Physics and Astronomy › Astronomy and Astrophysics

Lightning and Electromagnetic Phenomena

Works Count: 44314

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Description

This cluster of papers focuses on the global distribution, physics, and effects of lightning, including topics such as terrestrial gamma-ray flashes, the atmospheric electric circuit, climate change, thunderstorm dynamics, lightning detection systems, electromagnetic fields associated with lightning, and simulation of lightning-related phenomena.

Keywords

Lightning; Distribution; Physics; Terrestrial Gamma-Ray Flashes; Atmospheric Electric Circuit; Climate Change; Thunderstorms; Detection Systems; Electromagnetic Fields; Simulation

Distribution System Modeling and Analysis

2012-05-14

W.H. Kersting

For decades, distribution engineers did not have the sophisticated tools developed for analyzing transmission systems-often they had only their instincts. Things have changed, and we now have computer programs that … For decades, distribution engineers did not have the sophisticated tools developed for analyzing transmission systems-often they had only their instincts. Things have changed, and we now have computer programs that allow engineers to simulate, analyze, and optimize distribution systems. Powerful as these programs are, however, without a real unders

Contact electrification of insulating materials

2011-10-28

Daniel J. Lacks , R. Mohan Sankaran

The electrostatic charge that is generated when two materials are contacted or rubbed and then separated is a well-known physical process that has been studied for more than 2500 years. … The electrostatic charge that is generated when two materials are contacted or rubbed and then separated is a well-known physical process that has been studied for more than 2500 years. Contact electrification occurs in many contexts, both natural and technological. For example, in dust storms the collisions between particles lead to electrostatic charging and in extreme cases, extraordinary lightning displays. In electrophotography, toner particles are intentionally charged to guide their deposition in well-defined patterns. Despite such a long history and so many important consequences, a fundamental understanding of the mechanism behind contact electrification remains elusive. An open question is what type of species are transferred between the surfaces to generate charge—experiments suggest various species ranging from electrons to ions to nanoscopic bits of material, and theoretical work suggests that non-equilibrium states may play an important role. Another open question is the contact electrification that occurs when two insulating materials with identical physical properties touch—since there is no apparent driving force, it is not clear why charge transfer occurs. A third open question involves granular systems—models and experiments have shown that a particle-size dependence for the charging often exists. In this review, we discuss the fundamental aspects of contact electrification and highlight recent research efforts aimed at understanding these open questions.

The Schumann Resonance: A Global Tropical Thermometer

1992-05-22

Earle Williams

The Schumann resonance, a global electromagnetic phenomenon, is shown to be a sensitive measure of temperature fluctuations in the tropical atmosphere. The link between Schumann resonance and temperature is lightning … The Schumann resonance, a global electromagnetic phenomenon, is shown to be a sensitive measure of temperature fluctuations in the tropical atmosphere. The link between Schumann resonance and temperature is lightning flash rate, which increases nonlinearly with temperature in the interaction between deep convection and ice microphysics.

THUNDERSTORM CHARGE SEPARATION

1957-10-01

Steve Reynolds , M. Brook , Mary Foulks Gourley

A description of the known physical properties of a thunderstorm reveals that active charge separation occurs during that stage of the storm's life-cycle in which the growth of graupel by … A description of the known physical properties of a thunderstorm reveals that active charge separation occurs during that stage of the storm's life-cycle in which the growth of graupel by the accretion of supercooled droplets is the dominant process. Laboratory experiments under simulated thunderstorm conditions show that a graupel pellet, growing by the accretion of supercooled droplets, acquires negative charge as a result of collisions with ice crystals. Other experiments show that when two ice formations are placed in rubbing contact, the ice which is warmer, or which contains trace amounts of contaminants, acquires negative charge. Further experiments suggest that the charge separation results from potential differences which arise during the resolidification of a liquid layer formed at the ice-ice contact. Calculations indicate that the graupel pellets in a thunderstorm, as a result of the acquisition of the latent heat of supercooled droplets, will achieve temperatures several degrees warmer than coexisting ice crystals. Thus the graupel pellets will acquire negative charge as a result of rubbing contacts with ice crystals. The graupel pellets have much higher fall velocities than ice crystals, thus accounting for the polarity of the main thunderstorm dipole. Measurements suggest that the amount of charge separated per graupelcrystal collision is adequate to account for the magnitude of the charges of the main dipole.

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The electrical nature of storms

1998-10-01

Donald R. MacGorman , W. David Rust , Earle Williams

Tutorial: Basic Electricity and Magnetism 1. Overview of the Electrical Nature of the Earth's Atmosphere 2. Electrified Non-Thunderstorm Clouds 3. Introduction to the Electrical Nature of Thunderstorms 4. Corona and … Tutorial: Basic Electricity and Magnetism 1. Overview of the Electrical Nature of the Earth's Atmosphere 2. Electrified Non-Thunderstorm Clouds 3. Introduction to the Electrical Nature of Thunderstorms 4. Corona and Point Discharge 5. Lightning 6. Instruments 7. Observations of the Electrical Characteristics of Thunderstorms, Part 1 8. Observations of the Electrical Characteristics of Thunderstorms, Part 2 9. Numerical Models of Thunderstorm Electrification 10. Electrical Effects on Cloud Microphysics

Runaway electron mechanism of air breakdown and preconditioning during a thunderstorm

1992-06-01

A. V. Gurevich , G. M. Milikh , R. Roussel‐Dupré

A GPS‐based three‐dimensional lightning mapping system: Initial observations in central New Mexico

1999-12-01

W. Rison , R. J. Thomas , P. R. Krehbiel +2 more

A GPS‐based system has been developed that accurately locates the sources of VHF radiation from lightning discharges in three spatial dimensions and time. The observations are found to reflect the … A GPS‐based system has been developed that accurately locates the sources of VHF radiation from lightning discharges in three spatial dimensions and time. The observations are found to reflect the basic charge structure of electrified storms. Observations have also been obtained of a distinct type of energetic discharge referred to as positive bipolar breakdown, recently identified as the source of trans‐ionospheric pulse pairs (TIPPs) observed by satellites from space. The bipolar breakdown has been confirmed to occur between the main negative and upper positive charge regions of a storm and found to be the initial event of otherwise normal intracloud discharges. The latter is contrary to previous findings that the breakdown appeared to be temporally isolated from other lightning in a storm. Peak VHF radiation from the energetic discharges is observed to be typically 30 dB stronger than that from other lightning processes and to correspond to source power in excess of 100 kW over a 6 MHz bandwidth centered at 63 MHz.

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Lightning Physics and Effects

2004-03-16

Richard E. Orville

Lightning Physics and Effects is not a lightning book; it is a lightning encyclopedia. Rarely in the history of science has one contribution covered a subject with such depth and … Lightning Physics and Effects is not a lightning book; it is a lightning encyclopedia. Rarely in the history of science has one contribution covered a subject with such depth and thoroughness as to set the enduring standard for years, perhaps even decades, to come. This contribution covers all aspects of lightning, including lightning physics, lightning protection, and the interaction of lightning with a variety of objects and systems as well as the environment. The style of writing is well within the ability of the technical non‐expert and anyone interested in lightning and its effects. Potential readers will include physicists; engineers working in the power industry, communications, computer, and aviation industries; atmospheric scientists; geophysicists; meteorologists; atmospheric chemists; foresters; ecologists; physicians working in the area of electrical trauma; and, lastly, architects.

Television Image of a Large Upward Electrical Discharge Above a Thunderstorm System

1990-07-06

R. C. Franz , R. J. Nemzek , J. R. Winckler

An image of an unusual luminous electrical discharge over a thunderstorm 250 kilometers from the observing site has been obtained with a low-light-level television camera. The discharge began at the … An image of an unusual luminous electrical discharge over a thunderstorm 250 kilometers from the observing site has been obtained with a low-light-level television camera. The discharge began at the cloud tops at 14 kilometers and extended into the clear air 20 kilometers higher. The image, which had a duration of less than 30 milliseconds,resembled two jets or fountains and was probably caused by two localizd electric charge concentrations at the cloud tops. Large upward discharges may create a hazard for aircraft and rocket launches and, by penetrating into the ionosphere, may initiate whistler waves and other effects on a magnetospheric scale. Such upward electrical discharges may account for unexplained photometric observations of distant lightning events that showed a low rise rate of the luminous pulse and no electromagnetic sferic pulse of the type that accompanies cloud-to-earth lightning strokes. An unusually high rate of such photometric events was recorded during the night of 22 to 23 September 1989 during a storm associated with hurricane Hugo.

Transient Response of Multiconductor Transmission Lines Excited by a Nonuniform Electromagnetic Field

1980-05-01

Ashok K. Agrawal , Harold J. Price , Shyam Gurbaxani

The time-domain transmission-line equations for uniform multiconductor transmission lines in a conductive, homogeneous medium excited by a transient, nonuniform electromagnetic (EM) field, are derived from Maxwell's equations. Depending on how … The time-domain transmission-line equations for uniform multiconductor transmission lines in a conductive, homogeneous medium excited by a transient, nonuniform electromagnetic (EM) field, are derived from Maxwell's equations. Depending on how the line voltage is defined, two formulations are possible. One of these formulations is considerably more convenient to apply than the other. The assumptions made in the derivation of the transmission-line equations and the boundary conditions at the terminations are discussed. For numerical calculations, the transmission -line equations are represented by finite-difference techniques, and numerical examples are included.

The tripole structure of thunderstorms

1989-09-30

Earle Williams

Evidence for the tripole structure of electrified clouds is summarized. The observed structure is quantitatively consistent with the results of laboratory simulations and suggests that collision between ice crystals and … Evidence for the tripole structure of electrified clouds is summarized. The observed structure is quantitatively consistent with the results of laboratory simulations and suggests that collision between ice crystals and rimed graupel particles is the dominant mechanism for charge separation in thunderstorms. The physical basis for this mechanism is poorly understood.

Lightning physics and effects

2013-05-23

Jinliang He , Vladimir A. Rakov , Daohong Wang +1 more

Distribution system power flow analysis-a rigid approach

1991-07-01

T.-H. Chen , M.-S. Chen , Kab Ju Hwang +2 more

This approach is oriented toward applications in three phase distribution system operational analysis rather than planning analysis. The solution method is the optimally ordered triangular factorization Y/sub BUS/ method (implicit … This approach is oriented toward applications in three phase distribution system operational analysis rather than planning analysis. The solution method is the optimally ordered triangular factorization Y/sub BUS/ method (implicit Z/sub BUS/ Gauss method) which not only takes advantage of the sparsity of system equations but also has very good convergence characteristics on distribution problems. Detailed component models are needed for all system components in the simulation. Utilizing the phase frame representation for all network elements, a program called Generalized Distribution Analysis Systems, with a number of features and capabilities not found in existing packages, has been developed for large-scale distribution system simulations. The system being analyzed can be balanced or unbalanced and can be a radial, network, or mixed-type distribution system. Furthermore, because the individual phase representation is employed for both system and component models, the system can comprise single, double, and three-phase systems simultaneously.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>

Terrestrial Gamma-Ray Flashes Observed up to 20 MeV

2005-02-17

David M. Smith , Liliana I. Lopez , R. P. Lin +1 more

Terrestrial gamma-ray flashes (TGFs) from Earth's upper atmosphere have been detected with the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) satellite. The gamma-ray spectra typically extend up to 10 … Terrestrial gamma-ray flashes (TGFs) from Earth's upper atmosphere have been detected with the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) satellite. The gamma-ray spectra typically extend up to 10 to 20 megaelectron volts (MeV); a simple bremsstrahlung model suggests that most of the electrons that produce the gamma rays have energies on the order of 20 to 40 MeV. RHESSI detects 10 to 20 TGFs per month, corresponding to ∼50 per day globally, perhaps many more if they are beamed. Both the frequency of occurrence and maximum photon energy are more than an order of magnitude higher than previously known for these events.

Sprites produced by quasi‐electrostatic heating and ionization in the lower ionosphere

1997-03-01

Victor P. Pasko , U. S. Inan , T. F. Bell +1 more

Quasi‐electrostatic (QE) fields that temporarily exist at high altitudes following the sudden removal (e.g., by a lightning discharge) of thundercloud charge at low altitudes lead to ambient electron heating (up … Quasi‐electrostatic (QE) fields that temporarily exist at high altitudes following the sudden removal (e.g., by a lightning discharge) of thundercloud charge at low altitudes lead to ambient electron heating (up to ∼5 eV average energy), ionization of neutrals, and excitation of optical emissions in the mesosphere/lower ionosphere. Model calculations predict the possibility of significant (several orders of magnitude) modification of the lower ionospheric conductivity in the form of depletions of electron density due to dissociative attachment to O 2 molecules and/or in the form of enhancements of electron density due to breakdown ionization. Results indicate that the optical emission intensities of the 1st positive band of N 2 corresponding to fast (∼ 1 ms) removal of 100–300 C of thundercloud charge from 10 km altitude are in good agreement with observations of the upper part (“head” and “hair” [ Sentman et al. , 1995]) of the sprites. The typical region of brightest optical emission has horizontal and vertical dimensions ∼10 km, centered at altitudes 70 km and is interpreted as the head of the sprite. The model also shows the formation of low intensity glow (“hair”) above this region due to the excitation of optical emissions at altitudes ∼ 85 km during ∼ 500 μ s at the initial stage of the lightning discharge. Comparison of the optical emission intensities of the 1st and 2nd positive bands of N 2 , Meinel and 1st negative bands of , and 1st negative band of demonstrates that the 1st positive band of N 2 is the dominating optical emission in the altitude range around ∼70 km, which accounts for the observed red color of sprites, in excellent agreement with recent spectroscopic observations of sprites. Results indicate that the optical emission levels are predominantly defined by the lightning discharge duration and the conductivity properties of the atmosphere/lower ionosphere (i.e., relaxation time of electric field in the conducting medium). The model demonstrates that for low ambient conductivities the lightning discharge duration can be significantly extended with no loss in production of optical emissions. The peak intensity of optical emissions is determined primarily by the value of the removed thundercloud charge and its altitude. The preexisting inhomogeneities in the mesospheric conductivity and the neutral density may contribute to the formation of a vertically striated fine structure of sprites and explain why sprites often repeatedly occur in the same place in the sky as well as their clustering. Comparison of the model results for different types of lightning discharges indicates that positive cloud to ground discharges lead to the largest electric fields and optical emissions at ionospheric altitudes since they are associated with the removal of larger amounts of charge from higher altitudes.

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An electromagnetic model for transients in grounding systems

1990-01-01

Leonid Grčev , F. Dawalibi

The development and application of a computer model for analyzing the transient performance of grounding systems based on electromagnetic field theory is described. The use of a combination of numerical … The development and application of a computer model for analyzing the transient performance of grounding systems based on electromagnetic field theory is described. The use of a combination of numerical integration techniques, method of moments, adaptive interpolation, and fast Fourier transform constitutes the basis for the computation of various physical quantities such as the electric fields in the ground, longitudinal and leakage currents in the ground conductors, and ground impedances. It is shown that the analysis of conductors energized by current waves can require computations at frequencies higher than the significant frequencies in the spectrum of the excitation signal, while simpler models may fail to predict accurately the transient performance. The main limitation of the computer model is the time required for the analysis of large or complex grounding systems.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>

A Combined TOA/MDF Technology Upgrade of the U.S. National Lightning Detection Network

1998-04-01

Kenneth L. Cummins , Martin J. Murphy , Edward A. Bardo +3 more

The U.S. National Lightning Detection Network TM (NLDN) has provided lightning data covering the continental United States since 1989. Using information gathered from more than 100 sensors, the NLDN provides … The U.S. National Lightning Detection Network TM (NLDN) has provided lightning data covering the continental United States since 1989. Using information gathered from more than 100 sensors, the NLDN provides both real‐time and historical lightning data to the electric utility industry, the National Weather Service, and other government and commercial users. It is also the primary source of lightning data for use in research and climatological studies in the United States. In this paper we discuss the design, implementation, and data from the time‐of‐arrival/magnetic direction finder (TOA/MDF) network following a recent system‐wide upgrade. The location accuracy (the maximum dimension of a confidence region around the stroke location) has been improved by a factor of 4 to 8 since 1991, resulting in a median accuracy of 500 m. The expected flash detection efficiency ranges from 80% to 90% for those events with peak currents above 5 kA, varying slightly by region. Subsequent strokes and strokes with peak currents less than 5 kA can now be detected and located; however, the detection efficiency for these events is not quantified in this study because their peak current distribution is not well known.

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The Vertical Profile of Radar Reflectivity of Convective Cells: A Strong Indicator of Storm Intensity and Lightning Probability?

1994-08-01

Edward J. Zipser , Kurt Reed Lutz

Reflectivity data from Doppler radars are used to construct vertical profiles of radar reflectivity (VPRR) of convective cells in mesoscale convective systems (MCSS) in three different environmental regimes. The National … Reflectivity data from Doppler radars are used to construct vertical profiles of radar reflectivity (VPRR) of convective cells in mesoscale convective systems (MCSS) in three different environmental regimes. The National Center for Atmospheric Research CP-3 and CP-4 radars are used to calculate median VPRR for MCSs in the Oklahoma-Kansas Preliminary Regional Experiment for STORM-Central in 1985. The National Oceanic and Atmospheric Administration-Tropical Ocean Global Atmosphere radar in Darwin, Australia, is used to calculate VPRR for MCSs observed both in oceanic, monsoon regimes and in continental, break period regimes during the wet seasons of 1987/88 and 1988/89. The midlatitude and tropical continental VPRRs both exhibit maximum reflectivity somewhat above the surface and have a gradual decrease in reflectivity with height above the freezing level. In sharp contrast, the tropical oceanic profile has a maximum reflectivity at the lowest level and a very rapid decrease in reflectivity with height beginning just above the freezing level. The tropical oceanic profile in the Darwin area is almost the same shape as that for two other tropical oceanic regimes, leading to the conclusion that it is characteristic. The absolute values of reflectivity in the 0° to −20°C range are compared with values in the literature thought to represent a threshold for rapid storm electrification leading to lightning, about 40 dBZ at −10°C. Most oceanic cells have reflectivities below the threshold; most midlatitude continental cells exceed the threshold, and the tropical continental cells are about equally divided above and below the threshold. The large negative vertical gradient of reflectivity in this temperature range for oceanic storms is hypothesized to be a direct result of the characteristically weaker vertical velocities observed in MCSs over tropical oceans. It is proposed, as a necessary condition for rapid electrification, that a convective cell must have its updraft speed exceed some threshold value. Based upon field program data, a tentative estimate for the magnitude of this threshold is 6–7 m s−1 for mean speed and 10–12 m s−1 for peak speed.

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Wave Propagation in Overhead Wires with Ground Return

1926-10-01

John R. Carson

The problem of wave propagation along a transmission system composed of an overhead wire parallel to the (plane) surface of the earth, in spite of its great technical importance, does … The problem of wave propagation along a transmission system composed of an overhead wire parallel to the (plane) surface of the earth, in spite of its great technical importance, does not appear to have been satisfactorily solved.1 While a complete solution of the actual problem is impossible, on account of the inequalities in the earth's surface and its lack of conductive homogeneity, the solution of the problem, where the actual earth is replaced by a plane homogeneous semi-infinite solid, is of considerable theoretical and practical interest. The solution of this problem is given in the present paper, together with formulas for calculating inductive disturbances in neighboring transmission systems.

A simple lightning parameterization for calculating global lightning distributions

1992-06-20

Colin Price , David Rind

A simple parameterization has been developed to simulate global lightning distributions. Convective cloud top height is used as the variable in the parameterization, with different formulations for continental and marine … A simple parameterization has been developed to simulate global lightning distributions. Convective cloud top height is used as the variable in the parameterization, with different formulations for continental and marine thunderstorms. The parameterization has been validated using two lightning data sets: one global and one regional. In both cases the simulated lightning distributions and frequencies are in very good agreement with the observed lightning data. This parameterization could be used for global studies of lightning climatology; the Earth's electric circuit; in general circulation models for modeling global lightning activity, atmospheric NO x concentrations, and perhaps forest fire distributions for both the present and future climate; and, possibly, even as a short‐term forecasting aid.

The physics of lightning

2013-10-10

J. R. Dwyer , M. A. Uman

Accuracy of the Lightning Mapping Array

2004-07-27

Ronald J. Thomas , P. R. Krehbiel , W. Rison +4 more

The location accuracy of the New Mexico Tech Lightning Mapping Array (LMA) has been investigated experimentally using sounding balloon measurements, airplane tracks, and observations of distant storms. We have also … The location accuracy of the New Mexico Tech Lightning Mapping Array (LMA) has been investigated experimentally using sounding balloon measurements, airplane tracks, and observations of distant storms. We have also developed simple geometric models for estimating the location uncertainty of sources both over and outside the network. The model results are found to be a good estimator of the observed errors and also agree with covariance estimates of the location uncertainties obtained from the least squares solution technique. Sources over the network are located with an uncertainty of 6–12 m rms in the horizontal and 20–30 m rms in the vertical. This corresponds well with the uncertainties of the arrival time measurements, determined from the distribution of chi‐square values to be 40–50 ns rms. Outside the network the location uncertainties increase with distance. The geometric model shows that the range and altitude errors increase as the range squared, r 2 , while the azimuthal error increases linearly with r . For the 13 station, 70 km diameter network deployed during STEPS the range and height errors of distant sources were comparable to each other, while the azimuthal errors were much smaller. The difference in the range and azimuth errors causes distant storms to be elongated radially in plan views of the observations. The overall results are shown to agree well with hyperbolic formulations of time of arrival measurements [e.g., Proctor , 1971 ]. Two appendices describe (1) the basic operation of the LMA and the detailed manner in which its measurements are processed and (2) the effect of systematic errors on lightning observations. The latter provides an alternative explanation for the systematic height errors found by Boccippio et al. [2001] in distant storm data from the Lightning Detection and Ranging system at Kennedy Space Center.

Gridded lightning climatology from TRMM-LIS and OTD: Dataset description

2012-07-16

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

Gridded climatologies of total lightning flash rates observed by the spaceborne Optical Transient Detector (OTD) and Lightning Imaging Sensor (LIS) instruments have been updated. OTD collected data from May 1995 … Gridded climatologies of total lightning flash rates observed by the spaceborne Optical Transient Detector (OTD) and Lightning Imaging Sensor (LIS) instruments have been updated. OTD collected data from May 1995 to March 2000. LIS data (equatorward of about 38°) adds the years 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 gridded climatologies include annual mean flash rate on a 0.5° grid, mean diurnal cycle of flash rate on a 2.5° grid with 24 hour resolution, mean annual cycle of flash rate on a 0.5° or 2.5° grid with daily, monthly, or seasonal resolution, mean annual cycle of the diurnal cycle on a 2.5° grid with two hour resolution for each day, and time series of flash rate over the sixteen year record with roughly three-month smoothing. For some of these (e.g., annual cycle of the diurnal cycle), more smoothing is necessary for results to be robust. The mean global flash rate from the merged climatology is 46 flashes s− 1. This varies from around 35 flashes s− 1 in February (austral summer) to 60 flashes s− 1 in August (boreal summer). The peak annual flash rate at 0.5° scale is 160 fl km− 2 yr− 1 in eastern Congo. The peak monthly average flash rate at 2.5° scale is 18 fl km− 2 mo− 1 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. An August peak in northern Pakistan also exceeds any monthly averages from Africa, despite central Africa having the greatest yearly average.

The GOES-R Geostationary Lightning Mapper (GLM)

2013-02-04

Steven J. Goodman , Richard J. Blakeslee , William J. Koshak +7 more

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Preliminary results from the Sprites94 Aircraft Campaign: 1. Red sprites

1995-05-15

D. D. Sentman , E. M. Wescott , Danny Osborne +2 more

The dual jet aircraft Sprites94 campaign yielded the first color imagery and unambiguously triangulated physical dimensions and heights of upper atmospheric optical emissions associated with thunderstorm systems. Low light level … The dual jet aircraft Sprites94 campaign yielded the first color imagery and unambiguously triangulated physical dimensions and heights of upper atmospheric optical emissions associated with thunderstorm systems. Low light level television images, in both color and in black and white (B/W), obtained during the campaign show that there are at least two distinctively different types of optical emissions spanning part or all of the distance between the anvil tops and the ionosphere. The first of these emissions, dubbed “sprites” after their elusive nature, are luminous structures of brief (< 16 ms) duration with a red main body that typically spans the altitude range 50–90 km, and possessing lateral dimensions of 5–30 km. Faint bluish tendrils often extend downward from the main body of sprites, occasionally appearing to reach cloud tops near 20 km. In this paper the principal characteristics of red sprites as observed during the Sprites94 campaign are described. The second distinctive type of emissions, “blue jets,” are described in a companion paper [ Wescott et al., this issue].

The Life Cycle of Thunderstorm Gust Fronts as Viewed with Doppler Radar and Rawinsonde Data

1982-08-01

Roger M. Wakimoto

This paper presents the time-dependent analysis of the thunderstorm gust front with the use of Project NIMROD data. RHI cross sections of reflectivity and Doppler velocity are constructed to determine … This paper presents the time-dependent analysis of the thunderstorm gust front with the use of Project NIMROD data. RHI cross sections of reflectivity and Doppler velocity are constructed to determine the entire vertical structure. The life cycle of the gust front is divided into four stages: 1) the formative stage; 2) the early mature stage; 3) the late mature stage; and 4) the dissipation stage. A new finding is a horizontal roll detected in the reflectivity pattern resulting from airflow that is deflected upward by the ground, while carrying some of the smaller precipitation ahead of the main echo core of the squall line. This feature is called a “precipitation roll”. As determined from rawinsonde data, the cold air behind the gust front accounts for the observed surface pressure rise. Calculations confirm that the collision of two fluids produce a nonhydrostatic pressure at the leading edge of the outflow. The equation governing the propagation speed of a density current accurately predicts the movement of the gust front.

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Magnetic field of lightning return stroke

1969-12-20

M. A. Uman , D. Kenneth McLain

NO<sub>x</sub> from lightning: 1. Global distribution based on lightning physics

1997-03-01

Colin Price , Joyce E. Penner , Michael J. Prather

This paper begins a study on the role of lightning in maintaining the global distribution of nitrogen oxides (NO x ) in the troposphere. It presents the first global and … This paper begins a study on the role of lightning in maintaining the global distribution of nitrogen oxides (NO x ) in the troposphere. It presents the first global and seasonal distributions of lightning‐produced NO x (LNO x ) based on the observed distribution of electrical storms and the physical properties of lightning strokes. We derive a global rate for cloud‐to‐ground (CG) flashes of 20–30 flashes/s with a mean energy per flash of 6.7×10 9 J. Intracloud (IC) flashes are more frequent, 50–70 flashes/s but have 10% of the energy of CG strokes and, consequently, produce significantly less NO x . It appears to us that the majority of previous studies have mistakenly assumed that all lightning flashes produce the same amount of NO x , thus overestimating the NO x production by a factor of 3. On the other hand, we feel these same studies have underestimated the energy released in CG flashes, resulting in two negating assumptions. For CG energies we adopt a production rate of 10×10 16 molecules NO/J based on the current literature. Using a method to simulate global lightning frequencies from satellite‐observed cloud data, we have calculated the LNO x on various spatial (regional, zonal, meridional, and global) and temporal scales (daily, monthly, seasonal, and interannual). Regionally, the production of LNO x is concentrated over tropical continental regions, predominantly in the summer hemisphere. The annual mean production rate is calculated to be 12.2 Tg N/yr, and we believe it extremely unlikely that this number is less than 5 or more than 20 Tg N/yr. Although most of LNO x , is produced in the lowest 5 km by CG lightning, convective mixing in the thunderstorms is likely to deposit large amounts of NO x , in the upper troposphere where it is important in ozone production. On an annual basis, 64% of the LNO x , is produced in the northern hemisphere, implying that the northern hemisphere should have natural ozone levels as much as 2 times greater than the southern hemisphere, even before anthropogenic influences. The amount of O 3 produced from this NO x is expected to exceed the stratospheric source by a factor of 1.5, and thus the hemispheric asymmetry in LNO x would lead to a significant excess of northern hemisphere O 3 even in the preindustrial troposphere. (The monthly climatologies for LNO x on a 1°×1° latitude‐longitude grid can be obtained by e‐mail to [email protected]).

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A compensation-based power flow method for weakly meshed distribution and transmission networks

1988-05-01

D. Shirmohammadi , Hong Hu , A. Semlyen +1 more

A power flow method is described for solving weakly meshed distribution and transmission networks, using a multiport compensation technique and basic formations of Kirchoff's laws. This method has excellent convergence … A power flow method is described for solving weakly meshed distribution and transmission networks, using a multiport compensation technique and basic formations of Kirchoff's laws. This method has excellent convergence characteristics and is robust. A computer program implementing this scheme was developed and successfully applied to several practical distribution and transmission networks with radial and weakly meshed structures. The method can be applied to the solution of both the three-phase (unbalanced) and single-phase (balanced) representation of the network, however, only the single-phase representation is treated in detail.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>

A universal model for accurate calculation of electromagnetic transients on overhead lines and underground cables

1999-07-01

A.S. Morched , Bjørn Gustavsen , M. Tartibi

This paper presents a transmission line model for the simulation of electromagnetic transients in power systems. The model can be applied to both overhead lines and cables, even in the … This paper presents a transmission line model for the simulation of electromagnetic transients in power systems. The model can be applied to both overhead lines and cables, even in the presence of a strongly frequency dependent transformation matrix and widely different modal time delays. This has been achieved through a phase domain formulation where the modal characteristics have been utilized in the approximation for the propagation matrix. High computational efficiency is achieved by grouping modes with nearly equal velocities and by columnwise realization of the matrices for propagation and characteristic admittance.

An Overview of Lightning Locating Systems: History, Techniques, and Data Uses, With an In-Depth Look at the U.S. NLDN

2009-07-28

Kenneth L. Cummins , Martin J. Murphy

Lightning in all corners of the world is monitored by one or more land- or space-based lightning locating systems (LLSs). The applications that have driven these developments are numerous and … Lightning in all corners of the world is monitored by one or more land- or space-based lightning locating systems (LLSs). The applications that have driven these developments are numerous and varied. This paper describes the history leading to modern LLSs that sense lightning radiation fields at multiple remote sensors, focusing on the interactions between enabling technology, scientific discovery, technical development, and uses of the data. An overview of all widely used detection and location methods is provided, including a general discussion of their relative strengths and weaknesses for various applications. The U.S. National Lightning Detection Network (NLDN) is presented as a case study, since this LLS has been providing real-time lightning information since the early 1980s, and has provided continental-scale (U.S.) information to research and operational users since 1989. This network has also undergone a series of improvements during its >20-year life in response to evolving detection technologies and expanding requirements for applications. Recent analyses of modeled and actual performance of the current NLDN are also summarized. The paper concludes with a view of the short- and long-term requirements for improved lightning measurements that are needed to address some open scientific questions and fill the needs of emerging applications.

Review and evaluation of lightning return stroke models including some aspects of their application

1998-01-01

Vladimir A. Rakov , M. A. Uman

Four classes of models of the lightning return stroke are reviewed. These four classes are: (1) the gas dynamic models; (2) the electromagnetic models; (3) the distributed-circuit models; and (4) … Four classes of models of the lightning return stroke are reviewed. These four classes are: (1) the gas dynamic models; (2) the electromagnetic models; (3) the distributed-circuit models; and (4) the "engineering" models. Validation of the reviewed models is discussed. For the gas dynamic models, validation is based on observations of the optical power and spectral output from natural lightning. The electromagnetic, distributed-circuit, and "engineering" models are most conveniently validated using measured electric and magnetic fields from natural and triggered lightning. Based on the entirety of the validation results and on mathematical simplicity, we rank the "engineering" models in the following descending order: MTLL, DU, MTLE, BG, and TL. When only the initial peak values of the channel-base current and remote electric or magnetic field are concerned, the TL model is preferred. Additionally discussed are several issues in lightning return-stroke modeling that either have been ignored to keep the modeling straightforward or have not been recognized, such as the treatment of the upper, in-cloud portion of the lightning channel, the boundary conditions at the ground, including the presence of a vertically extended strike object, the return-stroke speed at early times, the initial bi-directional extension of the return stroke channel, and the relation between leader and return stroke models. Various aspects of the calculation of lightning electric and magnetic fields in which return stroke models are used to specify the source are considered, including equations for fields and channel-base current, as well as a discussion of channel tortuosity and branches.

Accurate Modelling of Frequency-Dependent Transmission Lines in Electromagnetic Transient Simulations

1982-01-01

José R. Martí

The parameters of transmission lines with ground return are highly dependent on the frequency. Accurate modelling of this frequency dependence over the entire frequency range of the signals is of … The parameters of transmission lines with ground return are highly dependent on the frequency. Accurate modelling of this frequency dependence over the entire frequency range of the signals is of essential importance for the correct simulation of electromagnetic transient conditions. Closed mathematical solutions of the frequency-dependent line equations in the time domain are very difficult. Numerical approximation techniques are thus required for practical solutions. The oscillatory nature of the problem, however, makes ordinary numerical techniques very susceptible to instability and to accuracy errors. The, methods presented in this paper are aimed to overcome these numerical difficulties.

Introduction to Electrodynamics

2017-06-29

David J. Griffiths

This well-known undergraduate electrodynamics textbook is now available in a more affordable printing from Cambridge University Press. The Fourth Edition provides a rigorous, yet clear and accessible treatment of the … This well-known undergraduate electrodynamics textbook is now available in a more affordable printing from Cambridge University Press. The Fourth Edition provides a rigorous, yet clear and accessible treatment of the fundamentals of electromagnetic theory and offers a sound platform for explorations of related applications (AC circuits, antennas, transmission lines, plasmas, optics and more). Written keeping in mind the conceptual hurdles typically faced by undergraduate students, this textbook illustrates the theoretical steps with well-chosen examples and careful illustrations. It balances text and equations, allowing the physics to shine through without compromising the rigour of the math, and includes numerous problems, varying from straightforward to elaborate, so that students can be assigned some problems to build their confidence and others to stretch their minds. A Solutions Manual is available to instructors teaching from the book; access can be requested from the resources section at www.cambridge.org/electrodynamics.

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Simulated Electrification of a Small Thunderstorm with Two-Moment Bulk Microphysics

2009-07-30

Edward R. Mansell , Conrad L. Ziegler , Eric C. Bruning

Abstract Electrification and lightning are simulated for a small continental multicell storm. The results are consistent with observations and thus provide additional understanding of the charging processes and evolution of … Abstract Electrification and lightning are simulated for a small continental multicell storm. The results are consistent with observations and thus provide additional understanding of the charging processes and evolution of this storm. The first six observed lightning flashes were all negative cloud-to-ground (CG) flashes, after which intracloud (IC) flashes also occurred between middle and upper levels of the storm. The model simulation reproduces the basic evolution of lightning from low and middle levels to upper levels. The observed lightning indicated an initial charge structure of at least an inverted dipole (negative charge above positive). The simulations show that noninductive charge separation higher in the storm can enhance the main negative charge sufficiently to produce negative CG flashes before upper-level IC flashes commence. The result is a “bottom-heavy” tripole charge structure with midlevel negative charge and a lower positive charge region that is more significant than the upper positive region, in contrast to the traditional tripole structure that has a less significant lower positive charge region. Additionally, the occurrence of cloud-to-ground lightning is not necessarily a result of excess net charge carried by the storm, but it is primarily caused by the local potential imbalance between the lowest charge regions. The two-moment microphysics scheme used for this study predicted mass mixing ratio and number concentration of cloud droplets, rain, ice crystals, snow, and graupel. Bulk particle density of graupel was also predicted, which allows a single category to represent a greater range of particle characteristics. (An additional hail category is available but was not needed for the present study.) The prediction of hydrometeor number concentration is particularly critical for charge separation at higher temperatures (−5° &lt; T &lt; −20°C) in the mixed phase region, where ice crystals are produced by rime fracturing (Hallett–Mossop process) and by splintering of freezing drops. Cloud droplet concentration prediction also affected the rates of inductive charge separation between graupel and droplets.

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Discovery of Intense Gamma-Ray Flashes of Atmospheric Origin

1994-05-27

G. J. Fishman , P. N. Bhat , Robert S. Mallozzi +7 more

Detectors aboard the Compton Gamma Ray Observatory have observed an unexplained terrestrial phenomenon: brief, intense flashes of gamma rays. These flashes must originate in the atmosphere at altitudes above at … Detectors aboard the Compton Gamma Ray Observatory have observed an unexplained terrestrial phenomenon: brief, intense flashes of gamma rays. These flashes must originate in the atmosphere at altitudes above at least 30 kilometers in order to escape atmospheric absorption and reach the orbiting detectors. At least a dozen such events have been detected over the past 2 years. The photon spectra from the events are very hard (peaking in the high-energy portion of the spectrum) and are consistent with bremsstrahlung emission from energetic (million—electron volt) electrons. The most likely origin of these high-energy electrons, although speculative at this time, is a rare type of high-altitude electrical discharge above thunderstorm regions.

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Global frequency and distribution of lightning as observed from space by the Optical Transient Detector

2003-01-03

Hugh J. Christian , Richard J. Blakeslee , Dennis J. Boccippio +7 more

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 … 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 70° inclination low Earth 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 1 year period, and the average duration of each observation is 2 min. The OTD instrument optically detects lightning flashes that occur within its 1300 × 1300 km 2 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 fl s −1 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. The Congo basin, which stands out year‐round, shows a peak mean annual flash density of 80 fl km −2 yr −1 in Rwanda, and includes an area of over 3 million km 2 exhibiting flash densities greater than 30 fl km −2 yr −1 (the flash density of central Florida). Lightning is predominant in the northern Atlantic and western Pacific Ocean basins year‐round where instability is produced from cold air passing over warm ocean water. Lightning is less frequent in the eastern tropical Pacific and Indian Ocean basins where the air mass is warmer. A dominant Northern Hemisphere summer peak occurs in the annual cycle, and evidence is found for a tropically driven semiannual cycle.

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Macromodeling of Multiport Systems Using a Fast Implementation of the Vector Fitting Method

2008-06-01

Dirk Deschrijver , Michał Mrozowski , Tom Dhaene +1 more

Broadband macromodeling of large multiport systems by vector fitting can be time consuming and resource demanding when all elements of the system matrix share a common set of poles. This … Broadband macromodeling of large multiport systems by vector fitting can be time consuming and resource demanding when all elements of the system matrix share a common set of poles. This letter presents a robust approach which removes the sparsity of the block-structured least-squares equations by a direct application of the QR decomposition. A 60-port printed circuit board example illustrates that considerable savings in terms of computation time and memory requirements are obtained.

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Improving the Pole Relocating Properties of Vector Fitting

2006-06-28

Bjørn Gustavsen

This paper describes a modification of the vector fitting (VF) procedure for rational function approximation of frequency-domain responses. The modification greatly improves the ability of VF to relocate poles to … This paper describes a modification of the vector fitting (VF) procedure for rational function approximation of frequency-domain responses. The modification greatly improves the ability of VF to relocate poles to better positions, thereby improving its convergence performance and reducing the importance of the initial pole set specification. This is achieved by replacing the high-frequency asymptotic requirement of the VF scaling function with a more relaxed condition. Calculated results demonstrate a major improvement of performance when fitting responses that are contaminated with noise. The procedure is also shown to be advantageous for wideband modeling of transmission lines, network equivalents, and transformers.

Digital Computer Solution of Electromagnetic Transients in Single-and Multiphase Networks

1969-04-01

H.W. Dommel

Electromagnetic transients in arbitrary single- or multiphase networks are solved by a nodal admittance matrix method. The formulation is based on the method of characteristics for distributed parameters and the … Electromagnetic transients in arbitrary single- or multiphase networks are solved by a nodal admittance matrix method. The formulation is based on the method of characteristics for distributed parameters and the trapezoidal rule of integration for lumped parameters. Optimally ordered triangular factorization with sparsity techniques is used in the solution. Examples and programming details illustrate the practicality of the method.

Contrasting convective regimes over the Amazon: Implications for cloud electrification

2002-10-10

Earle Williams , Daniel Rosenfeld , Nicholaus M. Madden +7 more

Four distinct meteorological regimes in the Amazon basin have been examined to distinguish the contributions from boundary layer aerosol and convective available potential energy (CAPE) to continental cloud structure and … Four distinct meteorological regimes in the Amazon basin have been examined to distinguish the contributions from boundary layer aerosol and convective available potential energy (CAPE) to continental cloud structure and electrification. The lack of distinction in the electrical parameters (peak flash rate, lightning yield per unit rainfall) between aerosol‐rich October and aerosol‐poor November in the premonsoon regime casts doubt on a primary role for the aerosol in enhancing cloud electrification. Evidence for a substantial role for the aerosol in suppressing warm rain coalescence is identified in the most highly polluted period in early October. The electrical activity in this stage is qualitatively peculiar. During the easterly and westerly wind regimes of the wet season, the lightning yield per unit of rainfall is positively correlated with the aerosol concentration, but the electrical parameters are also correlated with CAPE, with a similar degree of scatter. Here cause and effect are difficult to establish with available observations. This ambiguity extends to the “green ocean” westerly regime, a distinctly maritime regime over a major continent with minimum aerosol concentration, minimum CAPE, and little if any lightning.

Rational approximation of frequency domain responses by vector fitting

1999-07-01

Bjørn Gustavsen , A. Semlyen

The paper describes a general methodology for the fitting of measured or calculated frequency domain responses with rational function approximations. This is achieved by replacing a set of starting poles … The paper describes a general methodology for the fitting of measured or calculated frequency domain responses with rational function approximations. This is achieved by replacing a set of starting poles with an improved set of poles via a scaling procedure. A previous paper (Gustavsen et al., 1997) described the application of the method to smooth functions using real starting poles. This paper extends the method to functions with a high number of resonance peaks by allowing complex starting poles. Fundamental properties of the method are discussed and details of its practical implementation are described. The method is demonstrated to be very suitable for fitting network equivalents and transformer responses. The computer code is in the public domain, available from the first author.

Riming Electrification as a Charge Generation Mechanism in Thunderstorms

1978-08-01

Tsutomu Takahashi

Riming electrification was studied in cold room experiments simulating thunderstorm conditions. When both ice crystals and supercooled droplets coexist in the experimental chamber, high electric charge occurs on the riming … Riming electrification was studied in cold room experiments simulating thunderstorm conditions. When both ice crystals and supercooled droplets coexist in the experimental chamber, high electric charge occurs on the riming probes. Both the sign and magnitude of riming electrification are highly dependent on the temperature and cloud water content. Electric charge of the order of 10−4 esu (33 fC) is separated on riming with each ice crystal collision under conditions typical of the in-cloud environment of continental thunderstorms. This amount of charge is sufficient to produce the high electrification required for lightning discharge within reasonably short periods of time. The effect of the electrical field on charge separation during the riming and effect of the freezing potential of drops of rime also were examined. It appears that these effects play only a secondary role for charge separation in thunderstorms. Three different physical mechanisms of charge separation during riming are proposed and discussed to explain the riming charge under different conditions of temperature and cloud water content. Possible differences in the character of thunderstorms at various geographical locations are briefly considered.

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Handbook of Atmospheric Electrodynamics (1995)

2017-11-22

Lightning parameters for Engineering Application

1980-01-01

R.B. Anderson

An Efficient Lightning Classifier Using a Self‐Supervised Learning Neural Network

2025-06-24

Jingyu Lu , Jinliang Li , Yü Liu +7 more | Geophysical Research Letters

Abstract The automatic classification of lightning discharge processes is a critical challenge in both lightning physics research and protection. Despite recent advancements in artificial intelligence‐based classification models, rely on supervised … Abstract The automatic classification of lightning discharge processes is a critical challenge in both lightning physics research and protection. Despite recent advancements in artificial intelligence‐based classification models, rely on supervised learning, which demands extensive manually labeled samples and data preparation. To overcome these limitations, this paper proposes a self‐supervised neural network based on the masked autoencoder framework. The model first undergoes self‐supervised pretraining with a large amount of unlabeled lightning waveform to capture general signal features by reconstructing the masked parts, followed by supervised finetuning with minimal labeled data to further optimize its performance on classification task. The model achieves 98.30% accuracy on the Beijing Broadband Lightning NETwork data set. By applying the model to two public data sets, it demonstrates competitive performance (97.94% and 98.29%) with significantly less labeled data. T‐distributed stochastic neighbor embedding visualizations confirm that the combination of the pretraining and finetuning stages is critical for achieving optimal performance.

Evaluation of video evidence of possible ball lightning

2025-06-23

Karl Stephan , Richard Sonnenfeld , J. Bertoloni | Quarterly Journal of the Royal Meteorological Society

Abstract Though ball lightning has been reported by eyewitnesses for centuries, very few photographs or other objective data exist that can be unequivocally described as evidence of ball lightning. In … Abstract Though ball lightning has been reported by eyewitnesses for centuries, very few photographs or other objective data exist that can be unequivocally described as evidence of ball lightning. In this article, we analyze a video recording made during a thunderstorm in Bozeman, Montana, in August of 2023 that shows objects less than 10 m from the camera. Many of the characteristics of these objects match those attributed to ball lightning, such as duration and estimated luminosity, although the possibility that they were burning objects from a power‐line arc cannot be eliminated. As more video evidence possibly pertaining to ball lightning arises in the future, the analytical methods demonstrated in this article should contribute to further critical analysis and study of this enigmatic phenomenon.

Characterization of Hybrid Lightning Flashes Observed by Fast Antenna Lightning Mapping Array in Summer Thunderstorms

2025-06-22

Dongdong Shi , Jie Shao , Rubin Jiang +3 more | Atmosphere

Using the observation data from Fast Antenna Lightning Mapping Array, we have sub-divided 288 hybrid flashes that are obviously different from traditional intracloud (IC) and negative cloud-to-ground (NCG) flashes into … Using the observation data from Fast Antenna Lightning Mapping Array, we have sub-divided 288 hybrid flashes that are obviously different from traditional intracloud (IC) and negative cloud-to-ground (NCG) flashes into three types: IC–NCG lightning (85), NCG–IC lightning (95), and the flashes (108) with negative leaders originating from the upper parts of bi-level structures of IC flashes. Hereinafter, we refer to these hybrid flashes as hybrid A, B, and C, respectively. The statistical comparisons indicate that characteristics from preliminary breakdown (PB) to return stroke (RS) are significantly different. On average, hybrid A and C flashes have higher initiation altitudes, larger PB–RS intervals, and longer propagation lengths than hybrid B flashes (7.9, 7.8 vs. 5.7 km; 430.3, 239.3 vs. 54.4 ms; 6.4, 7.8 vs. 2.3 km). Compared to 1562 IC and 844 CG flashes, hybrid flashes unsurprisingly have much larger horizontal flash sizes (189, 210, and 126.9 km2 vs. 86.1 and 80.2 km2). In addition, hybrid B flashes tend to produce more RSs and larger RS1st peak currents. The striking points of hybrid C flashes appear to be close to or out of the cloud edge. Based on these statistical results, we discuss the formation mechanisms of three types of hybrid flashes.

An Audiovisual Introduction to Streamer Physics

2025-06-20

Christoph Köhn | Atmosphere

Streamers are small, thin plasma channels that form the precursors of hot lightning leaders and that are associated with phenomena such as transient luminous events or terrestrial gamma-ray flashes. We … Streamers are small, thin plasma channels that form the precursors of hot lightning leaders and that are associated with phenomena such as transient luminous events or terrestrial gamma-ray flashes. We provide an easily accessible audiovisual introduction for students and early researchers, serving as a supplement to traditional review papers. This overview contains an introduction to the collision-dominated motion of electrons in an ambient field and an ambient gas, including a discussion of cross-sections and friction force. Based on this, we will discuss electron avalanches before moving to streamers. Here, we will focus on the avalanche-to-streamer transition and present properties and different modeling approaches. Finally, we will discuss streamers in different gas mixtures as well as their relation to lightning and plasma chemistry. The viewer of the supplementary video will receive a first overview of streamer physics.

A Finite Element Framework to Implement Lightning Induced Load

2025-06-20

Akshay Sontakkey , Mangesh Kotambkar | Iranian Journal of Science and Technology Transactions of Mechanical Engineering

Unveil the TGF-lightning relation with a large sample of TGFs detected by Insight-HXMT

2025-06-18

Qi-Bin Yi , Haoxuan Guo , S. Xiong +7 more | Science China Physics Mechanics and Astronomy

Impact of Smoke Aerosol Loading on Lightning Characteristics of Pyrocumulonimbus Compared With Other High‐Based Thunderstorms

2025-06-17

Elena Dworak , David A. Peterson , Pablo E. Saide +2 more | Journal of Geophysical Research Atmospheres

Abstract Pyrocumulonimbus (pyroCb) is a form of deep convection that is generated by the heating from large wildfires and specific meteorology known for producing lightning. We study the lightning characteristics … Abstract Pyrocumulonimbus (pyroCb) is a form of deep convection that is generated by the heating from large wildfires and specific meteorology known for producing lightning. We study the lightning characteristics of five pyroCb events in British Columbia, Canada, from June 29 to July 1 of 2021, and compare them to other clean and smoke‐filled high‐based thunderstorms in the same region and season using ground‐based lightning detection data, satellite retrievals, meteorological and atmospheric composition reanalysis, and observed thermodynamic profiles. One large pyroCb event over the Sparks Lake fire that generated persistent overshooting tops had a remarkable amount of lightning activity, with 5,600 total lightning strikes, while the rest of the pyroCb events corresponded with lower injection altitudes and minimal to no observed lightning activity. The cloud‐to‐cloud (CC) to cloud‐to‐ground (CG) lightning ratio (CC:CG) in this Sparks Lake pyroCb was significantly higher than in other high‐based storms but displayed similar lightning density and slightly lower peak current distributions. All clean and smoke‐filled thunderstorms produced significant levels of lightning activity, regardless of their cloud‐top altitudes. However, ingestion of smoke significantly reduced the percentage of positive polarity CG strikes when compared to clean cases. These results set a reference for identifying the characteristics of pyrogenic lightning and improved predictions of lightning‐caused fire ignitions, which will aid in understanding pyroCb activity and related impacts.

FEA on surge response of FGGM-based cylindrical-shell tower grounding grid

2025-06-17

Weichen Yan , Xiangxu Kong | Electrical Engineering

None

2025-06-16

Serge Soula | Comptes Rendus Mécanique

Les orages sont associés à des nuages de fort développement vertical appelés cumulonimbus qui abritent des régions chargées électriquement. Ils produisent des éclairs au sein du nuage et entre celui-ci … Les orages sont associés à des nuages de fort développement vertical appelés cumulonimbus qui abritent des régions chargées électriquement. Ils produisent des éclairs au sein du nuage et entre celui-ci et le sol. Au-dessus du nuage, plusieurs types de décharges électriques peuvent se produire et sont regroupés sous le terme TLE, de l’anglais Transient Luminous Event : les blue starters , les blue jets et les jets géants émergent du sommet nuageux et se différencient par l’altitude qu’ils atteignent (environ 20 km, 40 km et 90 km, respectivement), la région du nuage où ils démarrent et la polarité de la charge qu’ils transfèrent ; les sprites (farfadets en français) qui se déclenchent aux alentours de 70 km d’altitude au-dessus des régions stratiformes suite à un éclair nuage-sol positif ; les Elves sous la forme d’un anneau lumineux à la base de l’ionosphère (90 km la nuit) produites par des puissants éclairs nuage-sol. Cet article décrit les principales caractéristiques et les mécanismes de formation de ces TLEs.

Bayesian analysis of the detection performance of the Geostationary Lightning Mappers

2025-06-13

Katrina S. Virts , William J. Koshak | Journal of Atmospheric and Oceanic Technology

Abstract Geostationary Lightning Mappers (GLMs) aboard Geostationary Operational Environmental Satellites (GOES-16/-17/-18) have collectively provided over five years of continuous observations of total lightning for the western hemisphere. Quantifying GLM’s detection … Abstract Geostationary Lightning Mappers (GLMs) aboard Geostationary Operational Environmental Satellites (GOES-16/-17/-18) have collectively provided over five years of continuous observations of total lightning for the western hemisphere. Quantifying GLM’s detection performance is a necessary step toward accurately interpreting the data and analyzing it with lightning detections from other sensors and networks, including the new Lightning Imager (LI) on Meteosat-12. This study compares lightning observations from the GLM sensors with each other and with ground-based reference sensors including Earth Networks Total Lightning Network (ENTLN) and Global Lightning Dataset (GLD360). ENTLN and GLD360 detection performance throughout the GLM field of view is both imperfect and imperfectly known; thus, we adopt a Bayesian approach that estimates the upper limit of the absolute detection efficiency (ADE) of each system being analyzed. The results illustrate the geographical pattern and diurnal cycle of GLM performance. GLM ADE is consistently high near the center of its field of view but decreases steadily beyond ~4,000 km from the satellite subpoint. ADE is also lower in areas with frequent inverted polarity thunderstorms. Aggregate ADEs (averaged over all flashes) are 82.6% (GLM16), 72.3% (GLM17), and 82.5% (GLM18). GLM18 is more sensitive than GLM16/17 throughout its field of view, but GLM17/18 aggregate ADE is biased lower because ~90% of the lightning they observe is more than 4,000 km from the satellite subpoint, where GLM performance decreases. Each GLM exhibits a pronounced diurnal cycle, with ADE ~11–16% lower during the day.

On the impact of thunder on cloud ice crystals and droplets

2025-06-12

Konstantinos Kourtidis , Stavros Stathopoulos , Vassilis Amiridis | Atmospheric chemistry and physics

Abstract. Calculations are presented on the impact of thunder on cloud particles. The results show that the creation of a shock wave front near a lightning channel results in shattering … Abstract. Calculations are presented on the impact of thunder on cloud particles. The results show that the creation of a shock wave front near a lightning channel results in shattering of ice crystals, droplets, and dust aerosols, this being a yet unidentified mechanism for secondary ice production in clouds. At low altitudes shattering is more efficient. At the distance where the shock wave front decays to audio wave, another mechanism can cause agglomeration of particles. The cloud particles' characteristics appear to be not very suitable for extensive acoustic agglomeration if the sound pressure level (SPL) is below 120 dB. Nevertheless, even for SPL<120 dB, some agglomeration will occur. Agglomeration will occur readily if SPL > 135 dB at sound frequencies of 10 to 200 Hz. Agglomeration efficiency increases with height. More agglomeration will occur in pyroclouds, due to their large particle number densities. These results show that the electrical environment in clouds has, through thunder, effects on the size distribution and number density of ice particles and droplets, will hence influence thundercloud radiative properties, and may be a significant driver of secondary ice production. As global warming may influence the occurrence rate of lightning, a climate feedback may be induced by the mechanisms discussed here.

High‐Speed Video Observation of Needles Formed During the Leader Stage in a Positive Cloud‐to‐Ground Flash

2025-06-10

Bin Wu , Qi Qi , Weitao Lyu +4 more | Geophysical Research Letters

Abstract High‐speed video and electric field records of a positive cloud‐to‐ground (+CG) flash were used to examine six needles that were formed during the leader stage (a previously undocumented phenomenon … Abstract High‐speed video and electric field records of a positive cloud‐to‐ground (+CG) flash were used to examine six needles that were formed during the leader stage (a previously undocumented phenomenon in +CGs), each including the initial extension followed by flickering events, and subsequently re‐illuminated after the return‐stroke (RS) onset. During the leader stage, both the initial extension and following flickering events of these six needles always initiated from the lateral surface of the positive leader branch channel core. In contrast, after the RS onset, these six needles initially extended from the channel core, while the following flickering events initiated at a distance from the core and were bidirectional processes. We interpreted the disparity as being due to differences in the corona‐sheath structure before and after the RS onset.

Mechanism analysis and test verification of lightning attenuation in supersonic airflow injector

2025-06-02

Honglin Qin , Ping Huang , Han Jia +1 more | Electric Power Systems Research

A novel approach for enhancing substation grounding grid design using diverse shapes

2025-06-02

Avani Mistry , Ravindrakumar Yadav , Kaustubh Vyas | International Journal of Emerging Electric Power Systems

Abstract Substations are one of the key elements in electrical power system network. Efficient grounding in substation design forms the base for ensuring the safety of the person and equipments. … Abstract Substations are one of the key elements in electrical power system network. Efficient grounding in substation design forms the base for ensuring the safety of the person and equipments. Depending on the geometrical aspect of the substation, five different grid shapes are applicable. In this paper all 5-grid shape analysis is carried out to have comparison on performance analysis of the grid designing process. Also, in grid design calculations a concept of three different lengths is introduced which makes the grid designing simple and error free. Also, all the calculations are carried out owing to five different grid designing methods. Various softwares are used to make grid designing effective and lesser time consuming. Mathematically calculated results incorporating the length updation with grid shape applications are verified by ESGSD software. The methodology developed in this paper is applicable to any shape of the grid and ensures the safety and reliability of the grounding grid.

Magnetopause Location and Solar Wind Turbulence Level During FDs and Their Impacts on the Global Electric Circuit

2025-06-01

Gang Li , Shuai Fu , Xiaocheng Guo +3 more | Space Weather

Abstract During Forbush decreases (FDs), the fluxes of high‐energy galactic cosmic rays (GCRs) are suppressed. As a consequence, the ionization profile of the atmosphere is affected and the global electric … Abstract During Forbush decreases (FDs), the fluxes of high‐energy galactic cosmic rays (GCRs) are suppressed. As a consequence, the ionization profile of the atmosphere is affected and the global electric circuit system is perturbed. Recently, using cosmic ray measurements from the Alpha Magnetic Spectrometer (AMS‐02) onboard the International Space Station to classify FDs, Tacza et al. (2024, https://doi.org/10.1029/2023SW003852 ) have shown that the potential gradients (PGs) in ground‐based measurements taken in fair weather conditions only show noticeable increases during large FDs, but not in smaller FDs. In this work, continuing Tacza et al. (2024, https://doi.org/10.1029/2023SW003852 ), we further examine why large FDs are PG‐effective but smaller FDs are not. For the events examined in Tacza et al. (2024, https://doi.org/10.1029/2023SW003852 ), we compute the subsolar standoff distance during FDs using both an empirical formula and a magnetohydrodynamic (MHD) simulation. We find that PG‐effective and PG‐ineffective FDs naturally fall into two populations based on the subsolar standoff distance and the GCR flux amplitude decrease as measured from AMS‐02. We also find the MHD turbulence level, as measured by the root mean square of , correlates with . We extend the analysis to include all FDs as reported in Wang et al. (2023, https://doi.org/10.3847/1538‐4357/acca1b ), separating into Coronal Mass Ejection (CME) associated and Corotating Interaction Region associated two subclasses, and find this two population remain conspicuous. Based on our findings, we propose a new classification scheme of FDs.

Propagation Characteristics of Lightning‐Generated Whistlers in the Ionosphere: Statistical and Simulation‐Based Analysis

2025-06-01

Xiang Tian , Moran Liu , Shimin He +3 more | Journal of Geophysical Research Space Physics

Abstract Lightning‐generated whistlers (LGWs) are electromagnetic waves in the very‐low‐frequency band generated by lightning and propagate in the ionosphere. LGWs are an inexpensive ionospheric detection medium that can be used … Abstract Lightning‐generated whistlers (LGWs) are electromagnetic waves in the very‐low‐frequency band generated by lightning and propagate in the ionosphere. LGWs are an inexpensive ionospheric detection medium that can be used to reconstruct ionospheric electron density based on their dispersion characteristics. The propagation characteristics of LGWs determine their propagation paths in the ionosphere, and the correct calculation of these paths is a prerequisite for electron density inversion. Here the observations from the China Seismo‐Electromagnetic Satellite in broad areas at about 500 km altitude are used to perform wave vector direction statistics and propagation characteristics analysis for fractional‐hop whistlers that propagate from the Earth to the spacecraft. The propagation characteristics of whistlers are analyzed and distinguished using observational statistics of wave vector directions and simulation based on the finite difference time domain model. The results indicate that the wave normal angles of whistlers in low latitudes are significantly larger than those in mid latitudes. Low‐latitude whistlers preferentially propagate obliquely outward in the magnetic meridian plane in a nonducted mode in the ionosphere. Mid‐latitude whistlers may still propagate in a nonducted mode, even when their wave normal angles are relatively small. The wave normal angles of LGWs in the ionosphere show no significant longitudinal dependence and exhibit a clear latitudinal distribution pattern. The LGWs wave vector exhibits minimal vertical deviation at low and high latitudes, with significantly larger deviations near 30°N mid‐latitudes. This paper reveals the propagation characteristics of LGWs in the ionosphere through observations, statistics, and simulation.

Microphysical and Cloud-to-Ground Lightning Characteristics of Three Tornadoes in a Squall Line

2025-06-01

Min Bao , Tinglong Zhang , Hongwu Guo +4 more | Journal of Atmospheric and Solar-Terrestrial Physics

Study on the electric field and current intensity in lightning discharge channel based on the Hα broadening

2025-06-01

Linhui Chen , Ping Yuan , Rubin Jiang +2 more | Atmospheric Research

Simulations of lightning overvoltages in overhead transmission lines using EMTP/ATP

2025-05-30

J. Furgał | PRZEGLĄD ELEKTROTECHNICZNY

Modeling Streamer Discharge in Air Using Implicit and Explicit Finite Difference Methods with Flux Correction

2025-05-29

Hasupama Jayasinghe , Liliana Arévalo , Richard A. Morrow +1 more | Plasma

Implementing a computationally efficient numerical model for a single streamer discharge is essential to understand the complex processes such as lightning initiation and electrical discharges in high voltage systems. In … Implementing a computationally efficient numerical model for a single streamer discharge is essential to understand the complex processes such as lightning initiation and electrical discharges in high voltage systems. In this paper, we present a streamer discharge simulation in air, by solving one-dimensional (1D) drift diffusion reaction (DDR) equations for charged species with the disc approximation for electric field. A recently developed fourth-order space and time-centered implicit finite difference method (FDM) with a flux-corrected transport (FCT) method is applied to solve the DDR equations, followed by a comparative simulation using the well-established explicit FDM with FCT. The results demonstrate good agreement between implicit and explicit FDMs, verifying their reliability for streamer modeling. The total electrons, total charge, streamer position, and hence the streamer bridging time obtained using the FDMs with FCT agree with the same streamer computed in the literature using different numerical methods and dimensions. The electric field is obtained with good accuracy due to the inclusion of image charges representing the electrodes in the disc method. This accuracy can be further improved by introducing more image charges. Both implicit and explicit FDMs effectively capture the key streamer behavior, including the variations in charged particle densities and electric field. However, the implicit FDM is computationally more efficient.

Novel Compacting Grounding system for mitigating Ground Potential Rise and backflashovers

2025-05-28

Jesus E. Guevara Asorza , Walter Luiz Manzi de Azevedo , José Pissolato Filho | Electric Power Systems Research

Lightning jump as precursor of very large hail occurrence: first evidence in the Italian territory

2025-05-28

Federico Vermi , Vincenzo Capozzi , Giulio Monte +2 more | Bulletin of Atmospheric Science and Technology

Insights into thunderstorm characteristics from geostationary lightning jump and dive observations

2025-05-27

Felix Erdmann , D. R. Poelman

Abstract. The objective of this study is to gain a deeper understanding of geostationary (GEO) satellite data, with a specific emphasis on sudden increases in a storm's lightning activity, referred … Abstract. The objective of this study is to gain a deeper understanding of geostationary (GEO) satellite data, with a specific emphasis on sudden increases in a storm's lightning activity, referred to as lightning jumps (LJs), and decreases, known as lightning dives (LDs). To achieve this, observations from the Geostationary Lightning Mapper (GLM) and the Advanced Baseline Imager (ABI) on the GOES satellite are utilized to analyze the cloud characteristics of thunderstorms. Storms are then categorized based on whether they produced GEO LJs, GEO LDs, and/or severe weather. While non-severe thunderstorms have a mean cloud top temperature of 236 K, cloud tops are about 20 K colder for severe storms as well as those producing LJs and LDs. Overshooting tops (OTs) in storms producing LJs and LDs as well as in severe storms were about 3.4, 1.9, and 2.6 K colder, respectively, than the cloud cell as a consequence of structured and intense updrafts. On the other hand, OTs are rare and shallow in the non-severe storms and thunderstorms without LJs and LDs. Accordingly, the convective rain rates (CRRs) of the LJ- (23 mm h−1) and LD-producing storms (20 mm h−1) and severe storms (20 mm h−1) are on average more than 3 times higher than in non-severe thunderstorms and storms without LJs or LDs. Thunderstorms experiencing multiple GEO LJs during their lifecycle feature average cloud top temperatures of 213 K, with an average of 0.5 OTs being 4.8 K colder than the anvil and a mean CRR exceeding 26.4 mm h−1. Therefore, especially those storms with multiple LJs have the highest potential to produce dangerous-weather events.

Spatio-temporal evolution characteristics of optical radiation for tall-object lightning return stroke channels

2025-05-26

Xuejuan Wang , Binghao Wang , Weitao Lyu +7 more

ELF/VLF Radio Bursts Associated With Transient Luminous Events: Radio Metrics

2025-05-26

Q. A. Flint , R. C. Moore , Thomas Ashcraft +2 more

Abstract Extremely low‐frequency (ELF, 33,000 Hz) and very low frequency (VLF, 330 kHz) radio impulses known as ELF/VLF transients have been observed for over 80 years and have been closely … Abstract Extremely low‐frequency (ELF, 33,000 Hz) and very low frequency (VLF, 330 kHz) radio impulses known as ELF/VLF transients have been observed for over 80 years and have been closely associated with lightning and lightning‐related phenomena. Observations of ELF/VLF radio transients performed by the University of Florida's global ELF/VLF receiver network are used to determine quantitative metrics by which to characterize the ELF/VLF transients as Q‐bursts and N‐bursts. As a result of this effort, a new type of transient is identified and deemed the VO‐burst. These metrics are used to analyze the ELF/VLF transients observed simultaneously with ground‐based amateur optical observations of sprites and gigantic jets. Four case studies support the conclusions that sprites are associated with N‐bursts, whereas gigantic jets are associated with Q‐bursts. Additional observations performed during rocket‐triggered lightning experiments at Camp Blanding, Florida, suggest that typical cloud‐to‐ground lightning return strokes are associated with VO‐bursts, which do not exhibit any significant ELF component. While these new radio metrics can be employed to automatically process ELF/VLF transient observations to distinguish between Q‐bursts, N‐bursts, and VO‐bursts, we propose that this additional quantitative characterization of radio bursts could also be employed to detect and distinguish between various types of transient luminous events, but more observations are required to rigorously establish this relationship.

Improving thunderstorm and lightning prediction using a novel hybrid index and machine learning techniques: a case study in Northeast India

2025-05-26

G. K. Sawaisarje , G. P. Singh , Hemantkumar S. Chaudhari +2 more

Efficient modeling of parallel counterpoise wires using an FDTD-based transmission line approach

2025-05-26

Naiara Duarte , Rafael Alípio , Felipe Vasconcellos +1 more

Lightning-induced voltage on overhead conductors in urban areas: A study on how the air gap between buildings affects the shielding effect

2025-05-23

Susana Naranjo-Villamil , Daniele Mestriner

Overvoltages Transmitted in the Transformer Windings on the Lightning Impulse—An Analytical Method for Determination and Experimental Measurements

2025-05-23

Maria Cristina Nitu , Livia-Andreea Dina , Ileana-Diana Nicolae +2 more

Overvoltages are brief and significant increases in the voltage level in an electrical system. They can be caused by a variety of factors, but the most common are associated with … Overvoltages are brief and significant increases in the voltage level in an electrical system. They can be caused by a variety of factors, but the most common are associated with atmospheric discharges (lightning). When lightning strikes a power line, the resulting shock wave can induce surges in electrical equipment that is connected to that line, including transformers. The authors develop an analytical method in order to determine the maximum values of the overvoltages propagating in the transformer windings in case of lightning impulse. It is considered that the transmitted overvoltages consist of an inductive component (magnetic dispersion is neglected, as well as the energy exchange between the capacitances and inductances of the energized winding) and a capacitive component (between the energized winding and the receiving winding; in this case, the emphasis is on the energy exchange between the series capacitance and the inductance of the series winding). The proposed method was applied on a TTUS—ONAN/ONAF 31.5/40 MVA, 110/5/6.6 kV power transformer, and the obtained results were validated by experimental tests. The percentage error between the results obtained by modeling and the results obtained from transformer testing was less than 2%.

Lightning Damage Detection Method Using Autoencoder: A Case Study on Wind Turbines with Different Blade Damage Patterns

2025-05-22

Takuto Matsui , K. Matsuoka , Kazuo Yamamoto

There have been numerous reported accidents of lightning strikes damaging wind turbine blades, which poses a serious problem. In certain accidents, the blades that were struck by lightning continued to … There have been numerous reported accidents of lightning strikes damaging wind turbine blades, which poses a serious problem. In certain accidents, the blades that were struck by lightning continued to rotate, resulting in breakage due to centrifugal force. Considering this background, wind turbines situated in Japan have been mandated to be equipped with emergency stop devices. Consequently, upon detection of a lightning strike by the device installed on the wind turbine, the turbine is promptly stopped. In order to restart the wind turbine, it is necessary to verify its soundness by conducting a visual inspection. However, conducting prompt inspections can be difficult due to various factors, including inclement weather. Therefore, this process prolongs the downtime of wind turbines and reduces their availability. In this study, an approach was proposed: a SCADA data analysis method using an autoencoder to assess the soundness of wind turbines without visual inspection. The present method selected wind speed and rotational speed as effective features, employing a sliding window for pre-processing, based on previous studies. Besides, the assessment of a trained autoencoder was conducted through the utilization of the confusion matrix and the receiver operating characteristic curve. It was suggested that the availability of wind turbines could be improved by employing this proposed method to remotely and automatically verify the soundness after lightning detection.

Why Schonland Failed in His Search for Runaway Electrons From Thunderstorms

2025-05-22

A. Chilingarian , Earle Williams , G. Hovsepyan +1 more

Abstract B.F.J. Schonland, advised and encouraged by C.T.R. Wilson, made two unsuccessful searches for runaway electrons from thunderstorms in the 1930s. These findings stand in marked contrast with research results … Abstract B.F.J. Schonland, advised and encouraged by C.T.R. Wilson, made two unsuccessful searches for runaway electrons from thunderstorms in the 1930s. These findings stand in marked contrast with research results over the last decade and ironically set this field of research back many decades. Schonland's lack of success is traced to gamma ray attenuation in the atmosphere above Johannesburg (1,780 m MSL) and to his restriction to nine thunderstorms.

Downward terrestrial gamma-ray flash associated with collision of lightning leaders

2025-05-21

Yuuki Wada , Takeshi Morimoto , Ting Wu +6 more

Lightning discharges can produce transient gamma-ray emissions called terrestrial gamma-ray flashes (TGFs), which originates from electrons accelerated to relativistic energies in strong electric fields. However, it is not yet understood … Lightning discharges can produce transient gamma-ray emissions called terrestrial gamma-ray flashes (TGFs), which originates from electrons accelerated to relativistic energies in strong electric fields. However, it is not yet understood how lightning produces an enormous number of relativistic electrons in dense atmospheres. We present that, thanks to a ground-based observation with optical, radio frequency and high-energy measurements focused on television transmission towers in Kanazawa, Japan, a TGF and a cloud-to-ground discharge of −56 kA occurred when a downward negative leader was colliding with an upward positive leader from the tower. Because the cloud-to-ground current followed the TGF by 30 μs, the TGF started when two leaders approached each other. Our results indicate that an immense number of electrons were produced and accelerated to relativistic energies in a strong and compact electric-field region between the two leaders.

What is missing when evaluating lightning damage during the return stroke process? –The damage effect of ion enthalpy flux

2025-05-21

Peifeng Wang , Gang Liu , Lyuwen Chen +3 more

Analysis of temporal and spatial distribution of CG lightning activity and its relationship with terrain features around Jiuxianshan mountain

2025-05-20

Biao Zhu , Binbin Lin , Bing Liu +1 more

New Method for Single-Site Cloud-to-Ground Lightning Location Based on Tri-Pre Processing

2025-05-19

Bingzhe Dai , Qilin Zhang , Jie Li +2 more

The single-site lightning detection system can provide timely and effective information on lightning activity in areas where a multi-site lightning network cannot be built. Using deep learning, the single-site lightning … The single-site lightning detection system can provide timely and effective information on lightning activity in areas where a multi-site lightning network cannot be built. Using deep learning, the single-site lightning detection achieves better performance than traditional methods, but it is highly dependent on the quality of the training dataset. To address this, this paper proposes a method called Tri-Pre to improve dataset quality and thereby enhance the performance of single-site cloud-to-ground lightning detection based on deep learning. After using the Tri-Pre method, the location model’s distance estimation error decreases by 36.08%. For lightning with propagation distances greater than 1000 km, the average relative error of the results from the built model based on the Tri-Pre method is 3.78%. When verified using additional measured data, the model also shows satisfactory accuracy, particularly for lightning with propagation distances beyond 1000 km. Specifically, for lightning with propagation distances between 1500 and 1600 km, the average relative location error is approximately 5.46%.

Destructive and Non-Destructive Analysis of Lightning-Induced Damage in Protected and Painted Composite Aircraft Laminates

2025-05-19

Audrey Bigand , Christine Espinosa , Jean‐Marc Bauchire

The use of CFRP composite increased significantly since the last 40 years for aircraft structure. Unfortunately, such structures are subjected to significant damages if struck by lightning compared to metallic … The use of CFRP composite increased significantly since the last 40 years for aircraft structure. Unfortunately, such structures are subjected to significant damages if struck by lightning compared to metallic structure. This is mainly due to the low conductivity of this material, which cannot evacuate the current without high Joule heating. Lightning strike-induced damage in a composite laminate is composed of in-depth delamination, fibre breakage, and resin deterioration due to the surface explosion and the core current flow linked to interaction of the arc with the surface. But very rare previous studies dedicated to the analysis of damage as a direct effect of lightning have considered the spurious effect of the paint that always covers real aeronautic structures neither on the thermal nor the mechanical loads that are the root cause of these damages. We present in this paper a coupled non-destructive and destructive damage analysis to support the proposition of damage scenarios depending on the presence and thickness of the paint. The mechanical and thermal sources contribution in the global loading on the core damage is discussed, which confirms previous studies’ analysis and modelling and is in accordance with existing works in the literature.