both halos and elves. The models also include a detailed set of kinetic reactions to calculate the temporal evolution of other species. Our results suggest an important enhancement of some molecular species produced by halos, as NOx , N2 O and other metastable species. The quantification of their production could be useful to understand the role of thunderstorms in the climate of our planet. In the case of TLEs produced by NBP, our model confirms the appearance of double elves and allows us to compute their spectral characteristics.

  18. Evaluation of lightning performance of transmission lines protected by metal oxide surge arresters using artificial intelligence techniques

    Energy Technology Data Exchange (ETDEWEB)

    Christodoulou, C.A.; Perantzakis, G. [Technological Educational Institute (TEI) of Lamia, Department of Electrical Engineering, Lamia (Greece); Spanakis, G.E. [School of Electrical and Computer Engineering, National Technical University of Athens, Athens (Greece); Karampelas, P. [Hellenic American University, Manchester, NH (United States)

    2012-12-15

    Lightning and switching overvoltages are the main causes for faults in electrical networks. In the last decades, several different conventional methodologies have been used for the adjustment of the lightning performance of high voltage transmission lines, which are protected against lightning using overhead ground wires and surge arresters. The current paper proposes a new developed Artificial Neural Network (ANN), based on the Q-learning algorithm, in order to estimate the lightning failure rate of lines of the Hellenic system. The results obtained by the ANN model exhibit a satisfactory correlation in comparison with the real recorded data or the simulations results taken from a conventional method. (orig.)

  19. 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

    2010-09-15

    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.

  20. On the sensitivity of cloud-to-ground lightning activity to surface air temperature changes at different timescales in São Paulo, Brazil

    Science.gov (United States)

    Pinto, O.; Pinto, I. R. C. A.

    2008-10-01

    This paper presents a study about the sensitivity of cloud-to-ground (CG) lightning activity to changes in surface air temperature at daily, monthly, yearly, and decadal timescales in the city of São Paulo (Brazil). Lightning data collected in the city by the Brazilian Lightning Detection Network (BrasilDat) from 1999 to 2006 and thunderstorm day data obtained from 1951 to 2006 were analyzed and compared with surface air temperature data. The lightning activity increases significantly with increasing temperature, with a sensitivity of approximately 40% per 1°C for daily and monthly timescales and approximately 30% per 1°C for decadal timescale. For the yearly timescale, the increase is not statistically significant. The lower sensitivity for the decadal timescale suggests that the lightning sensitivity to changes in surface air temperature decreases for larger timescales, in agreement with what is expected on the basis of convective adjustment. The decadal lightning sensitivity found in this study is in reasonable agreement with the increase in the global lightning activity estimated by most climate models. The study is the first to investigate in detail this relationship in a large urban area inside the tropics and should contribute to the effort to understand the impact of the global warming on lightning activity.

  1. Forecasting the onset of Cloud-Ground Lightning Using Layered Vertically Integrated Liquid Water

    National Research Council Canada - National Science Library

    D'Arcangelo, David

    2000-01-01

    ...), Florida is critical for personnel safety, but presents a difficult problem. Current methods for predicting CG lightning onset rely on radar analyses that require a reflectivity threshold to be exceeded at a specified temperature level...

  2. Investigating Possible Causative Mechanisms Behind the Houston Cloud-to-Ground Lightning Anomaly

    National Research Council Canada - National Science Library

    Gauthier, Michael L; Petersen, Walter A

    2005-01-01

    Anthropogenic influences such as the Urban Heat Island (UHI) and increased aerosol concentrations have been postulated for many years to have an effect on lower tropospheric chemistry, convection, lightning and rainfall...

  3. Investigation of Axial Electric Field Measurements with Grounded-Wire TEM Surveys

    Science.gov (United States)

    Zhou, Nan-nan; Xue, Guo-qiang; Li, Hai; Hou, Dong-yang

    2018-01-01

    The grounded-wire transient electromagnetic (TEM) surveying is often performed along the equatorial direction with its observation lines paralleling to the transmitting wire with a certain transmitter-receiver distance. However, such method takes into account only the equatorial component of the electromagnetic field, and a little effort has been made on incorporating the other major component along the transmitting wire, here denoted as axial field. To obtain a comprehensive understanding of its fundamental characteristics and guide the designing of the corresponding observation system for reliable anomaly detection, this study for the first time investigates the axial electric field from three crucial aspects, including its decay curve, plane distribution, and anomaly sensitivity, through both synthetic modeling and real application to one major coal field in China. The results demonstrate a higher sensitivity to both high- and low-resistivity anomalies by the electric field in axial direction and confirm its great potentials for robust anomaly detection in the subsurface.

  4. Ground level gamma-ray and electric field enhancements during disturbed weather: Combined signatures from convective clouds, lightning and rain

    Science.gov (United States)

    Reuveni, Yuval; Yair, Yoav; Price, Colin; Steinitz, Gideon

    2017-11-01

    We report coincidences of ground-level gamma-ray enhancements with precipitation events and strong electric fields typical of thunderstorms, measured at the Emilio Segre Cosmic Ray observatory located on the western slopes of Mt. Hermon in northern Israel. The observatory hosts 2 × 2″ Nal(TI) gamma ray scintillation detectors alongside a vertical atmospheric electric field (Ez) mill and conduction current (Jz) plates. During several active thunderstorms that occurred near the Mt. Hermon station in October and November 2015, we recorded prolonged periods of gamma ray enhancements, which lasted tens of minutes and coincided with peaks both in precipitation and the vertical electric field. Two types of events were detected: slow increase (up to 300 min) of atmospheric gamma ray radiation due to radon progeny washout (or rainout) along with minutes of Ez enhancement, which were not associated with the occurrences of nearby CG lightning discharges. The second type showed 30 min bursts of gamma rays, coinciding with minutes of Ez enhancement that closely matched the occurrences of nearby CG lightning discharges, and are superimposed on the radiation from radon daughters washed out to near surface levels by precipitation. We conclude that a superposition of accelerated high energy electrons by thunderstorm electric fields and radon progeny washout (or rainout) explains the relatively fast near surface gamma-ray increase, where the minutes-scale vertical electric field enhancement are presumably caused due to nearby convective clouds. Our results show that the mean exponential half-life depletion times of the residual nuclei produced during events without lightning occurrences were between 25-65 min, compared to 55-100 min when lightning was present, indicating that different types of nuclei were involved.

  5. International Aerospace and Ground Conference on Lightning and Static Electricity Held in Dayton, Ohio on 24-26 June 1986

    Science.gov (United States)

    1986-10-01

    1978) 11. Strawe, I>.F. et al, Proc. of 7th Int Genf , on Lightning and Static Electricity, C2-𔃻 ,"�) 12. Krehbiel, P.R. et al, J. Geophys R., 84...strokes. One can hardly recognize the effect of the propaga- tion distance in the spectra of negative strokes. Con- cerning the spectra of the positive...the characteristics of the positive ground strokes. Con- cerning parameters, which are included in this model, we faithfully follow Master et. al

  6. The Way of Reducing Current Values in Optical Ground Wires at Asymmetrical Faults on Overhead Transmission Lines

    Directory of Open Access Journals (Sweden)

    Egamnazarov Georgiy

    2016-12-01

    Full Text Available Given the fact that the installing costs of an optical ground wire on overhead lines directly depend on its cross-section, which in turn depends on the level of fault current it should withstand, in order to reduce these current values in the optical ground wire, I suggested performing its isolated descents from the end towers of the line with its transition to an optical cable. The research was carried out on the example of a 500 kV overhead line in the National Electric Power Grid. The Method of Symmetrical Components for calculating asymmetrical fault currents was not used; therefore, calculations were carried out on the base of presenting the line as a multi-wire system for the considered case as a five-wire system (optical ground wire, steel ground wire, and three phase wires. Such approach allows taking into account the initial asymmetry of the line parameters and modeling any kind of asymmetrical faults. The analyses of calculated results were performed. The conclusive evidence that the optical ground wire isolated descents from the end towers of the line give the possibility of reducing the level of maximal fault current distribution values in it and therefore its cross section, is presented.

  7. The Almena, Kansas, Tornadic Storm of 3 June 1999: A Long-Lived Supercell with Very Little Cloud-to-Ground Lightning

    Science.gov (United States)

    McCaul, Eugene W., Jr.; Buechler, Dennis E.; Hodanish, Stephen; Goodman, Steven J.; Arnold, James E. (Technical Monitor)

    2001-01-01

    The visual, radar, and lightning characteristics of a severe thunderstorm that spawned a large F3 tornado near Almena, Kansas, on 3 June 1999 are documented. The storm is interesting in that it transitioned from a low-precipitation to classic supercell, then back to low-precipitation supercell again prior to dissipation after sunset. Remarkably, the storm produced only 17 cloud-to-ground lightning flashes during its 4.5 h lifetime, despite VIL values reaching 95 kg/sq m, reflectivities of 50 dBZ or greater at altitudes of 14 km, and baseball-size hail at the surface. In contrast, total lightning rates inferred from a portable lightning detector during the large tornado were very high, approximately 100/min as expected for a storm of this size and intensity.

  8. Analysis of Cloud-to-Ground Lightning Clusters with Radar Composite Imagery

    National Research Council Canada - National Science Library

    Scott, Rhonda

    2001-01-01

    ...). Parsons finding could not be acted on because no individual storms were studied. The primary goal of this research is to determine whether the techniques used by Parsons can be applied to storms by examining the radar imagery and lightning data...

  9. Operational Cloud-to-Ground Lightning Initiation Forecasting Utilizing S-Band Dual-Polarization Radar

    Science.gov (United States)

    2014-03-27

    Kumjian, 2013a; 2013c). 2.6 Dual-Polarization Studies of Lightning Initiation Since the implementation of DP radar, meteorologist and...Course in Cloud Physics. Butterworth- Heinmann Pub. Rinehart, R. E., 2010: Radar for Meteorologists . 5th ed. Rinehart. Rutledge, S. A., and W. A

  10. A Stochastic Analysis of the Transient Current Induced along the Thin Wire Scatterer Buried in a Lossy Medium

    Directory of Open Access Journals (Sweden)

    Silvestar Šesnić

    2016-01-01

    Full Text Available The paper deals with the stochastic collocation analysis of a time domain response of a straight thin wire scatterer buried in a lossy half-space. The wire is excited either by a plane wave transmitted through the air-ground interface or by an equivalent current source representing direct lightning strike pulse. Transient current induced at the center of the wire, governed by corresponding Pocklington integrodifferential equation, is determined analytically. This antenna configuration suffers from uncertainties in various parameters, such as ground properties, wire dimensions, and position. The statistical processing of the results yields additional information, thus enabling more accurate and efficient analysis of buried wire configurations.

  11. Minimum depth of investigation for grounded-wire TEM due to self-transients

    Science.gov (United States)

    Zhou, Nannan; Xue, Guoqiang

    2018-05-01

    The grounded-wire transient electromagnetic method (TEM) has been widely used for near-surface metalliferous prospecting, oil and gas exploration, and hydrogeological surveying in the subsurface. However, it is commonly observed that such TEM signal is contaminated by the self-transient process occurred at the early stage of data acquisition. Correspondingly, there exists a minimum depth of investigation, above which the observed signal is not applicable for reliable data processing and interpretation. Therefore, for achieving a more comprehensive understanding of the TEM method, it is necessary to perform research on the self-transient process and moreover develop an approach for quantifying the minimum detection depth. In this paper, we first analyze the temporal procedure of the equivalent circuit of the TEM method and present a theoretical equation for estimating the self-induction voltage based on the inductor of the transmitting wire. Then, numerical modeling is applied for building the relationship between the minimum depth of investigation and various properties, including resistivity of the earth, offset, and source length. It is guide for the design of survey parameters when the grounded-wire TEM is applied to the shallow detection. Finally, it is verified through applications to a coal field in China.

  12. Experimentally verified inductance extraction and parameter study for superconductive integrated circuit wires crossing ground plane holes

    International Nuclear Information System (INIS)

    Fourie, Coenrad J; Wetzstein, Olaf; Kunert, Juergen; Meyer, Hans-Georg; Toepfer, Hannes

    2013-01-01

    As the complexity of rapid single flux quantum (RSFQ) circuits increases, both current and power consumption of the circuits become important design criteria. Various new concepts such as inductive biasing for energy efficient RSFQ circuits and inductively coupled RSFQ cells for current recycling have been proposed to overcome increasingly severe design problems. Both of these techniques use ground plane holes to increase the inductance or coupling factor of superconducting integrated circuit wires. New design tools are consequently required to handle the new topographies. One important issue in such circuit design is the accurate calculation of networks of inductances even in the presence of finite holes in the ground plane. We show how a fast network extraction method using InductEx, which is a pre- and post-processor for the magnetoquasistatic field solver FastHenry, is used to calculate the inductances of a set of SQUIDs (superconducting quantum interference devices) with ground plane holes of different sizes. The results are compared to measurements of physical structures fabricated with the IPHT Jena 1 kA cm −2 RSFQ niobium process to verify accuracy. We then do a parameter study and derive empirical equations for fast and useful estimation of the inductance of wires surrounded by ground plane holes. We also investigate practical circuits and show excellent accuracy. (paper)

  13. International Aerospace and Ground Conference on Lightning and Static Electricity (8th): Lightning Technology Roundup, held at Fort Worth, Texas on 21-23 June 1983.

    Science.gov (United States)

    1983-06-01

    Technique 16-1 D. Auckland , J.A. Birketi (Syracuse Research Corp.) Some Results and Limitations of Preny Analysis of In-Flight Lightning Data 17-1 T...Deficiencies D. Auckland , J. Birken, R. Wallenberg, SRO, (Syracuse, New York~) Unprotected Redoing Lightning Tests and Implications Keviar Airframe...mesocyclone., and some- to be characterized by its field change, while times tornadoes . They occur in squall lines or the faster T is used to study vaveform

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

    CSIR Research Space (South Africa)

    Simpson, LA

    2011-09-01

    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....

  15. Autonomous Inspection Robot for Power Transmission Lines Maintenance While Operating on the Overhead Ground Wires

    Directory of Open Access Journals (Sweden)

    Zheng Li

    2010-12-01

    Full Text Available This paper describes the development of a mobile robot capable of clearing such obstacles as counterweights, anchor clamps, and torsion tower. The mobile robot walks on overhead ground wires in 500KV power tower. Its ultimate purpose is to automate to inspect the defect of power transmission line. The robot with 13 motors is composed of two arms, two wheels, two claws, two wrists, etc. Each arm has 4 degree of freedom. Claws are also mounted on the arms. An embedded computer based on PC/104 is chosen as the core of control system. Visible light and thermal infrared cameras are installed to obtain the video and temperature information, and the communication system is based on wireless LAN TCP/IP protocol. A prototype robot was developed with careful considerations of mobility. The new sensor configuration is used for the claw to grasp the overhead ground wires. The bridge is installed in the torsion tower for the robot easy to cross obstacles. The new posture plan is proposed for obstacles cleaning in the torsion tower. Results of experiments demonstrate that the robot can be applied to execute the navigation and inspection tasks.

  16. Autonomous Inspection Robot for Power Transmission Lines Maintenance While Operating on the Overhead Ground Wires

    Directory of Open Access Journals (Sweden)

    Zheng Li

    2011-01-01

    Full Text Available This paper describes the development of a mobile robot capable of clearing such obstacles as counterweights, anchor clamps, and torsion tower. The mobile robot walks on overhead ground wires in 500KV power tower. Its ultimate purpose is to automate to inspect the defect of power transmission line. The robot with 13 motors is composed of two arms, two wheels, two claws, two wrists, etc. Each arm has 4 degree of freedom. Claws are also mounted on the arms. An embedded computer based on PC/104 is chosen as the core of control system. Visible light and thermal infrared cameras are installed to obtain the video and temperature information, and the communication system is based on wireless LAN TCP/IP protocol. A prototype robot was developed with careful considerations of mobility. The new sensor configuration is used for the claw to grasp the overhead ground wires. The bridge is installed in the torsion tower for the robot easy to cross obstacles. The new posture plan is proposed for obstacles cleaning in the torsion tower. Results of experiments demonstrate that the robot can be applied to execute the navigation and inspection tasks.

  17. Total Lightning as an Indicator of Mesocyclone Behavior

    Science.gov (United States)

    Stough, Sarah M.; Carey, Lawrence D.; Schultz, Christopher J.

    2014-01-01

    Apparent relationship between total lightning (in-cloud and cloud to ground) and severe weather suggests its operational utility. Goal of fusion of total lightning with proven tools (i.e., radar lightning algorithms. Preliminary work here investigates circulation from Weather Suveilance Radar- 1988 Doppler (WSR-88D) coupled with total lightning data from Lightning Mapping Arrays.

  18. Some features of stepped and dart-stepped leaders near the ground in natural negative cloud-to-ground lightning discharges

    Directory of Open Access Journals (Sweden)

    X. Qie

    2002-06-01

    Full Text Available Characteristics of the electric fields produced by stepped and dart-stepped leaders 200 µs just prior to the return strokes during natural negative cloud-to-ground (CG lightning discharges have been analyzed by using data from a broad-band slow antenna system with 0.08 µs time resolution in southeastern China. It has been found that the electric field changes between the last stepped leader and the first return stroke could be classified in three categories. The first type is characterized by a small pulse superimposed on the abrupt beginning of the return stroke, and accounts for 42% of all the cases. The second type accounts for 33.3% and is characterized by relatively smooth electric field changes between the last leader pulse and the following return stroke. The third type accounts for 24.7%, and is characterized by small pulses between the last recognizable leader pulse and the following return stroke. On the average, the time interval between the successive leader pulses prior to the first return strokes and subsequent return strokes was 15.8 µs and 9.4 µs, respectively. The distribution of time intervals between successive stepped leader pulses is quite similar to Gaussian distribution while that for dart-stepped leader pulses is more similar to a log-normal distribution. Other discharge features, such as the average time interval between the last leader step and the first return stroke peak, the ratio of the last leader pulse peak to that of the return stroke amplitude are also discussed in the paper.Key words. Meteology and atmospheric dynamics (atmospheric electricity; lightning – Radio science (electromagnetic noise and interference

  19. Some features of stepped and dart-stepped leaders near the ground in natural negative cloud-to-ground lightning discharges

    Directory of Open Access Journals (Sweden)

    X. Qie

    Full Text Available Characteristics of the electric fields produced by stepped and dart-stepped leaders 200 µs just prior to the return strokes during natural negative cloud-to-ground (CG lightning discharges have been analyzed by using data from a broad-band slow antenna system with 0.08 µs time resolution in southeastern China. It has been found that the electric field changes between the last stepped leader and the first return stroke could be classified in three categories. The first type is characterized by a small pulse superimposed on the abrupt beginning of the return stroke, and accounts for 42% of all the cases. The second type accounts for 33.3% and is characterized by relatively smooth electric field changes between the last leader pulse and the following return stroke. The third type accounts for 24.7%, and is characterized by small pulses between the last recognizable leader pulse and the following return stroke. On the average, the time interval between the successive leader pulses prior to the first return strokes and subsequent return strokes was 15.8 µs and 9.4 µs, respectively. The distribution of time intervals between successive stepped leader pulses is quite similar to Gaussian distribution while that for dart-stepped leader pulses is more similar to a log-normal distribution. Other discharge features, such as the average time interval between the last leader step and the first return stroke peak, the ratio of the last leader pulse peak to that of the return stroke amplitude are also discussed in the paper.

    Key words. Meteology and atmospheric dynamics (atmospheric electricity; lightning – Radio science (electromagnetic noise and interference

  20. Processing grounded-wire TEM signal in time-frequency-pseudo-seismic domain: A new paradigm

    Science.gov (United States)

    Khan, M. Y.; Xue, G. Q.; Chen, W.; Huasen, Z.

    2017-12-01

    Grounded-wire TEM has received great attention in mineral, hydrocarbon and hydrogeological investigations for the last several years. Conventionally, TEM soundings have been presented as apparent resistivity curves as function of time. With development of sophisticated computational algorithms, it became possible to extract more realistic geoelectric information by applying inversion programs to 1-D & 3-D problems. Here, we analyze grounded-wire TEM data by carrying out analysis in time, frequency and pseudo-seismic domain supported by borehole information. At first, H, K, A & Q type geoelectric models are processed using a proven inversion program (1-D Occam inversion). Second, time-to-frequency transformation is conducted from TEM ρa(t) curves to magneto telluric MT ρa(f) curves for the same models based on all-time apparent resistivity curves. Third, 1-D Bostick's algorithm was applied to the transformed resistivity. Finally, EM diffusion field is transformed into propagating wave field obeying the standard wave equation using wavelet transformation technique and constructed pseudo-seismic section. The transformed seismic-like wave indicates that some reflection and refraction phenomena appear when the EM wave field interacts with geoelectric interface at different depth intervals due to contrast in resistivity. The resolution of the transformed TEM data is significantly improved in comparison to apparent resistivity plots. A case study illustrates the successful hydrogeophysical application of proposed approach in recovering water-filled mined-out area in a coal field located in Ye county, Henan province, China. The results support the introduction of pseudo-seismic imaging technology in short-offset version of TEM which can also be an useful aid if integrated with seismic reflection technique to explore possibilities for high resolution EM imaging in future.

  1. A Method to Estimate the Probability that Any Individual Cloud-to-Ground Lightning Stroke was Within Any Radius of Any Point

    Science.gov (United States)

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

    2011-01-01

    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.

  2. 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

    2016-05-01

    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.

  3. GAI LONG RANGE LIGHTNING NETWORK V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The US National Lightning Detection Network is a commercial network that records the time, polarity, signal strength, and number of cloud-to-ground lightning flashes...

  4. The evolution of discharge current and channel radius in cloud-to-ground lightning return stroke process

    Science.gov (United States)

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

    2017-09-01

    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.

  5. Striking Distance Determined From High-Speed Videos and Measured Currents in Negative Cloud-to-Ground Lightning

    Science.gov (United States)

    Visacro, Silverio; Guimaraes, Miguel; Murta Vale, Maria Helena

    2017-12-01

    First and subsequent return strokes' striking distances (SDs) were determined for negative cloud-to-ground flashes from high-speed videos exhibiting the development of positive and negative leaders and the pre-return stroke phase of currents measured along a short tower. In order to improve the results, a new criterion was used for the initiation and propagation of the sustained upward connecting leader, consisting of a 4 A continuous current threshold. An advanced approach developed from the combined use of this criterion and a reverse propagation procedure, which considers the calculated propagation speeds of the leaders, was applied and revealed that SDs determined solely from the first video frame showing the upward leader can be significantly underestimated. An original approach was proposed for a rough estimate of first strokes' SD using solely records of current. This approach combines the 4 A criterion and a representative composite three-dimensional propagation speed of 0.34 × 106 m/s for the leaders in the last 300 m propagated distance. SDs determined under this approach showed to be consistent with those of the advanced procedure. This approach was applied to determine the SD of 17 first return strokes of negative flashes measured at MCS, covering a wide peak-current range, from 18 to 153 kA. The estimated SDs exhibit very high dispersion and reveal great differences in relation to the SDs estimated for subsequent return strokes and strokes in triggered lightning.

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

    Science.gov (United States)

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

    2015-10-16

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

  7. The lightning climatology of South Africa

    Directory of Open Access Journals (Sweden)

    Morné Gijben

    2012-03-01

    Full Text Available In 2005, the South African Weather Service installed a state-of-the-art cloud-to-ground lightning detection network across the country. The data recorded by this network in 2006 was utilised in the development of an initial lightning climatology of South Africa. Until 2010, this climatology was based on data from a single year. This paper updates this climatology with the lightning data for the 2006–2010 period, which is the first actual lightning climatology by the South African Weather Service based on data covering 5 years. A number of different maps were created from these lightning data. These were lightning ground flash density, median peak kiloampere, percentage positive and average flash multiplicity maps. These four maps were in turn used to develop lightning intensity risk, positive lightning risk and total lightning risk maps. Analysis of the maps showed that the highest concentrations of lightning are found over the central to northern interior of the country, with areas along the northern parts of the eastern escarpment experiencing the highest flash densities and falling within the extreme risk category. Both the positive and total lightning risks are severe for almost the entire country. Only towards the west of the country does the lightning risk decrease. This lightning climatology can now be used throughout South Africa for various disciplines. It will be especially useful for setting lightning safety standards and identifying priority areas for installing lightning conductors and conducting public awareness campaigns.

  8. Observations of the ground-attachment process in natural lightning in the absence of tall strike objects

    Science.gov (United States)

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

    2017-12-01

    Synchronized high-speed (124 or 210 kiloframes per second) video images and wideband electromagnetic field records of the attachment process were obtained for 4 negative strokes in natural lightning at the Lightning Observatory in Gainesville, Florida. The apparent strike objects were trees, whose heights were less than 30 m or so. Upward connecting leaders (UCLs) and multiple upward unconnected leaders were imaged in multiple frames. The majority of these upward positive leaders exhibited a pulsating behavior (brightening/fading cycles). UCLs, whose maximum extent ranged from 11 to 25 m, propagated at speeds ranging from 1.8×105 to 6.0×105 m/s with a mean of 3.4×105 m/s. Within about 100 m of the ground, the ratio of speeds of the downward negative leader and the corresponding UCL was about 3-4 for 2 events and 0.5 for 1 event. The breakthrough phase (BTP), corresponding to leader extensions inside the common streamer zone (CSZ), was imaged for 2 events. The initial length of CSZ was estimated to be about 30-40 m. For 2 events, estimated speeds of positive and negative leaders inside the CSZ were found to be between 2.4×106 and 3.7×106 m/s. For 1 event, opposite polarity leaders were observed to accelerate inside the CSZ. Further, in this same event, a space-leader-like formation, accompanied by significant intensification of UCL and apparently associated with the onset of BTP, was imaged. We speculate that the step-wise extension of the downward leader facilitated corona streamer bursts from both the downward negative and upward positive (UCL) leader tips, resulting in the establishment of CSZ. First speed profiles for colliding positive and negative leaders were obtained. In one event, the negative leader speed increased from 7.2 ×105 in virgin air to 2.5×106 (by a factor of 3.5), and then to 3.2×106 m/s just prior to the fast transition (FT) in the return-stroke field waveform. The positive leader accelerated from 1.8×105 (in virgin air) to 2.5×106

  9. Developing a Forecast Tool for Cloud-to-Ground Lightning in the North Central and Northeastern United States

    National Research Council Canada - National Science Library

    Folsom, Manuel

    2004-01-01

    .... The 15th Operational Weather Squadron requested a forecast tool capable of predicting CG lightning within a 25 and 10 nautical mile radius of the 13 military locations in their area of responsibility...

  10. Direct and nearby lightning strike interaction with test power distribution lines

    Science.gov (United States)

    Schoene, Jens Daniel

    The interaction of direct and nearby rocket-triggered lightning with two unenergized three-phase power distribution lines of about 800 m length was studied at the International Center for Lightning Research and Testing in Florida. A horizontally-configured line was tested in 1999 and 2000, a vertically-configured line in 2001, 2002, and 2003, and a vertically-configured line with overhead ground wire in 2004. All lines were equipped with arresters and, additionally, in 2003, the vertical line had a polemounted transformer. During the 2000, 2001, and 2002 direct strike experiments, arresters frequently failed, but there was no arrester failures either during the 2003 direct strike experiment when the transformer was on the line or during the 2004 direct strike experiment when the lightning current was injected into the overhead ground wire. All line configurations except the one tested in 2004 commonly exhibited flashovers. The division of return stroke currents for the vertically-configured line was initially similar to the division on the horizontally-configured line (that is, the arresters closest to the strike point conducted the bulk of the impulsive current). After some tens of microseconds the currents in all arresters on the vertically-configured line equalized, while the close arrester currents on the horizontally-configured line still conducted significantly more current than the remote arresters. The lightning current division for direct strikes to a phase conductor is successfully modeled with the Electromagnetic Transient Program (EMTP) for the vertically-configured line and, if the residual voltage of the close arresters is reduced by 20%, successfully modeled for the horizontally-configured line. Currents on the vertically-configured line induced by nearby lightning strikes were measured and compared to results calculated using the LIOV-EMTP96 code. It was found that during a lightning strike 11 m from a grounded line pole, a significant fraction of

  11. Effect of Combined Spaceborne Microwave and Continuous Lightning Measurements on Precipitation Forecasts of the 1998 Ground-Hog Day Storm

    Science.gov (United States)

    Weinman, James A.; Chang, Dong-Eon; Morales, Carlos A.

    2000-01-01

    We evaluated the impact of several newly available sources of meteorological data on mesoscale model forecasts of precipitation produced by the extra-tropical cyclone that struck Florida on February 2, 1998. Precipitation distributions of convective rainfall events were derived from Special Sensor Microwave Imager (SSM/I) and Multi-Channel Passive Microwave Sensor (TMI) microwave radiometric data by means of the Goddard PROFiling (GPROF) algorithm. Continuous lightning distributions were obtained from sferics measurements obtained from a network of VLF radio receivers. Histograms of coincident sferics frequency distributions were matched to those of precipitation to derive bogus convective rainfall rates from the continuously available sferics measurements. SSM/I and TMI microwave data were used to derive Integrated Precipitable Water (IPW) distributions. The TMI also provided sea surface temperatures (SSTS) of the Loop Current and Gulf Stream with improved structural detail. A series of experiments assimilated IPW and latent heating from the bogus convective rainfall for six-hours in the MM5 mesoscale forecast model to produce nine-hour forecasts of all rainfall as well as other weather parameters. Although continuously assimilating latent heating only slightly improved the surface pressure distribution forecast, it significantly improved the precipitation forecasts. Correctly locating convective rainfall was found critical for assimilating latent heating in the forecast model, but measurement of the rainfall intensity proved to be less important. The improved SSTs also had a positive impact on rainfall forecasts for this case. Assimilating bogus rainfall in the model produced nine-hour forecasts of radar reflectivity distributions that agreed well with coincident observations from the TRMM spaceborne precipitation radar, ground based radar and spaceborne microwave measurements.

  12. US COMPOSITE LIGHTNING DAILY TOTAL FROM NATL LIGHTNING NETWORK V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The Global Hydrology Resource Center generates a cloud-to-ground lightning product from the data collected from the U.S. National Lightning Detection Network, a...

  13. US COMPOSITE LIGHTNING 15MIN TOTAL FROM NATL LIGHTNING NETWORK V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The Lightning Imaging Sensor (LIS) Science Computing Facility (SCF) generates a cloud-to-ground lightning product from the data collected from the U.S. National...

  14. Wire-grid electromagnetic modelling of metallic cylindrical objects with arbitrary section, for Ground Penetrating Radar applications

    Science.gov (United States)

    Adabi, Saba; Pajewski, Lara

    2014-05-01

    This work deals with the electromagnetic wire-grid modelling of metallic cylindrical objects, buried in the ground or embedded in a structure, for example in a wall or in a concrete slab. Wire-grid modelling of conducting objects was introduced by Richmond in 1966 [1] and, since then, this method has been extensively used over the years to simulate arbitrarily-shaped objects and compute radiation patterns of antennas, as well as the electromagnetic field scattered by targets. For any wire-grid model, a fundamental question is the choice of the optimum wire radius and grid spacing. The most widely used criterion to fix the wire size is the so-called same-area rule [2], coming from empirical observation: the total surface area of the wires has to be equal to the surface area of the object being modelled. However, just few authors have investigated the validity of this criterion. Ludwig [3] studied the reliability of the rule by examining the canonical radiation problem of a transverse magnetic field by a circular cylinder fed with a uniform surface current, compared with a wire-grid model; he concluded that the same-area rule is optimum and that too thin wires are just as bad as too thick ones. Paknys [4] investigated the accuracy of the same-area rule for the modelling of a circular cylinder with a uniform current on it, continuing the study initiated in [3], or illuminated by a transverse magnetic monochromatic plane wave; he deduced that the same-area rule is optimal and that the field inside the cylinder is most sensitive to the wire radius than the field outside the object, so being a good error indicator. In [5], a circular cylinder was considered, embedded in a dielectric half-space and illuminated by a transverse magnetic monochromatic plane wave; the scattered near field was calculated by using the Cylindrical-Wave Approach and numerical results, obtained for different wire-grid models in the spectral domain, were compared with the exact solution. The

  15. 30 CFR 57.12065 - Short circuit and lightning protection.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Short circuit and lightning protection. 57... MINES Electricity Surface Only § 57.12065 Short circuit and lightning protection. Powerlines, including trolley wires, and telephone circuits shall be protected against short circuits and lightning. ...

  16. 30 CFR 56.12065 - Short circuit and lightning protection.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Short circuit and lightning protection. 56... Electricity § 56.12065 Short circuit and lightning protection. Powerlines, including trolley wires, and telephone circuits shall be protected against short circuits and lightning. ...

  17. Lightning Injuries

    Science.gov (United States)

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

  18. Modern concepts of treatment and prevention of lightning injuries.

    Science.gov (United States)

    Edlich, Richard F; Farinholt, Heidi-Marie A; Winters, Kathryne L; Britt, L D; Long, William B

    2005-01-01

    Lightning is the second most common cause of weather-related death in the United States. Lightning is a natural atmospheric discharge that occurs between regions of net positive and net negative electric charges. There are several types of lightning, including streak lightning, sheet lightning, ribbon lightning, bead lightning, and ball lightning. Lightning causes injury through five basic mechanisms: direct strike, flash discharge (splash), contact, ground current (step voltage), and blunt trauma. While persons struck by lightning show evidence of multisystem derangement, the most dramatic effects involve the cardiovascular and central nervous systems. Cardiopulmonary arrest is the most common cause of death in lightning victims. Immediate resuscitation of people struck by lightning greatly affects the prognosis. Electrocardiographic changes observed following lightning accidents are probably from primary electric injury or burns of the myocardium without coronary artery occlusion. Lightning induces vasomotor spasm from direct sympathetic stimulation resulting in severe loss of pulses in the extremities. This vasoconstriction may be associated with transient paralysis. Damage to the central nervous system accounts for the second most debilitating group of injuries. Central nervous system injuries from lightning include amnesia and confusion, immediate loss of consciousness, weakness, intracranial injuries, and even brief aphasia. Other organ systems injured by lightning include the eye, ear, gastrointestinal system, skin, and musculoskeletal system. The best treatment of lightning injuries is prevention. The Lightning Safety Guidelines devised by the Lightning Safety Group should be instituted in the United States and other nations to prevent these devastating injuries.

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

    Science.gov (United States)

    Case, Jonathan; Spratt, Scott; Sharp, David

    2006-01-01

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

  20. Lightning surge overvoltages on a feeding system of a MAGLEV train; Jiki fujoshiki tetsudo no kidenkei ni okeru kaminari saji kaden`atsu

    Energy Technology Data Exchange (ETDEWEB)

    Muragishi, H.; Samejima, J.; Nagaoka, N.; Ametani, A. [Doshisha Univ., Kyoto (Japan); Seki, A. [Japan Central Railway Co., Nagoya (Japan)

    1997-03-20

    This paper investigates lighting surge overvoltages on a coil system of a magnetic-levitation train, when lightning hits an overhead ground wire (GW) to protect the coils. The paper considers an elevated railroad with height of about 20 m from the earth surface and iron structures which were neglected in the previous investigations. The overvoltage induced to the coil due to the lightning current on the GW increases by about 30% when considering the grounding lead of the GW. The iron structures reduce the lightning overvoltages by about 10% when the structure is assumed to be directly grounded to the earth. If the grounding lead of the structure is taken into account, the reduction effect is not much noticeable. The induced overvoltage to the coil enters into a power feeding cable, and produces an overvoltage which may exceed the cable sheath insulation level. The overvoltage can be controlled by an arrester. 15 refs., 14 figs., 3 tabs.

  1. Three-Dimensional Reconstruction of Cloud-to-Ground Lightning Using High-Speed Video and VHF Broadband Interferometer

    Science.gov (United States)

    Li, Yun; Qiu, Shi; Shi, Lihua; Huang, Zhengyu; Wang, Tao; Duan, Yantao

    2017-12-01

    The time resolved three-dimensional (3-D) spatial reconstruction of lightning channels using high-speed video (HSV) images and VHF broadband interferometer (BITF) data is first presented in this paper. Because VHF and optical radiations in step formation process occur with time separation no more than 1 μs, the observation data of BITF and HSV at two different sites provide the possibility of reconstructing the time resolved 3-D channel of lightning. With the proposed procedures for 3-D reconstruction of leader channels, dart leaders as well as stepped leaders with complex multiple branches can be well reconstructed. The differences between 2-D speeds and 3-D speeds of leader channels are analyzed by comparing the development of leader channels in 2-D and 3-D space. Since return stroke (RS) usually follows the path of previous leader channels, the 3-D speeds of the return strokes are first estimated by combination with the 3-D structure of the preceding leaders and HSV image sequences. For the fourth RS, the ratios of the 3-D to 2-D RS speeds increase with height, and the largest ratio of the 3-D to 2-D return stroke speeds can reach 2.03, which is larger than the result of triggered lightning reported by Idone. Since BITF can detect lightning radiation in a 360° view, correlated BITF and HSV observations increase the 3-D detection probability than dual-station HSV observations, which is helpful to obtain more events and deeper understanding of the lightning process.

  2. How to create ball lightning

    Science.gov (United States)

    Golka, Robert K., Jr.

    1991-01-01

    Procedures are given on how to produce ball lightning. Necessary equipment includes a transformer of 150,000 watts capable of providing approximately 10,000 amperes at 15 volts, 60 cycles; thick one inch cables of stranded wire leading into a 3 by 4 by 1 foot plastic tank; a quarter inch thick 4 by 6 inch aluminum plate to be used as one of the discharge electrodes; and another electrode of heavy copper wire with the insulation stripped back 6 inches.

  3. Optimization of Hellenic overhead high-voltage transmission lines lightning protection

    Energy Technology Data Exchange (ETDEWEB)

    Christodoulou, C.A.; Fotis, G.P.; Stathopulos, I.A. [National Technical University of Athens, School of Electrical and Computer Engineering, High Voltage Laboratory, 9 Iroon Politechniou Street, Zografou, 157 80 Athens (Greece); Ekonomou, L. [A.S.PE.T.E. - School of Pedagogical and Technological Education, Department of Electrical Engineering Educators, N. Heraklion, 141 21 Athens (Greece); Harkiolakis, N. [Hellenic American University, IT Faculty, 12 Kaplanon Street, 106 80 Athens (Greece)

    2009-04-15

    It is well known that the lightning protection of transmission lines is exclusively relying on their correct initial design. Although detailed engineering studies are usually performed by electric power utilities for the design of new transmission lines, there are reported cases where the design is based simply on tradition or on utilities' standardization policy. In this paper, the lightning protection of high-voltage transmission lines is faced as an optimization problem where optimum design parameters are calculated for the lines, relating their cost with the lightning failures' cost, aiming to reduce or even eliminate lightning failures. The optimization method considers all the available protection means, i.e. ground wires and surge arresters. In order to validate the effectiveness of the proposed method, it is applied on several operating Hellenic transmission lines of 150 kV carefully selected among others due to their high failure rates during lightning thunderstorms. The obtained optimum parameters, which reduce the failure rates caused by lightning are compared with the operating transmission lines' existing parameters showing the usefulness of the method, which can prove to be a valuable tool for the studies of electric power system designers. (author)

  4. Energy dispatching analysis of lightning surges on underground cables in a cable connection station

    Energy Technology Data Exchange (ETDEWEB)

    Hong-Chan Chang; Fu-Hsien Chen; Tai-Hsiang Chen [Department of Electrical Engineering, National Taiwan University of Science and Technology, 43, Sec. 4, Keelung Rd., Taipei (China); Cheng-Chien Kuo [Department of Electrical Engineering, St. John' s University, 499, Sec. 4, TamKing Rd., Tamsui, Taipei (China)

    2011-01-15

    The paper aimed to simulate the transient over-voltage phenomena which occur at 345 kV and 161 kV underground cables, when lighting strikes on or near the cable connection station, by using the Electro-Magnetic Transients Program (EMTP). A feasibility study on changing related parameters, as well as cable connections and grounding methods to reduce the impact caused by lightning strikes, will be thoroughly conducted. The various components required for a detailed simulation including; lightning surges, transmission line and tower, arrester, and underground cables are all considered. Then, the transient voltage of the cables will be analyzed under different situations including; connection methods, grounding locations, length of the grounding wire of arrester, and the grounding resistance for different locations. The simulation results show that the length of the grounding wire is more sensitive to the transient over-voltage which occurred when a common grounding topology was adopted. In contrast, the use of an independent grounding topology resulted in a reduction of the grounding resistance, which effectively decreased the over-voltage, thereby avoiding surpassing the shielding voltage level of the cable, caused by the rise of ground voltage. (author)

  5. Energy dispatching analysis of lightning surges on underground cables in a cable connection station

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Hong-Chan, E-mail: hcchang@mail.ntust.edu.t [Department of Electrical Engineering, National Taiwan University of Science and Technology, 43, Sec. 4, Keelung Rd., Taipei, Taiwan (China); Chen, Fu-Hsien, E-mail: fu@mail.sju.edu.t [Department of Electrical Engineering, National Taiwan University of Science and Technology, 43, Sec. 4, Keelung Rd., Taipei, Taiwan (China); Kuo, Cheng-Chien, E-mail: cckuo@mail.sju.edu.t [Department of Electrical Engineering, St. John' s University, 499, Sec. 4, TamKing Rd., Tamsui, Taipei, Taiwan (China); Chen, Tai-Hsiang, E-mail: thchen@yahoo.com.t [Department of Electrical Engineering, National Taiwan University of Science and Technology, 43, Sec. 4, Keelung Rd., Taipei, Taiwan (China)

    2011-01-15

    The paper aimed to simulate the transient over-voltage phenomena which occur at 345 kV and 161 kV underground cables, when lighting strikes on or near the cable connection station, by using the Electro-Magnetic Transients Program (EMTP). A feasibility study on changing related parameters, as well as cable connections and grounding methods to reduce the impact caused by lightning strikes, will be thoroughly conducted. The various components required for a detailed simulation including; lightning surges, transmission line and tower, arrester, and underground cables are all considered. Then, the transient voltage of the cables will be analyzed under different situations including; connection methods, grounding locations, length of the grounding wire of arrester, and the grounding resistance for different locations. The simulation results show that the length of the grounding wire is more sensitive to the transient over-voltage which occurred when a common grounding topology was adopted. In contrast, the use of an independent grounding topology resulted in a reduction of the grounding resistance, which effectively decreased the over-voltage, thereby avoiding surpassing the shielding voltage level of the cable, caused by the rise of ground voltage.

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

    OpenAIRE

    Shimoji, Nobuaki; Aoyama, Ryoma

    2014-01-01

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

  7. Ball lightning.

    OpenAIRE

    Stenhoff, Mark

    1988-01-01

    Ball lightning is alleged by some to be a rare atmospheric phenomenon usually associated with thunderstorms, while others hold that it does not exist. This controversy has continued for centuries. This study comprises a critical evaluation of evidence for the existence of ball lightning. An historical review of the controversy is first presented, giving a chronological account of developments in ball lightning theories and of important observations alleged to be of the phenomenon. Other pheno...

  8. Lightning Technology.

    Science.gov (United States)

    1980-04-01

    thunder . The thunder signals were recorded on a second FM magnetic tape channel. In this manner, the time of occurrence, the nature of the lightning ...from the Kiva to the lightning cur- rent element of interest is based on the assumption that the time from flash to thunder multiplied by the speed of...some corona-like discharges before the main lightning event. The acoustically determined (per section 4) thunder sources are displayed in figure 5.4

  9. Utilizing Four Dimensional Lightning and Dual-Polarization Radar to Develop Lightning Initiation Forecast Guidance

    Science.gov (United States)

    2015-03-26

    lightning based on size and composite Z alone. Since the focus was airmass thunderstorms, any days with complex areas or lines of thunder - storms...Doppler radar signatures of developing thunder - storms and their potential to indicate the onset of cloud-to-ground lightning . Mon. Wea. Rev., 122...UTILIZING FOUR DIMENSIONAL LIGHTNING AND DUAL-POLARIZATION RADAR TO DEVELOP LIGHTNING INITIATION FORECAST GUIDANCE THESIS Andrew J. Travis, Captain

  10. Lightning mapper development: Status and requirements

    Science.gov (United States)

    Christian, H. J.

    1984-01-01

    The feasibility for the detection and location of lightning on a continuous basis using a sensor in geostationary orbit was established. Measurements of the optical characteristics of lightning and the capabilities of solid state mosaic focal plane arrays, indicate that the question is how high a detection efficiency can be achieved. The lightning mapper development to strengthen the scientific justification for placing a lightning sensor in geostationary orbit is discussed. The U-2 and ground based lightning research, modeling, and theoretical studies are reported.

  11. The Load of Lightning-induced Nitrogen Oxides and Its Impact on the Ground-level Ozone during Summertime over the Mountain West States

    Science.gov (United States)

    Lightning-induced nitrogen oxides (LNOX), in the presence of sunlight, volatile organic compounds and water, can be a relatively large but uncertain source for ozone (O3) and hydroxyl radical (OH) in the atmosphere. Using lightning flash data from the National Lightning Detection...

  12. Quantification of Lightning-induced Nitrogen Oxides in CMAQ and the Assessment of its impact on Ground-level Air Quality

    Science.gov (United States)

    Lightning-induced nitrogen oxides (LNOX), in the presence of sunlight, volatile organic compounds and water, can be a relatively large but uncertain source for ozone (O3) and hydroxyl radical (OH) in the atmosphere. Using lightning flash data from the National Lightning Detection...

  13. Multiparameter Investigation of Significant Lightning Producing Storms in Northeastern Colorado

    National Research Council Canada - National Science Library

    Gauthier, Michael

    1999-01-01

    We present a regional, summer season, climatology of cloud to ground (CG) lightning immediately east of the central Rocky mountains from 1996-98 using data from the National Lightning Detection Network (NLDN...

  14. The TETRA-II Experiment to Observe Terrestrial Gamma Flashes at Ground Level - Analysis of Nearby Thunderstorm Activity and Comparison with Lightning Data

    Science.gov (United States)

    Smith, D.; Adams, C.; Cherry, M. L.; Al-Nussirat, S.; Bai, S.; Banadaki, Y.; Bitzer, P. M.; Hoffman, J.; Khosravi, E.; Legault, M.; Orang, M.; Pleshinger, D. J.; Rodriguez, R.; Trepanier, J. C.; Sunda-Meya, A.; Zimmer, N.

    2017-12-01

    Terrestrial gamma ray flashes (TGFs) are millisecond bursts of high-energy electrons propagated within the atmosphere. An upgraded version of the TGF and Energetic Thunderstorm Rooftop Array (TETRA-II) consists of an array of BGO scintillators to detect TGFs from thunderstorms at ground-level in four locations: the campus of Louisiana State University (LSU) in Baton Rouge, Louisiana; the campus of the University of Puerto Rico at Utuado, Puerto Rico, in conjunction with the already existing Puerto Rico Lightning Detection Network (PRLDN) of radio receivers; the Centro Nacional de Metrologia de Panama (CENAMEP) in Panama City, Panama; and the Severe Weather Institute and Radar & Lightning Laboratories in Huntsville, Alabama. The original TETRA-I array of NaI scintillators at LSU detected 37 millisecond-scale bursts of gamma-rays at energies of 50 keV-2 MeV associated with nearby (< 8 km) thunderstorms. TETRA-II began operation in May 2016 and now has approximately an order of magnitude greater sensitivity to individual events than TETRA-I. The ability to observe ground-level bursts from close to the source allows an analysis of the storm cells producing these events. An analysis of storms associated with TETRA II gamma-ray events is provided using NEXRAD Level II base-reflectivity scans to determine specific storm features before, during, and after the occurrence of each event. Louisiana events appear to occur within most major thunderstorm types, in particular as the cell is transitioning into the dissipating stage of evolution.

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

    DEFF Research Database (Denmark)

    Vogel, Stephan; Holbøll, Joachim; Lopez, Javier

    2016-01-01

    The goal of a lightning exposure assessment is to identify the number, type and characteristics of lightning discharges to a certain structure. There are various Lightning Location System (LLS) technologies available, each of them are characterized by individual performance characteristics....... In this work, these technologies are reviewed and evaluated in order to obtain an estimation of which technologies are eligible to perform a lightning assessment to wind turbines. The results indicate that ground-based mid-range low frequency (LF) LLS systems are most qualified since they combine a wide...... coverage with a good accuracy for downward lightning. Furthermore, advances in the technology indicate the detection of certain upward lightning events. A correlation between the size of the uncertainty ellipse and the peak current of the lightning detections is presented. Furthermore, lightning data from...

  16. Using Total Lightning Observations to Enhance Lightning Safety

    Science.gov (United States)

    Stano, Geoffrey T.

    2012-01-01

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

  17. Lightning Injuries

    Science.gov (United States)

    ... News) Small Study Uncovers Brain Disease in Former Soccer Players (Video) Anterior Cruciate Ligament (Video) Resisted Finger Abduction and Extension With Putty Additional Content Medical News Lightning Injuries By Daniel P. Runde, MD, MME, Assistant Clinical ...

  18. Lightning Protection

    Science.gov (United States)

    1994-01-01

    Kit-built airplanes are more affordable because they are assembled by the owner and do not require Federal Aviation Administration (FAA) certification. The Glasair III, is an advanced technology homebuilt, constructed of a fiberglass and graphite fiber composite material, and equipped with digital instruments. Both technologies make the airplane more susceptible to lightning effects. When Glasair manufacturer, Stoddard-Hamilton, decided that lightning protection would enable more extensive instrument flight and make the plane more marketable, they proposed a joint development program to NASA Langley Research Center (LAR). Under a Small Business Innovation Research (SBIR) contract, Langley contractors designed and tested a lightning protection system, and the Glasair III-LP became the first kit-built composite aircraft to be lightning tested and protection-verified under FAA guidelines for general aviation aircraft.

  19. Lightning strikes

    International Nuclear Information System (INIS)

    Dance, B.

    1982-01-01

    If a nuclear weapon were struck by a powerful lightning flash, what would happen Scientists have assembled a simulator to produce exceptionally powerful discharges to try to find the answer to this question by practical test. The Sandia facility enables the extremely powerful lightning discharges which occur only once in every hundred lightning strokes to be duplicated. A bolt is composed of a series of strokes between two clouds or between one cloud and the earth. The simulator consists of four circuits, an inductor, a resistor and a special crowbar-switch developed at Sandia. The crowbar is for accuracy in the simulation of a lightning stroke. The test data is conveyed to computers for analysis by means of fibre-optic links. The first series of tests involve the warhead for the Air-Launched Cruise Missile

  20. Relativistic-microwave theory of ball lightning

    OpenAIRE

    H.-C. Wu

    2016-01-01

    Ball lightning, a fireball sometimes observed during lightnings, has remained unexplained. Here we present a comprehensive theory for the phenomenon: At the tip of a lightning stroke reaching the ground, a relativistic electron bunch can be produced, which in turn excites intense microwave radiation. The latter ionizes the local air and the radiation pressure evacuates the resulting plasma, forming a spherical plasma bubble that stably traps the radiation. This mechanism is verified by partic...

  1. Stabilization and manipulation of electronically phase-separated ground states in defective indium atom wires on silicon.

    Science.gov (United States)

    Zhang, Hui; Ming, Fangfei; Kim, Hyun-Jung; Zhu, Hongbin; Zhang, Qiang; Weitering, Hanno H; Xiao, Xudong; Zeng, Changgan; Cho, Jun-Hyung; Zhang, Zhenyu

    2014-11-07

    Exploration and manipulation of electronic states in low-dimensional systems are of great importance in the fundamental and practical aspects of nanomaterial and nanotechnology. Here, we demonstrate that the incorporation of vacancy defects into monatomic indium wires on n-type Si(111) can stabilize electronically phase-separated ground states where the insulating 8×2 and metallic 4×1 phases coexist. Furthermore, the areal ratio of the two phases in the phase-separated states can be tuned reversibly by electric field or charge doping, and such tunabilities can be quantitatively captured by first principles-based modeling and simulations. The present results extend the realm of electronic phase separation from strongly correlated d-electron materials typically in bulk form to weakly interacting sp-electron systems in reduced dimensionality.

  2. Attempts to create ball lightning with triggered lightning

    Science.gov (United States)

    Hill, Jonathan D.; Uman, Martin A.; Stapleton, Michael; Jordan, Douglas M.; Chebaro, Alexander M.; Biagi, Christopher J.

    2010-08-01

    We describe attempts to create ball lightning by directing lightning, triggered from natural thunderclouds using the rocket-and-wire technique, through a variety of materials. Some of the observed phenomena have features in common with natural ball lightning or with laboratory attempts to create it: flame-like luminosity for up to 0.5 s above salt water; constant-luminosity silicon fragments falling for about 1 s under the influence of gravity; a 0.7 m region of stationary luminosity whose bottom was 0.3 m above a stainless steel surface to which arcing had occurred; and a glow for about 0.5 s above pine tree sections.

  3. Geological Effects on Lightning Strike Distributions

    KAUST Repository

    Berdahl, J. Scott

    2016-05-16

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

  4. Features of Upward Positive Leaders Initiated From Towers in Natural Cloud-to-Ground Lightning Based on Simultaneous High-Speed Videos, Measured Currents, and Electric Fields

    Science.gov (United States)

    Visacro, Silverio; Guimaraes, Miguel; Murta Vale, Maria Helena

    2017-12-01

    Original simultaneous records of currents, close electric field, and high-speed videos of natural negative cloud-to-ground lightning striking the tower of Morro do Cachimbo Station are used to reveal typical features of upward positive leaders before the attachment, including their initiation and mode of propagation. According to the results, upward positive leaders initiate some hundreds of microseconds prior to the return stroke, while a continuous uprising current of about 4 A and superimposed pulses of a few tens amperes flow along the tower. Upon leader initiation, the electric field measured 50 m away from the tower at ground level is about 60 kV/m. The corresponding average field roughly estimated 0.5 m above the tower top is higher than 0.55 MV/m. As in laboratory experiments, the common propagation mode of upward positive leaders is developing continuously, without steps, from their initiation. Unlike downward negative leaders, upward positive leaders typically do not branch off, though they can bifurcate under the effect of a downward negative leader's secondary branch approaching their lateral surface. The upward positive leader's estimated average two-dimensional propagation speed, in the range of 0.06 × 106 to 0.16 × 106 m/s, has the same order of magnitude as that of downward negative leaders. Apparently, the speed tends to increase just before attachment.

  5. Technique for the comparison of light spectra from natural and laboratory generated lightning current arcs

    Science.gov (United States)

    Mitchard, D.; Clark, D.; Carr, D.; Haddad, A.

    2016-08-01

    A technique was developed for the comparison of observed emission spectra from lightning current arcs generated through self-breakdown in air and the use of two types of initiation wire, aluminum bronze and nichrome, against previously published spectra of natural lightning events. A spectrograph system was used in which the wavelength of light emitted by the lightning arc was analyzed to derive elemental interactions. A lightning impulse of up to 100 kA was applied to a two hemispherical tungsten electrode configuration which allowed the effect of the lightning current and lightning arc length to be investigated. A natural lightning reference spectrum was reconstructed from literature, and generated lightning spectra were obtained from self-breakdown across a 14.0 mm air gap and triggered along initiation wires of length up to 72.4 mm. A comparison of the spectra showed that the generated lightning arc induced via self-breakdown produced a very similar spectrum to that of natural lightning, with the addition of only a few lines from the tungsten electrodes. A comparison of the results from the aluminum bronze initiation wire showed several more lines, whereas results from the nichrome initiation wire differed greatly across large parts of the spectrum. This work highlights the potential use for spectrographic techniques in the study of lightning interactions with surrounding media and materials, and in natural phenomena such as recently observed ball lightning.

  6. Technique for the comparison of light spectra from natural and laboratory generated lightning current arcs

    Energy Technology Data Exchange (ETDEWEB)

    Mitchard, D., E-mail: mitcharddr@cardiff.ac.uk; Clark, D.; Carr, D.; Haddad, A. [Morgan-Botti Lightning Laboratory, Advanced High Voltage Research Centre, School of Engineering, Cardiff University, CF24 3AA Wales (United Kingdom)

    2016-08-29

    A technique was developed for the comparison of observed emission spectra from lightning current arcs generated through self-breakdown in air and the use of two types of initiation wire, aluminum bronze and nichrome, against previously published spectra of natural lightning events. A spectrograph system was used in which the wavelength of light emitted by the lightning arc was analyzed to derive elemental interactions. A lightning impulse of up to 100 kA was applied to a two hemispherical tungsten electrode configuration which allowed the effect of the lightning current and lightning arc length to be investigated. A natural lightning reference spectrum was reconstructed from literature, and generated lightning spectra were obtained from self-breakdown across a 14.0 mm air gap and triggered along initiation wires of length up to 72.4 mm. A comparison of the spectra showed that the generated lightning arc induced via self-breakdown produced a very similar spectrum to that of natural lightning, with the addition of only a few lines from the tungsten electrodes. A comparison of the results from the aluminum bronze initiation wire showed several more lines, whereas results from the nichrome initiation wire differed greatly across large parts of the spectrum. This work highlights the potential use for spectrographic techniques in the study of lightning interactions with surrounding media and materials, and in natural phenomena such as recently observed ball lightning.

  7. A Performance Evaluation of Lightning-NO Algorithms in CMAQ

    Science.gov (United States)

    In the Community Multiscale Air Quality (CMAQv5.2) model, we have implemented two algorithms for lightning NO production; one algorithm is based on the hourly observed cloud-to-ground lightning strike data from National Lightning Detection Network (NLDN) to replace the previous m...

  8. Characterization of infrasound from lightning

    Science.gov (United States)

    Assink, J. D.; Evers, L. G.; Holleman, I.; Paulssen, H.

    2008-08-01

    During thunderstorm activity in the Netherlands, electromagnetic and infrasonic signals are emitted due to the process of lightning and thunder. It is shown that correlating infrasound detections with results from a electromagnetic lightning detection network is successful up to distances of 50 km from the infrasound array. Infrasound recordings clearly show blastwave characteristics which can be related to cloud-ground discharges, with a dominant frequency between 1-5 Hz. Amplitude measurements of CG discharges can partly be explained by the beam pattern of a line source with a dominant frequency of 3.9 Hz, up to a distance of 20 km. The ability to measure lightning activity with infrasound arrays has both positive and negative implications for CTBT verification purposes. As a scientific application, lightning studies can benefit from the worldwide infrasound verification system.

  9. The lightning climatology of South Africa

    OpenAIRE

    Morné Gijben

    2012-01-01

    In 2005, the South African Weather Service installed a state-of-the-art cloud-to-ground lightning detection network across the country. The data recorded by this network in 2006 was utilised in the development of an initial lightning climatology of South Africa. Until 2010, this climatology was based on data from a single year. This paper updates this climatology with the lightning data for the 2006–2010 period, which is the first actual lightning climatology by the South African Weather Serv...

  10. Lightning NOx Estimates from Space-Based Lightning Imagers

    Science.gov (United States)

    Koshak, William J.

    2017-01-01

    The intense heating of air by a lightning channel, and subsequent rapid cooling, leads to the production of lightning nitrogen oxides (NOx = NO + NO2) as discussed in Chameides [1979]. In turn, the lightning nitrogen oxides (or "LNOx" for brevity) indirectly influences the Earth's climate because the LNOx molecules are important in controlling the concentration of ozone (O3) and hydroxyl radicals (OH) in the atmosphere. Climate is most sensitive to O3 in the upper troposphere, and LNOx is the most important source of NOx in the upper troposphere at tropical and subtropical latitudes; hence, lightning is a useful parameter to monitor for climate assessments. The National Climate Assessment (NCA) program was created in response to the Congressionally-mandated Global Change Research Act (GCRA) of 1990. Thirteen US government organizations participate in the NCA program which examines the effects of global change on the natural environment, human health and welfare, energy production and use, land and water resources, human social systems, transportation, agriculture, and biological diversity. The NCA focuses on natural and human-induced trends in global change, and projects major trends 25 to 100 years out. In support of the NCA, the NASA Marshall Space Flight Center (MSFC) continues to assess lightning-climate inter-relationships. This activity applies a variety of NASA assets to monitor in detail the changes in both the characteristics of ground- and space- based lightning observations as they pertain to changes in climate. In particular, changes in lightning characteristics over the conterminous US (CONUS) continue to be examined by this author using data from the Tropical Rainfall Measuring Mission Lightning Imaging Sensor. In this study, preliminary estimates of LNOx trends derived from TRMM/LIS lightning optical energy observations in the 17 yr period 1998-2014 are provided. This represents an important first step in testing the ability to make remote retrievals

  11. The Relationship Between Cloud-to-Ground Lightning and Precipitations Ice Mass: A Radar study over Houston

    National Research Council Canada - National Science Library

    Gauthier, Michael L; Petersen, Walter A; Carey, Lawrence D; Christian, Jr., Hugh J

    2006-01-01

    Using seven summer-seasons (1997-2003, over 46,000 volumes) of NEXRAD data, coincident climatologies of summer-season ground flash densities and radar derived, column integrated, precipitation ice mass (IM...

  12. Relativistic-microwave theory of ball lightning

    Science.gov (United States)

    Wu, H.-C.

    2016-06-01

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

  13. Relativistic-microwave theory of ball lightning.

    Science.gov (United States)

    Wu, H-C

    2016-06-22

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

  14. Lightning Bugs

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 7; Issue 9. Lightning Bugs. B Gajendra Babu M Kannan. General Article Volume 7 Issue 9 September 2002 pp 49-55. Fulltext. Click here to view fulltext PDF. Permanent link: http://www.ias.ac.in/article/fulltext/reso/007/09/0049-0055. Keywords.

  15. Projeto de aterramento para sistema monofilar com retorno pelo terra Grounding project for single wire earth return system

    Directory of Open Access Journals (Sweden)

    Humberto C Bertolo

    2011-02-01

    Full Text Available Este trabalho apresenta o projeto de aterramento elétrico para Sistema Monofilar com Retorno pela Terra (MRT, em solicitações de baixas frequências, utilizando-se o método das imagens e considerando a simplificação do método dos potenciais constantes. Simulou-se o comportamento de três diferentes configurações de aterramento: hastes em triângulo, em quadrado vazio e para nove hastes, formando uma malha com quatro quadrados. A partir da simulação obtiveram-se o valor da resistência de aterramento para cada configuração e os potenciais gerados na superfície do solo. Com base nesses resultados foi possível comparar os valores tabelados para resistências mínimas, em função da potência do transformador, aplicados para diferentes concessionárias de energia que utilizam o Sistema MRT, com os valores calculados que mantêm os potenciais no solo em níveis seguros para seres humanos e animais. Os resultados mostraram que é possível utilizar aterramentos mais simples e mais baratos, pois os gradientes de tensões no solo se mantiveram em níveis seguros.This work presents a grounding project for a Single Wire Earth Return (SWER system in low frequency applications, through the use of the image method, a simplification of the constant potential method. The responses of three different grounding configurations were simulated: electrodes in triangular format, electrodes placed in the corners of a square and nine electrodes placed in the corners of a grid with four squares. With the mentioned simulation it was possible to calculate the ground resistance and the surface voltage of each configuration. Based on these results, it was possible to compare the values for minimal resistance, depending on the power of the transformer, applied to various power utilities that use the SWER system with the values that hold the potential in the soil at safe levels for human beings and animals. Results showed that it is possible to use simpler and

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

    Science.gov (United States)

    Blakeslee, R.J.

    2007-01-01

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

  17. Observations of a bi-directional lightning leader producing an M-component

    Science.gov (United States)

    Kotovsky, D. A.; Uman, M. A.; Wilkes, R.; Carvalho, F. L.; Jordan, D. M.

    2017-12-01

    Lightning discharges to ground often exhibit millisecond-scale surges in the continuing currents following return strokes, called M-components. Relatively little is known regarding the source of M-component charge and the mechanisms by which that charge is transferred to ground. In this work, we seek to directly address these questions by presenting correlated high-speed video and Lightning Mapping Array (LMA) observations of a bi-directional leader that resulted in an M-component occurring in a rocket-and-wire triggered lightning flash. The observed leader initiated in the decayed remnants of a positive leader channel that had traversed virgin air approximately 90 msec prior. Three-dimensional locations and speeds of the photographed bi-directional leader and M-component processes are calculated by mapping video images to the observed LMA channel geometry. Both ends of the bi-directional leader exhibited speeds on the order of 2 x106 m sec-1 over 570 meters of the visible channel. Propagation of the luminosity wave from the in-cloud leader to ground ( 8.8 km channel length) exhibited appreciable dispersion, with rise-times (10-90%) increasing from 330 to 410 μsec and pulse-widths (half-maximum) increasing from 380 to 810 μsec - the M-component current pulse measured at ground-level exhibited a rise-time of 290 μsec and a pulse-width of 770 μsec. Group velocities of the luminosity wave have been calculated as a function of frequency, increasing from 2 x107 to 6 x107 m sec-1 over the dominant signal bandwidth (DC to 2 kHz). Additionally, multiple waves of luminosity are observed within the in-cloud channel, indicating nuanced wave phenomena possibly associated with reflection from the end of the leader channel and attachment with the main lightning channel carrying continuing current to ground.

  18. Lightning attachment process to common buildings

    Science.gov (United States)

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

    2017-05-01

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

  19. A Comparison of Horizontal Cloud-To-Ground Lightning Flash Distance Using Weather Surveillance Radar And The Distance Between Successive Flashes Method

    National Research Council Canada - National Science Library

    Cox, Christopher

    1999-01-01

    On April 29th, 1996 an airman servicing a C-130 aircraft on Huriburt AFB Florida was struck and killed by a lightning flash that traveled an estimated 7 to 10 miles from storms south of the airfield...

  20. Positive lightning and severe weather

    Science.gov (United States)

    Price, C.; Murphy, B.

    2003-04-01

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

  1. HURRICANE AND SEVERE STORM SENTINEL (HS3) WORLD WIDE LIGHTNING LOCATION NETWORK (WWLLN) STORMS V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The World Wide Lightning Location Network (WWLLN) is a global, ground-based lightning sensor network operated by the University of Washington in Seattle. This...

  2. Tropic lightning: myth or menace?

    Science.gov (United States)

    McCarthy, John

    2014-11-01

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

  3. The effect of the Earth's oblate spheroid shape on the accuracy of a time-of-arrival lightning ground strike locating system

    Science.gov (United States)

    Casper, Paul W.; Bent, Rodney B.

    1991-01-01

    The algorithm used in previous technology time-of-arrival lightning mapping systems was based on the assumption that the earth is a perfect spheroid. These systems yield highly-accurate lightning locations, which is their major strength. However, extensive analysis of tower strike data has revealed occasionally significant (one to two kilometer) systematic offset errors which are not explained by the usual error sources. It was determined that these systematic errors reduce dramatically (in some cases) when the oblate shape of the earth is taken into account. The oblate spheroid correction algorithm and a case example is presented.

  4. Lightning activity during the 1999 Superior derecho

    Science.gov (United States)

    Price, Colin G.; Murphy, Brian P.

    2002-12-01

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

  5. Visual Analytics approach for Lightning data analysis and cell nowcasting

    Science.gov (United States)

    Peters, Stefan; Meng, Liqiu; Betz, Hans-Dieter

    2013-04-01

    Thunderstorms and their ground effects, such as flash floods, hail, lightning, strong wind and tornadoes, are responsible for most weather damages (Bonelli & Marcacci 2008). Thus to understand, identify, track and predict lightning cells is essential. An important aspect for decision makers is an appropriate visualization of weather analysis results including the representation of dynamic lightning cells. This work focuses on the visual analysis of lightning data and lightning cell nowcasting which aim to detect and understanding spatial-temporal patterns of moving thunderstorms. Lightnings are described by 3D coordinates and the exact occurrence time of lightnings. The three-dimensionally resolved total lightning data used in our experiment are provided by the European lightning detection network LINET (Betz et al. 2009). In all previous works, lightning point data, detected lightning cells and derived cell tracks are visualized in 2D. Lightning cells are either displayed as 2D convex hulls with or without the underlying lightning point data. Due to recent improvements of lightning data detection and accuracy, there is a growing demand on multidimensional and interactive visualization in particular for decision makers. In a first step lightning cells are identified and tracked. Then an interactive graphic user interface (GUI) is developed to investigate the dynamics of the lightning cells: e.g. changes of cell density, location, extension as well as merging and splitting behavior in 3D over time. In particular a space time cube approach is highlighted along with statistical analysis. Furthermore a lightning cell nowcasting is conducted and visualized. The idea thereby is to predict the following cell features for the next 10-60 minutes including location, centre, extension, density, area, volume, lifetime and cell feature probabilities. The main focus will be set to a suitable interactive visualization of the predicted featured within the GUI. The developed visual

  6. Acoustic Manifestations of Natural versus Triggered Lightning

    Science.gov (United States)

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

    2010-12-01

    Positive leaders are rarely detected by VHF lightning detection systems; positive leader channels are usually outlined only by recoil events. Positive cloud-to-ground (CG) channels are usually not mapped. The goal of this work is to study the types of thunder produced by natural versus triggered lightning and to assess which types of thunder signals have electromagnetic activity detected by the lightning mapping array (LMA). Towards this end we are investigating the lightning detection capabilities of acoustic techniques, and comparing them with the LMA. In a previous study we used array beam forming and time of flight information to locate acoustic sources associated with lightning. Even though there was some mismatch, generally LMA and acoustic techniques saw the same phenomena. To increase the database of acoustic data from lightning, we deployed a network of three infrasound arrays (30 m aperture) during the summer of 2010 (August 3 to present) in the Magdalena mountains of New Mexico, to monitor infrasound (below 20 Hz) and audio range sources due to natural and triggered lightning. The arrays were located at a range of distances (60 to 1400 m) surrounding the triggering site, called the Kiva, used by Langmuir Laboratory to launch rockets. We have continuous acoustic measurements of lightning data from July 20 to September 18 of 2009, and from August 3 to September 1 of 2010. So far, lightning activity around the Kiva was higher during the summer of 2009. We will present acoustic data from several interesting lightning flashes including a comparison between a natural and a triggered one.

  7. Lightning protection design external tank /Space Shuttle/

    Science.gov (United States)

    Anderson, A.; Mumme, E.

    1979-01-01

    The possibility of lightning striking the Space Shuttle during liftoff is considered and the lightning protection system designed by the Martin Marietta Corporation for the external tank (ET) portion of the Shuttle is discussed. The protection system is based on diverting and/or directing a lightning strike to an area of the spacecraft which can sustain the strike. The ET lightning protection theory and some test analyses of the system's design are reviewed including studies of conductivity and thermal/stress properties in materials, belly band feasibility, and burn-through plug grounding and puncture voltage. The ET lightning protection system design is shown to be comprised of the following: (1) a lightning rod on the forward most point of the ET, (2) a continually grounded, one inch wide conductive strip applied circumferentially at station 371 (belly band), (3) a three inch wide conductive belly band applied over the TPS (i.e. the insulating surface of the ET) and grounded to a structure with eight conductive plugs at station 536, and (4) a two inch thick TPS between the belly bands which are located over the weld lands.

  8. Visual Analysis for Nowcasting of Multidimensional Lightning Data

    Directory of Open Access Journals (Sweden)

    Stefan Peters

    2013-08-01

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

  9. Lightning NOx Statistics Derived by NASA Lightning Nitrogen Oxides Model (LNOM) Data Analyses

    Science.gov (United States)

    Koshak, William; Peterson, Harold

    2013-01-01

    What is the LNOM? The NASA Marshall Space Flight Center (MSFC) Lightning Nitrogen Oxides Model (LNOM) [Koshak et al., 2009, 2010, 2011; Koshak and Peterson 2011, 2013] analyzes VHF Lightning Mapping Array (LMA) and National Lightning Detection Network(TradeMark) (NLDN) data to estimate the lightning nitrogen oxides (LNOx) produced by individual flashes. Figure 1 provides an overview of LNOM functionality. Benefits of LNOM: (1) Does away with unrealistic "vertical stick" lightning channel models for estimating LNOx; (2) Uses ground-based VHF data that maps out the true channel in space and time to < 100 m accuracy; (3) Therefore, true channel segment height (ambient air density) is used to compute LNOx; (4) True channel length is used! (typically tens of kilometers since channel has many branches and "wiggles"); (5) Distinction between ground and cloud flashes are made; (6) For ground flashes, actual peak current from NLDN used to compute NOx from lightning return stroke; (7) NOx computed for several other lightning discharge processes (based on Cooray et al., 2009 theory): (a) Hot core of stepped leaders and dart leaders, (b) Corona sheath of stepped leader, (c) K-change, (d) Continuing Currents, and (e) M-components; and (8) LNOM statistics (see later) can be used to parameterize LNOx production for regional air quality models (like CMAQ), and for global chemical transport models (like GEOS-Chem).

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

    Directory of Open Access Journals (Sweden)

    Javor Vesna

    2008-01-01

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

  11. Lightning and Life on Exoplanets

    Science.gov (United States)

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

    2016-07-01

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

  12. On the initiation of lightning in thunderclouds.

    Science.gov (United States)

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

    2017-05-02

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

  13. The lightning flash

    CERN Document Server

    Cooray, Vernon

    2014-01-01

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

  14. Lightning safety of animals.

    Science.gov (United States)

    Gomes, Chandima

    2012-11-01

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

  15. A solid state lightning propagation speed sensor

    Science.gov (United States)

    Mach, Douglas M.; Rust, W. David

    1989-01-01

    A device to measure the propagation speeds of cloud-to-ground lightning has been developed. The lightning propagation speed (LPS) device consists of eight solid state silicon photodetectors mounted behind precision horizontal slits in the focal plane of a 50-mm lens on a 35-mm camera. Although the LPS device produces results similar to those obtained from a streaking camera, the LPS device has the advantages of smaller size, lower cost, mobile use, and easier data collection and analysis. The maximum accuracy for the LPS is 0.2 microsec, compared with about 0.8 microsecs for the streaking camera. It is found that the return stroke propagation speed for triggered lightning is different than that for natural lightning if measurements are taken over channel segments less than 500 m. It is suggested that there are no significant differences between the propagation speeds of positive and negative flashes. Also, differences between natural and triggered dart leaders are discussed.

  16. Lightning phenomenology in the Tampa Bay Area

    Science.gov (United States)

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

    1984-01-01

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

  17. Lightning protection for wind turbines in Vietnam

    Directory of Open Access Journals (Sweden)

    Thuan Nguyen

    2017-01-01

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

  18. Electrostatic charge bounds for ball lightning models

    Energy Technology Data Exchange (ETDEWEB)

    Stephan, Karl D [Department of Technology, Texas State University, San Marcos, TX 78666 (United States)], E-mail: kdstephan@txstate.edu

    2008-03-15

    Several current theories concerning the nature of ball lightning predict a substantial electrostatic charge in order to account for its observed motion and shape (Turner 1998 Phys. Rep. 293 1; Abrahamson and Dinniss 2000 Nature 403 519). Using charged soap bubbles as a physical model for ball lightning, we show that the magnitude of charge predicted by some of these theories is too high to allow for the types of motion commonly observed in natural ball lightning, which includes horizontal motion above the ground and movement near grounded conductors. Experiments show that at charge levels of only 10-15 nC, 3-cm-diameter soap bubbles tend to be attracted by induced charges to the nearest grounded conductor and rupture. We conclude with a scaling rule that can be used to extrapolate these results to larger objects and surroundings.

  19. Electrostatic charge bounds for ball lightning models

    Science.gov (United States)

    Stephan, Karl D.

    2008-03-01

    Several current theories concerning the nature of ball lightning predict a substantial electrostatic charge in order to account for its observed motion and shape (Turner 1998 Phys. Rep. 293 1; Abrahamson and Dinniss 2000 Nature 403 519). Using charged soap bubbles as a physical model for ball lightning, we show that the magnitude of charge predicted by some of these theories is too high to allow for the types of motion commonly observed in natural ball lightning, which includes horizontal motion above the ground and movement near grounded conductors. Experiments show that at charge levels of only 10-15 nC, 3-cm-diameter soap bubbles tend to be attracted by induced charges to the nearest grounded conductor and rupture. We conclude with a scaling rule that can be used to extrapolate these results to larger objects and surroundings.

  20. Recent Advancements in Lightning Jump Algorithm Work

    Science.gov (United States)

    Schultz, Christopher J.; Petersen, Walter A.; Carey, Lawrence D.

    2010-01-01

    In the past year, the primary objectives were to show the usefulness of total lightning as compared to traditional cloud-to-ground (CG) networks, test the lightning jump algorithm configurations in other regions of the country, increase the number of thunderstorms within our thunderstorm database, and to pinpoint environments that could prove difficult for any lightning jump configuration. A total of 561 thunderstorms have been examined in the past year (409 non-severe, 152 severe) from four regions of the country (North Alabama, Washington D.C., High Plains of CO/KS, and Oklahoma). Results continue to indicate that the 2 lightning jump algorithm configuration holds the most promise in terms of prospective operational lightning jump algorithms, with a probability of detection (POD) at 81%, a false alarm rate (FAR) of 45%, a critical success index (CSI) of 49% and a Heidke Skill Score (HSS) of 0.66. The second best performing algorithm configuration was the Threshold 4 algorithm, which had a POD of 72%, FAR of 51%, a CSI of 41% and an HSS of 0.58. Because a more complex algorithm configuration shows the most promise in terms of prospective operational lightning jump algorithms, accurate thunderstorm cell tracking work must be undertaken to track lightning trends on an individual thunderstorm basis over time. While these numbers for the 2 configuration are impressive, the algorithm does have its weaknesses. Specifically, low-topped and tropical cyclone thunderstorm environments are present issues for the 2 lightning jump algorithm, because of the suppressed vertical depth impact on overall flash counts (i.e., a relative dearth in lightning). For example, in a sample of 120 thunderstorms from northern Alabama that contained 72 missed events by the 2 algorithm 36% of the misses were associated with these two environments (17 storms).

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

    Science.gov (United States)

    1992-11-01

    component list and data were taken from the operating system manual. DATA AQUISITION COMPONENTS 1. Compaq 386SX computer 2. HP Laserjet III printer 3. HP ...C.J.Hardwick Lightning Test and Technology, Culham Laboratory, Abingdon, Oxon, UK. Telephone ( 0235 ) 464264 Fax ( 0235 ) 464325 ABSTRACT It is important to...FF FF22 F5I M •ý III 8ii H H HH H HHHHH 25 •- .ci25 CL<CL> < HP > ) 20 80 I ~15 010 40 5 0 0 1500 1600 1700 1800 1200 1300 1400 1500 1600 TIME (CST) TIME

  2. Properties of the unusually short pulse sequences occurring prior to the first strokes of negative cloud-to-ground lightning flashes

    Czech Academy of Sciences Publication Activity Database

    Kolmašová, Ivana; Santolík, O.; Farges, T.; Rison, W.; Lán, Radek; Uhlíř, Luděk

    2014-01-01

    Roč. 41, č. 14 (2014), s. 5316-5324 ISSN 0094-8276 R&D Projects: GA ČR(CZ) GA14-31899S Grant - others:Rada Programu interní podpory projektů mezinárodní spolupráce AV ČR M100421206 Institutional support: RVO:68378289 Keywords : lightning initiation * preliminary breakdown pulses * duration of breakdown process Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 4.456, year: 2013 http://onlinelibrary.wiley.com/doi/10.1002/2014GL060913/abstract

  3. A Fossilized Energy Distribution of Lightning

    Science.gov (United States)

    Pasek, Matthew A.; Hurst, Marc

    2016-07-01

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

  4. A Fossilized Energy Distribution of Lightning.

    Science.gov (United States)

    Pasek, Matthew A; Hurst, Marc

    2016-07-28

    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.

  5. Estimation of Sparkover Rate of Medium-Voltage Line due to Direct Lightning Hit Taking Account of Statistics on Observed Return-Stroke Current

    Science.gov (United States)

    Hongo, Yasuji; Michishita, Koji

    The overvoltage associated with direct lightning hits has been the important factor for the insulation design of a distribution line. In this paper, the sparkover rate of a medium-voltage line associated with direct lightning hits is investigated based on numerical calculations obtained by using EMTP and statistical analysis by taking account of the correlation between the peak value and the front duration of return-stroke current waveform. When the line is equipped with surge arresters at the interval of 100m in addition to the overhead ground wire, the sparkover rate associated with subsequent strokes is higher than that associated with first strokes. This demonstrates the importance of the study of current parameters for subsequent strokes.

  6. Basic Wiring.

    Science.gov (United States)

    Kaltwasser, Stan; And Others

    This module is the first in a series of three wiring publications; it serves as the foundation for students enrolled in a wiring program. It is a prerequisite to either "Residential Wiring" or "Commercial and Industrial Wiring." The module contains 16 instructional units that cover the following topics: occupational…

  7. Lightning-Sensor Data Help In Understanding Thunderstorms

    Science.gov (United States)

    Goodman, Steven J.

    1992-01-01

    NASA technical memorandum discusses research on use of data from network of ground-based magnetic direction-finding ground-strike lightning sensors to diagnose and predict occurrence and evolution of thunderstorms. Purposes of study to explore applicability and limitations of extrapolation techniques used to generate forecasts from data; to examine physically-based, nonlinear mathematical models for applicability to lightning-forecast problem; and to determine valid extrapolation ranges of such models for various weather scenarios.

  8. Advancing research and applications with lightning detection and mapping systems

    Science.gov (United States)

    MacGorman, Donald R.; Goodman, Steven J.

    2011-11-01

    Southern Thunder 2011 Workshop; Norman, Oklahoma, 11-14 July 2011 The Southern Thunder 2011 (ST11) Workshop was the fourth in a series intended to accelerate research and operational applications made possible by the expanding availability of ground-based and satellite systems that detect and map all types of lightning (in-cloud and cloud-to-ground). This community workshop, first held in 2004, brings together lightning data providers, algorithm developers, and operational users in government, academia, and industry.

  9. A first look at lightning energy determined from GLM

    Science.gov (United States)

    Bitzer, P. M.; Burchfield, J. C.; Brunner, K. N.

    2017-12-01

    The Geostationary Lightning Mapper (GLM) was launched in November 2016 onboard GOES-16 has been undergoing post launch and product post launch testing. While these have typically focused on lightning metrics such as detection efficiency, false alarm rate, and location accuracy, there are other attributes of the lightning discharge that are provided by GLM data. Namely, the optical energy radiated by lightning may provide information useful for lightning physics and the relationship of lightning energy to severe weather development. This work presents initial estimates of the lightning optical energy detected by GLM during this initial testing, with a focus on observations during field campaign during spring 2017 in Huntsville. This region is advantageous for the comparison due to the proliferation of ground-based lightning instrumentation, including a lightning mapping array, interferometer, HAMMA (an array of electric field change meters), high speed video cameras, and several long range VLF networks. In addition, the field campaign included airborne observations of the optical emission and electric field changes. The initial estimates will be compared with previous observations using TRMM-LIS. In addition, a comparison between the operational and scientific GLM data sets will also be discussed.

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

    Directory of Open Access Journals (Sweden)

    Colin Price

    2008-01-01

    Full Text Available 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 characteristics of derecho producing mesoscale convective systems

    Science.gov (United States)

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

    2016-06-01

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

  12. Surge voltages and currents into a customer due to nearby lightning

    Energy Technology Data Exchange (ETDEWEB)

    Ametani, Akihiro; Matsuoka, Kae [Power System Analysis Laboratory, Doshisha University, Kyo-tanabe, Kyoto 610-0321 (Japan); Omura, Hiroshi; Nagai, Yoshiyuki [Power Engineering R and D Center, Kansai Electric Power Co., Amagasaki, Osaka 661-0794 (Japan)

    2009-03-15

    This paper presents experimental results of lightning surges incoming into a customer due to lightning to an antenna of the customer, a pole and a ground nearby the customer, and briefly discusses lightning current distribution in the customer, a distribution line and a telephone line. Based on experimental results, modeling of each component is explained, and EMTP simulations are carried out. The ground voltage rise is represented by a mutual resistance between grounding electrodes. EMTP simulation results have been observed to agree qualitatively with the measured results, and it becomes possible to investigate lightning surges and current distribution in a customer by an EMTP simulation. (author)

  13. Launch pad lightning protection effectiveness

    Science.gov (United States)

    Stahmann, James R.

    1991-01-01

    Using the striking distance theory that lightning leaders will strike the nearest grounded point on their last jump to earth corresponding to the striking distance, the probability of striking a point on a structure in the presence of other points can be estimated. The lightning strokes are divided into deciles having an average peak current and striking distance. The striking distances are used as radii from the points to generate windows of approach through which the leader must pass to reach a designated point. The projections of the windows on a horizontal plane as they are rotated through all possible angles of approach define an area that can be multiplied by the decile stroke density to arrive at the probability of strokes with the window average striking distance. The sum of all decile probabilities gives the cumulative probability for all strokes. The techniques can be applied to NASA-Kennedy launch pad structures to estimate the lightning protection effectiveness for the crane, gaseous oxygen vent arm, and other points. Streamers from sharp points on the structure provide protection for surfaces having large radii of curvature. The effects of nearby structures can also be estimated.

  14. Preliminary lightning observations over Greece

    Science.gov (United States)

    Chronis, Themis G.

    2012-02-01

    The first Precision Lightning Network, monitoring the Cloud-to-Ground (CG) lightning stroke activity over Greece and surrounding waters is operated and maintained by the Hellenic National Meteorological Service. This paper studies the regional (land/water interface), seasonal and diurnal variability of the CG strokes as a function of density, polarity and peak current. Additional investigation uniquely links the CG stroke current to sea surface salinity and cloud electrical capacitance. In brief, this study's major findings area as follows: (1) The seasonal maps of thunder days agree well with the regional climatic convective characteristics of the study area, (2) the CG diurnal variability is consistent with the global lightning activity observations over land and ocean, (3) the maxima of monthly averaged CG counts are located over land and water during typical summer and fall months respectively for both polarities, (4) CG peak currents show a distinct seasonality with larger currents during relatively colder months and smaller currents during summer months, and (5) strong linear trends between -CGs and sea surface salinity; (6) this trend is absent for +CGs data analysis of the employed database relate to the thunderstorm's RC constant and agrees with previous numerical modeling studies.

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

    Science.gov (United States)

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

    2017-07-01

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

  16. Lightning and Climate

    Science.gov (United States)

    Williams, E.

    2012-12-01

    Lightning is of interest in the domain of climate change for several reasons: (1) thunderstorms are extreme forms of moist convection, and lightning flash rate is a sensitive measure of that extremity, (2) thunderstorms are deep conduits for delivering water substance from the boundary layer to the upper troposphere and stratosphere, and (3) global lightning can be monitored continuously and inexpensively within a natural framework (the Earth-ionosphere waveguide and Schumann resonances). Lightning and temperature, and lightning and upper tropospheric water vapor, are positively correlated on weather-related time scales (diurnal, semiannual, and annual) with a lightning temperature sensitivity of order 10% per oC. Lightning also follows temperature variations on the ENSO time scale, both locally and globally. The response of lightning in some of its extreme forms (exceptional flash rates and the prevalence of sprite-producing mesoscale lightning, for example) to temperature variations will be addressed. Consistently obtained records of lightning activity on longer time scales are scarce as stable detection networks are uncommon. As a consequence, thunder day data have been used to extend the lightning record for climate studies, with evidence for increases over decades in urban areas. Global records of lightning following Schumann resonance intensity and from space-based optical sensors (OTD and LIS) are consistent with the record of ionospheric potential representing the global electrical circuit in showing flat behavior over the few decades. This flatness is not well understood, though the majority of all lightning flashes are found in the tropics, the most closely regulated portion of the atmosphere. Other analysis of frequency variations of Schumann resonances in recent decades shows increased lightning in the northern hemisphere, where the global warming is most pronounced. The quantity more fundamental than temperature for lightning control is cloud buoyancy

  17. Characterizing wind turbine system response to lightning activity

    Energy Technology Data Exchange (ETDEWEB)

    McNiff, B.; LaWhite, N. [McNiff Light Industry, Harborside, ME (United States); Muljadi, E. [National Renewable Energy Lab., Golden, CO (United States)

    1998-07-01

    A lightning protection research program was instituted by National Renewable Energy Laboratory to minimize lightning damage to wind turbines and to further the understanding of effective damage mitigation techniques. To that end, a test program is under way to observe lightning activity, protection system response, and damage at a wind power plant in the Department of Energy (DOE) and Electric Power Research Institute (EPRI) Turbine Verification Program. The authors installed Lightning activated surveillance cameras along with a special storm tracking device to observe the activity in the wind plant area. They instrumented the turbines with lightning and ground current detection devices to log direct and indirect strike activity at each unit. They installed a surge monitor on the utility interface to track incoming activity from the transmission lines. Maintenance logs are used to verify damage and determine downtime and repair costs. Actual strikes to turbines were recorded on video and ancillary devices. The test setup and some results are discussed in this paper.

  18. Dynamics of branching of negative downward lightning leaders

    Science.gov (United States)

    Zhang, Xuewei; Zhu, Yujie; Gu, Shanqiang; He, Jinliang

    2017-11-01

    The branching of negative downward lightning leaders is of both theoretical insterest and practical importance. In the lightning protection of ground structures, a clearer understanding of the mechanism and dynamics of leader branching is needed to identify possible lightning strike locations as well as vulnerable parts of the protection systems. In this work, we start with the image analysis of a lightning leader process recorded with a high-speed camera and to show that the anode-directed streamer zone developed from space stems in front of a leader tip needs be smaller in size (electric field at the discharge front, which may result in new bursts of streamers. This model, if further verified, could be the foundation of inferring the structure and dynamics of the streamer zone from the morphology of the leader channel, which would significantly advance the knowledge of the streamer zone in negative lightning leaders.

  19. An Operational Perspective of Total Lightning Information

    Science.gov (United States)

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

    2009-01-01

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

  20. Birth of ball lightning

    Science.gov (United States)

    Lowke, J. J.; Smith, D.; Nelson, K. E.; Crompton, R. W.; Murphy, A. B.

    2012-10-01

    Many observations of ball lightning report a ball of light, about 10 cm in diameter, moving at about walking speed, lasting up to 20 s and frequently existing inside of houses and even aeroplanes. The present paper reports detailed observations of the initiation or birth of ball lightning. In two cases, navigation crew of aircraft saw ball lightning form at the windscreen inside the cockpit of their planes. In the first case, the ball lightning occurred during a thunderstorm, with much lightning activity outside of the plane. In the second case, large "horns" of electrical corona were seen outside of the plane at the surface of the radome, just prior to the formation of the ball lightning. A third case reports ball lightning formed inside of a house, during a thunderstorm, at a closed glass window. It is proposed, based on two-dimensional calculations of electron and ion transport, that ball lightning in these cases is driven and formed by atmospheric ions impinging and collecting on the insulating surface of the glass or Perspex windows. This surface charge can produce electric fields inside of the cockpit or room sufficient to sustain an electric discharge. Charges of opposite sign to those outside of the window accumulate on the inside surface of the glass, leaving a ball of net charge moving inside of the cockpit or room to produce a pulsed discharge on a microsecond time scale.

  1. Lightning injury: a review.

    Science.gov (United States)

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

    2008-08-01

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

  2. Conceptual design of a spaceborne lightning sensor

    Science.gov (United States)

    Wolfe, W. L.; Nagler, M.

    1980-01-01

    A conceptual design of a broad-area optical lightning telescope sensor (BOLTS) designed to provide full-time (day/night) coverage of the continental United States from a geosynchronous orbit is described. Variations are discussed that could cover the whole globe from four to five geosynchronous satellites or cover only smaller areas with a high (2.5 km) resolution. The design is based on research results of the initial phase of a NASA-sponsored program. The ground resolution will be 8 x 8 km. The focal plane is an 800 x 800 pixel CCD array, electronically subdivided to allow for the high data rates (1000 frames per sec) imposed by the characteristics of lightning flashes. It will detect lightning strokes whose optical power is greater than 10 million watts, with a probability of detection of 0.9, and a false alarm rate of 0.1.

  3. The Intra-Cloud Lightning Fraction in the Contiguous United States

    Science.gov (United States)

    Medici, Gina; Cummins, Kenneth L.; Koshak, William J.; Rudlosky, Scott D.; Blakeslee, Richard J.; Goodman, Steven J.; Cecil, Daniel J.; Bright, David R.

    2015-01-01

    Lightning is dangerous and destructive; cloud-to-ground (CG) lightning flashes can start fires, interrupt power delivery, destroy property and cause fatalities. Its rate-of-occurrence reflects storm kinematics and microphysics. For decades lightning research has been an important focus, and advances in lightning detection technology have been essential contributors to our increasing knowledge of lightning. A significant step in detection technology is the Geostationary Lightning Mapper (GLM) to be onboard the Geostationary Operational Environment Satellite R-Series (GOES-R) to be launched in early 2016. GLM will provide continuous "Total Lightning" observations [CG and intra-cloud lightning (IC)] with near-uniform spatial resolution over the Americas by measuring radiance at the cloud tops from the different types of lightning. These Total Lightning observations are expected to significantly improve our ability to nowcast severe weather. It may be important to understand the long-term regional differences in the relative occurrence of IC and CG lightning in order to understand and properly use the short-term changes in Total Lightning flash rate for evaluating individual storms.

  4. Using the VAHIRR Radar Algorithm to Investigate Lightning Cessation

    Science.gov (United States)

    Stano, Geoffrey T.; Schultz, Elise V.; Petersen, Walter A.

    2012-01-01

    Accurately determining the threat posed by lightning is a major area for improved operational forecasts. Most efforts have focused on the initiation of lightning within a storm, with far less effort spent investigating lightning cessation. Understanding both components, initiation and cessation, are vital to improving lightning safety. Few organizations actively forecast lightning onset or cessation. One such organization is the 45th Weather Squadron (45WS) for the Kennedy Space Center (KSC) and Cape Canaveral Air Force Station (CCAFS). The 45WS has identified that charged anvil clouds remain a major threat of continued lightning and can greatly extend the window of a potential lightning strike. Furthermore, no discernable trend of total lightning activity has been observed consistently for all storms. This highlights the need for more research to find a robust method of knowing when a storm will cease producing lightning. Previous lightning cessation work has primarily focused on forecasting the cessation of cloud-to -ground lightning only. A more recent, statistical study involved total lightning (both cloud-to-ground and intracloud). Each of these previous works has helped the 45WS take steps forward in creating improved and ultimately safer lightning cessation forecasts. Each study has either relied on radar data or recommended increased use of radar data to improve cessation forecasts. The reasoning is that radar data is able to either directly or by proxy infer more about dynamical environment leading to cloud electrification and eventually lightning cessation. The authors of this project are focusing on a two ]step approach to better incorporate radar data and total lightning to improve cessation forecasts. This project will utilize the Volume Averaged Height Integrated Radar Reflectivity (VAHIRR) algorithm originally developed during the Airborne Field Mill II (ABFM II) research project. During the project, the VAHIRR product showed a trend of increasing

  5. Wire Chamber

    CERN Multimedia

    Magnetoscriptive readout wire chamber. Multi-wire detectors contain layers of positively and negatively charged wires enclosed in a chamber full of gas. A charged particle passing through the chamber knocks negatively charged electrons out of atoms in the gas, leaving behind positive ions. The electrons are pulled towards the positively charged wires. They collide with other atoms on the way, producing an avalanche of electrons and ions. The movement of these electrons and ions induces an electric pulse in the wires which is collected by fast electronics. The size of the pulse is proportional to the energy loss of the original particle.

  6. Wire chamber

    CERN Multimedia

    1967-01-01

    Magnetoscriptive readout wire chamber.Multi-wire detectors contain layers of positively and negatively charged wires enclosed in a chamber full of gas. A charged particle passing through the chamber knocks negatively charged electrons out of atoms in the gas, leaving behind positive ions. The electrons are pulled towards the positively charged wires. They collide with other atoms on the way, producing an avalanche of electrons and ions. The movement of these electrons and ions induces an electric pulse in the wires which is collected by fast electronics. The size of the pulse is proportional to the energy loss of the original particle.

  7. Application of a relational data base for documenting the ground test accelerator cable routing and wiring interconnections

    International Nuclear Information System (INIS)

    Blackwell, D.B.; Rogers, W.L.; Brown, V.W.; Ekeroth, G.A.; McGill, T.O.

    1991-01-01

    The Ground Test Accelerator (GTA) has many different types of equipment and interconnections to support the operation. Various functions are performed by these equipments such as signal generation, instrument control, and diagnostics. All of the thousands of signals must be routed from the protected tunnel area into the operational control area of the building. Tabulating the routing of these cables, interconnections, terminations, and even the installation status, results in an enormous amount of data collection and maintenance. A relational data base program called Wireflex was written to allow real-time storage, instant recall, and reporting of this information. The operational environment is the VAX network with password security to protect the integrity of the stored data. The format of the program data bases, with the relationships and interchange of information, is described. Examples of input forms show the type of information being stored and the indexing for searching specific entries. Reports are also included displaying the flexibility of types as well as the ability to recover specific entries or ranges of information

  8. wire chamber

    CERN Multimedia

    Proportional multi-wire chamber. Multi-wire detectors contain layers of positively and negatively charged wires enclosed in a chamber full of gas. A charged particle passing through the chamber knocks negatively charged electrons out of atoms in the gas, leaving behind positive ions. The electrons are pulled towards the positively charged wires. They collide with other atoms on the way, producing an avalanche of electrons and ions. The movement of these electrons and ions induces an electric pulse in the wires which is collected by fast electronics. The size of the pulse is proportional to the energy loss of the original particle. Proportional wire chambers allow a much quicker reading than the optical or magnetoscriptive readout wire chambers.

  9. Infrasound Observations from Lightning

    Science.gov (United States)

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

    2008-12-01

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

  10. Lightning in aeronautics

    International Nuclear Information System (INIS)

    Lago, F

    2014-01-01

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

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

    Science.gov (United States)

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

    2006-12-01

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

  12. The relation between TGF and lightning

    Science.gov (United States)

    Ostgaard, N.; Gjesteland, T.; Hansen, R. S.; Carlson, B. E.; Collier, A.

    2012-12-01

    Based on TGF observation from space and radio emissions from lightning there seems to be growing evidence that TGFs are related to positive intracloud lightning bringing negative charges upward. On the other hand, short bursts of X-rays and gammarays observed on the ground have been associated with negative cloud to ground discharges bringing negative charges downward. X-rays are also observed in laboratory experiments during the (negative) leader formation prior to the return stroke. All these observations may indicate that X- and gamma-ray production is a natural consequence of the electrical discharge in thunderstorms and that TGFs are more common than previously believed. This is partly supported by the identification of more than twice as many TGFs in the RHESSI dataset (Gjesteland et al., 2012). An analysis of the TGF distribution as seen from space (Østgaard et al., 2012) concluded that we can not rule out the idea that all lightning discharges produce TGFs. In this paper we will present some new data relating TGFs to the lightning discharge. The observations will be discussed in the context of existing theories for X- and gamma-ray production in thunderstorms.

  13. Observation of the Optical and Spectral Characteristics of Ball Lightning

    Science.gov (United States)

    Cen, Jianyong; Yuan, Ping; Xue, Simin

    2014-01-01

    Ball lightning (BL) has been observed with two slitless spectrographs at a distance of 0.9 km. The BL is generated by a cloud-to-ground lightning strike. It moves horizontally during the luminous duration. The evolution of size, color, and light intensity is reported in detail. The spectral analysis indicates that the radiation from soil elements is present for the entire lifetime of the BL.

  14. Simulating lightning tests to radar system

    NARCIS (Netherlands)

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

    2010-01-01

    The risk of destruction due to lightning makes simulating the effects of lightning strikes a necessity. We modeled a radar enclosure and simulated the effect of a lightning strike. The results have been validated using full threat lightning current tests.

  15. Command Wire Sensor Measurements

    Science.gov (United States)

    2012-09-01

    CFAR Constant False Alarm Rate CWIE Command Wire-Improvised Explosive Device EMI Electromagnetic Induction GPR Ground Penetrating Radar...this, some type of constant false alarm rate ( CFAR ) receiver is required. CFAR automatically raises the threshold level to keep clutter echoes and

  16. Storm Tracking in the Southwest using 2D Lightning Fields

    Science.gov (United States)

    Signell, J.; Smith, J. A.; Baeck, M. L.

    2016-12-01

    We explore the climatology of thunderstorms through analyses of cloud-to-ground lightning data from the National Lightning Detection Network (NLDN). We assess a 2D storm tracking algorithm that only uses cloud-to-ground lightning data. The NLDN consists of over 100 ground-based sensors that since 1991 have detected and recorded the timing and location of lightning strikes in the continental US. Writing tools in Python - an open source programming language - and wrapping a pre-existing geostatistical library in R (SpatialVx developed by NCAR), we developed a reproducible workflow to explore the structure and evolution of thunderstorms using NLDN data. We found that 2D lightning tracking compares favorably to conventional 3D radar tracking conducted using the Thunderstorm Identification, Tracking, Analysis and Nowcasting (TITAN) algorithms. The results point to synergistic analyses of thunderstorm properties using both radar and lightning data. Analyses are motivated by problems that center on examining the climatology of flash flood producing storm systems; results are illustrated for the Southwestern US.

  17. Upward Lightning in Brazil

    Science.gov (United States)

    Schumann, C.; Saba, M. M.; Alves, J.; Warner, T. A.; Albrecht, R. I.; Bie, L. L.

    2012-12-01

    Observations of upward lightning from tall objects have been reported since 1939. Interest in this subject has grown recently, some of it because of the rapid expansion of wind power generation. Also, with the increasing number of tall buildings and towers, there will be a corresponding increase in the number of upward lightning flashes from these structures. Reports from recent field observations are beginning to address the nature of upward lightning initiation, but much still needs to be learned. Examples are studies of upward lightning from towers in winter thunderstorms in Japan (Wang and Takagi, 2010; and Lu et al., 2009) and summer thunderstorms in Europe (Miki et al., 2005; Flache et al., 2008; and Diendorfer et al., 2009; Zhou et al., 2011) and in North America (Mazur and Ruhnke, 2011; Hussein et al., 2011; Warner, 2011, and Warner et al., 2011). Up to January 2012, no upward flash had ever been registered in Brazil. With the help of some video cameras, we recorded 15 upward lightning which started from one of the towers located on Peak Jaraguá in the city of São Paulo. This paper describes the first results of this field campaign. A combination of high-speed video and standard definition video were used to record upward lightning flashes from multiple towers in Sao Paulo, Brazil, a city located in southeastern Brazil with a population over 10 million people, an average elevation of around 800 meters above sea level, and a flash density of 15 flashes/km2/year. Observations of 15 upward flashes made with these assets were analyzed along with BrasilDAT Lightning Detection Network and a lightning mapping array (LMA) and electric field sensors.

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

    Science.gov (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.

  19. Ball lightning burn.

    Science.gov (United States)

    Selvaggi, Gennaro; Monstrey, Stan; von Heimburg, Dennis; Hamdi, Mustapha; Van Landuyt, Koen; Blondeel, Phillip

    2003-05-01

    Ball lightning is a rare physical phenomenon, which is not yet completely explained. It is similar to lightning but with different, peculiar characteristics. It can be considered a mix of fire and electricity, concentrated in a fireball with a diameter of 20-cm that most commonly appears suddenly, even in indoor conditions, during a thunderstorm. It moves quickly for several meters, can change direction, and ultimately disappears. During a great storm, a 28-year-old man and his 5-year-old daughter sustained burn wounds after ball lightning came from the outdoors through a chimney. These two patients demonstrated signs of fire and electrical injuries. The father, who lost consciousness, sustained superficial second-degree burn wounds bilaterally on the zygomatic area and deep second-degree burn wounds on his right hand (total body surface area, 4%). His daughter demonstrated superficial second-degree burn wounds on the left part of the face and deep second-degree and third-degree burn wounds (total body surface area, 30%) on the left neck, both upper arms, and the back. In this article, the authors report the first two cases of burn injuries resulting from ball lightning contact indoors. The literature on this rare phenomenon is reviewed to elucidate the nature of ball lightning. Emphasis is placed on the nature of injuries after ball lightning contact, the therapy used, and the long-term complications.

  20. Situational Lightning Climatologies

    Science.gov (United States)

    Bauman, William; Crawford, Winifred

    2010-01-01

    Research has revealed distinct spatial and temporal distributions of lightning occurrence that are strongly influenced by large-scale atmospheric flow regimes. It was believed there were two flow systems, but it has been discovered that actually there are seven distinct flow regimes. The Applied Meteorology Unit (AMU) has recalculated the lightning climatologies for the Shuttle Landing Facility (SLF), and the eight airfields in the National Weather Service in Melbourne (NWS MLB) County Warning Area (CWA) using individual lightning strike data to improve the accuracy of the climatologies. The software determines the location of each CG lightning strike with 5-, 10-, 20-, and 30-nmi (.9.3-, 18.5-, 37-, 55.6-km) radii from each airfield. Each CG lightning strike is binned at 1-, 3-, and 6-hour intervals at each specified radius. The software merges the CG lightning strike time intervals and distance with each wind flow regime and creates probability statistics for each time interval, radii, and flow regime, and stratifies them by month and warm season. The AMU also updated the graphical user interface (GUI) with the new data.

  1. wire chamber

    CERN Multimedia

    Was used in ISR (Intersecting Storage Ring) split field magnet experiment. Multi-wire detectors contain layers of positively and negatively charged wires enclosed in a chamber full of gas. A charged particle passing through the chamber knocks negatively charged electrons out of atoms in the gas, leaving behind positive ions. The electrons are pulled towards the positively charged wires. They collide with other atoms on the way, producing an avalanche of electrons and ions. The movement of these electrons and ions induces an electric pulse in the wires which is collected by fast electronics. The size of the pulse is proportional to the energy loss of the original particle.

  2. Wire chamber

    CERN Multimedia

    Multi-wire detectors contain layers of positively and negatively charged wires enclosed in a chamber full of gas. A charged particle passing through the chamber knocks negatively charged electrons out of atoms in the gas, leaving behind positive ions. The electrons are pulled towards the positively charged wires. They collide with other atoms on the way, producing an avalanche of electrons and ions. The movement of these electrons and ions induces an electric pulse in the wires which is collected by fast electronics. The size of the pulse is proportional to the energy loss of the original particle.

  3. wire chamber

    CERN Multimedia

    Multi-wire detectors contain layers of positively and negatively charged wires enclosed in a chamber full of gas. A charged particle passing through the chamber knocks negatively charged electrons out of atoms in the gas, leaving behind positive ions. The electrons are pulled towards the positively charged wires. They collide with other atoms on the way, producing an avalanche of electrons and ions. The movement of these electrons and ions induces an electric pulse in the wires which is collected by fast electronics. The size of the pulse is proportional to the energy loss of the original particle.

  4. wire chamber

    CERN Multimedia

    1985-01-01

    Multi-wire detectors contain layers of positively and negatively charged wires enclosed in a chamber full of gas. A charged particle passing through the chamber knocks negatively charged electrons out of atoms in the gas, leaving behind positive ions. The electrons are pulled towards the positively charged wires. They collide with other atoms on the way, producing an avalanche of electrons and ions. The movement of these electrons and ions induces an electric pulse in the wires which is collected by fast electronics. The size of the pulse is proportional to the energy loss of the original particle.

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

    Science.gov (United States)

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

    2017-01-01

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

  6. A Spatial and Temporal Analysis of Upward Triggered Lightning

    Science.gov (United States)

    Ballweber, A. J.

    2013-12-01

    Alana Ballweber, John H. Helsdon Jr., and Tom A. Warner South Dakota School of Mines and Technology Ten tall communication towers lining the ridge in Rapid City, South Dakota provide a unique opportunity to study the phenomenon of lightning-triggered upward lightning. The Upward Lightning Triggering Study (UPLIGHTS), seeks to determine if upward positive leaders are triggered from these towers by: (1) the approach of horizontally propagating negative stepped leaders associated with either intracloud development or following a positive cloud-to-ground (+CG) return stroke, and/or (2) a +CG return stroke as it propagates through a previously formed leader network near the towers. As part of the UPLIGHTS research, two separate lightning mapping devices were used to aid in a 3D re-creation of the triggering flash, a 3D digital interferometer and a Lightning Mapping Array. Through the use of these two devices, we present findings founded on the analysis of data collected from these assets during the 2013 storm season. Specifically, we quantify the spatial and temporal relationship of the triggering flash leader activity relative to the tall objects when upward leaders develop and when upward leaders fail to develop. Furthermore, the lightning mapping devices were correlated with high-speed optical and electrical field observations to provide a further insight as to why certain flashes trigger upward lightning from tall structures and others do not.

  7. The Evolution and Structure of Extreme Optical Lightning Flashes.

    Science.gov (United States)

    Peterson, Michael; Rudlosky, Scott; Deierling, Wiebke

    2017-12-27

    This study documents the composition, morphology, and motion of extreme optical lightning flashes observed by the Lightning Imaging Sensor (LIS). The furthest separation of LIS events (groups) in any flash is 135 km (89 km), the flash with the largest footprint had an illuminated area of 10,604 km 2 , and the most dendritic flash has 234 visible branches. The longest-duration convective LIS flash lasted 28 s and is overgrouped and not physical. The longest-duration convective-to-stratiform propagating flash lasted 7.4 s, while the longest-duration entirely stratiform flash lasted 4.3 s. The longest series of nearly consecutive groups in time lasted 242 ms. The most radiant recorded LIS group (i.e., "superbolt") is 735 times more radiant than the average group. Factors that impact these optical measures of flash morphology and evolution are discussed. While it is apparent that LIS can record the horizontal development of the lightning channel in some cases, radiative transfer within the cloud limits the flash extent and level of detail measured from orbit. These analyses nonetheless suggest that lightning imagers such as LIS and Geostationary Lightning Mapper can complement ground-based lightning locating systems for studying physical lightning phenomena across large geospatial domains.

  8. The Evolution and Structure of Extreme Optical Lightning Flashes

    Science.gov (United States)

    Peterson, Michael; Rudlosky, Scott; Deierling, Wiebke

    2017-12-01

    This study documents the composition, morphology, and motion of extreme optical lightning flashes observed by the Lightning Imaging Sensor (LIS). The furthest separation of LIS events (groups) in any flash is 135 km (89 km), the flash with the largest footprint had an illuminated area of 10,604 km2, and the most dendritic flash has 234 visible branches. The longest-duration convective LIS flash lasted 28 s and is overgrouped and not physical. The longest-duration convective-to-stratiform propagating flash lasted 7.4 s, while the longest-duration entirely stratiform flash lasted 4.3 s. The longest series of nearly consecutive groups in time lasted 242 ms. The most radiant recorded LIS group (i.e., "superbolt") is 735 times more radiant than the average group. Factors that impact these optical measures of flash morphology and evolution are discussed. While it is apparent that LIS can record the horizontal development of the lightning channel in some cases, radiative transfer within the cloud limits the flash extent and level of detail measured from orbit. These analyses nonetheless suggest that lightning imagers such as LIS and Geostationary Lightning Mapper can complement ground-based lightning locating systems for studying physical lightning phenomena across large geospatial domains.

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

    OpenAIRE

    Montany?, Joan; van der Velde, Oscar; Williams, Earle R.

    2015-01-01

    Lightning flashes are known to initiate in regions of strong electric fields inside thunderstorms, between layers of positively and negatively charged precipitation particles. For that reason, lightning inception is typically hidden from sight of camera systems used in research. Other technology such as lightning mapping systems based on radio waves can typically detect only some aspects of the lightning initiation process and subsequent development of positive and negative leader...

  10. Evidence for solar wind modulation of lightning

    Science.gov (United States)

    Scott, C. J.; Harrison, R. G.; Owens, M. J.; Lockwood, M.; Barnard, L.

    2014-05-01

    The response of lightning rates over Europe to arrival of high speed solar wind streams at Earth is investigated using a superposed epoch analysis. Fast solar wind stream arrival is determined from modulation of the solar wind V y component, measured by the Advanced Composition Explorer spacecraft. Lightning rate changes around these event times are determined from the very low frequency arrival time difference (ATD) system of the UK Met Office. Arrival of high speed streams at Earth is found to be preceded by a decrease in total solar irradiance and an increase in sunspot number and Mg II emissions. These are consistent with the high speed stream’s source being co-located with an active region appearing on the Eastern solar limb and rotating at the 27 d period of the Sun. Arrival of the high speed stream at Earth also coincides with a small (˜1%) but rapid decrease in galactic cosmic ray flux, a moderate (˜6%) increase in lower energy solar energetic protons (SEPs), and a substantial, statistically significant increase in lightning rates. These changes persist for around 40 d in all three quantities. The lightning rate increase is corroborated by an increase in the total number of thunder days observed by UK Met stations, again persisting for around 40 d after the arrival of a high speed solar wind stream. This result appears to contradict earlier studies that found an anti-correlation between sunspot number and thunder days over solar cycle timescales. The increase in lightning rates and thunder days that we observe coincides with an increased flux of SEPs which, while not being detected at ground level, nevertheless penetrate the atmosphere to tropospheric altitudes. This effect could be further amplified by an increase in mean lightning stroke intensity that brings more strokes above the detection threshold of the ATD system. In order to remove any potential seasonal bias the analysis was repeated for daily solar wind triggers occurring during the summer

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

    Science.gov (United States)

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

    1998-01-01

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

  12. A Familiar Plasma: Lightning 3. A Recipe of Science Education; Scientific Demonstrations of Lightning

    Science.gov (United States)

    Takaki, Koichi; Ihara, Satoshi; Takahashi, Tohru; Sugiyama, Toshiki

    Four scientific demonstrative presentations concerning a lightning are presented in this article. All presentations can be easily performed on the scientific events held in educational and/or research institutions, such as university, college, research center, elementary, secondary and high schools. The first topic is long gap discharge which shows the model of the lightning from lightning clouds to ground. The high voltage is generated using an impulse voltage generator, which consists five capacitors, gap switches, and dc high-voltage power supply. Human shaped wet sponges were employed in the presentation as a human-body. The second topic is turning-on a fluorescent lamp without direct power supply using Tesla coil as electromagnetic wave radiation source. We show not only some commercial products of Tesla coil but also show how to construct the Tesla coil with much higher output voltage than the merchandise. The third demonstration is a ball lightning using a microwave. Finally, we show a handicraft of small lightning generation on the name card using a piezoelectric crystal in an electric throwaway lighter.

  13. Characterizing the Relationships Among Lightning and Storm Parameters: Lightning as a Proxy Variable

    Science.gov (United States)

    Goodman, S. J.; Raghavan, R.; William, E.; Weber, M.; Boldi, B.; Matlin, A.; Wolfson, M.; Hodanish, S.; Sharp. D.

    1997-01-01

    We have gained important insights from prior studies that have suggested relationships between lightning and storm growth, decay, convective rain flux, vertical distribution of storm mass and echo volume in the region, and storm energetics. A study was initiated in the Summer of 1996 to determine how total (in-cloud plus ground) lightning observations might provide added knowledge to the forecaster in the determination and identification of severe thunderstorms and weather hazards in real-time. The Melbourne Weather Office was selected as a primary site to conduct this study because Melbourne is the only site in the world with continuous and open access to total lightning (LDAR) data and a Doppler (WSR-88D) radar. A Lightning Imaging Sensor Data Applications Demonstration (LISDAD) system was integrated into the forecaster's workstation during the Summer 1996 to allow the forecaster to interact in real-time with the multi-sensor data being displayed. LISDAD currently ingests LDAR data, the cloud-to-ground National Lightning Detection Network (NLDN) data, and the Melbourne radar data in f real-time. The interactive features provide the duty forecaster the ability to perform quick diagnostics on storm cells of interest. Upon selection of a storm cell, a pop-up box appears displaying the time-history of various storm parameters (e.g., maximum radar reflectivity, height of maximum reflectivity, echo-top height, NLDN and LDAR lightning flash rates, storm-based vertically integrated liquid water content). This product is archived to aid on detailed post-analysis.

  14. Performance assessment of Beijing Lightning Network (BLNET) and comparison with other lightning location networks across Beijing

    Science.gov (United States)

    Srivastava, Abhay; Tian, Ye; Qie, Xiushu; Wang, Dongfang; Sun, Zhuling; Yuan, Shanfeng; Wang, Yu; Chen, Zhixiong; Xu, Wenjing; Zhang, Hongbo; Jiang, Rubin; Su, Debin

    2017-11-01

    The performances of Beijing Lightning Network (BLNET) operated in Beijing-Tianjin-Hebei urban cluster area have been evaluated in terms of detection efficiency and relative location accuracy. A self-reference method has been used to show the detection efficiency of BLNET, for which fast antenna waveforms have been manually examined. Based on the fast antenna verification, the average detection efficiency of BLNET is 97.4% for intracloud (IC) flashes, 73.9% for cloud-to-ground (CG) flashes and 93.2% for the total flashes. Result suggests the CG detection of regional dense network is highly precise when the thunderstorm passes over the network; however it changes day to day when the thunderstorms are outside the network. Further, the CG stroke data from three different lightning location networks across Beijing are compared. The relative detection efficiency of World Wide Lightning Location Network (WWLLN) and Chinese Meteorology Administration - Lightning Detection Network (CMA-LDN, also known as ADTD) are approximately 12.4% (16.8%) and 36.5% (49.4%), respectively, comparing with fast antenna (BLNET). The location of BLNET is in middle, while WWLLN and CMA-LDN average locations are southeast and northwest, respectively. Finally, the IC pulses and CG return stroke pulses have been compared with the S-band Doppler radar. This type of study is useful to know the approximate situation in a region and improve the performance of lightning location networks in the absence of ground truth. Two lightning flashes occurred on tower in the coverage of BLNET show that the horizontal location error was 52.9 m and 250 m, respectively.

  15. National athletic trainers' association position statement: lightning safety for athletics and recreation.

    Science.gov (United States)

    Walsh, K M; Bennett, B; Cooper, M A; Holle, R L; Kithil, R; López, R E

    2000-10-01

    To educate athletic trainers and others about the dangers of lightning, provide lightning-safety guidelines, define safe structures and locations, and advocate prehospital care for lightning-strike victims. Lightning may be the most frequently encountered severe-storm hazard endangering physically active people each year. Millions of lightning flashes strike the ground annually in the United States, causing nearly 100 deaths and 400 injuries. Three quarters of all lightning casualties occur between May and September, and nearly four fifths occur between 10:00 AM and 7:00 PM, which coincides with the hours for most athletic or recreational activities. Additionally, lightning casualties from sports and recreational activities have risen alarmingly in recent decades. The National Athletic Trainers' Association recommends a proactive approach to lightning safety, including the implementation of a lightning-safety policy that identifies safe locations for shelter from the lightning hazard. Further components of this policy are monitoring local weather forecasts, designating a weather watcher, and establishing a chain of command. Additionally, a flash-to-bang count of 30 seconds or more should be used as a minimal determinant of when to suspend activities. Waiting 30 minutes or longer after the last flash of lightning or sound of thunder is recommended before athletic or recreational activities are resumed. Lightning- safety strategies include avoiding shelter under trees, avoiding open fields and spaces, and suspending the use of land-line telephones during thunderstorms. Also outlined in this document are the prehospital care guidelines for triaging and treating lightning-strike victims. It is important to evaluate victims quickly for apnea, asystole, hypothermia, shock, fractures, and burns. Cardiopulmonary resuscitation is effective in resuscitating pulseless victims of lightning strike. Maintenance of cardiopulmonary resuscitation and first-aid certification should

  16. LOFAR lightning imaging: Mapping lightning with nanosecond precision

    NARCIS (Netherlands)

    B.M. Hare; O. Scholten; A. Bonardi; S. Buitink; A. Corstanje; U. M. Ebert (Ute); H. Falcke; J.R. Hörandel (Jörg); H. Leijnse; P. Mitra; K. Mulrey; A. Nelles; J.P. Rachen; L. Rossetto; C. Rutjes (Casper); P. Schellart; S. Thoudam; T.N.G. Trinh (Gia); S. ter Veen (Sander); T. Winchen

    2018-01-01

    textabstractLightning mapping technology has proven instrumental in understanding lightning. In this work we present a pipeline that can use lightning observed by the LOw-Frequency ARray (LOFAR) radio telescope to construct a 3D map of the flash. We show that LOFAR has unparalleled precision, on the

  17. Laboratory demonstration of ball lightning

    Energy Technology Data Exchange (ETDEWEB)

    Egorov, Anton I; Stepanov, Sergei I; Shabanov, Gennadii D [B.P. Konstantinov St. Petersburg Institute of Nuclear Physics, Russian Academy of Sciences, Gatchina, Leningrad region, Rusian Federation (Russian Federation)

    2004-01-31

    A common laboratory facility for creating glowing flying plasmoids akin to a natural ball lightning, allowing a number of experiments to be performed to investigate the main properties of ball lightning, is described. (methodological notes)

  18. Emergency Preparedness and Response - Lightning

    Science.gov (United States)

    ... for Pet Owners Frequently Asked Questions Additional Information Lightning Language: English Español (Spanish) Recommend on Facebook Tweet ... you know what to do when you see lightning or when you hear thunder as a warning. ...

  19. A Distribution Line Model for Lightning Overvoltage Studies

    Science.gov (United States)

    Matsuura, Susumu; Noda, Taku; Asakawa, Akira; Yokoyama, Shigeru

    Recently, the focus of lightning protection measures for distribution lines has moved from a nearby lightning stroke to a direct lightning stroke. Studies of direct lightning stroke countermeasures are generally carried out by digital simulations using the EMTP (Electro-Magnetic Transients Program). Thus, components of a distribution line must be modeled appropriately in the EMTP for accurate simulations. The authors have previously clarified the surge response of a distribution line by pulse tests using a reduced-scale distribution line model. In this paper, first, the results of the pulse tests are simulated in the EMTP using a conventional model which represents a distribution pole by a single lossless distributed-parameter line model, and comparisons with the test results show that transient overvoltages generated at the insulators cannot accurately be reproduced by the conventional model. This indicates that a special treatment is required to represent the transient response of a distribution pole and wires. Then, this paper proposes new EMTP models of the pole and wires which can reproduce the transient overvoltages at the insulators. The parameter values of the proposed models can be determined based on a pulse test result.

  20. The Distribution of Lightning Channel Lengths in Northern Alabama Thunderstorms

    Science.gov (United States)

    Peterson, H. S.; Koshak, W. J.

    2010-01-01

    Lightning is well known to be a major source of tropospheric NOx, and in most cases is the dominant natural source (Huntreiser et al 1998, Jourdain and Hauglustaine 2001). Production of NOx by a segment of a lightning channel is a function of channel segment energy density and channel segment altitude. A first estimate of NOx production by a lightning flash can be found by multiplying production per segment [typically 104 J/m; Hill (1979)] by the total length of the flash s channel. The purpose of this study is to determine average channel length for lightning flashes near NALMA in 2008, and to compare average channel length of ground flashes to the average channel length of cloud flashes.

  1. Lightning and radar observations of hurricane Rita landfall

    Energy Technology Data Exchange (ETDEWEB)

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

    2009-01-01

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

  2. SECRET OF A BALL LIGHTNING

    Directory of Open Access Journals (Sweden)

    E.V. Savich

    2013-04-01

    Full Text Available A ball lightning is a natural phenomenon that occurs at a streak lightning stroke with its action by thermal and magnetic energy releasing around the streak lightning channel and transforming, in the end, the surrounding air into a steam cloud that transits into ferroelectric state under the magnetic field action.

  3. Lightning incidents in Mongolia

    Directory of Open Access Journals (Sweden)

    Myagmar Doljinsuren

    2015-11-01

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

  4. Characteristics of Lightning within Electrified Snowfall Events using Total Lightning Measurements

    Science.gov (United States)

    Schultz, C. J.; Bruning, E. C.; Lang, T. J.; Kuhlman, K. M.

    2015-12-01

    Lightning within heavy snowfall indicates the presence of heavy snowfall rates. Most studies within the literature examine this phenomenon using ground based networks that are primarily designed for identifying cloud to ground flashes. Thus, very little study of the three dimensional structure of the lightning flashes within heavy snowfall has been accomplished. Herein, total lightning mapping arrays, interferometers and ground based networks like the National Lightning Detection Network (NLDN) are utilized to document the characteristics of these flashes, including flash size, polarity, flash initiation location and inferred charge structure. A total of six events are examined, resulting in a total of approximately 80 flashes. Both individual case studies and overall population statistics will be used to characterize flashes within this winter environment. Many of these flashes are found to initiate from tall objects like television and radio communication towers, and come to ground in multiple locations along their path, resulting in one LMA derived flash containing multiple NLDN identified flashes. Cloud-to-ground flashes of both polarities are noted within the 80 flash sample. In one case, 3 separate flashes which resulted in ground flashes of both polarities were observed coming out of the same overall charge structure. This structure exhibited a highly sloped nature in the LMA data from east to west, and both +IC and -IC components of flashes were observed by the NLDN in the same region where the flashes initiated. A decrease in flash size is noted with time in at least three of these events due to weaker updraft (compared to their summertime thunderstorm counter parts) and smaller available of supercooled liquid water as inferred through trends in radar observations. These limiting factors are hypothesized to result in slower charging rates, and smaller flash sizes with time. Several flashes also exhibit sloped structures that match reflectivity

  5. An Algorithm for Obtaining the Distribution of 1-Meter Lightning Channel Segment Altitudes for Application in Lightning NOx Production Estimation

    Science.gov (United States)

    Peterson, Harold; Koshak, William J.

    2009-01-01

    An algorithm has been developed to estimate the altitude distribution of one-meter lightning channel segments. The algorithm is required as part of a broader objective that involves improving the lightning NOx emission inventories of both regional air quality and global chemistry/climate models. The algorithm was tested and applied to VHF signals detected by the North Alabama Lightning Mapping Array (NALMA). The accuracy of the algorithm was characterized by comparing algorithm output to the plots of individual discharges whose lengths were computed by hand; VHF source amplitude thresholding and smoothing were applied to optimize results. Several thousands of lightning flashes within 120 km of the NALMA network centroid were gathered from all four seasons, and were analyzed by the algorithm. The mean, standard deviation, and median statistics were obtained for all the flashes, the ground flashes, and the cloud flashes. One-meter channel segment altitude distributions were also obtained for the different seasons.

  6. Optimizing Precipitation Thresholds for Best Correlation Between Dry Lightning and Wildfires

    Science.gov (United States)

    Vant-Hull, Brian; Thompson, Tollisha; Koshak, William

    2018-03-01

    This work examines how to adjust the definition of "dry lightning" in order to optimize the correlation between dry lightning flash count and the climatology of large (>400 km2) lightning-ignited wildfires over the contiguous United States (CONUS). The National Lightning Detection Network™ and National Centers for Environmental Prediction Stage IV radar-based, gauge-adjusted precipitation data are used to form climatic data sets. For a 13 year analysis period over CONUS, a correlation of 0.88 is found between annual totals of wildfires and dry lightning. This optimal correlation is found by defining dry lightning as follows: on a 0.1° hourly grid, a precipitation threshold of no more than 0.3 mm may accumulate during any hour over a period of 3-4 days preceding the flash. Regional optimized definitions vary. When annual totals are analyzed as done here, no clear advantage is found by weighting positive polarity cloud-to-ground (+CG) lightning differently than -CG lightning. The high variability of dry lightning relative to the precipitation and lightning from which it is derived suggests it would be an independent and useful climate indicator.

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

    Science.gov (United States)

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

    2015-06-16

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

  8. Climate change. Projected increase in lightning strikes in the United States due to global warming.

    Science.gov (United States)

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

    2014-11-14

    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. Copyright © 2014, American Association for the Advancement of Science.

  9. The GOES-R Geostationary Lightning Mapper (GLM) and the Global Observing System for Total Lightning

    Science.gov (United States)

    Goodman, Steven J.; Blakeslee, R. J.; Koshak, W.; Buechler, D.; Carey, L.; Chronis, T.; Mach, D.; Bateman, M.; Peterson, H.; McCaul, E. W., Jr.; hide

    2014-01-01

    for the existing GOES system currently operating over the Western Hemisphere. New and improved instrument technology will support expanded detection of environmental phenomena, resulting in more timely and accurate forecasts and warnings. Advancements over current GOES include a new capability for total lightning detection (cloud and cloud-to-ground flashes) from the Geostationary Lightning Mapper (GLM), and improved temporal, spatial, and spectral resolution for the next generation Advanced Baseline Imager (ABI). The GLM will map total lightning continuously day and night with near-uniform spatial resolution of 8 km with a product latency 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 among a number of potential applications. The GLM will help address the National Weather Service requirement for total lightning observations globally to support warning decision-making and forecast services. Science and application development along with pre-operational product demonstrations and evaluations at NWS national centers, forecast offices, and NOAA testbeds will prepare the forecasters to use GLM as soon as possible after the planned launch and check-out of GOES-R in 2016. New applications will use GLM alone, in combination with the ABI, or integrated (fused) with other available tools (weather radar and ground strike networks, nowcasting systems, mesoscale analysis, and numerical weather prediction models) in the hands of the forecaster responsible for issuing more timely and accurate forecasts and warnings.

  10. Experimental Study on Surge Propagation Characteristics of Rail and Lightning Overvoltages on Level Crossing

    Science.gov (United States)

    Arai, Hideki; Matsubara, Hiroji; Miyajima, Kiyotomi; Yokoyama, Shigeru; Sato, Kazutoshi

    Lightning protection measures are required for the railway signalling system because suspension and delays of trains due to lightnings may cause social confusion. Therefore, we carried out experiments on propagation characteristics of lightning surges along a rail, and injected a lightning surge current into the rail or wayside ground to raise their potentials, in order to measure the lightning overvoltages on a level crossing for the insulation design. There are no precedents that have carried out these experiments in the field until now. We could obtain the following results. (1) The surge impedance of the rail is 56Ω and the surge propagation velocity in the rail is 55m/μs. (2) The surge attenuation depends only on the duration of wave tail of the traveling lightning surge along the rail and decreases as the duration of wave tail becomes longer. (3) Flashovers may occur at the terminals in the equipment of the level crossing in case 1) a 2kA lightning surge current is directly injected into the rail, or 2) a 10kA lightning surge current is injected into the wayside ground at a vertical distance of 2m from the rail. (4) We can estimate the lightning overvoltages on the terminals in the equipment of the level crossing according to the vertical distance from the rail of the lighting stroke and the level of the stroke current.

  11. Formation of ball lightning

    Energy Technology Data Exchange (ETDEWEB)

    Silberg, P.A. (2833 Lawton Drive, Amarillo, Texas (USA))

    A plasma continuum model for the formation of ball lightning is developed based on a substantial number of reports that the ball is often in the discharge column of a previous lightning stroke. The usual method of setting up the plasma equation for a one-component electron plasma is used. An approximate equation for the plasma is derived from the describing equation which is then solved exactly in terms of the Jacobi elliptic functions. The formation of the ball is based on a nonlinearity of the plasma equation which under certain circumstances permits the field to collapse into a small region. This collapse is interpreted to be ball lightning. The approximate equation derived for the plasma has the same form as a previous equation used to describe the formation of the fireball plasma.

  12. The Geostationary Lightning Mapper: Its Design and Performance

    Science.gov (United States)

    Christian, H. J., Jr.; Stewart, M. F.

    2017-12-01

    The Geostationary Lightning Mapper (GLM) is the first instrument in geostationary orbit that was specifically designed to detect and locate lightning. The GLM is required to detect greater than 70% of the lightning flashes that occur within its field of view and to locate these flashes to within 8 kilometers, the nominal size of a thunderstorm footprint on the ground. However, the GLM was actually designed to detect 90% of viewable lightning flashes, a goal which it will likely achieve. The design of the GLM is based on the proven design of the Lightning Imaging Sensor (LIS), which has been demonstrated to detect greater than 80% of the lightning flashes within its field of view. The primary key to high detection efficiency is high radiometric throughput. The GLM was designed to have 10% greater throughput than LIS. A secondary key is the bandwidth of the telemetry downlink. A higher data rate allows lower threshold settings and hence a more sensitive instrument. While the GLM must process just over 100 times as many pixels as LIS, its telemetry bandwidth is a 1000 times greater, thus it is capable of operating at significantly more sensitive setting than LIS. During this presentation, LIS and GLM capabilities will be compared. Further, it will be pointed out where the GLM lightning detection capability can be further optimized. In addition, some of the unique design features of the GLM will be revealed such as the variable pitch pixels, the virtual baffle and the continuing current mode. It will be explained how these designs can serve to improve overall performance. Finally, a concept for scientifically based ground processing algorithms will be presented with an explanation of how improved ground processing can further optimize GLM performance.

  13. Electrical and Hydrometeor Structure of Thunderstorms that produce Upward Lightning

    Science.gov (United States)

    dos Santos Souza, J. C.; Albrecht, R. I.; Lang, T. J.; Saba, M. M.; Warner, T. A.; Schumann, C.

    2017-12-01

    Upward lightning (UL) flashes at tall structures have been reported to be initiated by in-cloud branching of a parent positive cloud-to-ground (CG) or intracloud (IC) lightning during the decaying stages of thunderstorms, and associated with stratiform precipitation. This in-cloud branching of the parent CG lightning into lower layers of the stratiform precipitation, as well as other situational modes of UL triggering, are indicative of a lower charge center. The objective of this study is to determine the hydrometeor characteristics of thunderstorms that produce UL, especially at the lower layers of the stratiform region where the bidirectional leader of the parent CG or IC lightning propagates through. We investigated 17 thunderstorms that produced 56 UL flashes in São Paulo, SP, Brazil and 10 thunderstorms (27 UL) from the UPLIGHTS field experiment in Rapid City, SD, USA. We used polarimetric radar data and 3D lighting mapping or the combination of total (i.e., intracloud and cloud-to-ground) and cloud-to-ground lightning strokes data. The Hydrometeor Identification for the thunderstorms of this study consider the information from polarimetric variables ZH, ZDR, KDP and RHOHV to infer radar echoes into rain (light, medium, heavy), hail, dry snow, wet snow, ice crystals, graupel and rain-hail mixtures. Charge structure is inferred by the 3D very-high-frequency (VHF) Lightning Mapping Array by monitoring lightning propagation closely in time and space and constructing vertical histograms of VHF source density. The results of this research project are important to increase the understanding of the phenomenon, the storm evolution and the predictability of UL.

  14. 29 CFR 1926.404 - Wiring design and protection.

    Science.gov (United States)

    2010-07-01

    ... 29 Labor 8 2010-07-01 2010-07-01 false Wiring design and protection. 1926.404 Section 1926.404... Requirements § 1926.404 Wiring design and protection. (a) Use and identification of grounded and grounding... construction sites, which are not a part of the permanent wiring of the building or structure and which are in...

  15. Produce documents and media information. [on lightning

    Science.gov (United States)

    Alzmann, Melanie A.; Miller, G.A.

    1994-01-01

    Lightning data and information were collected from the United States, Germany, France, Brazil, China, and Australia for the dual purposes of compiling a global lightning data base and producing publications on the Marshall Space Flight Center's lightning program. Research covers the history of lightning, the characteristics of a storm, types of lightningdischarges, observations from airplanes and spacecraft, the future fole of planes and spacecraft in lightning studies, lightning detection networks, and the relationships between lightning and rainfall. Descriptions of the Optical Transient Dectector, the Lightning Imaging Sensor, and the Lightning Mapper Sensor are included.

  16. The detection of lightning from geostationary orbit

    Science.gov (United States)

    Christian, Hugh J.; Blakeslee, Richard J.; Goodman, Steven J.

    1989-01-01

    Consideration is given to the development of the Lightning Mapper Sensor (LMS), a space sensor capable of mapping intracloud and cloud-to-ground lightning discharges from geostationary orbit during day and night. The LMS is expected to have a spatial resolution of 10 km and a detection efficiency of 90 percent. The LMS combines modern solid state mosaic focal planes with extensive on-board signal processing to make it possible to detect weak background-contaminated signals. The LMS is planned to have a 10.5 degree field of view covering all of the continental U.S. The characteristics and design of the LMS are described, noting the possible applications of the sensor.

  17. Protection of electrical and electronic equipment against lightning indirect effects on the Airbus A340 wing

    Science.gov (United States)

    Spiller, Olaf

    1991-01-01

    The provisions applied to the Airbus A340 wing wiring against lightning indirect effects are presented. The construction and installation of the wiring's shielding systems are described, and the analysis and tests performed to determine the effectiveness of the measures taken are discussed. A first evaluation of the results of the theoretical analysis together with the provisional results of tests indicate a sufficient safety margin between required and achieved protection levels.

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

    Science.gov (United States)

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

    2009-04-01

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

  19. Lightning Imaging with LOFAR

    Directory of Open Access Journals (Sweden)

    Scholten Olaf

    2017-01-01

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

  20. Cell-tracking with lightning data from LINET

    Directory of Open Access Journals (Sweden)

    H. D. Betz

    2008-07-01

    Full Text Available A new lightning detection network (LINET has been developed at the University of Munich, which locates and reports both cloud discharges and cloud-to-ground strokes with high accuracy. The network started operation in May 2006; since then lightning data for Europe are being delivered to many scientific groups, and to the German Weather Service (DWD on an operational basis (powered by nowcast GmbH, Germany. Using about 90 lightning sensors in 17 countries, an area from longitude 10° W–25° E to latitude 35° N–65° N is covered. Further expansion is in the planning stage with the aim to attain higher efficiency for Mediterranean storms. The total lightning capability, not readily available otherwise in large areas, is particularly helpful because it can provide useful information about the development of severe weather and strong storm cells. A cell-tracking module has been developed that allows the investigation of lightning parameters for specific convective cells. Present efforts are devoted to the question for what kind of storms and to what extent lightning-based cell tracking allows improved nowcasting. Numerous case studies have been carried out and typical examples will be presented.

  1. Photonuclear reactions triggered by lightning discharge

    Science.gov (United States)

    Enoto, Teruaki; Wada, Yuuki; Furuta, Yoshihiro; Nakazawa, Kazuhiro; Yuasa, Takayuki; Okuda, Kazufumi; Makishima, Kazuo; Sato, Mitsuteru; Sato, Yousuke; Nakano, Toshio; Umemoto, Daigo; Tsuchiya, Harufumi

    2017-11-01

    Lightning and thunderclouds are natural particle accelerators. Avalanches of relativistic runaway electrons, which develop in electric fields within thunderclouds, emit bremsstrahlung γ-rays. These γ-rays have been detected by ground-based observatories, by airborne detectors and as terrestrial γ-ray flashes from space. The energy of the γ-rays is sufficiently high that they can trigger atmospheric photonuclear reactions that produce neutrons and eventually positrons via β+ decay of the unstable radioactive isotopes, most notably 13N, which is generated via 14N + γ → 13N + n, where γ denotes a photon and n a neutron. However, this reaction has hitherto not been observed conclusively, despite increasing observational evidence of neutrons and positrons that are presumably derived from such reactions. Here we report ground-based observations of neutron and positron signals after lightning. During a thunderstorm on 6 February 2017 in Japan, a γ-ray flash with a duration of less than one millisecond was detected at our monitoring sites 0.5-1.7 kilometres away from the lightning. The subsequent γ-ray afterglow subsided quickly, with an exponential decay constant of 40-60 milliseconds, and was followed by prolonged line emission at about 0.511 megaelectronvolts, which lasted for a minute. The observed decay timescale and spectral cutoff at about 10 megaelectronvolts of the γ-ray afterglow are well explained by de-excitation γ-rays from nuclei excited by neutron capture. The centre energy of the prolonged line emission corresponds to electron-positron annihilation, providing conclusive evidence of positrons being produced after the lightning.

  2. The Kinematic and Microphysical Control of Storm Integrated Lightning Flash Extent

    Science.gov (United States)

    Carey, Lawrence D.; Koshak, William J.; Peterson, Harold S.; Shultz, Elise; Matthee, Retha; Shultz, Christopher J.; Petersen, Walter A.; Bain, Lamont

    2013-01-01

    To investigate the kinematic and microphysical control of lightning properties, particularly those that may govern the production of nitrogen oxides (NO(x)) in thunderstorms, such as flash rate, type (intracloud (IC) vs. cloud-to-ground (CG)) and extent.

  3. Science of Ball Lightning (Fire Ball)

    Science.gov (United States)

    Ohtsuki, Yoshi-Hiko

    1989-08-01

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

  4. Wiring design for the control of electromagnetic interference (EMI)

    Science.gov (United States)

    Kopasakis, George

    1995-01-01

    Wiring design is only one important aspect of EMI control. Other important areas for EMI are: circuit design, filtering, grounding, bonding, shielding, lighting, electrostatic discharge (ESD), transient suppression, and electromagnetic pulse (EMP). Topics covered include: wire magnetic field emissions at low frequencies; wire radiated magnetic field emissions at frequencies; wire design guidelines for EMI control; wire design guidelines for EMI control; high frequency emissions from cables; and pulse frequency spectra.

  5. Assessing the relationship between high lightning events and storm mode in northern and central Alabama

    Science.gov (United States)

    Willis, Morgan Terry

    Lightning is a dangerous and deadly hazard, yet it is often underestimated by the public and excluded from severe weather watches and warnings used by the National Weather Service. Previous studies have analyzed the relationship of lightning and storm intensity in relation to severe weather, but none have analyzed this relationship across all storm modes in an area including Northern and Central Alabama. This study attempts to assess the relationship between cloud-to-ground (CG) lightning and storm mode in storm events which occurred on lightning hazard days in Northern and Central Alabama during the years of 2007 to 2011. Storm variables for analysis included lightning flash rate, aspect ratio, total convective area above 20 dBZ, maximum convective area above 40 dBZ, and percent maximum convective area. Results show that lightning flash rates vary by season and storm mode. PCA and Cluster Analysis identified a total of 5 clusters of varying lightning flash rate and convective intensity. The storm mode events include non-summer linear, an anomalous MCS associated with a triple point frontal outflow boundary, summer airmass, non-seasonal weak, and summer MCS/MCC. Information obtained during this thesis has the potential to aid forecasters and emergency managers in Northern and Central Alabama by associating lightning flash rates with storm mode characteristics observed on lightning hazard days.

  6. A statistical scheme to forecast the daily lightning threat over southern Africa using the Unified Model

    Science.gov (United States)

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

    2017-09-01

    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.

  7. Eddy Current Model of Ball Lightning

    OpenAIRE

    Shelton, J. D.

    2011-01-01

    Eddy Current Model of Ball Lightning Calculations show that high-energy ball lightning may consist of a ball of plasma containing a large circular electric current arising as an eddy current generated by lightning. Synthetic ball lightning might serve as a method of plasma confinement for purposes of nuclear fusion. In this paper, three articles concerning ball lightning and the related phenomenon of large ball lightning are combined to provide insight into this rarely glimpsed occurrence.

  8. A Summary of the NASA Lightning Nitrogen Oxides Model (LNOM) and Recent Results

    Science.gov (United States)

    Koshak, William; Peterson, Harld

    2011-01-01

    The NASA Marshall Space Flight Center introduced the Lightning Nitrogen Oxides Model (LNOM) a couple of years ago to combine routine state-of-the-art measurements of lightning with empirical laboratory results of lightning NOx production. The routine measurements included VHF lightning source data [such as from the North Alabama Lightning Mapping Array (LMA)], and ground flash location, peak current, and stroke multiplicity data from the National Lightning Detection Network(TradeMark) (NLDN). Following these initial runs of LNOM, the model was updated to include several non-return stroke lightning NOx production mechanisms, and provided the impact of lightning NOx on an August 2006 run of CMAQ. In this study, we review the evolution of the LNOM in greater detail and discuss the model?s latest upgrades and applications. Whereas previous applications were limited to five summer months of data for North Alabama thunderstorms, the most recent LNOM analyses cover several years. The latest statistics of ground and cloud flash NOx production are provided.

  9. The Houston Lightning Mapping Array: Installation, Operation, and Preliminary Results

    Science.gov (United States)

    Orville, R. E.; Cullen, M. R.; Rodeheffer, D.; Krehbiel, P. R.; Rison, W.

    2012-12-01

    The Houston Lightning Mapping Array (LMA) was established in April 2012 and is a network of twelve time-of-arrival lightning sensors operating in the VHF around Houston, Texas. The network sensors are built by New Mexico Institute of Mining and Technology. Built stand-alone units, these LMA sensors use solar panels and cellular data modems for Internet connectivity. This enables the units to be placed in strategic locations at sites to minimize noise and interference by reducing dependence on wired power or communications lines. Twelve sensors are distributed around the Houston and provide total lightning data for the fourth most populated American city. The primary research goals of the network are to investigate the structure of total lightning within thunderstorm development and to examine any potential impact of the urban environment on lightning characteristics. Furthermore, the proximity to the coast and the Gulf of Mexico presents the opportunity to examine the total lightning structure within tropical cyclones that impact the Texas coastline. The availability of real-time LMA data provides a decision support tool for advanced warning of thunderstorm development. We present efforts with the Houston/Galveston Weather Forecast Office and the Spaceflight Meteorology Group at Johnson Space Center to integrate the real-time LMA data into operational display software. The network of 12 sensors has been operating continuously since installation in mid-April with 10 sensors surrounding the Houston area plus one in College Station and one in Galveston. Analysis of recent data will investigate three-dimensional thunderstorm activity.

  10. Lightning Forecasts and Data Assimilation into Numerical Weather Prediction Models

    Science.gov (United States)

    MacGorman, D. R.; Mansell, E. R.; Fierro, A.; Ziegler, C.

    2012-12-01

    This presentation reviews two aspects of lightning in numerical weather prediction (NWP) models: forecasting lightning and assimilating lightning data into NWP models to improve weather forecasts. One of the earliest routine forecasts of lightning was developed for fire weather operations. This approach used a multi-parameter regression analysis of archived cloud-to-ground (CG) lightning data and archived NWP data to optimize the combination of model state variables to use in forecast equations for various CG rates. Since then, understanding of how storms produce lightning has improved greatly. As the treatment of ice in microphysics packages used by NWP models has improved and the horizontal resolution of models has begun approaching convection-permitting scales (with convection-resolving scales on the horizon), it is becoming possible to use this improved understanding in NWP models to predict lightning more directly. An important role for data assimilation in NWP models is to depict the location, timing, and spatial extent of thunderstorms during model spin-up so that the effects of prior convection that can strongly influence future thunderstorm activity, such as updrafts and outflow boundaries, can be included in the initial state of a NWP model run. Radar data have traditionally been used, but systems that map lightning activity with varying degrees of coverage, detail, and detection efficiency are now available routinely over large regions and reveal information about storms that is complementary to the information provided by radar. Because data from lightning mapping systems are compact, easily handled, and reliably indicate the location and timing of thunderstorms, even in regions with little or no radar coverage, several groups have investigated techniques for assimilating these data into NWP models. This application will become even more valuable with the launch of the Geostationary Lightning Mapper on the GOES-R satellite, which will extend routine

  11. OLS ANALOG DERIVED LIGHTNING V11

    Data.gov (United States)

    National Aeronautics and Space Administration — The OLS Analog Derived Lightning dataset consists of global lightning signatures from the Defense Meteorological Satellite Program (DMSP) Operational Linescan System...

  12. Lightning protection of PV systems

    OpenAIRE

    Pons, Enrico; Tommasini, Riccardo

    2013-01-01

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

  13. Statistical analysis of storm electrical discharges reconstituted from a lightning mapping system, a lightning location system, and an acoustic array

    Science.gov (United States)

    Gallin, Louis-Jonardan; Farges, Thomas; Marchiano, Régis; Coulouvrat, François; Defer, Eric; Rison, William; Schulz, Wolfgang; Nuret, Mathieu

    2016-04-01

    In the framework of the European Hydrological Cycle in the Mediterranean Experiment project, a field campaign devoted to the study of electrical activity during storms took place in the south of France in 2012. An acoustic station composed of four microphones and four microbarometers was deployed within the coverage of a Lightning Mapping Array network. On the 26 October 2012, a thunderstorm passed just over the acoustic station. Fifty-six natural thunder events, due to cloud-to-ground and intracloud flashes, were recorded. This paper studies the acoustic reconstruction, in the low frequency range from 1 to 40 Hz, of the recorded flashes and their comparison with detections from electromagnetic networks. Concurrent detections from the European Cooperation for Lightning Detection lightning location system were also used. Some case studies show clearly that acoustic signal from thunder comes from the return stroke but also from the horizontal discharges which occur inside the clouds. The huge amount of observation data leads to a statistical analysis of lightning discharges acoustically recorded. Especially, the distributions of altitudes of reconstructed acoustic detections are explored in detail. The impact of the distance to the source on these distributions is established. The capacity of the acoustic method to describe precisely the lower part of nearby cloud-to-ground discharges, where the Lightning Mapping Array network is not effective, is also highlighted.

  14. 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)

    1995-01-01

    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.

  15. Ball lightning risk to aircraft

    Science.gov (United States)

    Doe, R.; Keul, A.

    2009-04-01

    Lightning is a rare but regular phenomenon for air traffic. Aircraft are designed to withstand lightning strikes. Research on lightning and aircraft can be called detailed and effective. In the last 57 years, 18 reported lightning aviation disasters with a fatality figure of at least 714 persons occurred. For comparison, the last JACDEC ten-year average fatality figure was 857. The majority encountered lightning in the climb, descent, approach and/or landing phase. Ball lightning, a metastable, rare lightning type, is also seen from and even within aircraft, but former research only reported individual incidents and did not generate a more detailed picture to ascertain whether it constitutes a significant threat to passenger and aircraft safety. Lacking established incident report channels, observations were often only passed on as "air-travel lore". In an effort to change this unsatisfactory condition, the authors have collected a first international dataset of 38 documented ball lightning aircraft incidents from 1938 to 2001 involving 13 reports over Europe, 13 over USA/Canada, and 7 over Russia. 18 (47%) reported ball lightning outside the aircraft, 18 (47%) inside, 2 cases lacked data. 8 objects caused minor damage, 8 major damage (total: 42%), only one a crash. No damage was reported in 18 cases. 3 objects caused minor crew injury. In most cases, ball lightning lasted several seconds. 11 (29%) incidents ended with an explosion of the object. A cloud-aircraft lightning flash was seen in only 9 cases (24%) of the data set. From the detailed accounts of air personnel in the last 70 years, it is evident that ball lightning is rarely, but consistently observed in connection with aircraft and can also occur inside the airframe. Reports often came from multiple professional witnesses and in several cases, damages were investigated by civil or military authorities. Although ball lightning is no main air traffic risk, the authors suggest that incident and accident

  16. Acoustic vs Interferometric Measurements of Lightning

    Science.gov (United States)

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

    2015-12-01

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

  17. Monitoring of lightning discharge

    International Nuclear Information System (INIS)

    Grigor'ev, V.A.

    2001-01-01

    The paper presents a brief description of a lightning discharge recording system developed at the NPO 'Monitoring Techniques' under the direction of V.M. Moskolenko (Moscow). The system provides information about dangerous environmental occurrences such as tornados and hurricanes, making the forecast of extreme situations possible, especially in the areas of dangerous industries and objects. The created automatic system can be useful in solving the tasks relating to nuclear test monitoring. (author)

  18. Ball Lightning Investigations

    Science.gov (United States)

    Bychkov, V. L.; Nikitin, A. I.; Dijkhuis, G. C.

    Ball lightning (BL) researches' review and theoretical models of three different authors are presented. The general review covers investigations from 1838 until the present day, and includes a discussion on observation data, experimental modeling, and theoretical approaches. Section 6.1 is written by Bychkov and Nikitin; authors of the sections 6.2, 6.3 and 6.4 are, respectively, Bychkov, Nikitin and Dijkhuis.

  19. Observations of Total Lightning Associated with Severe Convection During the Wet Season in Central Florida

    Science.gov (United States)

    Sharp, D.; Williams, E.; Weber, M.; Goodman, Steven J.; Raghavan, R.; Matlin, A.; Boldi, B.

    1998-01-01

    This paper will discuss findings of a collaborative lightning research project between National Aeronautics and Space Administration, the Massachusetts Institute of Technology and the National Weather Service office In Melbourne Florida. In August 1996, NWS/MLB received a workstation which incorporates data from the KMLB WSR-88D, Cloud to Ground (CG) stroke data from the National Lightning Detection Network (NLDN), and 3D volumetric lightning data collected from the Kennedy Space Centers' Lightning Detection And Ranging (LDAR) lightning system. The two primary objectives of this lightning workstation, called Lightning Imaging Sensor Data Applications Display (USDAD), are to: observe how total lightning relates to severe convective storm morphology over central Florida, and compare ground based total lightning data (LDAR) to a satellite based lightning detection system. This presentation will focus on objective #1. The LISDAD system continuously displays CG and total lighting activity overlaid on top of the KMLB composite reflectivity product. This allows forecasters to monitor total lightning activity associated with convective cells occurring over the central Florida peninsula and adjacent coastal waters. The LISDAD system also keeps track of the amount of total lightning data, and associated KMLB radar products with individual convective cells occurring over the region. By clicking on an individual cell, a history table displays flash rate information (CG and total lightning) in one minute increments, along with radar parameter trends (echo tops, maximum dBz and height of maximum dBz) every 5 minutes. This history table Is updated continuously, without user intervention, as long as the cell is identified. Reviewing data collected during the 1997 wet season (21 cases) revealed that storms which produced severe weather (hall greater or = 0.75 in. or wind damage) typically showed a rapid rise In total lightning prior to the onset of severe weather. On average, flash

  20. Two upward lightning at the Eagle Nest tower

    OpenAIRE

    Montañá Puig, Juan; Van der Velde, Oscar Arnoud; Romero Durán, David; March Nomen, Víctor; Solà de Las Fuentes, Gloria; Pineda Ruegg, Nicolau; Soula, Serge; Hermoso Alameda, Blas

    2012-01-01

    A new instrument composed by a high speed camera, two high energy detectors, a E-field antenna and a VHF antenna were installed at the Eagle Nest tower (northeast of Spain) during summer 2011. With this equipment several lightning flashes to the tower and its vicinity have been observed. This paper presents two examples: the first was an upward negative leader triggered by a close c1oud-to-ground flash and the second was an upward negative flash not associated with previous lightning activity...

  1. Lightning and Gunpowder in the 18th Century

    Science.gov (United States)

    Krider, E. P.

    2006-12-01

    On or before June, 1751, Benjamin Franklin and co-workers showed that gunpowder could be ignited by a small electric spark, and subsequently people used gunpowder to enhance the explosions of "thunder houses" to demonstrate that grounded metallic rods would protect model structures against lightning damage. Even before the sentry box and kite experiments proved that thunderclouds are electrified and that lightning is an electrical discharge in 1752, Franklin had hypothesized that a tall, well-grounded conductor might reduce or prevent lightning damage by silently discharging the cloud, and if a discharge did occur, then the tall rod would offer a preferred place for the lightning to strike, and the grounding conductors would guide the current into the ground in a harmless fashion. Over the next 10 years, experience gained through practice showed that grounded rods did indeed protect ordinary structures from lightning damage, but a question remained about the best way to protect gunpowder magazines. In 1762, Franklin recommended a tall "mast not far from it, which may reach 15 or 20 feet above the top of it, with a thick iron rod in one piece fastened to it, pointed at the highest end, and reaching down through the earth till it comes to water," and in 1772 he made a similar recommendation for protecting the British powder magazine at Purfleet. In 1780, Jan Ingenhousz asked Franklin to "communicate to me some short hints, which may occur to you about the most convenient manner of constructing gun powder magazines, the manner of preserving the powder from moisture and securing the building in the best manner from the effects of lightning." In his reply, Franklin detailed a method of protection that is almost perfect, "they should be constructed in the Ground; that the Walls should be lin'd with Lead, the Floor Lead, all 1/4 Inch thick & the Joints well solder'd; the Cover Copper; with a little Scuttle to enter, the whole in the Form of a Canister for Tea. If the

  2. Daylight time-resolved photographs of lightning.

    Science.gov (United States)

    Qrville, R E; Lala, G G; Idone, V P

    1978-07-07

    Lightning dart leaders and return strokes have been recorded in daylight with both good spatial resolution and good time resolution as part of the Thunder-storm Research International Program. The resulting time-resolved photographs are apparently equivalent to the best data obtained earlier only at night. Average two-dimensional return stroke velocities in four subsequent strokes between the ground and a height of 1400 meters were approximately 1.3 x 10(8) meters per second. The estimated systematic error is 10 to 15 percent.

  3. Short-term forecasting of lightning based on the surface wind field at Kennedy Space Center

    Science.gov (United States)

    Watson, Andrew I.; Lopez, Raul E.; Ortiz, Robert; Holle, Ronald L.

    1987-01-01

    Cloud-to-ground lightning is related in time and space to surface convergence for 244 days during the summer over a 790 sqkm network. The method uses surface convergence, particularly the average over the area, to identify the potential for new, local thunderstorm growth, and can be used to specify the likely time and location of lightning during the life cycle of the convection. A threshold of 0.0000075/sec change in divergence is used to define a convergence event, and a separation of 30 min between flashes defines a lightning event. Time intervals are found to be on the order of 1 hr from beginning convergence to first flash, and (CH110) 2 hr from beginning convergence to the end of lightning. Major differences between the convergence-lightning relationships based on low-level mean onshore and offshore flow are noted.

  4. European cold season lightning map for wind turbines based on radio soundings

    DEFF Research Database (Denmark)

    Vogel, Stephan; Holbøll, Joachim; Lopez, Javier

    2016-01-01

    In this paper, the meteorological data of cold season thunderstorms in Japan and Spain are reviewed to determine the threshold conditions at which cold season lightning was recorded in the past. The variables investigated are the height of the -10°C and 0°C isotherms above ground, the wind velocity...... conditions for self-triggered upward lightning, as being observed in Japan and Spain, are identified. This map may give an indication if a potential wind power plant or structure has the risk to be affected by frequent lightning attachments in the cold season which are predominantly upward initiated....... The advantage of using meteorological parameters to define cold season thunderstorm areas is the independence of Lightning Location Systems (LLS), which are limited to detect upward lightning. Additionally, meteorological data is publicly available....

  5. Fast electric field waveforms and near-surface electric field images of lightning discharges detected on Mt. Aragats in Armenia

    International Nuclear Information System (INIS)

    Chilingarian, A.; Khanikyants, Y.; Kozliner, L.; Soghomonyan, S.

    2016-01-01

    We present the observational data on fast electric waveforms that are detected at 3200 m altitudes above sea level on Mt. Aragats in Armenia during thunderstorms. We analyse the relations of these forms with count rates of particle flux (during Thunderstorm Ground Enhancements -TGEs); to the slow disturbance of the near-surface electrostatic field; and to the lightning location data from the World Wide Lightning Location Network (WWLLN). An observed negative lightning that decreases a negative charge overhead often abruptly terminates TGEs. By analysing the recorded fast electric field waveforms and comparing them with similar classified waveforms reported previously, we could identify the type and polarity of the observed lightnings. (author)

  6. Delayed gamma radiation from lightning induced nuclear reactions

    Science.gov (United States)

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

    2004-03-01

    An increase in atmospheric gamma radiation observed with NaI and Ge detectors positioned about 15 m above ground was observed following natural lightning near Tokyo, Japan [1]. Background subtracted gamma ray rates GRR following numerous lightning strokes observed since 2001 persisted for a few hours and subsequently decayed with a half-life of about 50 minutes. Using a 3x3 Ge detector, with 2 KeV resolution, positioned about 2 m from one of the NaI detectors increases in GRR were observed minutes after the onset of lightning with a delayed 50 min exponential decay. Although most of the increase in activity occured at less than a few 100 KeV, on July 11, 2003 a 1267 +/-2 KeV line was observed. Although the statistics of this event were poor, the appearance of this line with an exponential decay of 50 min half-life suggests the possibility that it may be due to 39Cl (1267 MeV; half-life = 55.5 min) via the 40Ar(gamma,p)39Cl, 40Ar(p,2p)39Cl and/or 40Ar(n,d)39Cl reactions. Observations of > 10 MeV gamma rays observed in NaI detectors within 10s of meters from and coincident with rocket-triggered lightning at the International Center for Lightning Research and Testing suggest that charged particles accelerated in intense electric fields associated with lightning give rise to photons with sufficient energy to initiate nuclear reactions [2]. Further work to explain the cause of this anomalous activity is underway using natural and triggered lightning. 1. M. B. Greenfield et al., Journal of Applied Physics 93 no. 3 (2003) pp 1839-184. 2. J. R. Dwyer et al., Science 299, (2003), pp 694-697 and recent communications

  7. Lightning injuries during snowy conditions

    OpenAIRE

    Cherington, M.; Breed, D. W.; Yarnell, P. R.; Smith, W. E.

    1998-01-01

    Skiers and other snow sports enthusiasts can become lightning casualties. Two such accidents are reported, one being fatal. There are fewer warning signals of impending lightning strikes in winter-like conditions. However, outdoor activists should be aware of at least two suspicious clues: the appearance of convective clouds, and the presence of graupel (snow pellets) during precipitation. 






  8. Lightning injuries during snowy conditions.

    Science.gov (United States)

    Cherington, M; Breed, D W; Yarnell, P R; Smith, W E

    1998-12-01

    Skiers and other snow sports enthusiasts can become lightning casualties. Two such accidents are reported, one being fatal. There are fewer warning signals of impending lightning strikes in winter-like conditions. However, outdoor activists should be aware of at least two suspicious clues: the appearance of convective clouds, and the presence of graupel (snow pellets) during precipitation.

  9. 14 CFR 25.581 - Lightning protection.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Lightning protection. 25.581 Section 25.581... STANDARDS: TRANSPORT CATEGORY AIRPLANES Structure Lightning Protection § 25.581 Lightning protection. (a) The airplane must be protected against catastrophic effects from lightning. (b) For metallic...

  10. Geostationary infrared methods for detecting lightning-producing cumulonimbus clouds

    Science.gov (United States)

    Matthee, Retha; Mecikalski, John R.

    2013-06-01

    This study documents the behavior of cloud top infrared (IR) fields known to describe physical processes associated with growing convective clouds, for 30 nonlightning and 33 cloud-to-ground (CG) lightning-producing convective storms. The goal is to define "critical" threshold values for up to 10 IR fields that delineate lightning from nonlightning convective storms. Meteosat Second Generation and United Kingdom Meteorological Office very low frequency arrival time difference satellite and lightning data, respectively, were used in this study. These were collected during the National Aeronautics and Space Administration (NASA) African Monsoon Multidisciplinary Analyses (NAMMA) field campaign in August-September 2006 in Equatorial Africa. The main conclusions show that eight of 10 IR fields that describe updraft strength, cloud depth, and glaciation (or ice at cloud top) are significantly different between the nonlightning and lightning-producing convective clouds. The lack of notch overlap in "box and whiskers" plots confirms a 95% confidence that the two data sets are different. Nonlightning-producing clouds are far less vertically developed and possess >50% weaker updrafts (as estimated from satellite trends), as well as little to no evidence of ice or glaciation at cloud top. Results from this study therefore can be used to nowcast and identify with high confidence convective clouds that are producing or are going to produce CG lightning using Meteosat data, assuming appropriate tracking of growing cumulus clouds is performed.

  11. Sprites, lightning, cloudtop temperatures and mesospheric electric field

    Science.gov (United States)

    São Sabbas, F.; Sentman, D.; Taylor, M.; Wescott, E.; Stenbaek-Nielsen, H.

    2003-04-01

    Sprites are one of the optical manifestations of electrical energy deposition in the mesosphere by lightning activity in the troposphere. Observations obtained from the Space Shuttle, and during ground and aircraft campaigns conducted in the U.S., Peru, Central America, Australia, Japan, Europe, Taiwan, and Brazil have confirmed the global aspect these phenomena. In order to better understand the mechanism and implications of energy deposition in the mesosphere, detailed studies of the characteristics of spatial and temporal relationship between sprites and lightning, and the characteristics of the generating meteorological system and of the surrounding atmosphere at the locations where sprites have been observed are necessary. The full problem includes consideration of both the source (lightning) characteristics, as well as the ambient medium where sprite ignition occurs. This paper summarizes results of a PhD thesis that examines (1) the observed relationships between the distribution of distance and time delays between the sprites and underlying causative lightning, (2) the correlations between sprites, lightning and cloudtop temperatures extracted from IR satellite images, and (3) the structure of electric fields in an inhomogeneous conductivity distribution at sprite initiation altitudes 75-85 km. The results suggest that conductivity inhomogeneities in the mesosphere may play an important role in determining the locations where sprite ignition occurs above a thunderstorm.

  12. Lightning-based propagation of convective rain fields

    Directory of Open Access Journals (Sweden)

    S. Dietrich

    2011-05-01

    Full Text Available This paper describes a new multi-sensor approach for continuously monitoring convective rain cells. It exploits lightning data from surface networks to propagate rain fields estimated from multi-frequency brightness temperature measurements taken by the AMSU/MHS microwave radiometers onboard NOAA/EUMETSAT low Earth orbiting operational satellites. Specifically, the method allows inferring the development (movement, morphology and intensity of convective rain cells from the spatial and temporal distribution of lightning strokes following any observation by a satellite-borne microwave radiometer. Obviously, this is particularly attractive for real-time operational purposes, due to the sporadic nature of the low Earth orbiting satellite measurements and the continuous availability of ground-based lightning measurements – as is the case in most of the Mediterranean region. A preliminary assessment of the lightning-based rainfall propagation algorithm has been successfully made by using two pairs of consecutive AMSU observations, in conjunction with lightning measurements from the ZEUS network, for two convective events. Specifically, we show that the evolving rain fields, which are estimated by applying the algorithm to the satellite-based rainfall estimates for the first AMSU overpass, show an overall agreement with the satellite-based rainfall estimates for the second AMSU overpass.

  13. Development of a self-consistent lightning NOx simulation in large-scale 3-D models

    Science.gov (United States)

    Luo, Chao; Wang, Yuhang; Koshak, William J.

    2017-03-01

    We seek to develop a self-consistent representation of lightning NOx (LNOx) simulation in a large-scale 3-D model. Lightning flash rates are parameterized functions of meteorological variables related to convection. We examine a suite of such variables and find that convective available potential energy and cloud top height give the best estimates compared to July 2010 observations from ground-based lightning observation networks. Previous models often use lightning NOx vertical profiles derived from cloud-resolving model simulations. An implicit assumption of such an approach is that the postconvection lightning NOx vertical distribution is the same for all deep convection, regardless of geographic location, time of year, or meteorological environment. Detailed observations of the lightning channel segment altitude distribution derived from the NASA Lightning Nitrogen Oxides Model can be used to obtain the LNOx emission profile. Coupling such a profile with model convective transport leads to a more self-consistent lightning distribution compared to using prescribed postconvection profiles. We find that convective redistribution appears to be a more important factor than preconvection LNOx profile selection, providing another reason for linking the strength of convective transport to LNOx distribution.

  14. [Lightning-caused fire, its affecting factors and prediction: a review].

    Science.gov (United States)

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

    2013-09-01

    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.

  15. Packaging Waste and Hitting Home Runs: How Education and Lightning Strike Detection Technology Supports Company and Community Activities

    International Nuclear Information System (INIS)

    Deecke, T.A.; Hyde, J.V.; Hylko, J.M.

    2006-01-01

    The weather is the most significant and unmanageable variable when performing environmental remediation activities. This variable can contribute to the failure of a project in two ways: 1) severe injury to an employee or employees following a cloud-to-ground lightning strike without prior visual or audible warnings; and 2) excessive 'down time' associated with mobilization and demobilization activities after a false alarm (e.g., lightning was seen in the distance but was actually moving away from the site). Therefore, in order for a project to be successful from both safety and financial viewpoints, the uncertainties associated with inclement weather, specifically lightning, need to be understood to eliminate the element of surprise. This paper discusses educational information related to the history and research of lightning, how lightning storms develop, types of lightning, the mechanisms of lightning injuries and fatalities, and follow-up medical treatment. Fortunately, lightning storm monitoring does not have to be either costly or elaborate. WESKEM, LLC selected the Boltek StormTracker Lightning Detection System with the Aninoquisi Lightning 2000 TM software. This fixed system, used in combination with online weather web pages, monitors and alarms WESKEM, LLC field personnel in the event of an approaching lightning storm. This application was expanded to justify the purchase of the hand-held Sky Scan Lightning/Storm Detector Model P5 used by the Heath Youth Athletic Association (HYAA) which is a non-profit, charitable organization offering sports programs for the youth and young adults in the local community. Fortunately, a lightning injury or fatality has never occurred on a WESKEM Paducah project or an HYAA-sponsored event. Using these fixed and hand-held systems will continue to prevent such injuries from occurring in the foreseeable future. (authors)

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

    Science.gov (United States)

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

    2016-05-01

    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.

  17. Geostationary Lightning Mapper: Lessons Learned from Post Launch Test

    Science.gov (United States)

    Edgington, S.; Tillier, C. E.; Demroff, H.; VanBezooijen, R.; Christian, H. J., Jr.; Bitzer, P. M.

    2017-12-01

    Pre-launch calibration and algorithm design for the GOES Geostationary Lightning Mapper resulted in a successful and trouble-free on-orbit activation and post-launch test sequence. Within minutes of opening the GLM aperture door on January 4th, 2017, lightning was detected across the entire field of view. During the six-month post-launch test period, numerous processing parameters on board the instrument and in the ground processing algorithms were fine-tuned. Demonstrated on-orbit performance exceeded pre-launch predictions. We provide an overview of the ground calibration sequence, on-orbit tuning of the instrument, tuning of the ground processing algorithms (event filtering and navigation). We also touch on new insights obtained from analysis of a large and growing archive of raw GLM data, containing 3e8 flash detections derived from over 1e10 full-disk images of the Earth.

  18. Comparisons Between Total Lightning Data, Mesocyclone Strength, and Storm Damage Associated with the Florida Tornado Outbreak of February 23, 1998

    Science.gov (United States)

    Hodanish, S; Sharp, D.; Williams, E.; Boldi, B.; Goodman, Steven J.; Raghavan, R.; Matlin, A.; Weber, M.

    1998-01-01

    During the early morning hours of February 23 1998, the worst tornado outbreak ever recorded occurred over the central Florida peninsula. At least 7 confirmed tornadoes, associated with 4 supercells, developed, with 3 of the tornadoes reaching F3 intensity. Many of the tornadoes where on the ground for tens of miles, uncommon for the state of Florida. A total of 42 people were killed, with over 250 people injured. During the outbreak, National Weather Service Melbourne, in collaboration with the National Aeronautics and Space Administration and the Massachusetts Institute of Technology was collecting data from a unique lightning observing system called Lightning Imaging Sensor Data Applications Display (LISDAD, Boldi et.al., this conference). This system marries radar data collected from the KMLB WSR-88D, cloud to ground data collected from the National Lightning Detection Network, and total lightning data collected from NASKs Lightning Detection And Ranging system. This poster will display, concurrently, total lightning data (displayed in 1 minute increments), time/height storm relative velocity products from the KMLB WSR-88D, and damage information (tornado/hail/wind) from each of the supercell thunderstorms. The primary objective of this poster presentation is to observe how total lightning activity changes as the convective storm intensifies, and how the lightning activity changes with respect to mesocyclone strength (vortex stretching) and damaging weather on the ground.

  19. Preliminary results of the study of lightning location relative to storm structure and dynamics

    Science.gov (United States)

    Rust, W. D.; Taylor, W. L.; Macgorman, D.

    1981-01-01

    Lightning is being studied relative to storm structure using a VHF space-time discharge mapping system, radar, a cloud-to-ground flash locator, acoustic reconstruction of thunder, and other instrumentation. The horizontal discharge processes within the cloud generally propagate at speeds of 10,000-100,000 m/s. Horizontal extents of lightning were found up to 90 km. In an analysis of a limited number of flashes, lightning occurred in or near regions of high cyclonic shear. Positive cloud-to-ground flashes have been observed emanating from several identifiable regions of severe storms. Lightning echoes observed with 10-cm radar generally are 10-25 dB greater than the largest precipitation echo in the storm.

  20. Observations of simultaneous upward lightning leaders from multiple tall structures

    Science.gov (United States)

    Warner, Tom A.

    2012-11-01

    We present high-speed camera observations (up to 7200 images per second) and correlated electric field measurements of upward lightning leaders initiated simultaneously from multiple tall towers. Four towers spanning a horizontal distance of 2.9 km and ranging in height from 121 to 191 m, developed upward leaders following a nearby positive cloud-to-ground (+ CG) flash on 7/16/09 UT in Rapid City, South Dakota, USA during the summer thunderstorm season. The optical and electric field observations suggest that all four upward propagating leaders were positive polarity (i.e., upward negative lightning) and initiated simultaneously approximately 2 ms following the + CG return stroke. There was significant intracloud flash activity prior to the return stroke, and upward leader initiation coincided with the passage of horizontally extensive in-cloud negative breakdown following the + CG return stroke. This observation supports the idea that downward positive cloud-to-ground lightning can trigger upward negative lightning from multiple tall objects. Specifically, the triggering component is an area of horizontally propagating negative breakdown following the + CG return stroke that influences a broad area resulting in simultaneous or near-simultaneous, positive polarity upward leader initiation from multiple tall objects.

  1. Reconstruction of lightning channel geometry by localizing thunder sources

    Science.gov (United States)

    Bodhika, J. A. P.; Dharmarathna, W. G. D.; Fernando, Mahendra; Cooray, Vernon

    2013-09-01

    Thunder is generated as a result of a shock wave created by sudden expansion of air in the lightning channel due to high temperature variations. Even though the highest amplitudes of thunder signatures are generated at the return stroke stage, thunder signals generated at other events such as preliminary breakdown pulses also can be of amplitudes which are large enough to record using a sensitive system. In this study, it was attempted to reconstruct the lightning channel geometry of cloud and ground flashes by locating the temporal and spatial variations of thunder sources. Six lightning flashes were reconstructed using the recorded thunder signatures. Possible effects due to atmospheric conditions were neglected. Numerical calculations suggest that the time resolution of the recorded signal and 10 ms-1error in speed of sound leads to 2% and 3% errors, respectively, in the calculated coordinates. Reconstructed channel geometries for cloud and ground flashes agreed with the visual observations. Results suggest that the lightning channel can be successfully reconstructed using this technique.

  2. Unsolved Mystery of Ball Lightning

    Science.gov (United States)

    Bychkov, V. L.

    Ball lightning is an unusual phenomenon always drawing attention of people. There are still questions about its origination, features, interaction with environment, and phenomena related to it. On a way of studying this phenomenon, there are a lot of difficulties, the basic of them is insufficiency of authentic, scientific data. The chapter sets as the purpose to interest the reader in the problem, to describe conditions of ball lightning occurrence, theories, and its hypotheses explanation, to include readers in a circle of experimental searches in creation of a ball lightning and its analogues, and to describe fascination of a problem and difficulty of its solution.

  3. Comparison of Lightning Activity and Radar-Retrieved Microphysical Properties in EULINOX Storms

    OpenAIRE

    Fehr, T.; Dotzek, N.; Höller, H.

    2005-01-01

    A combined analysis of microphysical thunderstorm properties derived by C-band polarimetric Doppler radar measurements and lightning observations from two ground-based systems are presented. Three types of storms, a multicell, a supercell, and a squall line, that were observed during the European Lightning Nitrogen Oxides project (EULINOX) are investigated. Correlations are sought between the mass of rain, graupel, hail, and snow derived form radar observations at different height levels and ...

  4. Bandwidth improvement for germanium photodetector using wire bonding technology.

    Science.gov (United States)

    Chen, Guanyu; Yu, Yu; Deng, Shupeng; Liu, Lei; Zhang, Xinliang

    2015-10-05

    We demonstrate an ultrahigh speed germanium photodetector by introducing gold wires into the discrete ground electrodes with standard wire bonding technology. To engineer the parasitic parameter, the physical dimension of the gold wire used for wire bonding is specially designed with an inductance of about 450 pH. Simulation and experimental results show that the bandwidth of the photodetector can be effectively extended from less than 30 GHz to over 60 GHz.

  5. Total Lightning Characteristics with Respect to Radar-Derived Mesocyclone Strength

    Science.gov (United States)

    Stough, Sarah M.; Carey, Lawrence D.; Schultz, Christopher J.

    2015-01-01

    Recent work investigating the microphysical and kinematic relationship between a storm's updraft, its total lightning production, and manifestations of severe weather has resulted in development of tools for improved nowcasting of storm intensity. The total lightning jump algorithm, which identifies rapid increases in total lightning flash rate that often precede severe events, has shown particular potential to benefit warning operations. Maximizing this capability of total lightning and its operational implementation via the lightning jump may best be done through its fusion with radar and radar-derived intensity metrics. Identification of a mesocyclone, or quasi-steady rotating updraft, in Doppler velocity is the predominant radar-inferred early indicator of severe potential in a convective storm. Fused lightning-radar tools that capitalize on the most robust intensity indicators would allow enhanced situational awareness for increased warning confidence. A foundational step toward such tools comes from a better understanding of the updraft-centric relationship between intensification of total lightning production and mesocyclone development and strength. The work presented here utilizes a sample of supercell case studies representing a spectrum of severity. These storms are analyzed with respect to total lightning flash rate and the lightning jump alongside mesocyclone strength derived objectively from the National Severe Storms Laboratory (NSSL) Mesocyclone Detection Algorithm (MDA) and maximum azimuthal shear through a layer. Early results indicate that temporal similarities exist in the trends between total lightning flash rate and low- to mid-level rotation in supercells. Other characteristics such as polarimetric signatures of rotation, flash size, and cloud-to-ground flash ratio are explored for added insight into the significance of these trends with respect to the updraft and related processes of severe weather production.

  6. Lightning related fatalities in livestock: veterinary expertise and the added value of lightning location data.

    Science.gov (United States)

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

    2015-01-01

    Although lightning strike is an important cause of sudden death in livestock on pasture and among the main reasons why insurance companies consult an expert veterinarian, scientific information on this subject is limited. The aim of the present study was to provide objective information on the circumstantial evidence and pathological findings in lightning related fatalities (LRF), based on a retrospective analysis of 410 declarations, examined by a single expert veterinarian in Flanders, Belgium, from 1998 to 2012. Predictive logistic models for compatibility with LRF were constructed based on anamnestic, environmental and pathological factors. In addition, the added value of lightning location data (LLD) was evaluated. Pathognomonic singe lesions were present in 84/194 (43%) confirmed reports. Factors which remained significantly associated with LRF in the multivariable model were age, presence of a tree or open water in the near surroundings, tympany and presence of feed in the oral cavity at the time of investigation. This basic model had a sensitivity (Se) of 53.8% and a specificity (Sp) of 88.2%. Relying only on LLD to confirm LRF in livestock resulted in a high Se (91.3%), but a low Sp (41.2%), leading to a high probability that a negative case would be wrongly accepted as an LRF. The best results were obtained when combining the model based on the veterinary expert investigation (circumstantial evidence and pathological findings), together with the detection of cloud-to-ground (CG) lightning at the time and location of death (Se 89.1%; Sp 66.7%). Copyright © 2014 Elsevier Ltd. All rights reserved.

  7. Optical design of the lightning imager for MTG

    Science.gov (United States)

    Lorenzini, S.; Bardazzi, R.; Di Giampietro, M.; Feresin, F.; Taccola, M.; Cuevas, L. P.

    2017-11-01

    The Lightning Imager for Meteosat Third Generation is an optical payload with on-board data processing for the detection of lightning. The instrument will provide a global monitoring of lightning events over the full Earth disk from geostationary orbit and will operate in day and night conditions. The requirements of the large field of view together with the high detection efficiency with small and weak optical pulses superimposed to a much brighter and highly spatial and temporal variable background (full operation during day and night conditions, seasonal variations and different albedos between clouds oceans and lands) are driving the design of the optical instrument. The main challenge is to distinguish a true lightning from false events generated by random noise (e.g. background shot noise) or sun glints diffusion or signal variations originated by microvibrations. This can be achieved thanks to a `multi-dimensional' filtering, simultaneously working on the spectral, spatial and temporal domains. The spectral filtering is achieved with a very narrowband filter centred on the bright lightning O2 triplet line (777.4 nm +/- 0.17 nm). The spatial filtering is achieved with a ground sampling distance significantly smaller (between 4 and 5 km at sub satellite pointing) than the dimensions of a typical lightning pulse. The temporal filtering is achieved by sampling continuously the Earth disk within a period close to 1 ms. This paper presents the status of the optical design addressing the trade-off between different configurations and detailing the design and the analyses of the current baseline. Emphasis is given to the discussion of the design drivers and the solutions implemented in particular concerning the spectral filtering and the optimisation of the signal to noise ratio.

  8. 2016 T Division Lightning Talks

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-11-29

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

  9. 2017 T Division Lightning Talks

    Energy Technology Data Exchange (ETDEWEB)

    Ramsey, Marilyn Leann [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Abeywardhana, Jayalath AMM [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Adams, Colin Mackenzie [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Adams, Luke Clyde [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Carter, Austin Lewis [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Ducru, Pablo Philippe [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Duignan, Thomas John [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Gifford, Brendan Joel [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Hills, Benjamin Hale [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Hoffman, Kentaro Jack [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Khair, Adnan Ibne [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Kochanski, Kelly Anne Pribble [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Ledwith, Patrick John [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Leveillee, Joshua Anthony [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Lewis, Sina Genevieve [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Ma, Xiaoyu [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Merians, Hugh Drake [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Moore, Bryan Alexander [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Nijjar, Parmeet Kaur [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Oles, Vladyslav [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Olszewski, Maciej W. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Philipbar, Brad Montgomery [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Reisner, Andrew Ray [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Roberts, David Benjamin [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Rufa, Dominic Antonio [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Sifain, Andrew E. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Smith, Justin Steven [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Smith, Lauren Taylor Wisbey [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Svolos, Lampros [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Thibault, Joshua Ryan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Ushijima-Mwesigwa, Hayato Montezuma [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Weaver, Claire Marie [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Witzen, Wyatt Andrew [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Zentgraf, Sabine Silvia [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Alred, John Michael [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-10-06

    All members of the T Division Community, students, staff members, group leaders, division management, and other interested individuals are invited to come and support the following student(s) as they present their Lightning Talks.

  10. Acoustic localization of triggered lightning

    Science.gov (United States)

    Arechiga, Rene O.; Johnson, Jeffrey B.; Edens, Harald E.; Thomas, Ronald J.; Rison, William

    2011-05-01

    We use acoustic (3.3-500 Hz) arrays to locate local (thunder produced by triggered lightning in the Magdalena Mountains of central New Mexico. The locations of the thunder sources are determined by the array back azimuth and the elapsed time since discharge of the lightning flash. We compare the acoustic source locations with those obtained by the Lightning Mapping Array (LMA) from Langmuir Laboratory, which is capable of accurately locating the lightning channels. To estimate the location accuracy of the acoustic array we performed Monte Carlo simulations and measured the distance (nearest neighbors) between acoustic and LMA sources. For close sources (6 km) the error increases to 800 m for the nearest neighbors and 650 m for the Monte Carlo analysis. This work shows that thunder sources can be accurately located using acoustic signals.

  11. Noncontextual Wirings

    Science.gov (United States)

    Amaral, Barbara; Cabello, Adán; Cunha, Marcelo Terra; Aolita, Leandro

    2018-03-01

    Contextuality is a fundamental feature of quantum theory necessary for certain models of quantum computation and communication. Serious steps have therefore been taken towards a formal framework for contextuality as an operational resource. However, the main ingredient of a resource theory—a concrete, explicit form of free operations of contextuality—was still missing. Here we provide such a component by introducing noncontextual wirings: a class of contextuality-free operations with a clear operational interpretation and a friendly parametrization. We characterize them completely for general black-box measurement devices with arbitrarily many inputs and outputs. As applications, we show that the relative entropy of contextuality is a contextuality monotone and that maximally contextual boxes that serve as contextuality bits exist for a broad class of scenarios. Our results complete a unified resource-theoretic framework for contextuality and Bell nonlocality.

  12. Lightning Imaging Sensor (LIS) for the International Space Station (ISS): Mission Description and Science Goals

    Science.gov (United States)

    Blakeslee, R. J.; Christian, H. J.; Mach, D. M.; Buechler, D. E.; Koshak, W. J.; Walker, T. D.; Bateman, M.; Stewart, M. F.; O'Brien, S.; Wilson, T.; hide

    2015-01-01

    In recent years, the NASA Marshall Space Flight Center, the University of Alabama in Huntsville, and their partners have developed and demonstrated space-based lightning observations as an effective remote sensing tool for Earth science research and applications. The Lightning Imaging Sensor (LIS) on the Tropical Rainfall Measuring Mission (TRMM) continues to acquire global observations of total (i.e., intracloud and cloud-to-ground) lightning after 17 years on-orbit. However, TRMM is now low on fuel, so this mission will soon be completed. As a follow on to this mission, a space-qualified LIS built as the flight spare for TRMM has been selected for flight as a science mission on the International Space Station (ISS). The ISS LIS will be flown as a hosted payload on the Department of Defense Space Test Program (STP) H5 mission, which has a January 2016 baseline launch date aboard a SpaceX launch vehicle for a 2-4 year or longer mission. The LIS measures the amount, rate, and radiant energy of total lightning over the Earth. More specifically, it measures lightning during both day and night, with storm scale resolution (approx. 4 km), millisecond timing, and high, uniform detection efficiency, without any land-ocean bias. Lightning is a direct and most impressive response to intense atmospheric convection. It has been found that lightning measured by LIS can be quantitatively related to thunderstorm and other geophysical processes. Therefore, the ISS LIS lightning observations will continue to provide important gap-filling inputs to pressing Earth system science issues across a broad range of disciplines, including weather, climate, atmospheric chemistry, and lightning physics. A unique contribution from the ISS platform will be the availability of real-time lightning data, especially valuable for operational applications over data sparse regions such as the oceans. The ISS platform will also uniquely enable LIS to provide simultaneous and complementary observations

  13. Industrial accidents triggered by lightning.

    Science.gov (United States)

    Renni, Elisabetta; Krausmann, Elisabeth; Cozzani, Valerio

    2010-12-15

    Natural disasters can cause major accidents in chemical facilities where they can lead to the release of hazardous materials which in turn can result in fires, explosions or toxic dispersion. Lightning strikes are the most frequent cause of major accidents triggered by natural events. In order to contribute towards the development of a quantitative approach for assessing lightning risk at industrial facilities, lightning-triggered accident case histories were retrieved from the major industrial accident databases and analysed to extract information on types of vulnerable equipment, failure dynamics and damage states, as well as on the final consequences of the event. The most vulnerable category of equipment is storage tanks. Lightning damage is incurred by immediate ignition, electrical and electronic systems failure or structural damage with subsequent release. Toxic releases and tank fires tend to be the most common scenarios associated with lightning strikes. Oil, diesel and gasoline are the substances most frequently released during lightning-triggered Natech accidents. Copyright © 2010 Elsevier B.V. All rights reserved.

  14. Location accuracy evaluation of lightning location systems using natural lightning flashes recorded by a network of high-speed cameras

    Science.gov (United States)

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

    2014-12-01

    This work presents a method for the evaluation of location accuracy of all Lightning Location System (LLS) in operation in southeastern Brazil, using natural cloud-to-ground (CG) lightning flashes. This can be done through a multiple high-speed cameras network (RAMMER network) installed in the Paraiba Valley region - SP - Brazil. The RAMMER network (Automated Multi-camera Network for Monitoring and Study of Lightning) is composed by four high-speed cameras operating at 2,500 frames per second. Three stationary black-and-white (B&W) cameras were situated in the cities of São José dos Campos and Caçapava. A fourth color camera was mobile (installed in a car), but operated in a fixed location during the observation period, within the city of São José dos Campos. The average distance among cameras was 13 kilometers. Each RAMMER sensor position was determined so that the network can observe the same lightning flash from different angles and all recorded videos were GPS (Global Position System) time stamped, allowing comparisons of events between cameras and the LLS. The RAMMER sensor is basically composed by a computer, a Phantom high-speed camera version 9.1 and a GPS unit. The lightning cases analyzed in the present work were observed by at least two cameras, their position was visually triangulated and the results compared with BrasilDAT network, during the summer seasons of 2011/2012 and 2012/2013. The visual triangulation method is presented in details. The calibration procedure showed an accuracy of 9 meters between the accurate GPS position of the object triangulated and the result from the visual triangulation method. Lightning return stroke positions, estimated with the visual triangulation method, were compared with LLS locations. Differences between solutions were not greater than 1.8 km.

  15. Observations of lightning in convective supercells within tropical storms and hurricanes

    Science.gov (United States)

    Lyons, Walter A.; Keen, Cecil S.

    1994-01-01

    Cloud-to-ground (CG) lightning observations from land-based lightning detection networks now allow monitoring this component of the electrical structure of tropical storms and hurricanes within a few hundred kilometers of the United States coastline. Several case studies confirm the long-held opinion that lightning is rather common within the outer rainbands. The general absence of CG lightning within the interior of mature tropical cyclones is also apparent. On the other hand, bursts of CG lightning near the circulation center of developing storms appear to precede periods of further deepening. The CG events are associated with convective supercells, whose anvil canopies can often obscure much of the underlying storm. Near-eyewall CG bursts preceding periods of intensification were noted in Hurricanes Diana (1984) and Florence (1988). A detailed case study of the 1987 unnamed tropical storm that struck the Texas-Louisiana coastline reveals that lightning was associated with two large supercells. These supercells appeared to be the trigger for the development of a closed circulation that formed several hours after the apparent low pressure center made landfall. Further studies of lightning may provide additional insight into the role of convective supercells in tropical storm intensification. It may also provide a useful diagnostic of impending deepening.

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

    Directory of Open Access Journals (Sweden)

    Luo Hanwu

    2016-01-01

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

  17. Preliminary Design of a Lightning Optical Camera and ThundEr (LOCATE) Sensor

    Science.gov (United States)

    Phanord, Dieudonne D.; Koshak, William J.; Rybski, Paul M.; Arnold, James E. (Technical Monitor)

    2001-01-01

    The preliminary design of an optical/acoustical instrument is described for making highly accurate real-time determinations of the location of cloud-to-ground (CG) lightning. The instrument, named the Lightning Optical Camera And ThundEr (LOCATE) sensor, will also image the clear and cloud-obscured lightning channel produced from CGs and cloud flashes, and will record the transient optical waveforms produced from these discharges. The LOCATE sensor will consist of a full (360 degrees) field-of-view optical camera for obtaining CG channel image and azimuth, a sensitive thunder microphone for obtaining CG range, and a fast photodiode system for time-resolving the lightning optical waveform. The optical waveform data will be used to discriminate CGs from cloud flashes. Together, the optical azimuth and thunder range is used to locate CGs and it is anticipated that a network of LOCATE sensors would determine CG source location to well within 100 meters. All of this would be accomplished for a relatively inexpensive cost compared to present RF lightning location technologies, but of course the range detection is limited and will be quantified in the future. The LOCATE sensor technology would have practical applications for electric power utility companies, government (e.g. NASA Kennedy Space Center lightning safety and warning), golf resort lightning safety, telecommunications, and other industries.

  18. Two-wire Interface for Digital Microphones

    NARCIS (Netherlands)

    Groothedde, Wouter; Klumperink, Eric A.M.; Nauta, Bram; Eschauzier, Rudolphe Gustave Hubertus; van Rijn, Nico

    2003-01-01

    A two-wire interface for a digital microphone circuit includes a power line and a ground line. The interface utilizes the ground line as a "voltage active line" to transmit both clock and data signals between the digital microphone circuit and a receiving circuit. The digital microphone circuit

  19. Two-Wire interface for digital microphones

    NARCIS (Netherlands)

    Groothedde, Wouter; Klumperink, Eric A.M.; Nauta, Bram; Eschauzier, Rudolphe Gustave Hubertus; van Rijn, Nico

    2005-01-01

    A two-wire interface for a digital microphone circuit includes a power line and a ground line. The interface utilizes the ground line as a "voltage active line" to transmit both clock and data signals between the digital microphone circuit and a receiving circuit. The digital microphone circuit

  20. 49 CFR 236.2 - Grounds.

    Science.gov (United States)

    2010-10-01

    ... circuit, except circuits which include any track rail and except the common return wires of single-wire, single-break, signal control circuits using a grounded common, and alternating current power distribution...

  1. A Study on the Practical Grounding System in Power Distribution Lines

    Science.gov (United States)

    Miyazaki, Teru; Okabe, Shigemitsu; Aiba, Kiyoshi; Hirai, Takao; Yoshinaga, Jun

    It is important for electric power companies to maintain grounding resistances adequately for the safety of the public. But they have difficulty in managing those grounding systems because vast amounts of grounding electrodes are installed in distribution lines. Based on the statistical data of surge currents through lightning arrestors and electrical surges in customers, a rated value of the grounding resistance for lightning arrestors on distribution lines was specified in the 1960's. TEPCO had conducted field research to measure the waveforms of surge voltage and current in order to rationalize the lightning protection design of distribution lines. And the authors proposed a lightning-surges analysis model based on the observation data. In this study, a lightning surge analysis for the rationalization of the grounding system was carried out by means of the EMTP. The calculated results suggest that a practical grounding design is possible. That can be useful for the Electric Power Companies to manage grounding systems.

  2. GRIP LIGHTNING INSTRUMENT PACKAGE (LIP) V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The GRIP Lightning Instrument Package (LIP) dataset was collected by the Lightning Instrument Package (LIP), which consists of 6 rotating vane type electric field...

  3. NAMMA ATD LIGHTNING DATA V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The NAMMA ATD Lightning data provided by the UK Meterological Office from multiple outstations contains lightning stroke data, latitude and longitude, accuracy and...

  4. Lightning NOx and Impacts on Air Quality

    Science.gov (United States)

    Murray, Lee T.

    2016-01-01

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

  5. NAMMA LIGHTNING ZEUS DATA V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The NAMMA Lightning ZEUS data is provided by World-ZEUS Long Range Lightning Monitoring Network Data obtained from radio atmospheric signals located at thirteen...

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

    Science.gov (United States)

    Boccippio, Dennis

    2004-01-01

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

  7. Characteristics of lightning flashes generating sprites above storms

    Directory of Open Access Journals (Sweden)

    Soula Serge

    2016-01-01

    Full Text Available Sprites are Transient Luminous Events (TLEs that can extend vertically from 40 to 90 km and horizontally over several tens of km to form clusters of individual or multiple column or/and carrot-shaped luminous elements. They can even extend over more than 100 km in the form of sequential luminous emissions that are called “dancing sprites”. Their optical detection and other parameters describing the storm and the lightning activity associated allow us to understand the conditions of their production and their links with the lightning activity. Our observations confirm some characteristics of the sprites and put forward others: (i the sprites are essentially produced above the stratiform region of the Mesoscale Convective Systems after positive cloud-to-ground lightning flashes that produce large Charge Moment Change (CMC, with a shorter delay if the impulsive CMC (iCMC is larger. (ii The dancing sprites reflect the timing and the location of the successive lightning strokes that generate them. (iii The sprite elements can be shifted from the stroke location when their delay is large. (iv Bright sprites produce current signatures in ELF radiation a few milliseconds (<5 ms after the positive strokes that generate them.

  8. Objective Lightning Probability Forecasts for East-Central Florida Airports

    Science.gov (United States)

    Crawford, Winfred C.

    2013-01-01

    The forecasters at the National Weather Service in Melbourne, FL, (NWS MLB) identified a need to make more accurate lightning forecasts to help alleviate delays due to thunderstorms in the vicinity of several commercial airports in central Florida at which they are responsible for issuing terminal aerodrome forecasts. Such forecasts would also provide safer ground operations around terminals, and would be of value to Center Weather Service Units serving air traffic controllers in Florida. To improve the forecast, the AMU was tasked to develop an objective lightning probability forecast tool for the airports using data from the National Lightning Detection Network (NLDN). The resulting forecast tool is similar to that developed by the AMU to support space launch operations at Kennedy Space Center (KSC) and Cape Canaveral Air Force Station (CCAFS) for use by the 45th Weather Squadron (45 WS) in previous tasks (Lambert and Wheeler 2005, Lambert 2007). The lightning probability forecasts are valid for the time periods and areas needed by the NWS MLB forecasters in the warm season months, defined in this task as May-September.

  9. The Italian Lightning Detection System of CESI and its applications

    International Nuclear Information System (INIS)

    Iorio, R.

    1998-01-01

    Aim of the paper is to give a description of the CESI lightning detection system SIRF. The system allows the real time localization (latitude, longitude) of the striking point of a cloud-to-ground lightning flash. Electrical parameters of the impulsive currents related to the flash strokes are calculated as well. Based on sensors covering the whole Italian territory, SIRF configuration and of the basic calculation criteria for passing from the sensor raw data to the final flash data is given together with the evaluation of the system expected performance parameters (accuracy, detection efficiently, signal/noise ratio). Main uses of lightning data in several fields are then reported, with special reference to electrical applications. Mention is done about the different modalities adopted for data distribution, according to that either real time or passed time applications have to be carried out. In this latter case (e.g. statistics), a huge amount of data archived within the Lightning Data Base of SIRF is available [it

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

    Science.gov (United States)

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

    2011-01-01

    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.

  11. Z-M in lightning forecasting

    OpenAIRE

    Machina, Alexia J.

    2009-01-01

    Approved for public release, distribution unlimited Frozen hydrometeors are required for a storm to produce lightning. Previous research has made strong correlations between ice mass and lightning flash rate and lightning flash density. This study attempted to correlate ice mass to lightning potential Operational interest is centered at Cape Canaveral Air Force Station/Kennedy Space Center where accurate weather forecasting is vital to mission requirements, resource protection, and pe...

  12. Lightning electromagnetic radiation field spectra in the interval from 0.2 to 20 MHz

    Science.gov (United States)

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

    1990-11-01

    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.

  13. Lightning electromagnetic radiation field spectra in the interval from 0.2 to 20 MHz

    Science.gov (United States)

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

    1990-01-01

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Zach, J.J.

    1996-08-01

    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.

  15. 14 CFR 35.38 - Lightning strike.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Lightning strike. 35.38 Section 35.38... STANDARDS: PROPELLERS Tests and Inspections § 35.38 Lightning strike. The applicant must demonstrate, by... lightning strike without causing a major or hazardous propeller effect. The limit to which the propeller has...

  16. 14 CFR 420.71 - Lightning protection.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 4 2010-01-01 2010-01-01 false Lightning protection. 420.71 Section 420.71... TRANSPORTATION LICENSING LICENSE TO OPERATE A LAUNCH SITE Responsibilities of a Licensee § 420.71 Lightning protection. (a) Lightning protection. A licensee shall ensure that the public is not exposed to hazards due...

  17. Relating lightning data to fire occurrence data

    Science.gov (United States)

    F.H. Koch

    2009-01-01

    Lightning disturbance can affect forest health at various scales. Lightning strikes may kill or weaken individual trees. Lightning-damaged trees may in turn function as epicenters of pest outbreaks in forest stands, as is the case with the southern pine beetle and other bark beetles (Rykiel and others 1988).

  18. 49 CFR 176.120 - Lightning protection.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false Lightning protection. 176.120 Section 176.120 Transportation Other Regulations Relating to Transportation PIPELINE AND HAZARDOUS MATERIALS SAFETY... Requirements for Class 1 (Explosive) Materials Stowage § 176.120 Lightning protection. A lightning conductor...

  19. Wind turbine with lightning protection system

    DEFF Research Database (Denmark)

    2016-01-01

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

  20. Lightning Protection for Composite Aircraft Structures

    Science.gov (United States)

    Olson, G. O.

    1985-01-01

    Lightning protection system consisting of two layers of aluminum foil separated by layer of dielectric material protects graphite/epoxy composite structures on aircraft. Protective layer is secondarily applied lightning protection system, prime advantage of which is nullification of thermal and right angle effect of lightning arc attachment to graphite/epoxy laminate.

  1. Stretched Wire Mechanics

    Energy Technology Data Exchange (ETDEWEB)

    Bowden, Gordon; /SLAC

    2005-09-06

    Stretched wires are beginning to play an important role in the alignment of accelerators and synchrotron light sources. Stretched wires are proposed for the alignment of the 130 meter long LCLS undulator. Wire position technology has reached sub-micron resolution yet analyses of perturbations to wire straightness are hard to find. This paper considers possible deviations of stretched wire from the simple 2-dimensional catenary form.

  2. Upward streamers produced by a lightning strike to radio transmission towers

    Science.gov (United States)

    Krider, E. Philip; Wetmore, Ralph H.

    1987-01-01

    A lightning strike to the center of three 78-m radio transmission towers produced upward discharges with lengths of 40 and 79 m from each of the neighboring towers. This strike also caused a number of insulators on guy wires that supported the tower to flash over, and the locations of these points and the two-dimensional geometry of the discharge channels are projected onto a vertical plane that is centered on the tower.

  3. Measured current and close electric field changes associated with the initiation of upward lightning from a tall tower

    Science.gov (United States)

    Zhou, Helin; Diendorfer, Gerhard; Thottappillil, Rajeev; Pichler, Hannes; Mair, Martin

    2012-04-01

    We examine in detail the simultaneous lightning current waveforms, close electric field changes, and lightning location system data for upward lightning discharges initiated from the Gaisberg Tower (GBT) from 2005 to 2009. Out of 205 upward flashes, most of them (87% or 179/205) were initiated from the tower top without any nearby preceding lightning activity (called "self-initiated"), whereas 26 upward flashes (13%) were initiated from the tower top with immediately preceding nearby lightning activity (called "nearby-lightning-triggered"), including 15 positive ground flashes, one negative ground flashes, and 10 cloud discharges. The possible reasons for self-initiated upward flashes dominating at the GBT could be the field enhancement due to the Gaisberg Mountain above the surrounding terrain and low altitude of charge region during non-convective season (September to March), since we note that self-initiated lightning at the GBT occurred predominantly (79% or 142/179) during non-convective season. On the other hand the majority (85% or 22/26) of nearby-lightning-triggered upward flashes at the GBT occurring during convective season (April to August) and 80 nearby-lightning-triggered upward flashes out of 81 upward flashes observed at the ten tall towers in Rapid City in South Dakota of USA occurring during summer seasons, could be due to the result of high altitude of charge region. The triggering flashes were detected to be within 1 and 18 km distance and the time intervals between them and upward lightning initiation are in the range of 0.3 to 90.7 ms.

  4. Lightning protection design and testing of an all composite wet wing for the Egrett

    Science.gov (United States)

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

    1991-01-01

    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.

  5. Structure of laboratory ball lightning

    Science.gov (United States)

    Ito, Tsuyohito; Tamura, Tomoya; Cappelli, Mark A.; Hamaguchi, Satoshi

    2009-12-01

    Trajectories of self-sustained laboratory ball lightning, generated by arc discharges with silicon, are investigated for understanding the possibility of buoyant flight. Extremely low apparent densities are found, nearly approaching that of standard air. The freely buoyant balls are observed to survive for about 0.1 s, with significantly buoyant balls surviving for several seconds. These ball lightning objects are found to have a density and size that can easily allow them to be carried by a gentle breeze of a few meters per second. The results are interpreted by a model that is an extension of that first proposed by Abrahamson and Dinniss [J. Abrahamson and J. Dinniss, Nature (London) 403, 519 (2000)]. The buoyant behavior of ball lightning seen in our experiments is believed to arise as a result of the formation of a nanoparticle oxide network growing from a molten silicon core.

  6. New Physical Mechanism for Lightning

    Science.gov (United States)

    Artekha, Sergey N.; Belyan, Andrey V.

    2018-02-01

    The article is devoted to electromagnetic phenomena in the atmosphere. The set of experimental data on the thunderstorm activity is analyzed. It helps to identify a possible physical mechanism of lightning flashes. This mechanism can involve the formation of metallic bonds in thunderclouds. The analysis of the problem is performed at a microphysical level within the framework of quantum mechanics. The mechanism of appearance of metallic conductivity includes the resonant tunneling of electrons along resonance-percolation trajectories. Such bonds allow the charges from the vast cloud charged subsystems concentrate quickly in lightning channel. The formation of metal bonds in the thunderstorm cloudiness is described as the second-order phase transition. A successive mechanism for the process of formation and development of the lightning channel is suggested. This mechanism is associated with the change in the orientation of crystals in growing electric field. Possible consequences of the quantum-mechanical mechanism under discussion are compared with the results of observations.

  7. Physical nature of ball lightning

    Energy Technology Data Exchange (ETDEWEB)

    Stakhanov, I.P.

    1979-01-01

    An analysis is made of results obtained from the observations of ball lightning. Principal attention is given to data obtained during the last two decades. A brief critique is also offered on hypotheses about its origin. A more detailed presentation is made of the cluster hypothesis according to which ball lightning consists of complex compounds of ions and neutral molecules. The book is intended for a broad spectrum of readers, but is particularly directed toward those with a knowledge of physics and chemistry. 70 references, 24 figures, 17 tables.

  8. Using Flow Regime Lightning and Sounding Climatologies to Initialize Gridded Lightning Threat Forecasts for East Central Florida

    Science.gov (United States)

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

    2007-01-01

    Each morning, the forecasters at the National Weather Service in Melbourne, FL (NWS MLB) produce an experimental cloud-to-ground (CG) lightning threat index map for their county warning area (CWA) that is posted to their web site (httl://www.srh.weather.gov/mlb/ghwo/lightning.shtml) . Given the hazardous nature of lightning in East Central Florida, especially during the warm season months of May September, these maps help users factor the threat of lightning, relative to their location, into their daily plans. The maps are color-coded in five levels from Very Low to Extreme, with threat level definitions based on the probability of lightning occurrence and the expected amount of CG activity. On a day in which thunderstorms are expected, there are typically two or more threat levels depicted spatially across the CWA. The locations of relative lightning threat maxima and minima often depend on the position and orientation of the low-level ridge axis, forecast propagation and interaction of sea/lake/outflow boundaries, expected evolution of moisture and stability fields, and other factors that can influence the spatial distribution of thunderstorms over the CWA. The lightning threat index maps are issued for the 24-hour period beginning at 1200 UTC each day with a grid resolution of 5 km x 5 km. Product preparation is performed on the AWIPS Graphical Forecast Editor (GFE), which is the standard NWS platform for graphical editing. Until recently, the forecasters created each map manually, starting with a blank map. To improve efficiency of the forecast process, NWS MLB requested that the Applied Meteorology Unit (AMU) create gridded warm season lightning climatologies that could be used as first-guess inputs to initialize lightning threat index maps. The gridded values requested included CG strike densities and frequency of occurrence stratified by synoptic-scale flow regime. The intent was to improve consistency between forecasters while allowing them to focus on the

  9. Lightning characteristics observed by a VLF/LF lightning detection network (LINET in Brazil, Australia, Africa and Germany

    Directory of Open Access Journals (Sweden)

    H. Höller

    2009-10-01

    Full Text Available This paper describes lightning characteristics as obtained in four sets of lightning measurements during recent field campaigns in different parts of the world from mid-latitudes to the tropics by the novel VLF/LF (very low frequency/low frequency lightning detection network (LINET. The paper gives a general overview on the approach, and a synopsis of the statistical results for the observation periods as a whole and for one special day in each region. The focus is on the characteristics of lightning which can specifically be observed by this system like intra-cloud and cloud-to-ground stroke statistics, vertical distributions of intra-cloud strokes or peak current distributions. Some conclusions regarding lightning produced NOx are also presented as this was one of the aims of the tropical field campaigns TROCCINOX (Tropical Convection, Cirrus and Nitrogen Oxides Experiment and TroCCiBras (Tropical Convection and Cirrus Experiment Brazil in Brazil during January/February 2005, SCOUT-O3 (Stratospheric-Climate Links with Emphasis on the Upper Troposphere and Lower Stratosphere and TWP-ICE (Tropical Warm Pool-International Cloud Experiment during November/December 2005 and January/February 2006, respectively, in the Darwin area in N-Australia, and of AMMA (African Monsoon Multidisciplinary Analyses in W-Africa during June–November 2006.

    Regional and temporal characteristics of lightning are found to be dependent on orographic effects (e.g. S-Germany, Brazil, Benin, land-sea breeze circulations (N-Australia and especially the evolution of the monsoons (Benin, N-Australia. Large intra-seasonal variability in lightning occurrence was found for the Australian monsoon between the strong convection during build-up and break phases and the weak active monsoon phase with only minor lightning activity. Total daily lightning stroke rates can be of comparable intensity in all regions with the heaviest events found in Germany and N

  10. New Mission to Measure Global Lightning from the International Space Station (ISS)

    Science.gov (United States)

    Blakeslee, R. J.; Christian, H. J., Jr.; Mach, D. M.; Buechler, D. E.; Koshak, W. J.; Walker, T. D.; Bateman, M. G.; Stewart, M. F.; O'Brien, S.; Wilson, T. O.; Pavelitz, S. D.; Coker, C.

    2015-12-01

    Over the past 20 years, the NASA Marshall Space Flight Center, the University of Alabama in Huntsville, and their partners developed and demonstrated the effectiveness and value of space-based lightning observations as a remote sensing tool for Earth science research and applications, and, in the process, established a robust global lightning climatology. The observations included measurements from the Lightning Imaging Sensor (LIS) on the Tropical Rainfall Measuring Mission (TRMM) that acquired global observations of total lightning (i.e., intracloud and cloud-to-ground discharges) from November 1997 to April 2015 between 38° N/S latitudes, and its Optical Transient Detector predecessor that acquired observation from May 1995 to April 2000 over 75° N/S latitudes. In February 2016, as an exciting follow-on to these prior missions, a space-qualified LIS built as a flight-spare for TRMM will be delivered to the International Space Station (ISS) for a 2 year or longer mission, flown as a hosted payload on the Department of Defense Space Test Program-Houston 5 (STP-H5) mission. The LIS on ISS will continue observations of the amount, rate, and radiant energy of total lightning over the Earth. More specifically, LIS measures lightning during both day and night, with storm scale resolution (~4 km), millisecond timing, and high, uniform detection efficiency, without any land-ocean bias. Lightning is a direct and most impressive response to intense atmospheric convection. ISS LIS lightning observations will continue to provide important gap-filling inputs to pressing Earth system science issues across a broad range of disciplines. This mission will also extend TRMM time series observations, expand the latitudinal coverage to 54° latitude, provide real-time lightning data to operational users, espically over data sparse oceanic regions, and enable cross-sensor observations and calibrations that includes the new GOES-R Geostationary Lightning Mapper (GLM) and the Meteosat

  11. LRAT: Lightning Radiative Transfer

    Science.gov (United States)

    Phanord, Dieudonne D.

    1993-01-01

    In this report, we extend to cloud physics the work done for single and multiple scattering of electromagnetic waves. We consider the scattering of light, visible or infrared, by a spherical cloud represented by a statistically homogeneous ensemble of configurations of N identical spherical water droplets whose centers are uniformly distributed in its volume V. The ensemble is specified by the average number rho of scatterers in unit volume and by rho f(R) with f(R) as the distribution function for separations R of pairs. The incident light, vector-phi(sub 0) a plane electromagnetic wave with harmonic time dependence, is from outside the cloud. The propagation parameter kappa(sub 0) and the index of refraction eta(sub 0) determine physically the medium outside the distribution of scatterers. We solve the interior problem separately to obtain the bulk parameters for the scatterer equivalent to the ensemble of spherical droplets. With the interior solution or the equivalent medium approach, the multiple scattering problem is reduced to that of an equivalent single scatterer excited from outside illumination. A dispersion relation which determines the bulk propagation parameter K and the bulk index of refraction eta of the cloud is given in terms of the vector equivalent scattering amplitude vector-G and the dyadic scattering amplitude tilde-g of the single object in isolation. Based on this transfer model we will have the ability to consider clouds composed of inhomogeneous distribution of water and/or ice particles and we will be able to take into account particle size distributions within the cloud. We will also be able to study the effects of cloud composition (i.e., particle shape, size, composition, orientation, location) on the polarization of the single or the multiple scattered waves. Finally, this study will provide a new starting point for studying the problem of lightning radiative transfer.

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

    Science.gov (United States)

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

    2012-12-01

    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.

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

    Science.gov (United States)

    Tatematsu, Akiyoshi; Noda, Taku

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

  14. Modeling and experimental investigation of lightning arcs and overvoltages for medium voltage distribution lines

    Energy Technology Data Exchange (ETDEWEB)

    Omidiora, M. A.

    2011-07-01

    In this dissertation, lightning overvoltages in Medium Voltage (MV) lines are thoroughly investigated. The other goal is to propose new protection schemes for the designs. The lines consist of overhead lines, underground cables and covered conductors. These overvoltage problems range from direct and indirect strokes to lightning arcs. All the models and simulations are developed using the Electromagnetic Transient Program (EMTP) and Finite Element Method (FEM), while MATLAB is used for post-processing the results and identification of the model parameters. Improvement in the surge protection of MV overhead lines is demonstrated with a combination of surge arresters and a shield wire. Using the IEEE 34-node feeder injected with multiple lightning strokes, the feeder is simulated using EMTP. The response of the line is modeled both with and without the surge protection devices. The simulation study extends to the performance of a MV underground cable due to a nearby lightning discharge using FEM. The use of shield wire for limiting the overvoltage stress in the cables is proposed. A numerical analysis and simulations are performed to determine the outage rate of MV covered conductors due to lightning strokes of different characteristics. The optimum distance for surge protective devices on the conductors is also assessed. An enhancement in the surge analysis of distribution lines with the shielding effect of trees is proposed. An experimental study shows that a tree can intercept a lightning stroke in the vicinity of a distribution line. This study also analyzes experimental results of the shielding effectiveness of a tree and the induced voltages existing between the tree and the distribution line. The study is extended to evaluate the induced voltage on a distribution line for larger clearances using a Rusck model. This work investigates the lightning arc between an overhead line and a nearby tree under artificial rainfall. A full-scale laboratory experiment

  15. Average diurnal variation of summer lightning over the Florida peninsula

    Science.gov (United States)

    Maier, L. M.; Krider, E. P.; Maier, M. W.

    1984-01-01

    Data derived from a large network of electric field mills are used to determine the average diurnal variation of lightning in a Florida seacoast environment. The variation at the NASA Kennedy Space Center and the Cape Canaveral Air Force Station area is compared with standard weather observations of thunder, and the variation of all discharges in this area is compared with the statistics of cloud-to-ground flashes over most of the South Florida peninsula and offshore waters. The results show average diurnal variations that are consistent with statistics of thunder start times and the times of maximum thunder frequency, but that the actual lightning tends to stop one to two hours before the recorded thunder. The variation is also consistent with previous determinations of the times of maximum rainfall and maximum rainfall rate.

  16. Generation of Laboratory Ball Lightning

    Energy Technology Data Exchange (ETDEWEB)

    Oreshko, A G [Moscow Aviation Institute (State Technical University), Volokolamskoe shosse 4, 125871 Moscow (Russian Federation)

    2006-07-15

    The phenomenon of energy conversion in the streams of directed electrons and ions into electromagnetic radiation was found out experimentally and proved theoretically. The direct proofs of the domain mechanism of the charged particles acceleration and mechanism of ball lightning generation were obtained and the theoretical calculations were refined.

  17. A Conjecture Concerning Ball Lightning

    OpenAIRE

    Sturrock, P. A.

    2016-01-01

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

  18. Lightning protection of wind turbines

    Energy Technology Data Exchange (ETDEWEB)

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

    1999-03-01

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

  19. Laboratory-produced ball lightning

    Science.gov (United States)

    Golka, Robert K., Jr.

    1994-05-01

    For 25 years I have actively been searching for the true nature of ball lightning and attempting to reproduce it at will in the laboratory. As one might expect, many unidentified lights in the atmosphere have been called ball lightning, including Texas Maffa lights (automobile headlights), flying saucers (UFOs), swamp gas in Ann Arbor, Michigan, etc. For 15 years I thought ball lightning was strictly a high-voltage phenomenon. It was not until 1984 when I was short-circuiting the electrical output of a diesel electric railroad locomotive that I realized that the phenomenon was related more to a high current. Although I am hoping for some other types of ball lightning to emerge such as strictly electrostatic-electromagnetic manifestations, I have been unlucky in finding laboratory provable evidence. Cavity-formed plasmodes can be made by putting a 2-inch burning candle in a home kitchen microwave oven. The plasmodes float around for as long as the microwave energy is present.

  20. Measurement of RF lightning emissions

    Science.gov (United States)

    Lott, G. K., Jr.; Honnell, M. A.; Shumpert, T. H.

    1981-01-01

    A lightning radio emission observation laboratory is described. The signals observed and recorded include HF, VHF and UHF radio emissions, optical signature, electric field measurements, and thunder. The objectives of the station, the equipment used, and the recording methods are discussed.

  1. Wire bonding in microelectronics

    CERN Document Server

    Harman, George G

    2010-01-01

    Wire Bonding in Microelectronics, Third Edition, has been thoroughly revised to help you meet the challenges of today's small-scale and fine-pitch microelectronics. This authoritative guide covers every aspect of designing, manufacturing, and evaluating wire bonds engineered with cutting-edge techniques. In addition to gaining a full grasp of bonding technology, you'll learn how to create reliable bonds at exceedingly high yields, test wire bonds, solve common bonding problems, implement molecular cleaning methods, and much more. Coverage includes: Ultrasonic bonding systems and technologies, including high-frequency systems Bonding wire metallurgy and characteristics, including copper wire Wire bond testing Gold-aluminum intermetallic compounds and other interface reactions Gold and nickel-based bond pad plating materials and problems Cleaning to improve bondability and reliability Mechanical problems in wire bonding High-yield, fine-pitch, specialized-looping, soft-substrate, and extreme-temperature wire bo...

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2007-07-01

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

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

    Directory of Open Access Journals (Sweden)

    Chin-Leong Wooi

    2015-01-01

    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.

  4. The Colorado Lightning Mapping Array

    Science.gov (United States)

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

    2012-12-01

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

  5. Lightning Location Using Acoustic Signals

    Science.gov (United States)

    Badillo, E.; Arechiga, R. O.; Thomas, R. J.

    2013-05-01

    In the summer of 2011 and 2012 a network of acoustic arrays was deployed in the Magdalena mountains of central New Mexico to locate lightning flashes. A Times-Correlation (TC) ray-tracing-based-technique was developed in order to obtain the location of lightning flashes near the network. The TC technique, locates acoustic sources from lightning. It was developed to complement the lightning location of RF sources detected by the Lightning Mapping Array (LMA) developed at Langmuir Laboratory, in New Mexico Tech. The network consisted of four arrays with four microphones each. The microphones on each array were placed in a triangular configuration with one of the microphones in the center of the array. The distance between the central microphone and the rest of them was about 30 m. The distance between centers of the arrays ranged from 500 m to 1500 m. The TC technique uses times of arrival (TOA) of acoustic waves to trace back the location of thunder sources. In order to obtain the times of arrival, the signals were filtered in a frequency band of 2 to 20 hertz and cross-correlated. Once the times of arrival were obtained, the Levenberg-Marquardt algorithm was applied to locate the spatial coordinates (x,y, and z) of thunder sources. Two techniques were used and contrasted to compute the accuracy of the TC method: Nearest-Neighbors (NN), between acoustic and LMA located sources, and standard deviation from the curvature matrix of the system as a measure of dispersion of the results. For the best case scenario, a triggered lightning event, the TC method applied with four microphones, located sources with a median error of 152 m and 142.9 m using nearest-neighbors and standard deviation respectively.; Results of the TC method in the lightning event recorded at 18:47:35 UTC, August 6, 2012. Black dots represent the results computed. Light color dots represent the LMA data for the same event. The results were obtained with the MGTM station (four channels). This figure

  6. Evaluation of the Performance Characteristics of the CGLSS and NLDN Systems Based on Two Years of Ground-Truth Data from Launch Complex 39B, Kennedy Space Center, Florida

    Science.gov (United States)

    Mata, Carlos T.; Hill, Jonathan D.; Mata, Angel G.; Cummins, Kenneth L.

    2014-01-01

    From May 2011 through July 2013, the lightning instrumentation at Launch Complex 39B (LC39B) at the Kennedy Space Center, Florida, has obtained high-speed video records and field change waveforms (dE/dt and three-axis dH/dt) for 54 negative polarity return strokes whose strike termination locations and times are known with accuracy of the order of 10 m or less and 1 µs, respectively. A total of 18 strokes terminated directly to the LC39B lighting protection system (LPS), which contains three 181 m towers in a triangular configuration, an overhead catenary wire system on insulating masts, and nine down conductors. An additional 9 strokes terminated on the 106 m lightning protection mast of Launch Complex 39A (LC39A), which is located about 2.7 km southeast of LC39B. The remaining 27 return strokes struck either on the ground or attached to low-elevation grounded objects within about 500 m of the LC39B LPS. Leader/return stroke sequences were imaged at 3200 frames/sec by a network of six Phantom V310 high-speed video cameras. Each of the three towers on LC39B had two high-speed cameras installed at the 147 m level with overlapping fields of view of the center of the pad. The locations of the strike points of 54 return strokes have been compared to time-correlated reports of the Cloud-to-Ground Lightning Surveillance System (CGLSS) and the National Lightning Detection Network (NLDN), and the results of this comparison will be presented and discussed.

  7. TRMM-Based Lightning Climatology

    Science.gov (United States)

    Cecil, Daniel J.; Buechler, Dennis E.; Blakeslee, Richard J.

    2011-01-01

    Gridded climatologies of total lightning flash rates seen by the spaceborne Optical Transient Detector (OTD) and Lightning Imaging Sensor (LIS) have been updated. OTD collected data from May 1995 to March 2000. LIS data (equatorward of about 38 deg) has been added for 1998-2010. Flash counts from each instrument are scaled by the best available estimates of detection efficiency. The long LIS record makes the merged climatology most robust in the tropics and subtropics, while the high latitude data is entirely from OTD. The mean global flash rate from the merged climatology is 46 flashes per second. The peak annual flash rate at 0.5 deg scale is 160 fl/square km/yr in eastern Congo. The peak monthly average flash rate at 2.5 scale is 18 fl/square km/mo, from early April to early May in the Brahmaputra Valley of far eastern India. Lightning decreases in this region during the monsoon season, but increases further north and west. A monthly average peak from early August to early September in northern Pakistan also exceeds any monthly averages from Africa, despite central Africa having the greatest yearly average. Most continental regions away from the equator have an annual cycle with lightning flash rates peaking in late spring or summer. The main exceptions are India and southeast Asia, with springtime peaks in April and May. For landmasses near the equator, flash rates peak near the equinoxes. For many oceanic regions, the peak flash rates occur in autumn. This is particularly noticeable for the Mediterranean and North Atlantic. Landmasses have a strong diurnal cycle of lightning, with flash rates generally peaking between 3-5 pm local solar time. The central United States flash rates peak later, in late evening or early night. Flash rates peak after midnight in northern Argentina. These regions are known for large, intense, long-lived mesoscale convective systems.

  8. Anomalous lightning activity over the Metropolitan Region of São Paulo due to urban effects

    Science.gov (United States)

    Farias, W. R. G.; Pinto, O., Jr.; Naccarato, K. P.; Pinto, I. R. C. A.

    2009-02-01

    A significant enhancement in the number of negative cloud-to-ground (CG) lightning and a decrease in the percentage of positive CG flashes are observed over the city of São Paulo, similar to observations in other large urban areas. Strong evidence indicates that this anomalous behavior results from several mechanisms related to the urban effect. In this paper, we investigated the importance of the air pollution using CG lightning data provided by the Brazilian lightning detection network (BrasilDAT) for a 6-year period (1999-2004). Due to the large variations in the CG lightning activity in response to different meteorological processes, it is not an easy task to infer the contribution of air pollution to the enhancement in the lightning activity. In order to overcome such difficulty, two approaches were considered: (1) the weekly variation of the number of days with lightning in comparison to the mean concentration of particulate matter (PM 10), as well as other thermodynamical parameters; (2) the variation of the number of CG flashes and the maximum storm flash rate per individual thunderstorm for different levels of pollution. The results of both analyses suggest that: first, the enhancement in the CG lightning activity during the week days over São Paulo metropolitan region is related to the PM 10 concentration (pollution); second, the PM 10 concentration tends to increase the lifetime of the storms and, in consequence, the number of flashes per storm, and not the flash rate of the thunderstorm; and third, the effect of the pollution in the enhancement of the CG lightning activity is probably less significant compared to the effect of the urban heat island.

  9. WWLLN lightning and satellite microwave radiometrics at 37 to 183 GHz: Thunderstorms in the broad tropics

    Science.gov (United States)

    Solorzano, N. N.; Thomas, J. N.; Hutchins, M. L.; Holzworth, R. H.

    2016-10-01

    We investigate lightning strokes and deep convection through the examination of cloud-to-ground (CG) lightning from the World Wide Lightning Location Network (WWLLN) and passive microwave radiometer data. Microwave channels at 37 to 183.3 GHz are provided by the Tropical Rainfall Measuring Mission satellite (TRMM) Microwave Imager (TMI) and the Special Sensor Microwave Imager/Sounder (SSMIS) on the Defense Meteorological Satellite Program (DMSP) satellite F16. The present study compares WWLLN stroke rates and minimum radiometer brightness temperatures (Tbs) for two Northern Hemisphere and Southern Hemisphere summers (2009-2011) in the broad tropics (35°S to 35°N). To identify deep convection, we use lightning data and Tbs derived from all channels and differences in the Tbs (ΔTbs) of the three water vapor channels near 183.3 GHz. We find that stroke probabilities increase with increasing Tb depressions for all frequencies examined. Moreover, we apply methods that use the 183.3 GHz channels to pinpoint deep convection associated with lightning. High lightning stroke probabilities are found over land regions for both intense and relatively weak convective systems, although the TMI 85 GHz results should be used with caution as they are affected by a 7 km gap between the conical scans. Over the ocean, lightning is associated mostly with larger Tb depressions. Generally, our results support the noninductive thundercloud charging mechanism but do not rule out the inductive mechanism during the mature stages of storms. Lastly, we present a case study in which lightning stroke rates are used to reconstruct microwave radiometer Tbs.

  10. Global Frequency and Distribution of Lightning as Observed from Space by the Optical Transient Detector

    Science.gov (United States)

    Christian, Hugh J.; Blakeslee, Richard J.; Boccippio, Dennis J.; Boeck, William L.; Bucchler, Dennis E.; Driscoll, Kevin T.; Goodman, Steven J.; Hall, John M.; Koshak, William J.; Mach, Douglas M.; hide

    2002-01-01

    The Optical Transient Detector (OTD) is a space-based instrument specifically designed to detect and locate lightning discharges as it orbits the Earth. This instrument is a scientific payload on the MicroLab-1 satellite that was launched into a low-earth, 70 deg. inclination orbit in April 1995. Given the orbital trajectory of the satellite, most regions of the earth are observed by the OTD instrument more than 400 times during a one year period, and the average duration of each observation is 2 minutes. The OTD instrument optically detects lightning flashes that occur within its 1300x1300 sq km field-of-view during both day and night conditions. A statistical examination of OTD lightning data reveals that nearly 1.4 billion flashes occur annually over the entire earth. This annual flash count translates to an average of 44 +/- 5 lightning flashes (intracloud and cloud-to-ground combined) occurring around the globe every second, which is well below the traditional estimate of 100 flashes per second that was derived in 1925 from world thunder-day records. The range of uncertainty for the OTD global totals represents primarily the uncertainty (and variability) in the flash detection efficiency of the instrument. The OTD measurements have been used to construct lightning climatology maps that demonstrate the geographical and seasonal distribution of lightning activity for the globe. An analysis of this annual lightning distribution confirms that lightning occurs mainly over land areas, with an average land:ocean ratio of 10:1. A dominant Northern Hemisphere summer peak occurs in the annual cycle, and evidence is found for a tropically-driven semiannual cycle.

  11. A Cubesat Mission to Venus: A Low-Cost Approach to the Investigation of Venus Lightning

    Science.gov (United States)

    Majid, W.; Duncan, C.; Kuiper, T.; Russell, C. T.; Hart, R. A.; Lightsey, E.

    2013-12-01

    The occurrence of Venus lightning has been detected by atmospheric probes and landers on Venus; by ionospheric satellites; by an orbiting visible spectrometer; at radio frequencies by the Galileo spacecraft while flying by Venus; and by an Earth-based telescope. However, none of these detectors has enabled us to determine the global occurrence rate of lightning in the atmosphere of Venus, nor the altitude at which this lightning is generated. Such measurements are needed in order to determine the processes that generate Venus lightning and to establish the importance of Venus lightning in controlling the chemical composition of the Venus atmosphere. A simple and affordable mission to perform this mapping could be achieved with CubeSat technology. A mother spacecraft with at least three CubeSat partners using RF detection could map the occurrence of lightning globally and determine its altitude of origin, with triangulation of precisely timed RF event arrivals. Such a mission would provide space for complementary investigations and be affordable under the Discovery mission program. We are embarking on a program to develop CubeSat-based instrumentation for such a mission. The initial task is to develop a lightning detector in a CubeSat development kit using a software defined radio (SDR) operating at decameter wavelengths (5-50 MHz). This involves algorithm development as well as selecting or developing radio hardware for a CubeSat. Two units will be tested on the ground in a lightning zone such as New Mexico, where the Long Wavelength Array operates in the same frequency range. When the concept has been proven, flight subsystems such as solar panels, attitude sensing and communication radios will be added to the CubeSats to test performance in low Earth orbit. Experience gained from flight would enable a cluster of sensors to be proposed for a future Venus mission.

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

    Science.gov (United States)

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

  13. Water Desalination with Wires

    NARCIS (Netherlands)

    Porada, S.; Sales, B.B.; Hamelers, H.V.M.; Biesheuvel, P.M.

    2012-01-01

    We show the significant potential of water desalination using a novel capacitive wire-based technology in which anode/cathode wire pairs are constructed from coating a thin porous carbon electrode layer on top of electrically conducting rods (or wires). By alternately dipping an array of electrode

  14. The saptio-temporal distribution of lightning over the southern Levant and its relation to the regional synoptic systems

    Science.gov (United States)

    Shalev, S.; Izsak, T.; Saaroni, H.; Yair, Y.; Ziv, B.

    2010-09-01

    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 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.

  15. PS wire chamber

    CERN Document Server

    1970-01-01

    A wire chamber used at CERN's Proton Synchrotron accelerator in the 1970s. Multi-wire detectors contain layers of positively and negatively charged wires enclosed in a chamber full of gas. A charged particle passing through the chamber knocks negatively charged electrons out of atoms in the gas, leaving behind positive ions. The electrons are pulled towards the positively charged wires. They collide with other atoms on the way, producing an avalanche of electrons and ions. The movement of these electrons and ions induces an electric pulse in the wires which is collected by fast electronics. The size of the pulse is proportional to the energy loss of the original particle.

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

    Science.gov (United States)

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

    2015-01-01

    Using satellite-based methods that provide accurate 0-1 hour convective initiation (CI) nowcasts, and rely on proven success coupling satellite and radar fields in the Corridor Integrated Weather System (CIWS; operated and developed at MIT-Lincoln Laboratory), to subsequently monitor for first-flash lightning initiation (LI) and later period lightning trends as storms evolve. Enhance IR-based methods within the GOES-R CI Algorithm (that must meet specific thresholds for a given cumulus cloud before the cloud is considered to have an increased likelihood of producing lightning next 90 min) that forecast LI. Integrate GOES-R CI and LI fields with radar thresholds (e.g., first greater than or equal to 40 dBZ echo at the -10 C altitude) and NWP model data within the WDSS-II system for LI-events from new convective storms. Track ongoing lightning using Lightning Mapping Array (LMA) and pseudo-Geostationary Lightning Mapper (GLM) data to assess per-storm lightning trends (e.g., as tied to lightning jumps) and outline threat regions. Evaluate the ability to produce LI nowcasts through a "lightning threat" product, and obtain feedback from National Weather Service forecasters on its value as a decision support tool.

  17. Lightning Activity Relative to the Microphysical and Kinematic Structure of Storms during a Thunder-Snow Episode on 29-30 November 2006

    Science.gov (United States)

    Emersic, C.; Macgorman, D.; Schuur, T.; Lund, N.; Payne, C.; Bruning, E.

    2007-12-01

    We have examined lightning activity relative to the microphysical and kinematic structure of a winter thunderstorm complex (a thunder-snow episode) observed east of Norman, Oklahoma during the evening of 29-30 November 2006. Polarimetric radar provided information about the type of particles present in various regions of the storms. The Lightning Mapping Array (LMA) recorded VHF signals produced by developing lightning channels. The times of arrival of these lightning signals across the array were then used to reconstruct the location and structure of lightning, and these reconstructions were overlaid with radar data to examine the relationship between lightning properties and storm particle types. Four storms in this winter complex have been examined. It was inferred from lightning structure that, in their mature stage, all cells we examined had a positive tripole electrical structure (an upper positive charge center, a midlevel negative charge center, and a lower positive charge center). The storms began with lightning activity in the lower dipole (lower positive and midlevel negative regions), but this evolved into lightning activity throughout the tripole structure within approximately 15-20 minutes. In the longer lived storms, the mature stage lasted for approximately 1.5-2 hours. During this stage, the lower positive charge region was situated less than 5 km above ground, the midlevel negative charge region was typically above 5 km, and the upper positive charge region was located at an altitude of less than 10 km in all the storm cells analyzed. The charge regions descended over approximately the last 30 minutes of lightning activity, the lower charge regions eventually reaching ground. This resulted in the loss of the lower positive charge center and the subsequent diminishment of the lower negative charge center. Lightning initiation usually coincided with the edges of regions of high reflectivity and was coincident with the presence of graupel and ice

  18. Electric charge of a lightning ball

    Science.gov (United States)

    Grigor'ev, A. I.; Shiryaeva, S. O.; Petrushov, N. A.

    2016-09-01

    The electric charge of a lightning ball is found by comparing the electrohydrodynamic stabilities of a charged drop in an electrostatic suspension and a lightning ball floating in a superposition of the gravitational field and the surface electric field. It has been assumed that the electric field strength at the surface is limited by a breakdown value. For a lightning ball radius of 15 cm, its charge is estimated as several microcoulombs. Accordingly, the density of electrostatic energy accumulated in the lightning ball is on the order of one-hundredth of a joule per square centimeter. The density of the material that constitutes the lightning ball has been estimated for the case when the electric field strength at the site of its origination is several times higher than that in fine weather. The density of the lightning ball turns out to differ from that of air by only a few percents.

  19. Lightning transient analysis in wind turbine blades

    DEFF Research Database (Denmark)

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

    2013-01-01

    The transient behavior of lightning surges in the lightning protection system of wind turbine blades has been investigated in this paper. The study is based on PSCAD models consisting of electric equivalent circuits with lumped and distributed parameters involving different lightning current...... waveforms. The aim of the PSCAD simulations is to study the voltages induced by the lightning current in the blade that may cause internal arcing. With this purpose, the phenomenon of current reflections in the lightning down conductor of the blade and the electromagnetic coupling between the down conductor...... and other internal conductive elements of the blade is studied. Finally, several methods to prevent internal arcing are discussed in order to improve the lightning protection of the blade....

  20. 30 CFR 75.516 - Power wires; support.

    Science.gov (United States)

    2010-07-01

    .... All power wires (except trailing cables on mobile equipment, specially designed cables conducting high-voltage power to underground rectifying equipment or transformers, or bare or insulated ground and return... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Power wires; support. 75.516 Section 75.516...

  1. An Overview of the Total Lightning Jump Algorithm: Past, Present and Future Work

    Science.gov (United States)

    Schultz, Christopher J.; Petersen, Walter A.; Carey, Lawrence D.; Deierling, Wiebke; Kessinger, Cathy

    2011-01-01

    Rapid increases in total lightning prior to the onset of severe and hazardous weather have been observed for several decades. These rapid increases are known as lightning jumps and can precede the occurrence of severe weather by tens of minutes. Over the past decade, a significant effort has been made to quantify lightning jump behavior in relation to its utility as a predictor of severe and hazardous weather. Based on a study of 34 thunderstorms that occurred in the Tennessee Valley, early work conducted in our group at Huntsville determined that it was indeed possible to create a reasonable operational lightning jump algorithm (LJA) based on a statistical framework relying on the variance behavior of the lightning trending signal. We the expanded this framework and tested several variance-related LJA configurations on a much larger sample of 87 severe and non severe thunderstorms. This study determined that a configuration named the "2(sigma)" algorithm had the most promise in development of the operational LJA with a probability of detection (POD) of 87%, a false alarm rate (FAR) of 33%, a Heidke Skill Score (HSS) of 0.75. The 2(sigma) algorithm was then tested on an even larger sample of 711 thunderstorms of all types from four regions of the country where total lightning measurement capability existed. The result was very encouraging.Despite the larger number of storms and the inclusion of different regions of the country, the POD remained high (79%), the FAR was low (36%) and HSS was solid (0.71). Average lead time from jump to severe weather occurrence was 20.65 minutes, with a standard deviation of +/- 15 minutes. Also, trends in total lightning were compared to cloud to ground (CG) lightning trends, and it was determined that total lightning trends had a higher POD (79% vs 66%), lower FAR (36% vs 54 %) and a better HSS (0.71 vs 0.55). From the 711-storm case study it was determined that a majority of missed events were due to severe weather producing

  2. CAMEX-3 LIGHTNING INSTRUMENT PACKAGE (LIP) V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The CAMEX-3 Lightning Instrument Package (LIP) dataset contains electrical field measurements of lightning within storms studied during the Convection And Moisture...

  3. Stratospheric Joule heating by lightning continuing current inferred from radio remote sensing

    DEFF Research Database (Denmark)

    Fullekrug, M.; Ignaccolo, M.; Kuvshinov, A.

    2006-01-01

    to ground deposits electrical energy into the stratosphere resulting from quasi-static ( Joule) heating. The energy deposition is dominated by the lightning continuing current, and it is similar to 10(-5) J/m(3) at 30 km height. It is speculated that the initiation of blue jets and gigantic jets...

  4. On the Nature of Cloud Lightning

    Science.gov (United States)

    Betz, H. D.; Schmidt, K.; Oettinger, W. P.; Montag, B.; Wuerl, A.

    2009-04-01

    Studies of lightning discharges generally deal with electrical activities that occur both inside thunderclouds (IC) and may involve a ground connection (CG). Even though CG has been studied more extensively than IC, it is known that the two types of discharges are accompanied by emission of qualitatively similar radiation. Less well recognized is the observation that relatively strong strokes are produced not only in connection with CG, but also by discharge processes that do not connect to ground. These IC strokes tend to exhibit somewhat smaller field amplitudes than CG strokes, but they produce thunder and the field records often resemble the ones known from CG. In fact, the number of these IC-strokes is large enough to allow efficient monitoring of cloud activity with the same technique as one applies for CG detection (VLF/LF). Very frequently, IC-strokes are produced during the initial breakdown phase, whereby initiation is probably caused by electron runaway processes that extend over hundreds of meters. Further prominent discharge phases can be effectively observed, most important are stepped leaders with copious emission of VHF radio signals. Experimental data for the various cloud processes are discussed and evaluated with respect to theoretical and practical significance. Open questions on the production mechanisms are elucidated, and the relative occurrence of IC versus CG strokes is illustrated.

  5. Design and Construction of an X-ray Lightning Camera

    Science.gov (United States)

    Schaal, M.; Dwyer, J. R.; Rassoul, H. K.; Uman, M. A.; Jordan, D. M.; Hill, J. D.

    2010-12-01

    A pinhole-type camera was designed and built for the purpose of producing high-speed images of the x-ray emissions from rocket-and-wire-triggered lightning. The camera consists of 30 7.62-cm diameter NaI(Tl) scintillation detectors, each sampling at 10 million frames per second. The steel structure of the camera is encased in 1.27-cm thick lead, which blocks x-rays that are less than 400 keV, except through a 7.62-cm diameter “pinhole” aperture located at the front of the camera. The lead and steel structure is covered in 0.16-cm thick aluminum to block RF noise, water and light. All together, the camera weighs about 550-kg and is approximately 1.2-m x 0.6-m x 0.6-m. The image plane, which is adjustable, was placed 32-cm behind the pinhole aperture, giving a field of view of about ±38° in both the vertical and horizontal directions. The elevation of the camera is adjustable between 0 and 50° from horizontal and the camera may be pointed in any azimuthal direction. In its current configuration, the camera’s angular resolution is about 14°. During the summer of 2010, the x-ray camera was located 44-m from the rocket-launch tower at the UF/Florida Tech International Center for Lightning Research and Testing (ICLRT) at Camp Blanding, FL and several rocket-triggered lightning flashes were observed. In this presentation, I will discuss the design, construction and operation of this x-ray camera.

  6. Lightning Applications in Weather and Climate Research

    Science.gov (United States)

    Price, Colin G.

    2013-11-01

    Thunderstorms, and lightning in particular, are a major natural hazard to the public, aviation, power companies, and wildfire managers. Lightning causes great damage and death every year but also tells us about the inner working of storms. Since lightning can be monitored from great distances from the storms themselves, lightning may allow us to provide early warnings for severe weather phenomena such as hail storms, flash floods, tornadoes, and even hurricanes. Lightning itself may impact the climate of the Earth by producing nitrogen oxides (NOx), a precursor of tropospheric ozone, which is a powerful greenhouse gas. Thunderstorms themselves influence the climate system by the redistribution of heat, moisture, and momentum in the atmosphere. What about future changes in lightning and thunderstorm activity? Many studies show that higher surface temperatures produce more lightning, but future changes will depend on what happens to the vertical temperature profile in the troposphere, as well as changes in water balance, and even aerosol loading of the atmosphere. Finally, lightning itself may provide a useful tool for tracking climate change in the future, due to the nonlinear link between lightning, temperature, upper tropospheric water vapor, and cloud cover.

  7. OLS ANALOG DERIVED LIGHTNING V1

    Data.gov (United States)

    National Aeronautics and Space Administration — Global lightning signatures from the Defense Meteorological Satellite Program (DMSP) Operational Linescan System (OLS) have been analyzed from the filmstrip imagery....

  8. Optical characteristics of lightning and thunderstorm currents

    Science.gov (United States)

    Krider, E. P.; Blakeslee, R. J.

    1985-01-01

    Researchers determined that lightning can be used to determine the diurnal variations of thunderstorms, i.e., storms that produce audible thunder, and that these variations are also in good agreement with diurnal variations in rainfall and convective activity. Measurements of the Maxwell current density, J sub m, under active thunderstorms show that this physical quantity is quasi-steady between lightning discharges and that lightning does not produce large changes in J sub m. Maps of J sub m show contours of iso-current density that are consistent with the locations of radar echos and the locations of where lightning has altered the cloud charge distribution.

  9. Lightning Strike in Pregnancy With Fetal Injury.

    Science.gov (United States)

    Galster, Kellen; Hodnick, Ryan; Berkeley, Ross P

    2016-06-01

    Injuries from lightning strikes are an infrequent occurrence, and are only rarely noted to involve pregnant victims. Only 13 cases of lightning strike in pregnancy have been previously described in the medical literature, along with 7 additional cases discovered within news media reports. This case report presents a novel case of lightning-associated injury in a patient in the third trimester of pregnancy, resulting in fetal ischemic brain injury and long-term morbidity, and reviews the mechanics of lightning strikes along with common injury patterns of which emergency providers should be aware. Copyright © 2016 Wilderness Medical Society. Published by Elsevier Inc. All rights reserved.

  10. OPTICAL TRANSIENT DETECTOR (OTD) LIGHTNING V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The Optical Transient Detector (OTD) records optical measurements of global lightning events in the daytime and nighttime. The data includes individual point...

  11. An Analysis of Total Lightning Flash Rates Over Florida

    Science.gov (United States)

    Mazzetti, Thomas O.; Fuelberg, Henry E.

    2017-12-01

    Although Florida is known as the "Sunshine State", it also contains the greatest lightning flash densities in the United States. Flash density has received considerable attention in the literature, but lightning flash rate has received much less attention. We use data from the Earth Networks Total Lightning Network (ENTLN) to produce a 5 year (2010-2014) set of statistics regarding total flash rates over Florida and adjacent regions. Instead of tracking individual storms, we superimpose a 0.2° × 0.2° grid over the study region and count both cloud-to-ground (CG) and in-cloud (IC) flashes over 5 min intervals. Results show that the distribution of total flash rates is highly skewed toward small values, whereas the greatest rate is 185 flashes min-1. Greatest average annual flash rates ( 3 flashes min-1) are located near Orlando. The southernmost peninsula, North Florida, and the Florida Panhandle exhibit smaller average annual flash rates ( 1.5 flashes min-1). Large flash rates > 100 flashes min-1 can occur during any season, at any time during the 24 h period, and at any location within the domain. However, they are most likely during the afternoon and early evening in East Central Florida during the spring and summer months.

  12. Weekend-weekday lightning variability for an urban region

    Science.gov (United States)

    Bentley, M. L.; Stallins, J. A.; Ashley, W. S.

    2011-12-01

    We characterized differences in warm-season weekday and weekend aerosol conditions and cloud-to- ground (CG) flashes (1995-2008) for an 80,000 square kilometer region around Atlanta, Georgia. Under weekday aerosol concentrations, a greater augmentation of CG flash activity within a 100 km radius around Atlanta was found. On weekends these effects contracted toward the city. This minimized any weekly anthropogenic cycle over the more densely populated urban center even though this location had a higher flash density, a higher percentage of days with flashes, and stronger peak currents over the course of a week compared to the surrounding region. The sharper contrasts in weekday and weekend lightning regime developed outside the perimeter of the city over non urban land uses. Here lightning on weekend and weekdays differed more in its density, frequency, polarity, and peak current. Across the full extent of the study region, weekday peak currents were stronger and flash days more frequent, suggesting that weekly CG lightning signals have a regional component not tied to a single city source.

  13. Polymer-composite ball lightning.

    Science.gov (United States)

    Bychkov, V L

    2002-01-15

    Investigations into the state of ball lightning (BL) have been made, and both theory and experiments, related to so-called "polymer-composite" ball lightning, are presented. The properties of such a polymeric BL have been described and are that of a long-lived object capable of storing high energy. Results of experiments, starting with polymeric components in erosive gas discharge experiments, are described and discussed. The model of BL as a highly charged polymer-dielectric structure is described. According to this model BL appears as the result of the aggregation of natural polymers, such as lignin and cellulose, soot, polymeric silica and other natural dust particles. Its ability to glow is explained by the appearance over its perimeter of gas discharges near the highly charged BL surface, and electrical breakdown of some regions on the surface, consisting of polymerized and aggregated threads.

  14. Lightning Protection and Detection System

    Science.gov (United States)

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

    2017-01-01

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

  15. Indirect Lightning Safety Assessment Methodology

    Energy Technology Data Exchange (ETDEWEB)

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

    2009-04-24

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

  16. Saturn’s visible lightning, its radio emissions, and the structure of the 2009–2011 lightning storms

    OpenAIRE

    Dyudina, Ulyana A.; Ingersoll, Andrew P.; Ewald, Shawn P.; Porco, Carolyn C.; Fischer, Georg; Yair, Yoav

    2013-01-01

    Visible lightning on Saturn was first detected by the Cassini camera in 2009 at ∼35° South latitude. We report more lightning observations at ∼35° South later in 2009, and lightning in the 2010–2011 giant lightning storm at ∼35° North. The 2009 lightning is detected on the night side of Saturn in a broadband clear filter. The 2011 lightning is detected on the day side in blue wavelengths only. In other wavelengths the 2011 images lacked sensitivity to detect lightning, which leaves the lightn...

  17. A Fiber-Optic Aircraft Lightning Current Measurement Sensor

    Science.gov (United States)

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

    2013-01-01

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

  18. Lightning forecasting studies using LDAR, LLP, field mill, surface mesonet, and Doppler radar data

    Science.gov (United States)

    Forbes, Gregory S.; Hoffert, Steven G.

    1995-01-01

    The ultimate goal of this research is to develop rules, algorithms, display software, and training materials that can be used by the operational forecasters who issue weather advisories for daily ground operations and launches by NASA and the United States Air Force to improve real-time forecasts of lightning. Doppler radar, Lightning Detection and Ranging (LDAR), Lightning Location and Protection (LLP), field mill (Launch Pad Lightning Warning System -- LPLWS), wind tower (surface mesonet) and additional data sets have been utilized in 10 case studies of thunderstorms in the vicinity of KSC during the summers of 1994 and 1995. These case studies reveal many intriguing aspects of cloud-to-ground, cloud-to-cloud, in-cloud, and cloud-to-air lightning discharges in relation to radar thunderstorm structure and evolution. They also enable the formulation of some preliminary working rules of potential use in the forecasting of initial and final ground strike threat. In addition, LDAR and LLP data sets from 1993 have been used to quantify the lightning threat relative to the center and edges of LDAR discharge patterns. Software has been written to overlay and display the various data sets as color imagery. However, human intervention is required to configure the data sets for proper intercomparison. Future efforts will involve additional software development to automate the data set intercomparisons, to display multiple overlay combinations in a windows format, and to allow for animation of the imagery. The software package will then be used as a tool to examine more fully the current cases and to explore additional cases in a timely manner. This will enable the formulation of more general and reliable forecasting guidelines and rules.

  19. Slow Lightning in Water Plasmoids

    Science.gov (United States)

    Stephan, Karl; Dumas, Shelby; McMinn, Jonathan

    2012-10-01

    Water plasmoids are produced when a capacitor is discharged into a cathode at the surface of a weakly conducting water electrolyte. The resulting plasma jet forms a glowing spherical plasmoid which persists in air for up to 0.3 s and resembles ball lightning in some respects. This study shows that during the plasmoid's formation stage, surface discharges with unusual characteristics carry the large instantaneous discharge current. The liquid-surface discharges have some characteristics of both conventional solid-surface discharges (branching, fractal structure) and glow discharges (approximately constant current density from the discharge plasma to the water surface over a wide range of current). Dynamically, the surface discharge resembles a two-dimensional version of a lightning leader, but develops at much lower speeds: a maximum of about 0.3 m/s for the surface discharges in this study, compared to lightning leader speeds of 100 to 100,000 m/s. The low conductivity of the water used (about 20 mS/m) means that the surface discharges are interacting with a resistive barrier, which allows a significant tangential electric field on the surface. High-speed photography of the discharges is supplemented by spectroscopic and other experimental studies.

  20. Lightning Burns and Electrical Trauma in a Couple Simultaneously Struck by Lightning

    Directory of Open Access Journals (Sweden)

    Stephanie A. Eyerly-Webb

    2017-07-01

    Full Text Available More people are struck and killed by lightning each year in Florida than any other state in the United States. This report discusses a couple that was simultaneously struck by lightning while walking arm-in-arm. Both patients presented with characteristic lightning burns and were admitted for hemodynamic monitoring, serum labs, and observation and were subsequently discharged home. Despite the superficial appearance of lightning burns, serious internal electrical injuries are common. Therefore, lightning strike victims should be admitted and evaluated for cardiac arrhythmias, renal injury, and neurological sequelae.

  1. Backflashover simulation of HV transmission lines with enhanced counterpoise groundings

    Energy Technology Data Exchange (ETDEWEB)

    Gatta, F.M.; Geri, A.; Lauria, S.; Maccioni, M. [Department of Electrical Engineering, University of Rome ' ' La Sapienza' ' , Via Eudossiana no. 18, 00184 Roma (Italy)

    2009-07-15

    This paper deals with the backflashover phenomenon in HV overhead transmission lines (TLs) with towers grounded by means of long counterpoises, typically used in high resistivity soils. Although long counterpoises are effective in reducing the grounding impedance at power frequency, their impulse response may affect negatively the TL backflashover rate. The study is focused on the enhancement of TL lightning performance obtainable by adding a small number of vertical grounding rods to horizontal counterpoises. An extensive ATP-EMTP parametric analysis, based on a detailed 161 kV TL model including the leader progression model (LPM) of line insulations and the non-linear transient behaviour of grounding systems, has been carried out taking into account several different values of soil resistivity as well as varying numbers, locations and lengths of additional vertical rods. Critical lightning current ranges causing backflashover have been then predicted for several lightning waveforms, of different severity. The paper shows that the addition of a few vertical grounding rods significantly improves TL lightning performance by increasing critical lightning current values, even if their influence is negligible at power frequency. The authors have ascertained an increment of average critical backflashover current up to {proportional_to}55% for some typical TL grounding system configurations and lightning waveshapes. (author)

  2. The relationship of lightning activity and short-duation rainfall events during warm seasons over the Beijing metropolitan region

    Science.gov (United States)

    Wu, F.; Cui, X.; Zhang, D. L.; Lin, Q.

    2017-12-01

    The relationship between lightning activity and rainfall associated with 2925 short-duration rainfall (SDR) events over the Beijing metropolitan region (BMR) is examined during the warm seasons of 2006-2007, using the cloud-to-ground (CG) and intracloud (IC) lightning data from Surveillance et Alerte Foudre par Interférometrie Radioélectrique (SAFIR)-3000 and 5-min rainfall data from automatic weather stations (AWSs). To facilitate the analysis of the rainfall-lightning correlations, the SDR events are categorized into six different intensity grades according to their hourly rainfall rates (HRRs), and an optimal radius of 10 km from individual AWSs for counting their associated lightning flashes is used. Results show that the lightning-rainfall correlations vary significantly with different intensity grades. Weak correlations (R 0.4) are found in the weak SDR events, and 40-50% of the events are no-flash ones. And moderate correlation (R 0.6) are found in the moderate SDR events, and > 10-20% of the events are no-flash ones. In contrast, high correlations (R 0.7) are obtained in the SDHR events, and < 10% of the events are no-flash ones. The results indicate that lightning activity is observed more frequently and correlated more robust with the rainfall in the SDHR events. Significant time lagged correlations between lightning and rainfall are also found. About 80% of the SDR events could reach their highest correlation coefficients when the associated lightning flashes shift at time lags of < 25 min before and after rainfall begins. The percentages of SDR events with CG or total lightning activity preceding, lagging or coinciding with rainfall shows that (i) in about 55% of the SDR events lightning flashes preceded rainfall; (ii) the SDR events with lightning flashes lagging behind rainfall accounted for about 30%; and (iii) the SDR events without any time shifts accounted for the remaining 15%. Better lightning-rainfall correlations can be attained when time

  3. Initial electric field changes of lightning flashes in two thunderstorms

    Science.gov (United States)

    Chapman, Ryan; Marshall, Thomas; Karunarathne, Sumedhe; Stolzenburg, Maribeth

    2017-04-01

    The beginning of all 75 lightning flashes in two small thunderstorms was investigated using an array of electric field change (E-change) meters and an array of VHF sensors with the goal of determining if an initial E-change (IEC) preceded the initial breakdown (IB) pulses in each flash. IECs were found at the beginning of all 62 flashes in Storm 1 and all 13 flashes in Storm 2. Hence, it is concluded that an IEC is a fundamental part of most or all lightning initiations and that an IEC is needed prior to the first IB pulse in a flash. IEC durations averaged 0.23 ms for cloud-to-ground (CG) flashes (range 0.08-0.54 ms) and averaged 2.7 ms for normal intracloud (IC) flashes (range 0.04-9.8 ms). IEC point dipole moments averaged 26 C m for CG flashes (range 4-86 C m) and averaged -140 C m for normal IC flashes (range -8 to -650 C m). IEC current moments averaged 120 kA m for CG flashes (range 41-410 kA m) and averaged -91 kA m for normal IC flashes (range -2 to -630 kA m). E-change data support the suggestion that weak narrow bipolar event type events initiate some lightning flashes, but 41 of the 75 flashes had no detectable initiating pulse > 0.04 V m-1 range normalized to 100 km. Two flashes had two IECs; the second IEC of each flash initiated a new lightning channel that propagated in a new direction and at a higher altitude than the original development after the first IEC.

  4. Lightning-induced overvoltages in low-voltage systems

    Energy Technology Data Exchange (ETDEWEB)

    Hoeidalen, Hans Kristian

    1997-12-31

    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.

  5. Storm diagnostic/predictive images derived from a combination of lightning and satellite imagery

    Science.gov (United States)

    Goodman, Steven J.; Buechler, Dennis E.; Meyer, Paul J.

    1988-01-01

    A technique is presented for generating trend or convective tendency images using a combination of GOES satellite imagery and cloud-to-ground lightning observations. The convective tendency images can be used for short term forecasting of storm development. A conceptual model of cloud electrical development and an example of the methodology used to generate lightning/satellite convective tendency imagery are given. Successive convective tendency images can be looped or animated to show the previous growth or decay of thunderstorms and their associated lighting activity. It is suggested that the convective tendency image may also be used to indicate potential microburst producing storms.

  6. Effects of nearby buildings on lightning induced voltages on overhead power distribution lines

    OpenAIRE

    Borghetti, Alberto; Napolitano, Fabio; Nucci, Carlo Alberto; Paolone, Mario

    2013-01-01

    For the case of urban overhead lines, the presence of nearby buildings is expected to affect the overvoltages induced by nearby cloud-to-ground lightning return strokes. So far, this effect has been seldom taken into account in the literature on the subject. The paper presents a 3D FEM model that calculates the lightning electromagnetic pulse (LEMP) taking into account the presence of a building placed in proximity of the LEMP-coupled overhead line. As a first approximation, all the metallic ...

  7. Some of the ball lightning observations could be phosphenes induced by energetic radiation from thunderstorms and lightning

    Science.gov (United States)

    Cooray, G. K.; Cooray, G. V.; Dwyer, J. R.

    2011-12-01

    Ball Lightning was seen and described since antiquity and recorded in many places. However, so far no one has managed to generate them in the laboratory. It is possible that many different phenomena are grouped together and categorized simply as ball lightning. One such phenomenon could be the phosphenes induced in humans by energetic radiation and particles from lightning and thunderstorms. A phosphene is a visual sensation that is characterized by perceiving luminous phenomena without light entering the eye. Phosphenes are generated when electrical signals are created in the retina or the optical nerve by other means in the absence of light stimuli. The fact that energetic radiation produced by radium can give rise to phosphenes was first noted by Giesel in 1899 [1]. A resurge of studies related to the creation of phosphenes by energetic radiation took place after the reports of phosphenes observed in space by Apollo astronauts and first reported by Buzz Aldrin after the Apollo 11 flight to the moon in 1969 [2]. The shapes of the phosphenes observed by astronauts were either rods, comet shaped, or comprised of a single dot, several dots or blobs. The colors were mostly white, but some had been colored yellow, orange, blue, green or red. The majority of the astronauts had perceived some kind of motion in association with the phosphenes. Most of the time, they were moving horizontally (from the periphery of the vision to the center) and sometimes diagonally, but never vertically. Subsequent studies conducted in space and ground confirmed the creation of phosphenes by energetic radiation. From these studies the threshold energy dissipation in the eye tissue necessary for phosphenes induction was estimated to be 10 MeV/cm. In the present study a quantitative analysis of the energetic radiation generated in the form of X-rays, Gamma rays and relativistic electrons by thunderstorms and lightning was made to investigate whether this radiation is strong enough to induce

  8. Forecasting Lightning at Kennedy Space Center/Cape Canaveral Air Force Station, Florida

    Science.gov (United States)

    Lambert, Winfred; Wheeler, Mark; Roeder, William

    2005-01-01

    the equation development. Fifteen years (1 989-2003) of warm season data were used to develop the forecast equations. The data sources included a local network of cloud-to-ground lightning sensors called the Cloud-to-Ground Lightning Surveillance System (CGLSS), 1200 UTC Florida synoptic soundings, and the 1000 UTC CCAFS sounding. Data from CGLSS were used to determine lightning occurrence for each day. The 1200 UTC soundings were used to calculate the synoptic-scale flow regimes and the 1000 UTC soundings were used to calculate local stability parameters, which were used as candidate predictors of lightning occurrence. Five logistic regression forecast equations were created through careful selection and elimination of the candidate predictors. The resulting equations contain five to six predictors each. Results from four performance tests indicated that the equations showed an increase in skill over several standard forecasting methods, good reliability, an ability to distinguish between non-lightning and lightning days, and good accuracy measures and skill scores. Given the overall good performance the 45 WS requested that the equations be transitioned to operations and added to the current set of tools used to determine the daily lightning probability of occurrence.

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

    Science.gov (United States)

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

    2013-01-01

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

  10. Automated sensing of thunderstorm characteristics and lightning parameters in the south of the European part of the Russian Federation

    Science.gov (United States)

    Adzhiev, Anatoly Kh.; Boldyreff, Anton S.; Kuliev, Dalkhat D.; Borisov, Igor V.; Korogodova, Irina V.

    2017-10-01

    In the present study the results of instrument measurements of thunderstorm activity and lightning parameters on the territory of the south of the European part of the Russian Federation is received. The automated hardware-software complex for thunderstorm activity sensing is developed. It consists of lightning sensors, electric field mills, meteorological radiolocator (MRL-5) for sensing the radar characteristics of clouds, meteorological stations and software for data collection, analysis and processing. Features of spatial-temporal variations of the thunderstorm activity and lightning parameters on the territory of 650 km around the measurement center of High-Mountain Geophysical Institute (Nalchik) were found. The relations between the quantities of intracloud, cloud-to-cloud and cloud-to-ground (positive and negative) discharges were studied. Parameters of current of the lightning discharges of different polarities under the flat and mountainous terrain were received and analyzed in the paper.

  11. Lightning and precipitation history of a microburst-producing storm

    Science.gov (United States)

    Goodman, Steven J.; Buechler, Dennis E.; Wright, Patrick D.; Rust, W. David

    1988-01-01

    Quantitative measurements of the lightning and precipitation life cycle of a microburst-producing storm are discussed. The storm, which occurred on July 20, 1986 at Huntsville, Alabama, was studied using Doppler radar data. The storm produced 116 flashes, 6 of which were discharges to the ground. It is suggested that an abrupt decrease in the total flash rates is associated with storm collapse, and serves as a precursor to the arrival of the maximum microburst outflows at the surface. Ice-phase precipitation is shown to be an important factor in both the formation of the strong downdraft and the electrification of the storm.

  12. Towards plant wires

    OpenAIRE

    Adamatzky, Andrew

    2014-01-01

    In experimental laboratory studies we evaluate a possibility of making electrical wires from living plants. In scoping experiments we use lettuce seedlings as a prototype model of a plant wire. We approximate an electrical potential transfer function by applying direct current voltage to the lettuce seedlings and recording output voltage. We analyse oscillation frequencies of the output potential and assess noise immunity of the plant wires. Our findings will be used in future designs of self...

  13. The relationship of lightning activity and short-duration rainfall events during warm seasons over the Beijing metropolitan region

    Science.gov (United States)

    Wu, Fan; Cui, Xiaopeng; Zhang, Da-Lin; Qiao, Lin

    2017-10-01

    The relationship between lightning activity and rainfall associated with 2925 short-duration rainfall (SDR) events over the Beijing metropolitan region (BMR) is examined during the warm seasons of 2006-2007, using the cloud-to-ground (CG) and intracloud (IC) lightning data from Surveillance et Alerte Foudre par Interférometrie Radioélectrique (SAFIR)-3000 and 5-min rainfall data from automatic weather stations (AWSs). An optimal radius of 10 km around selected AWSs is used to determine the lightning-rainfall relationship. The lightning-rainfall correlations vary significantly, depending upon the intensity of SDR events. That is, correlation coefficient (R 0.7) for the short-duration heavy rainfall (SDHR, i.e., ≥ 20 mm h- 1) events is found higher than that (R 0.4) for the weak SDR (i.e., 5-10 mm h- 1) events, and lower percentage of the SDHR events (< 10%) than the weak SDR events (40-50%) are observed with few flashes. Significant time-lagged correlations between lightning and rainfall are also found. About 80% of the SDR events could reach their highest correlation coefficients when the associated lightning flashes shift at time lags of < 25 min before and after rainfall begins. Those events with lightning preceding rainfall account for 50-60% of the total SDR events. Better lightning-rainfall correlations can be attained when time lags are incorporated, with the use of total (CG and IC) lightning data. These results appear to have important implications for improving the nowcast of SDHR events.

  14. The North Alabama Lightning Mapping Array: Recent Severe Storm Observations and Future Prospects

    Science.gov (United States)

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

    2004-01-01

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

  15. Doppler Radar and Lightning Network Observations of a Severe Outbreak of Tropical Cyclone Tornadoes

    Science.gov (United States)

    Mccaul, Eugene W., Jr.; Buechler, Dennis E.; Goodman, Steven J.; Cammarata, Michael

    2004-01-01

    Data from a single Weather Surveillance Radar-1988 Doppler (WSR-88D) and the National Lightning Detection Network are used to examine the characteristics of the convective storms that produced a severe tornado outbreak, including three tornadoes that reached F3 intensity, within Tropical Storm Beryl s remnants on 16 August 1994. Comparison of the radar data with reports of tornadoes suggests that only 13 cells produced the 29 tornadoes that were documented in Georgia and the Carolinas on that date. Six of these cells spawned multiple tornadoes, and the radar data confirm the presence of miniature supercells. One of the cells was identifiable on radar for 11 h. spawning tornadoes over a time period spanning approximately 6.5 h. Several other tornadic cells also exhibited great longevity, with cell lifetimes longer than ever previously documented in a landfalling tropical cyclone (TC) tornado event. This event is easily the most intense TC tornado outbreak yet documented with WSR-88Ds. Time-height analyses of the three strongest tornadic supercells are presented in order to document storm kinematic structure and to show how these storms appear at different ranges from a WSR-88D. In addition, cloud-to-ground (CG) lightning data are examined in Beryl s remnants. Although the tornadic cells were responsible for most of Beryl's CG lightning, their flash rates were only weak to moderate, and in all the tornadic storms the lightning flashes were almost entirely negative in polarity. A few of the single-tornado storms produced no detectable CG lightning at all. There is evidence that CG lightning rates decreased during the tornadoes, compared to 30-min periods before the tornadoes. A number of the storms spawned tornadoes just after producing their final CG lightning flashes. Contrary to the findings for flash rates, both peak currents and positive flash percentages were larger in Beryl's nontornadic storms than in the tornadic ones.

  16. Photovoltaic Wire, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — This Small Business Innovation Research Phase I project will investigate a new architecture for photovoltaic devices based on nanotechnology: photovoltaic wire. The...

  17. Photovoltaic Wire Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This Small Business Innovation Research Phase I project will investigate a new architecture for photovoltaic devices based on nanotechnology: photovoltaic wire. The...

  18. Charpak hemispherical wire chamber

    CERN Document Server

    1970-01-01

    pieces. Mesures are of the largest one. Multi-wire detectors contain layers of positively and negatively charged wires enclosed in a chamber full of gas. A charged particle passing through the chamber knocks negatively charged electrons out of atoms in the gas, leaving behind positive ions. The electrons are pulled towards the positively charged wires. They collide with other atoms on the way, producing an avalanche of electrons and ions. The movement of these electrons and ions induces an electric pulse in the wires which is collected by fast electronics. The size of the pulse is proportional to the energy loss of the original particle.

  19. An Experimental Study of Lightning Overvoltages in Wind Turbine Generation Systems

    Science.gov (United States)

    Yamamoto, Kazuo; Ohta, Tomokatsu; Noda, Taku; Yokoyama, Shigeru; Ametani, Akihiro

    In order to obtain good wind conditions, wind turbine generation systems are built at places like hill countries and shorefronts where few tall structures are found. However, this increases the risk of lightning strikes. To promote wind power generation, lightning-protection methodologies for such wind turbine generation systems have to be established. This paper presents the results of an experimental study which investigates the lightning overvoltages in wind turbine generation systems. The experiments were carried out on actual ground soil using a reduced-size wind turbine model with its foundations. From the experiments, the following conclusions have been deduced: (i) Voltage rise due to the grounding impedance of the foundations can cause a significant overvoltage between the tower foot and an incoming cable like a power, a communication or a control line. (ii) The voltage rise of the foundations and that of the surrounding ground soil may cause an overvoltage at the outermost insulation layer of an incoming cable, which can result in a breakdown or a deterioration of the insulation (iii) Voltage and current waveforms to understand the traveling-wave phenomenon on a wind power generation system with its foundations were obtained. The data will be useful for developing an EMTP simulation model of a wind turbine generation system for lightning overvoltage studies.

  20. ASSESSMENT TO EFFECTIVENESS OF THE NEW EARLY STREAMER EMISSION LIGHTNING PROTECTION SYSTEM

    OpenAIRE

    A. Chen, Yen-Hong; Lin, Kai-Jan; M. Li, Yu-Chu

    2017-01-01

    A novel early streamer emission (ESE) lightning air terminal system is designed and fabricated. By comparing the intercepted artificial lightning striking numbers of the new ESE lightning protection device and the conventional lightning rod (CLR) lightning protection device in laboratory, the effectiveness of intercepting the artificial lightning strokes by the new ESE lightning protection device is superior to that by the conventional lightning rod lightning protection device. A modified Tes...

  1. MODELING OF OVERHEAD TRANSMISSION LINES FOR LIGHTNING OVERVOLTAGE CALCULATIONS MODELACIÓN DE LÍNEAS AÉREAS DE TRANSMISIÓN PARA EL CÁLCULO DE SOBRETENSIONES ORIGINADAS POR EL RAYO

    Directory of Open Access Journals (Sweden)

    Juan A Martínez-Velasco

    2010-04-01

    Full Text Available Several parts of an overhead transmission line have to be included in a model adequate for lightning overvoltage studies: wires (shield wires and phase conductors, towers, grounding, insulator strings and air clearances. An additional component, the surge arrester, should be added if the study is aimed at determining the lightning performance of a transmission line protected by surge arresters. This latter aspect is important since it can affect the model to be used for representing some parts of the line. Lightning is a physical phenomenon of random nature. The calculation of the lightning flashover rate must be performed taking into account this aspect, as well as the random behavior of some line component; e.g., insulator strings. The aim of this paper is twofold: on one hand, it presents a discussion about modeling guidelines proposed to date for representing overhead transmission lines in lightning studies; on the other hand, it proposes a methodology for selecting the most adequate model of an overhead transmission line in lightning overvoltage calculations, when using a time-domain simulation tool, e.g. an EMTP-like tool. This methodology is applied to a test transmission line.Un modelo de línea aérea de transmisión adecuado para el cálculo de sobretensiones originadas por el rayo debe incluir varias partes de la línea: conductores de fase y cables de guarda, torres, puestas a tierra, cadenas de aisladores y distancias en el aire. Un componente adicional, el pararrayos, puede ser necesario si el estudio tiene como objetivo evaluar el comportamiento frente al rayo de una línea de transmisión protegida mediante pararrayos. Este último aspecto es importante ya que el modelo a utilizar puede variar según se hayan instalado o no pararrayos para proteger la línea. El rayo es un fenómeno físico de naturaleza aleatoria. El cálculo de la tasa de contorneos (flameos causados por descargas atmosféricas ha de realizarse teniendo en

  2. 1998 wire development workshop proceedings

    International Nuclear Information System (INIS)

    1998-04-01

    This report consists of vugraphs of the presentations at the conference. The conference was divided into the following sessions: (1) First Generation Wire Development: Status and Issues; (2) First Generation Wire in Pre-Commercial Prototypes; (3) Second Generation Wire Development: Private Sector Progress and Issues; (4) Second Generation Wire Development: Federal Laboratories; and (5) Fundamental Research Issues for HTS Wire Development

  3. Phenomenon of ball lightning and its outgrowths

    Energy Technology Data Exchange (ETDEWEB)

    Torchigin, V.P. [Institute of Informatics Problems, Russian Academy of Sciences, Nakhimovsky prospect 36/1, 119278 Moscow (Russian Federation)]. E-mail: v_torchigin@mail.ru; Torchigin, A.V. [Institute of Informatics Problems, Russian Academy of Sciences, Nakhimovsky prospect 36/1, 119278 Moscow (Russian Federation)

    2005-03-28

    New physical phenomena deduced from properties of ball lightning are considered under assumption that ball lightning is a light bubble comprising of a thin spherical layer of compressed air where an intense light circulates in all possible directions. Explanation of behavior of autonomous luminous objects produced at gas discharge is presented.

  4. When Lightning Strikes a Second Time

    Science.gov (United States)

    Allen, Kent

    2017-01-01

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

  5. A model for lightning in littoral areas

    NARCIS (Netherlands)

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

    2009-01-01

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

  6. Lightning protecting materials used on radar system

    NARCIS (Netherlands)

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

    2009-01-01

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

  7. Lightning-caused fires in Central Spain

    DEFF Research Database (Denmark)

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

    2012-01-01

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

  8. [A case of fatal lightning stroke at an unusual site--the city center].

    Science.gov (United States)

    Kaliszan, Michał; Karnecki, Karol; Jankowski, Zbigniew

    2012-01-01

    A case of a fatal lighting stroke involving a young man staying in a storm near the center of a big city is presented. The atypical character of this case lies in the fact that the lightning stroke usually occurs in open areas (mountains, fields, meadows), or involves people trying to find shelter from the storm under a tree or an isolated object in an open area. In the described case, a contributory factor to the lightning stroke was the fact that during the storm, the man was most probably standing on metal heating pipes, built in the 70's and 80's, long stretches of which were erected high above the ground. Metal used in the construction of the pipes most probably attracted lightning and generated the current which electrocuted the man standing on their surface.

  9. Production mechanisms of leptons, photons, and hadrons and their possible feedback close to lightning leaders

    DEFF Research Database (Denmark)

    Köhn, Christoph; Diniz, Gabriel; Harakeh, Muhsin N.

    2017-01-01

    It has been discussed that lightning flashes emit high-energy electrons, positrons, photons,and neutrons with single energies of several tens of MeV. In the first part of this paper we study the absorption of neutron beams in the atmosphere. We initiate neutron beams of initial energies of 350 ke...... and m2 are possibly detectable at ground, at 6 km, or at 500 km altitude. In the second part of the paper we discuss a feedback model involving the generation and motion of electrons, positrons, neutrons, protons, and photons close to the vicinity of lightning leaders. In contrast to other feedback...... models, we do not consider large-scale thundercloud fields but enhanced fields of lightning leaders. We launch different photon and electron beams upward at 4 km altitude. We present the spatial and energy distribution of leptons, hadrons,and photons after different times and see that leptons, hadrons...

  10. Lightning enhancement over major oceanic shipping lanes

    Science.gov (United States)

    Thornton, Joel A.; Virts, Katrina S.; Holzworth, Robert H.; Mitchell, Todd P.

    2017-09-01

    Using 12 years of high-resolution global lightning stroke data from the World Wide Lightning Location Network (WWLLN), we show that lightning density is enhanced by up to a factor of 2 directly over shipping lanes in the northeastern Indian Ocean and the South China Sea as compared to adjacent areas with similar climatological characteristics. The lightning enhancement is most prominent during the convectively active season, November-April for the Indian Ocean and April-December in the South China Sea, and has been detectable from at least 2005 to the present. We hypothesize that emissions of aerosol particles and precursors by maritime vessel traffic lead to a microphysical enhancement of convection and storm electrification in the region of the shipping lanes. These persistent localized anthropogenic perturbations to otherwise clean regions are a unique opportunity to more thoroughly understand the sensitivity of maritime deep convection and lightning to aerosol particles.

  11. Mathematical physics approaches to lightning discharge problems

    Science.gov (United States)

    Kyrala, A.

    1985-01-01

    Mathematical physics arguments useful for lightning discharge and generation problems are pursued. A soliton Ansatz for the lightning stroke is treated including a charge generation term which is the ultimate source for the phenomena. Equations are established for a partially ionized plasma inding the effects of pressure, magnetic field, electric field, gravitation, viscosity, and temperature. From these equations is then derived the non-stationary generalized Ohm's Law essential for describing field/current density relationships in the horizon channel of the lightning stroke. The discharge initiation problem is discussed. It is argued that the ionization rate drives both the convective current and electric displacement current to increase exponentially. The statistical distributions of charge in the thundercloud preceding a lightning dischage are considered. The stability of the pre-lightning charge distributions and the use of Boltzmann relaxational equations to determine them are discussed along with a covered impedance path provided by the aircraft.

  12. Lightning injuries in sports and recreation.

    Science.gov (United States)

    Thomson, Eric M; Howard, Thomas M

    2013-01-01

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

  13. Progress towards a lightning ignition model for the Northern Rockies

    Science.gov (United States)

    Paul Sopko; Don Latham

    2010-01-01

    We are in the process of constructing a lightning ignition model specific to the Northern Rockies using fire occurrence, lightning strike, ecoregion, and historical weather, NFDRS (National Fire Danger Rating System), lightning efficiency and lightning "possibility" data. Daily grids for each of these categories were reconstructed for the 2003 fire season (...

  14. Wire Array Photovoltaics

    Science.gov (United States)

    Turner-Evans, Dan

    Over the past five years, the cost of solar panels has dropped drastically and, in concert, the number of installed modules has risen exponentially. However, solar electricity is still more than twice as expensive as electricity from a natural gas plant. Fortunately, wire array solar cells have emerged as a promising technology for further lowering the cost of solar. Si wire array solar cells are formed with a unique, low cost growth method and use 100 times less material than conventional Si cells. The wires can be embedded in a transparent, flexible polymer to create a free-standing array that can be rolled up for easy installation in a variety of form factors. Furthermore, by incorporating multijunctions into the wire morphology, higher efficiencies can be achieved while taking advantage of the unique defect relaxation pathways afforded by the 3D wire geometry. The work in this thesis shepherded Si wires from undoped arrays to flexible, functional large area devices and laid the groundwork for multijunction wire array cells. Fabrication techniques were developed to turn intrinsic Si wires into full p-n junctions and the wires were passivated with a-Si:H and a-SiNx:H. Single wire devices yielded open circuit voltages of 600 mV and efficiencies of 9%. The arrays were then embedded in a polymer and contacted with a transparent, flexible, Ni nanoparticle and Ag nanowire top contact. The contact connected >99% of the wires in parallel and yielded flexible, substrate free solar cells featuring hundreds of thousands of wires. Building on the success of the Si wire arrays, GaP was epitaxially grown on the material to create heterostructures for photoelectrochemistry. These cells were limited by low absorption in the GaP due to its indirect bandgap, and poor current collection due to a diffusion length of only 80 nm. However, GaAsP on SiGe offers a superior combination of materials, and wire architectures based on these semiconductors were investigated for multijunction

  15. Response of lightning energy and total electron content with sprites over Antarctic Peninsula

    Science.gov (United States)

    Suparta, W.; Yusop, N.

    2017-05-01

    This paper investigates the response of the lightning energy with the total electron content (TEC) derived from GPS over Antarctic Peninsula during St Patrick’s geomagnetic storm. During this event, sprite as one of the mesospheric transient luminous events (TLEs) associated with positive cloud-to-ground (+CG) lightning discharges can be generated. In this work, GPS and lightning data for the period from 14 to 20 March 2015 is analyzed. Geomagnetic activity and electric field data are also processed to relate the geomagnetic storm and lightning. Results show that during St Patrick’s geomagnetic storm, the lighting energy was produced up to ∼257 kJ. The ionospheric TEC was obtained 60 TECU, 38 TECU and 78 TECU between 18:00 and 21:00 UT for OHI3, PALV and ROTH stations, respectively. The peak of lightning energy was observed 14 hours after peaked of TEC. Sprite possibly generated through the electrical coupling process between the top cloud, middle and upper atmosphere with the DC electric field found to be ∼10 mVm-1 which leading to the sprite generation after the return strokes on 18 March 2015.

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

    Science.gov (United States)

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

    2000-01-01

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

  17. The Lightning Nitrogen Oxides Model (LNOM): Status and Recent Applications

    Science.gov (United States)

    Koshak, William; Khan, Maudood; Peterson, Harold

    2011-01-01

    Improvements to the NASA Marshall Space Flight Center Lightning Nitrogen Oxides Model (LNOM) are discussed. Recent results from an August 2006 run of the Community Multiscale Air Quality (CMAQ) modeling system that employs LNOM lightning NOx (= NO + NO2) estimates are provided. The LNOM analyzes Lightning Mapping Array (LMA) data to estimate the raw (i.e., unmixed and otherwise environmentally unmodified) vertical profile of lightning NOx. The latest LNOM estimates of (a) lightning channel length distributions, (b) lightning 1-m segment altitude distributions, and (c) the vertical profile of NOx are presented. The impact of including LNOM-estimates of lightning NOx on CMAQ output is discussed.

  18. Lightning - Apollo to Shuttle. [case histories and spacecraft protection

    Science.gov (United States)

    Durrett, W. R.

    1976-01-01

    The history of lightning striking NASA spacecraft and the development of lightning protection systems is reviewed from the Apollo 12 flight, involving a lightning strike thirty six seconds after launch, to the present date. Particular attention is paid to problems that may arise in this field in the context of planning and implementing the Space Shuttle program. The lightning protection design for Apollo is described: a folding mast mounted on top of the hammerhead crane on top of the Launcher Umbilical Tower, with a lightning rod on top. The effect of lightning storms on the launches of Apollos 12 through 17 is examined, as is the effect of lightning in the Skylab program. The lightning problems encountered by the Apollo-Soyuz mission and by the two unmanned Viking launches to Mars are discussed. The Lightning Detection And Ranging system for detecting RF emission from lightning discharges is described.

  19. Currents and radiated E-fields of upward initiated lightning from the Gaisberg Tower in Austria

    Science.gov (United States)

    Diendorfer, Gerhard; Zhou, Helin; Pichler, Hannes; Thottappillil, Rajeev; Mair, Martin

    2014-05-01

    current of return strokes (N=913) is 9.2 kA and similar to values observed in triggered lightning and to lightning location system peak current estimates for subsequent strokes in cloud-to-ground lightning. Detectability of upward flashes by typical lightning location systems strongly depends on the presence of fast rising current pulses, either as return strokes or superimposed pulses on the ICC. In addition to the current records, corresponding vertical electric fields at close distance (170m) and far distance (about 100 km) are measured with flat-plate antennas. Upward initiated lightning often shows extensive branching and this is assumed to be the reason for the observation of rather complex overall current waveforms. In the presentation we will provide a review of the statistical analyses of the lightning parameters. Records of the E-fields at a distance of about 100 km and radiated by the return strokes to the tower show a significantly shorter peak-to-zero time (10 µs) than typically observed in cloud-to-ground lightning (30 - 40 µs).

  20. Automating wiring formboard design

    NARCIS (Netherlands)

    Van den Berg, T.

    2013-01-01

    Increase in aircraft wiring complexity call for manufacturing design improvements to reduce cost and lead-time. To achieve such improvements, a joint research project was performed by the Flight Performance and Propulsion (FPP) group and Fokker Elmo BV, the second largest aircraft wiring harness

  1. Secret of a ball lightning

    OpenAIRE

    Савич, Эдуард Владимирович

    2013-01-01

    Шаровая молния – явление природы, происходящее при ударе линейной молнии с ее воздействием тепловой и магнитной энергии, возникающей вокруг канала линейной молнии и в результате образующей из окружающего воздуха облако пара, переходящего под воздействием магнитного поля сегнетоэлектрическое состояние. A ball lightning is a natural phenomenon that occurs at a streak lightning stroke with its action by thermal and magnetic energy releasing around the streak lightning channel and transforming...

  2. 3D modeling of lightning-induced electromagnetic pulses on Venus, Jupiter and Saturn

    Science.gov (United States)

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

    2017-04-01

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

  3. Plasma theory of ball lightning

    Energy Technology Data Exchange (ETDEWEB)

    Ostapenko, V.I.; Tolpygo, K.B.

    1984-02-01

    The high-energy density inside the ball lightning is due to existence of intense plasma oscillations and high kinetic and potential energy of electron gas which form a pulsating ball vibrating relative to the nearly stationary ionic ball. At sublight velocities of electrons one can neglect the processes of their scattering and recombination. One obtains a relation between parameters of the plasma ball from the condition of equality of excess pressure of ions and that of Madelung forces. The high lifetime of the ball lighting is connected with small Landau damping for the longest wave vibrations.

  4. Comparison Study of Lightning observations from VHF interferometer and Geostationary Lightning Mapper

    Science.gov (United States)

    Kudo, A.; Stock, M.; Ushio, T.

    2017-12-01

    We compared the optical observation from Geostationary Lightning Mapper (GLM) which is mounted on the geostationary meteorological satellite GOES-16 launched last year, and the radio observations from the ground-based VHF broad band interferometer. GLM detects 777.4 nm wavelength infrared optical signals from thunderstorm cells which are illuminated by the heated path during lightning discharge, and was developed mainly for the purpose of increasing the lead time for warning of severe weather and clarifying the discharge mechanism. Its detection has 2 ms frame rate, and 8 km square of space resolution at nadir. The VHF broad band interferometer is able to capture the electromagnetic waves from 20 MHz to 75 MHz and estimate the direction of arrival of the radiation sources using the interferometry technique. This system also has capability of observing the fast discharge process which cannot be captured by other systems, so it is expected to able to make detailed comparison. The recording duration of the system is 1 second. We installed the VHF broad band interferometer which consists of three VHF antenna and one fast antenna at Huntsville, Alabama from April 22nd to May 15th and in this total observation period, 720 triggers of data were observed by the interferometer. For comparison, we adopted the data from April 27th , April 30th. Most April 27th data has GLM "event" detection which is coincident time period. In time-elevation plot comparison, we found GLM detection timing was well coincide with interferometer during K-changes or return strokes and few detection during breakdown process. On the other hand, no GLM detection near the site for all data in April 30th and we are triyng to figure out the reason. We would like to thank University of Alabama Huntsville, New Mexico Institute of Mining and Technology, and RAIRAN Pte. Ltd for the help during the campaign.

  5. The Connection Between Terrestrial Gamma-Ray Flashes and Energetic In-Cloud Lightning Pulses

    Science.gov (United States)

    Cummer, S. A.; Lyu, F.; Briggs, M. S.; Cramer, E.; Stanbro, M.; Roberts, O.; Smith, D. M.

    2017-12-01

    Radio emissions continue to provide a unique view into the electrodynamics of terrestrial gamma ray flash (TGF) production. Here we will describe our most recent findings on the connection between energetic in-cloud pulses (EIPs) and TGFs. EIPs are a recently identified class of high peak-current lightning events that occur sometimes during the progression of lightning in-cloud negative leaders. They can be robustly detected and identified on the basis of signals from distant ground-based radio sensors. With limited statistics, previous work has shown that many, or perhaps even all, EIPs are associated with simultaneous TGFs. We have analyzed two additional years of ground-based radio and spacecraft TGF data, and report the resulting broader statistics on the EIP-TGF relationship, as well as the implications for the ability to detect a subpopulation of TGFs from ground-based radio sensors alone.

  6. Current Technology of the Lightning Mapping Array

    Science.gov (United States)

    Rodeheffer, D.; Rison, W.; Krehbiel, P. R.; Edens, H. E.; Thomas, R. J.

    2013-12-01

    The Lightning Mapping Array (LMA) is continuing to be developed technology-wise, involving both hardware configurations and software, to further simplify the deployment, operation and sensitivity of networks. This has included developing stations that operate on a complete standalone basis, utilizing battery backed-up solar power and cell phone data modems for connecting into the internet. Solid state disks not requiring cooling are used for onsite data storage, allowing the electronics to be housed in an RF-tight enclosure and the VHF receiving antenna to be co-located immediately above the station electronics, rather than 50 to 100 feet away. The combined changes enable stations to be placed in remote, RF-quiet locations for excellent sensitivity, and to have only a 4'x 4' freestanding footprint on the ground for ease of deployment. Networks that take advantage of the solar/cell modem design are the West Texas LMA (Texas Tech University), the Houston LMA (Texas A&M), and the North Colorado LMA (NMT/CSU), initially utilized in the 2012 DC3 atmospheric chemistry program. A similar network (operated in conjunction with NASA/MSFC) was set up on a temporary basis in Southern France leading up to the HyMeX field program in September and October of 2012. Each of the above networks is remotely monitored via the internet and feeds its data on a minute-by-minute basis back to a central processing computer at NM Tech (or TTU), where it is processed in real time and posted on the web in the two- and ten-minute time intervals. Examples of archived and current realtime data for the North Colorado LMA can be seen at http://lightning.nmt.edu/colma/ and /colma/current/. Finally, based on successful experiences with the above networks, we have developed what is termed the 'Sitetest' network, consisting of 9 or 10 stations each mounted on wooden pallets with lightweight enclosures and simple antenna hardware. The network was initially operated at Kennedy Space Center to test out

  7. Total Lightning Activity Associated with Tornadic Storms

    Science.gov (United States)

    Goodman, Steven J.; Buechler, Dennis; Hodanish, Stephen; Sharp, David; Williams, Earle; Boldi, Bob; Matlin, Anne; Weber, Mark

    1999-01-01

    Severe storms often have high flash rates (in excess of one flash per second) and are dominated by intracloud lightning activity. In addition to the extraordinary flash rates, there is a second distinguishing lightning characteristic of severe storms that seems to be important. When the total lightning history is examined, one finds sudden increases in the lightning rate, which we refer to as lightning "jumps," that precede the occurrence of severe weather by ten or more minutes. These jumps are typically 30-60 flashes/min, and are easily identified as anomalously large derivatives in the flash rate. This relationship is associated with updraft intensification and updraft strength is an important factor in storm severity (through the accumulation of condensate aloft and the stretching of vorticity). In several cases, evidence for diminishment of midlevel rotation and the descent of angular momentum from aloft is present prior to the appearance of the surface tornado. Based on our experience with severe and tornadic storms in Central Florida, we believe the total lightning may augment the more traditional use of NEXRAD radars and storm spotters. However, a more rigorous relation of these jumps to storm kinematics is needed if we are to apply total lightning in a decision tree that leads to improved warning lead times and decreased false alarm rates.

  8. A simple lightning assimilation technique for improving ...

    Science.gov (United States)

    Convective rainfall is often a large source of error in retrospective modeling applications. In particular, positive rainfall biases commonly exist during summer months due to overactive convective parameterizations. In this study, lightning assimilation was applied in the Kain-Fritsch (KF) convective scheme to improve retrospective simulations using the Weather Research and Forecasting (WRF) model. The assimilation method has a straightforward approach: force KF deep convection where lightning is observed and, optionally, suppress deep convection where lightning is absent. WRF simulations were made with and without lightning assimilation over the continental United States for July 2012, July 2013, and January 2013. The simulations were evaluated against NCEP stage-IV precipitation data and MADIS near-surface meteorological observations. In general, the use of lightning assimilation considerably improves the simulation of summertime rainfall. For example, the July 2012 monthly averaged bias of 6 h accumulated rainfall is reduced from 0.54 to 0.07 mm and the spatial correlation is increased from 0.21 to 0.43 when lightning assimilation is used. Statistical measures of near-surface meteorological variables also are improved. Consistent improvements also are seen for the July 2013 case. These results suggest that this lightning assimilation technique has the potential to substantially improve simulation of warm-season rainfall in retrospective WRF applications. The

  9. Lightning mapper and the future

    Science.gov (United States)

    Christian, H. J.

    1985-01-01

    A trade-off analysis was completed that reveals how the lightning mapper detection efficiency will change as a function of interference filter bandwidth, pixel field of view, and telescope aperture. It is shown that the critical parameter on which we have minimum flexibility is filter band-width. The problem is that too narrow a filter bandwidth is incompatible with wide areal coverage. The trade-off analysis demonstrates that an 80 percent lightning detection efficiency will technically be relatively straight-forward, while a 90 percent detection efficiency will apparently be difficult to achieve. Three focal plane designs are currently under consideration. One would use a single large, solid state silicon integrating array with multiple output channels and off-the-focal-plane analog, time domain, background removing fibers. A second design would use the same technology, but the sensor would consist of up to four virtually independent focal plane arrays. This design reduces the areal coverage of each detector. Thus narrower interference filters could be utilized. Superior performance would be realized at a probable increase in cost. The final design would use a three-dimensional focal plane in order to perform background removal at the focal plane. Superior performance would be achieved along with reduced weight and power requirements. Unfortunately, this focal plane technology is still under development.

  10. Spatio-temporal dimension of lightning flashes based on three-dimensional Lightning Mapping Array

    Science.gov (United States)

    López, Jesús A.; Pineda, Nicolau; Montanyà, Joan; Velde, Oscar van der; Fabró, Ferran; Romero, David

    2017-11-01

    3D mapping system like the LMA - Lightning Mapping Array - are a leap forward in lightning observation. LMA measurements has lead to an improvement on the analysis of the fine structure of lightning, allowing to characterize the duration and maximum extension of the cloud fraction of a lightning flash. During several years of operation, the first LMA deployed in Europe has been providing a large amount of data which now allows a statistical approach to compute the full duration and horizontal extension of the in-cloud phase of a lightning flash. The "Ebro Lightning Mapping Array" (ELMA) is used in the present study. Summer and winter lighting were analyzed for seasonal periods (Dec-Feb and Jun-Aug). A simple method based on an ellipse fitting technique (EFT) has been used to characterize the spatio-temporal dimensions from a set of about 29,000 lightning flashes including both summer and winter events. Results show an average lightning flash duration of 440 ms (450 ms in winter) and a horizontal maximum length of 15.0 km (18.4 km in winter). The uncertainties for summer lightning lengths were about ± 1.2 km and ± 0.7 km for the mean and median values respectively. In case of winter lightning, the level of uncertainty reaches up to 1 km and 0.7 km of mean and median value. The results of the successful correlation of CG discharges with the EFT method, represent 6.9% and 35.5% of the total LMA flashes detected in summer and winter respectively. Additionally, the median value of lightning lengths calculated through this correlative method was approximately 17 km for both seasons. On the other hand, the highest median ratios of lightning length to CG discharges in both summer and winter were reported for positive CG discharges.

  11. Urban Effects on Lightning Flash Density in the Coastal Region of Israel

    Science.gov (United States)

    Yair, Y.; Binshtok, G.; Price, C.

    2009-04-01

    Lightning in the coastal region of Israel occurs mostly in the December-February period, with an average flash density of ~1.2 flashes/km2/year, increasing from south to north and reaching a maximum near the port city of Haifa and the near-by Carmel Mountain. Based on lightning data from the LPATS system, obtained during the winter seasons of 2004/5-2006/7, we mapped flash density by using high-resolution Google-earth visualization tools. We note that maximum lightning activity occurs just west of the coastline above the Mediterranean Sea and decreases over land. The urban complex of the metropolitan Tel-Aviv area shows a clear increase in lightning density compared to more rural regions to its north and south. A second maximum is present near Haifa and its surrounding industrial complex. An increase in positive-ground flash density is present downwind from the Tel-Aviv urban area. A clear mid-week effect is also apparent in the flash density of positive ground flashes with peak currents > 50 kA north-east of the Tel-Aviv metropolitan area. Considering the Urban-Heat Island (UHI) effect, we can explain this as a dynamic consequence driven by wind-shear pushing the upper positive charge center eastward relative to the lower part of convective thunderstorms.

  12. Modeling of X-ray Images and Energy Spectra Produced by Stepping Lightning Leaders

    Science.gov (United States)

    Xu, Wei; Marshall, Robert A.; Celestin, Sebastien; Pasko, Victor P.

    2017-11-01

    Recent ground-based measurements at the International Center for Lightning Research and Testing (ICLRT) have greatly improved our knowledge of the energetics, fluence, and evolution of X-ray emissions during natural cloud-to-ground (CG) and rocket-triggered lightning flashes. In this paper, using Monte Carlo simulations and the response matrix of unshielded detectors in the Thunderstorm Energetic Radiation Array (TERA), we calculate the energy spectra of X-rays as would be detected by TERA and directly compare with the observational data during event MSE 10-01. The good agreement obtained between TERA measurements and theoretical calculations supports the mechanism of X-ray production by thermal runaway electrons during the negative corona flash stage of stepping lightning leaders. Modeling results also suggest that measurements of X-ray bursts can be used to estimate the approximate range of potential drop of lightning leaders. Moreover, the X-ray images produced during the leader stepping process in natural negative CG discharges, including both the evolution and morphological features, are theoretically quantified. We show that the compact emission pattern as recently observed in X-ray images is likely produced by X-rays originating from the source region, and the diffuse emission pattern can be explained by the Compton scattering effects.

  13. Lightning strike-induced brachial plexopathy

    Directory of Open Access Journals (Sweden)

    Amita N Bhargava

    2014-01-01

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

  14. Lightning on jupiter: rate, energetics, and effects.

    Science.gov (United States)

    Lewis, J S

    1980-12-19

    Voyager data on the optical and radio-frequency detection of lightning discharges in the atmosphere of Jupiter suggest a stroke rate significantly lower than on the earth. The efficiency of conversion of atmospheric convective energy flux into lightning is almost certainly less than on the earth, probably near 10(-7) rather than the terrestrial value of 10(-4). At this level the rate of production of complex organic molecules by lightning and by thunder shock waves is negligible compared to the rates of known photochemical processes for forming colored inorganic solids.

  15. Lightning on Jupiter - Rate, energetics, and effects

    Science.gov (United States)

    Lewis, J. S.

    1980-01-01

    Voyager data on the optical and radio-frequency detection of lightning discharges in the atmosphere of Jupiter suggest a stroke rate significantly lower than on the earth. The efficiency of conversion of atmospheric convective energy flux into lightning is almost certainly less than on the earth, probably near 10 to the -7th rather than the terrestrial value of 10 to the -4th. At this level the rate of production of complex organic molecules by lightning and by thunder shock waves is negligible compared to the rates of known photochemical processes for forming colored inorganic solids.

  16. Approximate expressions for lightning electromagnetic fields at near and far ranges: Influence of return-stroke speed

    Science.gov (United States)

    Chen, Yazhou; Wang, Xiaojia; Rakov, Vladimir A.

    2015-04-01

    The waveforms of lightning return-stroke electromagnetic fields on ground are studied using the transmission line model. Approximate expressions to calculate lightning electromagnetic fields at near and far ranges are presented. It is found that the waveforms of lightning electric and magnetic fields in the time domain at both near and far ranges can be expressed approximately as the channel-base current waveform multiplied by a factor which is a function of the return-stroke speed v and the horizontal distance r between the return-stroke channel and the observation point on ground. The ranges at which the approximate expressions are valid are determined. The ranges of validity increase with increasing the return-stroke speed, and the near and far field approximate expressions converge to the exact formula as the return-stroke speed approaches the speed of light.

  17. ENSO Related Inter-Annual Lightning Variability from the Full TRMM LIS Lightning Climatology

    Science.gov (United States)

    Clark, Austin; Cecil, Daniel

    2018-01-01

    The El Nino/Southern Oscillation (ENSO) contributes to inter-annual variability of lightning production more than any other atmospheric oscillation. This study further investigated how ENSO phase affects lightning production in the tropics and subtropics using the Tropical Rainfall Measuring Mission (TRMM) Lightning Imaging Sensor (LIS). Lightning data were averaged into mean annual warm, cold, and neutral 'years' for analysis of the different phases and compared to model reanalysis data. An examination of the regional sensitivities and preliminary analysis of three locations was conducted using model reanalysis data to determine the leading convective mechanisms in these areas and how they might respond to the ENSO phases

  18. Thermosonic wire bonding of IC devices using palladium wire

    International Nuclear Information System (INIS)

    Shze, J.H.; Poh, M.T.; Tan, R.M.

    1996-01-01

    The feasibility of replacing gold wire by palladium wire in thermosonic wire bonding of CMOS and bipolar devices are studied in terms of the manufacturability, physical, electrical and assembly performance. The results that palladium wire is a viable option for bonding the bipolar devices but not the CMOS devices

  19. Towards plant wires.

    Science.gov (United States)

    Adamatzky, Andrew

    2014-08-01

    In experimental laboratory studies we evaluate a possibility of making electrical wires from living plants. In scoping experiments we use lettuce seedlings as a prototype model of a plant wire. We approximate an electrical potential transfer function by applying direct current voltage to the lettuce seedlings and recording output voltage. We analyse oscillation frequencies of the output potential and assess noise immunity of the plant wires. Our findings will be used in future designs of self-growing wetware circuits and devices, and integration of plant-based electronic components into future and emergent bio-hybrid systems. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  20. Ongoing Explorations of Exceptional Lightning Discharges in Several Meteorological Regimes

    Science.gov (United States)

    Lyons, W. A.; Warner, T. A.; Cummer, S. A.; Lang, T. J.; Orville, R. E.

    2010-12-01

    As new observing technologies and methodologies become available to any scientific discipline, unexpected discoveries often follow. This has certainly been true with regard to atmospheric electricity and lightning studies, as witnessed by the advancements allowed by regional and national lightning detection networks and radar. More recently, the ability to operationally monitor CG impulse charge moment changes (iCMC) using the National Charge Moment Change Network (CMCN), the advent of deployable high speed video imagers (to 10,000 images/sec and even faster), low-light television (LLTV) systems for detecting transient luminous events (TLEs), 3-D Lightning Mapping Arrays (LMA), and new software tools which facilitate the analysis and display of these complex data sets, is creating new areas of exploration of the lightning discharge plus delving into the characteristics of the storms which generate exceptional lightning discharges. By flagging those +CGs with large iCMCs values (>~300 C km), it is now possible in real-time to identify convective storms highly likely to generate TLEs, especially sprites. The ability of LLTVs to monitor TLEs above storms at ranges approaching 900 km (under ideal conditions) has allowed coordinated measurements, using high speed (1000-10,000 images/sec) video systems, of +CGs triggering both sprites and upward discharges from tall broadcast towers. Four such events were captured in the Rapid City area in May and June, 2010. Detailed analyses of the lightning video, the TLE imagery, and the NLDN, CMCN, and NEXRAD data are delineating the time line of these complex discharges in the context of their meteorological environment. The use of LLTVs to monitor TLEs above distant LMAs enabled studies of two MCSs traversing the Oklahoma LMA (OKLMA) in 2007. Continued analyses of these discharges, some >200 km in length, find sprite parent +CGs lowering charge to ground from altitudes varying from 4 to 8 or 9 km AGL, depending upon storm

  1. Analysis and design of the installation of a lightning rod in risk areas of atmospheric discharge according to the standards NFPA 70, NFPA 780 and IEC 62305

    International Nuclear Information System (INIS)

    Cordoba Alfaro, Marco

    2012-01-01

    The design, analysis of the installation and handling of electrical protections oriented to atmospheric discharge in specific locations of the north zone of Costa Rica, are focused. Related topics with the devices of protection against atmospheric discharge, definitions, types, uses and characteristics were developed. The regulations NFPA 70, NFPA 780 and IEC 62305 are studied for the analysis and design of the lightning rod. The standards are analyzed, according to the rules applied at specialized companies in the elaboration and installation of lightning rod, in order to determine if these are adequate and used in correctly shape . A report is made about the design of a lightning rod and preventive measures for areas with regular activity of atmospheric discharges. The different devices for the elaboration and installation of a lightning rod are investigated in order to later use and exploitation. The design for the implementation of a system of conventional lightning rod, type tips of Franklin, was realized at the Iglesia Catedral of Ciudad Quesada. The materials that were used in this type of lightning rod, have followed the regulation NFPA 780. Several approximate plans of the cathedral have been performed to appreciate good the design, both in 2D as in 3D; these allow a better panorama of the installation. The distance between devices has been fundamental to take into account in the design of a system of lightning rod, as it marks an important difference between the area to protect and areas that may be exposed to an atmospheric discharge. The rule NFPA 780 has been established that to design the location of the lightning captors can use the rolling sphere method, also has marked the requirements of the downspouts systems and grounding systems. Before locating a lightning protection system it is important to be informed of the principal characteristics of the area to be protected; as on several occasions, the particularities of the selected area have

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

    DEFF Research Database (Denmark)

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

    2007-01-01

    Several processes acting below, in and above thunderstorms and in electrified shower clouds drive upward currents which close through the global atmospheric electric circuit, These are all simulated in a novel way using the software package PSpice. A moderate negative cloud-to-ground lightning...... cloud-to-ground lightning discharge from the bottom of a thunderstorm decreases the ionospheric potential by 0.014%. Such a discharge may trigger a sprite, causing the ionospheric potential to decrease by similar to 1 V. The time scales for the recovery of the ionospheric potential are shown...... to be similar to 250 s, which is of the same order as the CR time constant for the global circuit. Knowing the global average rate of lightning discharges, it is found that negative cloud-to-ground discharges increase the ionospheric potential by only similar to 4%, and that positive cloud-to-ground discharges...

  3. Exploring the Production of NOx by Lightning and Its Impact on Tropospheric Ozone

    Science.gov (United States)

    Gillani, Noor; Koshak, William; Biazar, Arastoo; Doty, Kevin; Mahon, Robert; Newchurch, Michael; Byun, Daewon; Emmons, Louisa

    2006-01-01

    transport and chemistry. In our approach for LNOx, (a) we utilize continuous observed lightning information from the NLDN ground network and from satellite imagers (OTD and LIS) to quantify lightning frequency and distribution at the spatial-temporal scales of models such as CMAQ; (b) we develop new methodologies to quantify flash-specific lightning energy dissipation as heat (epsilon) using data from the research-grade lightning measurement facility at NASA-KSC, and to parameterize epsilon based on regional lightning monitoring data (ground- and satellite-based); and, (c) we develop a new parameterization of NOx production as a function of epsilon and rho. Based on such observation-based information, we are working to develop a gridded, episodic LNOx emissions inventory for the USA for use in models like CMAQ. We are also developing approaches for global(MOZART)- regional(CMAQ) chemistry coupling to improve intercontinental transport and STE. Finally, we are developing new methodologies for assimilation of satellite-observed (GOES) clouds into meteorological modeling (MM5), to improve PFTE and to optimize co-location of cloud convection and observed lightning. We will incorporate these improvements in CMAQ simulations over the USA to better understand FT processes and chemistry, and its impact on ground-level ozone.

  4. Cryogenic Pressure Seal for Wires

    Science.gov (United States)

    Ciana, J. J.

    1984-01-01

    High-pressure-seal formed by forcing polyurethane into space surrounding wire or cable in special fitting. Wire or cable routed through fitting then through a tightly fitting cap. Wire insulation left intact. Cap filled with sealant and forced onto the fitting: this pushes sealant into fitting so it seals wire or cable in fitting as well as in cap.

  5. Intracloud lightning data in Brazil using LF detection range: first results

    Science.gov (United States)

    Naccarato, K.; Pinto, O.

    2009-12-01

    Brazil installed in 2007/2008 two LS7000 new generation Vaisala sensors in State of São Paulo (Southeastern Brazil) and two LS8000 sensors in State of Paraná (Southern Brazil). The sensors are located in São José dos Campos/SP (LS7000), Cachoeira Paulista/SP (LS7000), Novo Horizonte/PR (LS8000) and Santa Terezinha/PR (LS8000). According to the manufacturer, they can provide about 30% of intracloud activity data using LF (100-400kHz) detection range. Previous studies demonstrated that the new generation sensors (LSX000 series) has a higher detection efficiency compared to the latter generation sensors (IMPACT series) with a significant increase in the number of cloud-to-ground (CG) strokes reported with peak current lower than 20kA. However, a fraction of these events are intracloud (IC) discharges, which can be used together with the CG lightning information to provide total lighting data in the LF range. In the present work, the lightning data were provided by all 49 network sensors (including the LSX000 sensors) based on the IC/CG discrimination default criteria adopted by the manufacturer (waveform peak-to-zero time). Figure 1 shows the peak current distribution of the lightning strokes in State of Sao Paulo including the new LS7000 sensors compared to the solutions using the old IMPACT sensors. The number of low peak current events (from -5kA to +5kA) detected by the network with the LS7000 is significantly higher. Based on these results, the temporal and spatial variations of the IC lightning will be evaluated and compared to the corresponding variations of the CG lightning. Figure 1 - IC/CG lightning detection from IMPACT sensors (gray line) and LS7000 sensors (black line) showing the IC detection between -5kA and +5kA.

  6. Energy transfer problems of ball lightning

    Energy Technology Data Exchange (ETDEWEB)

    Egely, G.

    1986-04-01

    The paper analyzes the energy transport phenomenon of ball lightnings, but momentum and charge transport phenomena are considered as well. The physical properties as energy density and transfer are investigated using several observers' accounts of interactions with different objects. It is shown that contrary to previous assumptions the ball lightning has negative electric charge, and very high internal energy density. Both internal and external energy source models are analyzed, and it is shown that regardless to the details of a given model neither of them can explain actual observations. This has been validated by a well documented case study, and by several additional observations. An entirely new, testable model is suggested, which is able to stand for all observed properties of ball lightnings, and it explains the cause of rarity of ball lightnings, and the reasons of the unsuccessful experimental efforts. It is shown that the plasma sphere is just a visible side effect of a more important phenomenon.

  7. GRIP LIGHTNING INSTRUMENT PACKAGE (LIP) V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The Lightning Instrument Package (LIP) consists of 6 rotating vane type electric field sensors along with a central computer to record and monitor the instruments....

  8. Central hyperadrenergic state after lightning strike.

    Science.gov (United States)

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

    2013-08-01

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

  9. Lightning protection system for a wind turbine

    Science.gov (United States)

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

    2008-05-27

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

  10. Volcanic Lightning in Eruptions of Sakurajima Volcano

    Science.gov (United States)

    Edens, Harald; Thomas, Ronald; Behnke, Sonja; McNutt, Stephen; Smith, Cassandra; Farrell, Alexandra; Van Eaton, Alexa; Cimarelli, Corrado; Cigala, Valeria; Eack, Ken; Aulich, Graydon; Michel, Christopher; Miki, Daisuke; Iguchi, Masato

    2016-04-01

    In May 2015 a field program was undertaken to study volcanic lightning at the Sakurajima volcano in southern Japan. One of the main goals of the study was to gain a better understanding of small electrical discharges in volcanic eruptions, expanding on our earlier studies of volcanic lightning at Augustine and Redoubt volcanoes in Alaska, USA, and Eyjafjallajökull in Iceland. In typical volcanic eruptions, electrical activity occurs at the onset of an eruption as a near-continual production of VHF emissions at or near to the volcanic vent. These emissions can occur at rates of up to tens of thousands of emissions per second, and are referred to as continuous RF. As the ash cloud expands, small-scale lightning flashes of several hundred meters length begin to occur while the continuous RF ceases. Later on during the eruption larger-scale lightning flashes may occur within the ash cloud that are reminiscent of regular atmospheric lightning. Whereas volcanic lightning flashes are readily observed and reasonably well understood, the nature and morphology of the events producing continuous RF are unknown. During the 2015 field program we deployed a comprehensive set of instrumentation, including a 10-station 3-D Lightning Mapping Array (LMA) that operated in 10 μs high time resolution mode, slow and fast ΔE antennas, a VHF flat-plate antenna operating in the 20-80 MHz band, log-RF waveforms within the 60-66 MHz band, an infra-red video camera, a high-sensitivity Watec video camera, two high-speed video cameras, and still cameras. We give an overview of the Sakurajima field program and present preliminary results using correlated LMA, waveforms, photographs and video recordings of volcanic lightning at Sakurajima volcano.

  11. Improved Detection of Winter Lightning in the Tohoku Region of Japan using Vaisala’s LS700x Technology

    Science.gov (United States)

    Cummins, Kenneth L.; Honma, Noriyasu; Pifer, Alburt E.; Rogers, Tim; Tatsumi, Masataka

    The demand for both data quality and the range of Cloud-to-Ground (CG) lightning parameters is highest for forensic applications within the electric utility industry. For years, the research and operational communities within this industry in Japan have pointed out a limitation of these LLS networks in the detection and location of damaging (high-current and/or large charge transfer) lightning flashes during the winter months (so-called “Winter Lightning”). Most of these flashes appear to be upward-connecting discharges, frequently referred to as “Ground-to-Cloud” (GC) flashes. The basic architecture and design of Vaisala’s new LS700x lightning sensor was developed in-part to improve detection of these unusual and complex flashes. This paper presents our progress-to-date on this effort. We include a review of the winter lightning detection problem, an overview of the LS700x architecture, a discussion of how this architecture was exploited to evaluate and improve performance for winter lightning, and a presentation of results-to-date on performance improvement. A comparison of GC detection performance between Tohoku’s operational 9-sensor IMPACT (ALDF 141-T) LLS and its 6-sensor LS700x research network indicates roughly a factor-of-two improvement for this class of discharges, with an overall detection of 23/24 (96%) of GC flashes.

  12. Copper wire bonding

    CERN Document Server

    Chauhan, Preeti S; Zhong, ZhaoWei; Pecht, Michael G

    2014-01-01

    This critical volume provides an in-depth presentation of copper wire bonding technologies, processes and equipment, along with the economic benefits and risks.  Due to the increasing cost of materials used to make electronic components, the electronics industry has been rapidly moving from high cost gold to significantly lower cost copper as a wire bonding material.  However, copper wire bonding has several process and reliability concerns due to its material properties.  Copper Wire Bonding book lays out the challenges involved in replacing gold with copper as a wire bond material, and includes the bonding process changes—bond force, electric flame off, current and ultrasonic energy optimization, and bonding tools and equipment changes for first and second bond formation.  In addition, the bond–pad metallurgies and the use of bare and palladium-coated copper wires on aluminum are presented, and gold, nickel and palladium surface finishes are discussed.  The book also discusses best practices and re...

  13. A model for ball lightning

    International Nuclear Information System (INIS)

    Fryberger, D.

    1994-10-01

    A model for ball lightning (BL) is described. It is based upon the vorton model for elementary particles, which exploits the symmetry between electricity and magnetism. The core, or driving engine, of BL in this model is comprised of a vorton-antivorton plasma. The energy of BL, which derives from nucleon decay catalyzed by this plasma, leads, through various mechanisms, to BL luminosity as well as to other BL features. It is argued that this model could also be a suitable explanation for other luminous phenomena, such as the unidentified atmospheric light phenomena seen at Hessdalen. It is predicted that BL and similar atmospheric luminous phenomena should manifest certain features unique to this model, which would be observable with suitable instrumentation

  14. Characteristics of lightning flashes generating dancing sprites above thunderstorms

    Science.gov (United States)

    Soula, Serge; Mlynarczyk, Janusz; Füllekrug, Martin; Pineda, Nicolau; Georgis, Jean-François; van der Velde, Oscar; Montanyà, Joan; Fabro, Ferran

    2017-04-01

    During the night of October 29-30, 2013, a low-light video camera at Pic du Midi (2877 m) in the French Pyrénées, recorded TLEs above a very active storm over the Mediterranean Sea. The minimum cloud top temperature reached -73˚ C at ˜1600 UTC while its cloud to ground (CG) flash rate reached ˜30 fl min-1. Some sprite events with long duration are classified as dancing sprites. We analyze in detail the temporal evolution and estimated location of sprite elements for two cases of these events. They consist in series of sprite sequences with a duration that exceeds 1 second. By associating the cloud structure, the lightning activity, the electric field radiated in a broad range of low frequencies and the current moment waveform of the lightning strokes, some findings are highlighted: (i) In each series, successive sprite sequences reflect the occurrence time and location of individual positive lightning strokes across the stratiform region. (ii) The longer time-delayed (> 20 ms) sprite elements correspond to the lower impulsive charge moment changes (iCMC) of the parent stroke (< 200 C km) and they are shifted few tens of kilometres from their SP+CG stroke. However, both short and long time-delayed sprite elements also occur after strokes that produce a large iCMC and that are followed by a continuing current. (iii) The long time-delayed sprite elements produced during the continuing current correspond to surges in the current moment waveform. They occur sometimes at an altitude apparently lower than the previous short time-delayed sprite elements, possibly because of the lowered altitude of the ionosphere potential. (iv) The largest and brightest sprite elements produce significant current signatures, visible when their delay is not too short (˜3-5 ms).

  15. Magnetic paleointensities in fault pseudotachylytes and implications for earthquake lightnings

    Science.gov (United States)

    Leibovitz, Natalie Ruth

    pseudotachylyte samples. The cause of this IRM may be attributed to an LIRM produced by ground lightning (less likely), LIRM produced by an EQL (more likely), or a VRM imparted during laboratory preparation (not likely). The anomalously high NRM recorded in a few specimens points to LIRM as the most likely explanation for the dominant origin of magnetization.

  16. The Elusive Evidence of Volcanic Lightning.

    Science.gov (United States)

    Genareau, K; Gharghabi, P; Gafford, J; Mazzola, M

    2017-11-14

    Lightning strikes are known to morphologically alter and chemically reduce geologic formations and deposits, forming fulgurites. A similar process occurs as the result of volcanic lightning discharge, when airborne volcanic ash is transformed into lightning-induced volcanic spherules (LIVS). Here, we adapt the calculations used in previous studies of lightning-induced damage to infrastructure materials to determine the effects on pseudo-ash samples of simplified composition. Using laboratory high-current impulse experiments, this research shows that within the lightning discharge channel there is an ideal melting zone that represents roughly 10% or less of the total channel radius at which temperatures are sufficient to melt the ash, regardless of peak current. The melted ash is simultaneously expelled from the channel by the heated, expanding air, permitting particles to cool during atmospheric transport before coming to rest in ash fall deposits. The limited size of this ideal melting zone explains the low number of LIVS typically observed in volcanic ash despite the frequent occurrence of lightning during explosive eruptions.

  17. Rationales for the Lightning Launch Commit Criteria

    Science.gov (United States)

    Willett, John C. (Editor); Merceret, Francis J. (Editor); Krider, E. Philip; O'Brien, T. Paul; Dye, James E.; Walterscheid, Richard L.; Stolzenburg, Maribeth; Cummins, Kenneth; Christian, Hugh J.; Madura, John T.

    2016-01-01

    Since natural and triggered lightning are demonstrated hazards to launch vehicles, payloads, and spacecraft, NASA and the Department of Defense (DoD) follow the Lightning Launch Commit Criteria (LLCC) for launches from Federal Ranges. The LLCC were developed to prevent future instances of a rocket intercepting natural lightning or triggering a lightning flash during launch from a Federal Range. NASA and DoD utilize the Lightning Advisory Panel (LAP) to establish and develop robust rationale from which the criteria originate. The rationale document also contains appendices that provide additional scientific background, including detailed descriptions of the theory and observations behind the rationales. The LLCC in whole or part are used across the globe due to the rigor of the documented criteria and associated rationale. The Federal Aviation Administration (FAA) adopted the LLCC in 2006 for commercial space transportation and the criteria were codified in the FAA's Code of Federal Regulations (CFR) for Safety of an Expendable Launch Vehicle (Appendix G to 14 CFR Part 417, (G417)) and renamed Lightning Flight Commit Criteria in G417.

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

    Science.gov (United States)

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

  19. Calculation of transient potential rise on the wind turbine struck by lightning.

    Science.gov (United States)

    Xiaoqing, Zhang

    2014-01-01

    A circuit model is proposed in this paper for calculating the transient potential rise on the wind turbine struck by lightning. The model integrates the blade, sliding contact site, and tower and grounding system of the wind turbine into an equivalent circuit. The lightning current path from the attachment point to the ground can be fully described by the equivalent circuit. The transient potential responses are obtained in the different positions on the wind turbine by solving the circuit equations. In order to check the validity of the model, the laboratory measurement is made with a reduced-scale wind turbine. The measured potential waveform is compared with the calculated one and a better agreement is shown between them. The practical applicability of the model is also examined by a numerical example of a 2 MW Chinese-built wind turbine.

  20. The Rondonia Lightning Detection Network: Network Description, Science Objectives, Data Processing Archival/Methodology, and Results

    Science.gov (United States)

    Blakeslee, R. J.; Bailey, J. C.; Pinto, O.; Athayde, A.; Renno, N.; Weidman, C. D.

    2003-01-01

    A four station Advanced Lightning Direction Finder (ALDF) network was established in the state of Rondonia in western Brazil in 1999 through a collaboration of U.S. and Brazilian participants from NASA, INPE, INMET, and various universities. The network utilizes ALDF IMPACT (Improved Accuracy from Combined Technology) sensors to provide cloud-to-ground lightning observations (i.e., stroke/flash locations, signal amplitude, and polarity) using both time-of- arrival and magnetic direction finding techniques. The observations are collected, processed and archived at a central site in Brasilia and at the NASA/Marshall Space Flight Center in Huntsville, Alabama. Initial, non-quality assured quick-look results are made available in near real-time over the Internet. The network, which is still operational, was deployed to provide ground truth data for the Lightning Imaging Sensor (LIS) on the Tropical Rainfall Measuring Mission (TRMM) satellite that was launched in November 1997. The measurements are also being used to investigate the relationship between the electrical, microphysical and kinematic properties of tropical convection. In addition, the long-time series observations produced by this network will help establish a regional lightning climatological database, supplementing other databases in Brazil that already exist or may soon be implemented. Analytic inversion algorithms developed at the NASA/Marshall Space Flight Center have been applied to the Rondonian ALDF lightning observations to obtain site error corrections and improved location retrievals. The data will also be corrected for the network detection efficiency. The processing methodology and the results from the analysis of four years of network operations will be presented.