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The paper is devoted to the review of the data on the lightning parameters necessary for development and perfection of lightning protection systems. It is shown, that down to present time national and international lightning protection standards are based on the Berger’s data on distribution of lightning amplitudes currents. Experimental data on amplitude of the return-stroke current the received recently in Brazil, Japan, USA (Florida) and Austria are resulted. It is emphasized, that the given data on currents of a lightning are characterized by a wide scatter that specifies necessity of realization of the further researches. The detailed description of parameters of the return-stroke peak current, including duration of front time, duration of a pulse, a steepness of a current at the front is given. It is emphasized, that median value of amplitude of a current of the first making the return-stroke in 3-4 times is higher than a current of the subsequent components. The analysis measured median (50%) and severe (1%) values of lighting parameters which are necessary for construction of a curve of distribution in the assumption of its submission lognormal law is carried out. Results of theoretical researches are given according to extreme values of currents of a lightning. It is shown, that, depending on length of the lightning channel (from 4 up to 6 kms), the maximal current can vary from 300 kA up to 500 кА. The minimal value of lightning current is appreciated in 2 кА. The analysis of results of new direct measurements has shown, that for a lightning of positive polarity the maximal current can reach 340 кА, that appreciably is higher than a settlement maximum for a lightning of negative polarity (200 кА). Recent theoretical researches have allowed to prove experimentally received lognormal distribution of currents for lightning of negative polarity.

Using lightning observations from the Fengyun-4A Lightning Mapping Imager (FY-4A LMI), best-track data from the Shanghai Typhoon Institute, bright temperature (TBB) data from Himawari-8 satellite, and composite reflectivity (CR) data from the South China radar network, we investigate the spatiotemporal distribution of lightning activity and convective evolution during the landfall of Super Typhoon Mangkhut, the strongest landing typhoon in China in 2018. Three stages of active total lightning are observed, and differences of lightning characteristics between the inner core and the outer rainbands are present. The onset of inner-core lightning outbreak is about 4 h ahead of the maximum intensity of the storm, providing indicative information on the change of typhoon intensity. Lightning rates in the outer rainbands increase rapidly 12 h before the landfall, and lightning activity is mainly confined in the outer rainbands after the landfall. A good correlation in hourly variation is shown between lightning rates from the LMI and TBBs from the satellite. The averaged TBB within the inner core reaches its minimum (–80°C) when the inner-core lightning outbreak occurs, indicating the occurrence and enhancement of deep convection there. Lightning locations observed by the LMI has a good spatial correspondence with regions of low TBBs and high CRs, revealing the monitoring capability of the LMI to lightning activity and deep convection in landing typhoons. Comparisons between the World Wide Lightning Location Network (WWLLN) and the LMI reveal that the spatial distribution, temporal evolution, and radial pattern of lightning activity in Mangkhut observed by the two systems are consistent. Furthermore, due to the detection capability of total lightning, the LMI has advantages in revealing the higher ratio of intra-cloud lightning within the inner core in typhoon. The continuous and real-time observation of FY-4A LMI provides an unprecedented platform for monitoring total lightning and deep convection in landing typhoons in China, which will promote the generation of new research and applications in the future.

Direct lightning strikes to a structure are always a problem in the study of electrical protection systems. So, a study is carried out regarding the impact of a direct lightning strike on a structure. A complex structure will be an important issue in designing an effective lightning protection system and attaching a protection mechanism to the components to protect. In the present study, the effect of a direct lightning strike on a structure will be studied based on the distribution of surface currents and the intensity of the electric field using the electromagnetic computational method (Hybrid FEM / MoM) approach based on software simulation. The simulation is carried out by modeling two parameters, namely modeling lightning currents and modeling structures. The lightning current modeled has an amplitude of 40kA with a working frequency of 833.33 kHz, this is based on the IEC 62305 standard where the maximum current occurs when the lightning current wave reaches a face time of 1.2μs. In this study, Finite Difference Time Domain (FDTD) and Method of Moments (MoM) software can be used to model lightning strikes on a 75 m high telecommunications tower with lightning strike settings based on tropical lightning condition. The tower model used is without using a down conductor and using a down conductor. This research has a contribution in showing the distribution of lightning current that flows in the foot of tower and down conductor when tower is struck by lightning.

We report the results of the use of the World Wide Lightning Location Network data to analyze the core structure of super typhoons that occurred in the northwestern Pacific Ocean in 2012–2013. The distributions of lightning discharges are compared to the ocean-surface wind fields according to the data of the Advanced Scatterometer (ASCAT) and the infrared images of the Moderate Resolution Imaging Spectroradiometer (MODIS) onboard the MetTop-A and Aqua satellites, respectively. In the central regions of all of the studied typhoons, the structures that are fragments of circular or spiral mesometeorological-scale forms, which can be related to the presence of the cloud eyewall of typhoons, are observed even a day before the typhoon’s maximum intensity. These circular structures become completely apparent on the day of the typhoon’s maximum intensity and then begin to break down. It is shown that the position of the center of a typhoon and its traveling speed can be estimated from the distribution of lightning; in addition, the geometric characteristics of an eyewall, which are listed in reports on storms and typhoons, can be determined.

The reported lightning accidents that are available in the DesInventar database—which consist of 549 deaths, 498 injured people, 39 destroyed houses, and 741 damaged houses—were analyzed in terms of their geographical and temporal variation. The average lightning flash densities were calculated using zonal statistics using the geographic information system (GIS), referring to the respective raster maps generated based on Lightning Imaging Sensor (LIS) data from the Tropical Rainfall Measurement Mission (TRMM) Satellite. Hence, the variations of the lightning accidents—monthly and climate season-wise—in response to the lightning flash density were also reported. The calculated average lightning flash density in Sri Lanka is 8.26 flashes km-2 year-1, and the maximum average lightning flash density of 31.33 flashes km-2 year-1 is observed in April in a calendar year. April seems to be more vulnerable to lightning accidents, as the maximum number of deaths (150 deaths) and injuries (147 injuries) were recorded in this month. Most of the high-risk lightning accident regions that were identified in Sri Lanka are well known for agricultural activities, and those activities will eventually create the platform for lightning victims. In Sri Lanka, in a year, 12 people were killed and 11 people were injured, based on the reported accidents from 1974 to 2019. Conversely, a substantial increase in the number of deaths, injuries, and incidents of property damage has been observed in the last two decades (2000–2019). On average, for the period from 2000 to 2019, 18 people were killed and 16 people were injured per year. Furthermore, considering the population of the country, 0.56 people per million per year were killed, and 0.51 people per million per year were injured due to lightning accidents based on the reported accidents from 1974 to 2019. Moreover, for the 2000–2019 period, these estimated values are significantly higher, 0.86 people per million per year were killed, and 0.77 people per million per year were injured.

This paper presents the design, simulation and analysis of the distribution of lightning current and transient voltage in a 25 kV AC railway traction system. Consequently, the lightning protection system that may mitigate the adverse effects due to possible lightning strikes has been designed. The Mpumalanga- Richards Bay Coal line in South Africa has been considered for the analysis. The railway system is modelled, consisting of a mast, an insulator applying a back flashover control mechanism, overhead catenary wires, a pantograph, an AC locomotive and the rails. The main component of protection is the surge arrester that is designed using the PincetiGiannetoni model. The surge arrester is rated at 30 kV, with a nominal discharge current of 10 kA. The complete system is modelled and simulated in PSCAD software. The simulations are performed to detect the transient response of critical components of the system when lightning current is injected at locations of exposure, namely; the mast, catenary wires and the pantograph, in the absence and presence of surge arresters. The results show a significant decrease in the peak current and voltage of the selected components when surge arresters are connected.

For the organization of lightning protection measures, data on the nature of the distribution of lightning discharges, their number and current value over the territory are required. To this end, lightning direction finding systems are being developed and implemented in many countries around the world. Lightning direction finding technology significantly reduces the risk of lightning strikes, and also allows you to take into account thunderstorm activity in the design and placement of buildings and structures. It is aimed at minimizing serious disruptions in the power industry, mass accidents and damage to power lines, preventing the failure of sensitive electronics and communication networks, and so on, which, in turn, determines its high economic efficiency. This article discusses issues related to clustering and visual representation of long-term data on thunderstorm processes in the North Caucasus in 2009-2019. Information about lightning discharges was obtained on the basis OF ls8000 data from Vaisala using a network of lightning recorders at the geophysical situation monitoring center. The article presents a picture of the spatial and temporal distribution of thunderstorm clusters for the North Caucasus. This makes it possible to trace the dynamics of thunderstorm centers, the spatial position of thunderstorms, the characteristics of discharges per unit area and time, to determine the characteristic development trends, and to identify the main factors that affect the obtained characteristics of the spatial and temporal distributions of lightning activity.

Lightning is one of the inevitable disastrous phenomena which in addition to damaging tall edifices, might also consequently endanger humans due to lightning-human interactions. This research focuses on analyzing lightning hazards to humans in the vicinity of heritage monuments in India and Sri Lanka. Five monuments which include three giant stupas namely Ruwanweliseya, Jethawanaramaya and Abayagiriya from Sri Lanka and two large temples namely Brihadishvara Temple and Gangaikonda Cholapuram from India have been chosen for investigation. Lightning-human interaction mechanisms namely direct strike, side flash, aborted upward leader, step and touch voltages have been investigated for the most onerous scenario on humans in the vicinity of the monuments. Firstly, the electro-geometric model as stipulated in standards has been implemented to ascertain the effectiveness of lightning protection to the structures. Subsequently, the study has been extended to the computation of step and touch voltages utilizing lightning current and electrostatic models based on Finite Element Method (FEM) using COMSOL Multi-physics®. Detailed plots of electric field and voltage distribution of lightning on humans due to a typical lightning current of 30 kA have been obtained. The final study involves assessment of current through humans which is estimated based on lumped R-C human model representation using OrCAD Cadence®. The analyses reveal that humans are invariably shielded against direct strikes whereas effects due to side flashes are minimal. During strikes to the monuments, high voltage may appear due to step and touch potential under dry conditions, though such effects could be mitigated by appropriate earthing system.

In the study of lightning process, positioning technology is an indispensable basis of lightning. Generally, it uses the history lightning data to analysis the lightning location. The fast computation of the lightning unknown parameters and accuracy estimation is an important problem in lightning early warning, disaster prevention and mitigation and lightning in scientific research. Based on the current state of the lightning location technology development, this paper synthetically introduces the TOA method of lightning location technology in detail, and discusses the mathematical principle of lightning, and also lists the basic equations of two-dimensional positioning of lightning. From the positioning method, error source and its limitations and other aspects of analysis have been analyzed in the cloud-to-ground lightning positioning error influenced by the geometric positioning different models. The simulation results are obtained by using Monte Carlo method, according to the positioning errors of size grading and make the linear analysis results. Finally, based on the application of GDOP method, it analyzes the error on the calculation method. Using the T-type cloth station as an example for simulation, it obtains the error distribution and comparative analysis of the lightning location. This paper focuses on the positioning method, establishes error evaluation model, makes an analysis and simulation of the simulation and error of the lightning location, finally explores to precision improvement.

Due to the high-voltage tower’s protruding space and material characteristics, which is easy to form characteristics of the electric field distortion, so lead to attract the lightning downward leader and add the possibility of lightning strike. The induced over-voltage is generated on the equipment by the electromagnetic radiation in the nearby space which often has tunnel, basement and other equipment space, leading to damage and malfunction accident, etc. Through the establishment of the typical 500 kV high-voltage tower and tunnel model, and combine with the characteristics of lightning current amplitude of ground lightning return stroke in recent ten years lightning detection data in Hangzhou area. Then use these characteristics to simulate the lightning strike in the time-domain, so it can be concluded that the distribution of lightning current on the surface of tower and the variation of electromagnetic field in underground space such as tunnel. Qualitative and quantitative methods are used to summarize the effect of shielding and grounding on radiation shielding protection, which can provide reference for electromagnetic radiation protection in the space near tower project.

In this study, we collected lightning data recorded in the Joseon-wangjo-sillok, one of the Korean history books, and discuss the characteristics of the long term variations and distribution of lightning based on the data. Although historical data such as lightning records are fragmentary, they are important information of solar activity on a long term scale. We found that there is a difference between the monthly distribution of lightning recorded in the Joseon-wangjo-sillok and the monthly distribution of modern observations. This difference of distribution could be understood to reflect that the purpose of viewpoint of the observers is different between the past and the present. Nevertheless, it is a very interesting result that the periodicity calculated from the records of lightning recorded in the Joseon-wangjo-sillok is similar to the solar cycle which is widely known as almost periodically 11 years.

The organization of lightning protection measures is based on information about the nature of the distribution of lightning discharges, their number and the current value in the region of the location of the protection objects. Therefore, the most relevant direction of the study is to clarify the existing recommendations in the field of lightning protection. In the article, based on the data of long-term measurements of the LS 8000 lightning direction finding system located in the North Caucasus, the analysis of the registration of lightning parameters is carried out. The revealed regularities of the distribution of lightning discharges over the territory in different periods of the year are the basis for the approximation equations developed by the authors, which are used to describe the space-time density of lightning. Maps of the distribution of the number of lightning discharges per square kilometer obtained from the initial data and constructed according to the developed equations are presented, and the relevance of the results obtained is evaluated.

Lightning activities are distributed asymmetrically over the globe. Satellite images show that the Himalayan region is one of the prone zones of lightning activity. We do not understand such an uneven distribution of lightning activities as of today. To elaborate on the present-day understanding of lightning flashes over the Himalayan region, we have analyzed various atmospheric factors in association with Lightning Flash Density (LFD). For this purpose, we divided the Himalayan Range into three sections, namely, eastern, middle, and the western Himalayas. We explored the possible association of monthly mean Convective Available Potential Energy (CAPE), Surface Air Temperature (SAT), thermodynamic temperature of the top of the cloud; Cloud Top Temperature (CTT), Relative Humidity (RH), and Specific Humidity (SH) with LFD over the three sections of the Himalayan range. We observed that CAPE and SAT play a vital role in creating instability over that region. In contrast, moderate moisture (i.e., RH) is the most suitable condition for lightning activities over all three sections. The analysis shows that 50–60% RH at 700hpa is the most favorable condition for lightning over the Himalayan region.

Thunderstorms source of lightning discharge is a major hazard to humans. In India, the loss of human life due to thunderstorms is high because of frequent lightning during pre-monsoon season (March-May). Therefore, simulation of lightning flash counts based on various lightning parameterization schemes and Lightning Potential Index (LPI) in Weather Research and Forecasting (WRF) model are evaluated over Maharashtra, India. The offline diagnostic methods for calculating lightning flashes are also evaluated from the model generated storm parameters. The observation from Maharashtra Lightning Detection Network (LDN) is used to validate the simulated total lightning flash for four events. The lightning flashes calculations by following Price and Rind (1992) based on cloud top height (PR92CTH) and vertically integrated ice water path (IWP) simulated the spatial pattern comparably well. The lightning parameterization based on cloud top height defined by the radar reflectivity factor threshold of 20 dBZ (DLP2) has performed better as compared to observation. The results show (i) better spatial pattern and frequency distribution of lightning flashes, (ii) accumulated rainfall, maximum reflectivity and time evolutions are in good agreement with flashes, (iii) correlation between simulated flash and hydrometeors are higher, (iv) the number of matching grid boxes due to randomness is also higher, 74.9%, 56.5%, 68.1% and 82.7% of matching grid boxes for the four cases and (v) the results based on LPI are also in consistent with the results of DLP2. The study highlights the robustness of DLP2 and indicates a promising future for the operational forecast of lightning prediction.

Using NASA’s TRMM Lightning Imaging Sensor (LIS) data from 1998 to 2014, this paper presents a 17-year lightning climatology of Bangladesh, at 0.5° × 0.5° spatial resolution. Diurnal, seasonal, monthly and annual variations in the occurrence of lightning flashes were explored. The diurnal regime of lightning is dominated by afternoon/evening events. Overall, peak lightning activity occurs in the early morning (0200 LST) and evening (1900 LST). The distribution of lightning flash counts by season over Bangladesh landmass is as follows: pre-monsoon (69.2%), monsoon (24.1%), post-monsoon (4.6%) and winter (2.1%). Flash rate density (FRD) hotspots were primarily located in the north and north-eastern parts of Bangladesh, with a maximum of 72 fl km−2 year−1. Spatially, the distribution of FRD increases from the Bay of Bengal in the south to relatively higher elevations (of the Himalayan foothills) in the north. A spatial shift in FRD hotspots occurs with change in season. For example, in monsoon season, hotspots of lightning activity move in a south-westerly direction from their pre-monsoon location (i.e. north-eastern Bangladesh) towards West Bengal in India. South and south-eastern parts of Bangladesh experience high lightning activity during post-monsoon season due to regional orographic lifting and low-pressure systems (i.e. cyclone) in the Bay of Bengal. To the best of our knowledge, this is the first study focused on LIS-based lightning climatology over Bangladesh. This baseline study, therefore, is an essential first step towards effective management of lightning-related hazards in Bangladesh.

This paper presents a novel method for the power transformer insulation coordination, based on the risk of failure analysis due to lightning surges, that uses its insulation strength volt–time curve and a limit–state surface formulation. The limit–state surface is derived in a novel way, from the optimal number of systematic numerical simulations of transformer terminal overvoltages—emanating from station impinging lightning surges—while accounting for the transformer insulation volt–time curve and surge arresters protective characteristics and disposition. The proposed method further employs a state-of-the-art transmission line (TL) and substation equipment models for lightning-surge transient analysis, constructed in the EMTP software package. It also uses the electrogeometric model of lightning attachment to TLs, in order to estimate the expected number of direct lightning strikes, along with a bivariate statistical distribution of lightning currents. The main aspects of the proposed method are demonstrated by means of the computational example featuring an air-insulated substation power transformer lightning insulation coordination. Simulation results exhibit many benefits of the proposed method. Sensitivity analysis further reveals different influences that the various model parameters have on the transformer insulation coordination design.

We analyze variations of lightning activity presented by the lightning stroke number obtained by the World Wide Lightning Location Network (WWLLN) within the territory with boundaries 40–80° N and 60–180° E in 2009–2016. There are two regions with high lightning activity: western (48–60° N, 60–90° E) and eastern (40–55° N, 110–140° E). The lightning stroke density in these regions is 10–100 times higher than that in surrounding areas. The comparison between daily variations of lightning stroke number and the 10.7 cm solar radio flux shows no correlation: the linear cor-relation coefficient varied from –0.55 to 0.86 in the western region and from –0.78 to 0.39 in the eastern region during all summer seasons. During the ascending phase of solar cycle 24, there was a spatial lightning redistribution between the western and eastern regions of high lightning activity. During peaks of the solar cy-cle and its descending phase, the redistribution was not so pronounced as that during the ascending

The characteristics of lightning activity in tropical cyclones (TCs) over North Indian Ocean (NIO) are presented using sample of 21 TCs developed during 2010–2015 using TRMM and World Wide Lightning Location Network (WWLLN) datasets along with information from annual reports of Regional Specialized Meteorological Center (RSMC), New Delhi. The microphysical features such as Polarization Corrected Brightness Temperature (PCT), attenuation corrected reflectivity factor, Ice Water Path (IWP) play a pivotal role in development of convective systems within TCs. The TCs exhibited systematic variation in lightning flashes per day within 300 km of estimated center during their life cycle irrespective of their severity and flash rate within 300 km of storm center. The lightning flashes ranged from 1 to 3500 flashes per day during pre-cyclone stage, 100 to 8000 flashes per day during cyclone stage and 0 to 4300 flashes per day during post-cyclone stage. The TCs produced maximum flash density in eyewall region (20–40 km) and outer rainband region (200–260 km). The WWLLN recorded 165,512 flashes within 300 km of TC centers during their life cycle. The maximum flashes occurred during cyclone stage followed by pre-cyclone and post-cyclone. The time variation of flash rate for all cyclones was episodic and primarily peaked during late night and early morning hours. The diurnal variation of lightning flashes during TCs due to variation in detection efficiency of WWLLN also controls temporal distribution of lightning activity. During rapid intensification, TCs produced profuse lightning flashes per hour. Episodic lightning flashes per hour occurred during weakening stage and prior to landfall. It is evident that outbreaks of lightning flashes prior to maximum intensity change as manifested in maximum sustained wind speed and fall in estimated central pressure (ECP) indicate potential predictive value of lightning activity for TC intensity change.

Based on World Wide Lightning Location Network for 2012-2017 data, we describe the spatial and temporal distribution of lightning activity over Chilean territory. The thunderstorm days per year was computed using a threshold value of the human observation of 17.5 km based on the analysis of meteorological stations in Argentina and Poland. The maximum thunderstorm days were found in northeastern Chile in the Arica region, and specific behavior for Western Patagonia was evidenced. The analysis of lightning activity for every season of the year and the distribution of lightning during the day were computed and presented. The main activity is presented in summer, and the high lighting activity occurs in the afternoon in local time due to the presence of convective activity.

The annual total lightning number detected by the WWLLN variated in 2009-2018 with quasi-period of 3-4 years. The local peaks were in 2011, 2014, 2015, and 2017. The mean lightning density was about 0.034 stroke/km2, it was corrected on the relative detection efficiency of the network. The regions of high lightning density are generally associated with cyclonic activity occurring to the south (southern region of Yakutia) and the terrain orography influence (high lightning density along the western slopes of the Verkhoyanskiy, Momskiy and Cherskiy ranges). The lightning density increases with height in Yakutia. The distribution of lightning density depending on elevation had two modes with different slopes of the linear increase. The lightning density is greater along western side of mountain chains. The maximum total number of lightning strokes was observed in 2017. There are interannual quasi-fluctuations of the total number of lightning strokes during the season and by months.

HVDC cable systems connected to HVDC overhead lines are subject to fast front overvoltages emanating from the line when lightning strikes a shield wire (backflashover) or a pole conductor (shielding failure). Representative fast front overvoltage levels for HVDC cable systems are usually established without considering their statistical characteristics. A statistical method to determine overvoltages related to the acceptable mean time between failure (MTBF) for the cable system was developed previously. The method accounts for the statistical distribution of lightning current magnitudes as well as the attenuation of the overvoltage wave due to corona discharges on the line, since this effect dominates for system voltages up to about ±320 kV. To make the method suitable for higher system voltages as well, this article introduces an improved statistical method which also accounts for surge attenuation through resistive effects, soil ionization, and statistical treatment of overvoltages due to shielding failures. To illustrate the improved method, it is applied to a case study for a ±525 kV DC line.

The impacts of elevation, terrain slope and vegetation cover on lightning activity are investigated for contrasting environments in the north-east (NE) (21– $$29{^{\circ }}\hbox {N}$$ ; 86– $$94{^{\circ }}\hbox {E}$$ ) and the north-west (NW) (28– $$36{^{\circ }}\hbox {N}$$ ; 70– $$78{^{\circ }}\hbox {E}$$ ) regions of the Himalayan range. Lightning activity is more at a higher terrain slope/elevation in the dry NW region where vegetation cover is less, whereas it is more at a lower terrain slope/elevation in the moist NE region where vegetation cover is more. In the wet NE, 86% (84%) of the annual lightning flash rate density (LFRD) occurs at an elevation $${

The tripping frequency of 10kV distribution network line in Jinzhai County, caused by lightning accidents, is increasing in recent years. Effective protection measures to reduce the risks of line tripping becomes necessary. In this paper, statistics analyses on the events of lightning fall in Jinzhai area occurred in recent years were made. Damages caused by lightning accidents on distribution network were discussed in terms of distribution of lightning density and distribution of ground lightning intensity. The changing trend of line tripping caused by lightning accidents in recent years was studied, in comparison with the lightning withstand level of distribution network line at present. The results show that in the past three years, the increase of line tripping events is mainly due to the increase of ground lightning density and intensity in Jinzhai area. Lightning protection measures which mount lightning arresters on local poles and towers are confirmed to have limited effects on improving lightning protection performance on the whole 10kV distribution network, an innovative lightning protection scheme is put forward. The scheme could introduce improvement in insulation levels by installing Insulated cross arm in distribution network. The line model is simulated in EMTP. The performances of lightning protection before and after the application of the scheme are compared. The simulation results show that the innovative scheme can effectively improve the lightning resistance level of the entire line system. Following the above simulation results, the threats to the safety of substation operation, caused by the improvement of line insulation level, are further analyzed. The possible solutions for the threats are provided.

Based on the thunderstorm observation data from 1956 to 2013 of meteorological stations in Hunan, the lightning monitoring data from 2008 to 2017, and lightning disaster data from 2002 to 2017, the spatial and temporal distribution characteristics of lightening and lightning disaster in Hunan are analyzed. The results show that: the annual averaged days of thunderstorm in Hunan are 49.9 days, it is decreasing by the rate of 3.493d/10a; the CG lightning return stroke the whole province observed on average about 340,000 times per year; July and August are the peak months of the lightning return stroke; hourly distribution of lightning return stroke appeared as single-peak, the peak period is between 15 and 17 p.m.; Yueyang, Changsha, Huaihua and Shaoyang are lightning disaster-prone areas; most lightning casualties have occurred the rural, lightning protection safety work of the rural needs to be strengthened.

This paper presents statistical data about lightning damage on wind turbine blades reported at different wind farms in the U.S. The analysis is based on 304 cases of damage due to direct lightning attachment on the blade surface. This study includes a large variety of blades with different lengths, laminate structure, and lightning protection systems. The statistics consist of the distribution of lightning damage along the blade and classify the damage by severity. In addition, the frequency of lightning damage to more than one blade of a wind turbine after a thunderstorm is assessed. The results of the analysis show that the majority of lightning damage is concentrated at the tip of the blade. Furthermore, all of the blades involved in the study show great similarity in the distribution of damage along the blade and the characteristics of the damages, even concerning the significant differences in the blades' geometry and materials.

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

Lightning activity is analysed in a sector covering the Eastern Mediterranean (16–32°E, 34–46°N) for the years 2005–2014. The study is based on the use of cloud-to-ground (CG) lightning activity data retrieved from ZEUS system, operated by the National Observatory of Athens, and examines the seasonal, diurnal and spatial variability of the lightning activity. The effect of elevation, terrain slope, vegetation cover and convective available potential energy (CAPE) on the distribution of the CG lightning strokes is also investigated. Lightning is modulated by the diurnal cycle of insolation and the underlying topographic features of the region. The lightning strokes are more numerous over the mainland than over the sea. CG lightning activity is dominant over the land and the coastal areas during spring and summer while during the coldest period of the year it is dominant over the sea. The maximum value of lightning activity is observed in June and mostly in the afternoon. The orography and the terrain slope affect the distribution of lightning. During the warmest period of the year, the forested areas have an increased “lightning yield”. The number of CG lightning strokes increases with increasing CAPE and the high correlation between them indicates that CAPE values could be used as a proxy for the presence of lightning activity, at least over the eastern Mediterranean region.

Lightning activity over the Tibetan Plateau, which has an average altitude of higher than 4000 m above sea level, is investigated by using 20-year (1995–2014) LIS/OTD data. The effect of surface thermodynamics on lightning activity is examined for four sub-regions across the plateau based on the NCEP reanalysis data. The average lightning flash density over the entire Tibetan Plateau is 2.5 fl·km−2 yr−1, and the maximum flash density is 7.7 fl·km−2 yr−1 at eastern plateau. The geographical distribution of lightning flash density shows a gradual decrease from east to west across the Tibetan Plateau, from 4.3 fl·km−2 yr−1 on average over the Eastern Tibetan Plateau to 1.7 fl·km−2 yr−1 over the Western Tibetan Plateau. Over the plateau's main highland (>4500 m), there is a local maximum value of 5.7 fl·km−2 yr−1 in the center area of Nagqu. Lightning activity over the Tibetan Plateau mainly occurs in boreal summer, and 96.8% of the annual flashes occur during May–September. There is more lightning in the relatively dry spring, even in summer, over the main highland of the Tibetan Plateau. The results show that humidity and sensible heat fluxes play a vital role in the occurrence of lightning over the Tibetan Plateau. A new parameter, product of rainfall, Bowen ratio (defined as the ratio of the sensible heat fluxes to latent heat fluxes) and surface specific humidity, is proposed and shows a better correlation with lightning activity, generally displaying a larger correlation coefficient than rainfall alone or other parameters over the study sub-regions.

An improved stochastic method for computer simulation of lightning leaders is developed based on the results from optical observation data. The development and attachment process of downward negative cloud-to-ground lightning in the near-ground area is simulated. The distribution of lightning strike points influenced by tall structures is statistically analyzed. The results show that when downward negative leaders initiate at 1500 m height over a structure, the relative strike frequency for the structure increases at a decreasing rate as the structure height increases. The strike frequency for a 600 m tall structure is approximately 3.6 times that for a 100 m tall structure. Additionally, the structure may attract some lightning to hit itself and shift nearby ground strike points toward the structure. For taller structures, the deviation effect is more apparent. It is stipulated in this study that if the ground strike density in the vicinity of the structure is no more than 5% of the average density, then the structure has a sufficient protective effect on this area. The data indicate that there is a positive correlation between the protection distance and the height of the structure. The protection distances of structures of 100–600 m in height are 200 m, 280 m, 350 m, 400 m, 450 m, and 480 m approximatively, which show a declining rate of increase.

The first decadal lightning flash climatology for Europe is presented using ATDnet long-range lightning detection network operated by the Met Office. More than 148 million lightning flashes were detected by ATDnet in the study area between 2008 and 2017. The dataset contains up to 90% of cloud-to-ground flashes and 25% of cloud flashes in Europe during the study period. All maps were computed with a spatial resolution of 0.2°. The annual flash density was between 0.5 and 3.0 flashes per km−2 y−1 in most of Europe with a maximum of 7.8 flashes km−2 y−1 in the northeast of Italy. Most of continental Europe experienced 20–40 thunderstorm days annually but a small area on the border of Armenia and Turkey experienced up to 87.6 thunderstorm days. This number exceeds previous estimates of European maximum thunderstorm frequency. The North Atlantic Ocean had only up to 10 thunderstorm days and 0.1 flash km−2 y−1. Flash density per thunderstorm day varied from 0.1 fl km−2 in the northeast of Italy. Occasional intense storms were found to happen even in areas without regular thunderstorm activity, including the oceans to the north of the Arctic Circle. Most of the study area had a mid-latitude specific summer peak in lightning activity whereas the Mediterranean experienced an autumn maximum. From March to August, most of the lightning in Europe occurred over land whereas from September to February it was concentrated over the Mediterranean. The highest lightning frequency over land was observed during the afternoon hours and the lowest frequency at night. At sea the diurnal distribution of lightning peaked either at night or in the morning hours.

Lightning location systems geolocate lightning strokes. Given assumptions made in the geolocation models, errors in the reported locations can occur. Modelling these errors as a bivariate Gaussian distribution of historic stroke detections has found success in the form of confidence ellipses. However, the presence of outliers - strokes with large location errors - indicate that there is a better model for these errors. The Students’ t-distribution is a “heavier” tailed distribution. This paper investigates whether the bivariate Students’ t-distribution is a better model for such errors. A methodology for modelling and evaluating the distribution of location errors using maximum likelihood estimation, expectation-maximization and a Mahalanobis distance quality-of-fit test is described. This method is applied to stroke reports from the South African Lightning Detection Network and the Austrian Lightning Detection and Information System time-correlated with photographed lightning events to the Brixton Tower, South Africa and current measurements to the Gaisberg Tower, Austria respectively. In both cases, we find outliers in the distribution of location errors - even as the performance of the networks increase. Using the Mahalanobis test, we find the bivariate Students’ t-distribution to be a better statistical model for both the South African and the Austrian events.

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

The impact of the distribution of lightning strikes along the span on the backflashover rate of transmission lines was investigated, by using advanced methodologies and a 138-kV line as reference. The results, obtained using an attractive radius given by Love’s expression and distinct conditions of tower-footing grounding impedance and span lengths, indicated a larger span factor in relation to the traditional 0.6-factor. Factors about 0.81 for a 400-m span and 0.84 for a 600-m span length cases were found, suggesting that using the 0.6-factor would underestimate the backflashover rate.

The transient distribution of lightning current, which flows in a multilayer carbon-fiber-reinforced plastic (CFRP) material of aircraft, has been studied using the finite-difference time-domain (FDTD) method. Each layer of the multilayer CFRP panel has a fiber direction of 45°, 90°, −45° or 0°, and, therefore, has an anisotropic conductivity. It is quite difficult to represent such an anisotropic layered panel using the FDTD method with common rectangular prism or cubic cells. In this paper, the distribution of lightning currents on a 3-mm-thick multilayer CFRP panel, composed of 16 layers, is computed using the FDTD method with a conductivity matrix approach.

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

Lightning has been detected on Jupiter by all visiting spacecraft through night-side optical imaging and whistler (lightning-generated radio waves) signatures1–6. Jovian lightning is thought to be generated in the mixed-phase (liquid–ice) region of convective water clouds through a charge-separation process between condensed liquid water and water-ice particles, similar to that of terrestrial (cloud-to-cloud) lightning7–9. Unlike terrestrial lightning, which emits broadly over the radio spectrum up to gigahertz frequencies10,11, lightning on Jupiter has been detected only at kilohertz frequencies, despite a search for signals in the megahertz range 12 . Strong ionospheric attenuation or a lightning discharge much slower than that on Earth have been suggested as possible explanations for this discrepancy13,14. Here we report observations of Jovian lightning sferics (broadband electromagnetic impulses) at 600 megahertz from the Microwave Radiometer 15 onboard the Juno spacecraft. These detections imply that Jovian lightning discharges are not distinct from terrestrial lightning, as previously thought. In the first eight orbits of Juno, we detected 377 lightning sferics from pole to pole. We found lightning to be prevalent in the polar regions, absent near the equator, and most frequent in the northern hemisphere, at latitudes higher than 40 degrees north. Because the distribution of lightning is a proxy for moist convective activity, which is thought to be an important source of outward energy transport from the interior of the planet16,17, increased convection towards the poles could indicate an outward internal heat flux that is preferentially weighted towards the poles9,16,18. The distribution of moist convection is important for understanding the composition, general circulation and energy transport on Jupiter. Observations of broadband emission from lightning on Jupiter at 600 megahertz show a lightning discharge mechanism similar to that of terrestrial lightning and indicate increased moist convection near Jupiter’s poles.

To design a proper lightning protection system the electro-geometrical model (EGM) is widely used to place lightning conductors on structures. Among some other methods the standard IEC 62305 makes use of a rolling sphere model, in which it is analyzed if a sphere of a certain radius might touch a structure or its protecting lightning conductors. The radii of the spheres are connected to certain lightning peak currents, and these are associated with the distribution of lightning peak currents, published by CIGRE (CIGRE data). From these distributions the probabilities of exceeding a certain current level can be derived. These distributions were created mainly by real tower measurements on Monte San Salvatore (MSS) by Prof. Berger. Today a new simulation methodology, the dynamic electro-geometrical model (DEGM), uses this distribution and also the whole concept of the EGM. Because the peak current distribution was obtained from tower measurements, the distribution is falsified in comparison to a distribution on flat ground. To get undistorted results from the DEGM a converted distribution to flat ground is needed. An analytic approach is introduced to describe the problem itself, and after that the real geographical environment is used to compute the real interception areas at MSS measurement station in order to convert the peak current distribution derived from “Bergers Data” to flat ground. As an outcome, the median current peak values of a “normalized” peak current distribution are lower than those of the original distribution. Additionally, this corresponds better to distributions found by LDNs (Lightning Detection Networks).

Schumann resonance transients which propagate around the globe can potentially generate a correlated background in widely separated gravitational wave detectors. We show that due to the distribution of lightning hotspots around the globe these transients have characteristic time lags, and this feature can be useful to further suppress such a background, especially in searches of the stochastic gravitational-wave background. A brief review of the corresponding literature on Schumann resonances and lightnings is also given., 5 pages, revtex4, one table, version to be published in Modern Physics Letters A

Protection against lightning is always a challenging job for the researcher. The consequences due to lightning on different building shapes needs a comprehensive knowledge in order to provide the information to the common man. This paper is mainly concern with lightning pattern when it strikes on the building with different shape. The work is based on the practical experimental work in high voltage laboratory. Different shapes of the scaled structures have been selected in order to investigate the equal distribution of lightning voltage. The equal distribution of lightning voltage will provide the maximum probability of lightning strike on air terminal of the selected shapes. Building shapes have a very important role in lightning protection. The shapes of the roof tops have different geometry and the Franklin rod installation is also varies with changing the shape of the roof top. According to the ambient weather condition of Malaysia high voltage impulse is applied on the lightning rod installed on different geometrical shape. The equal distribution of high voltage impulse is obtained as the geometry of the scaled structure is identical and the air gap for all the tested object is kept the same. This equal distribution of the lightning voltage also proves that the probability of lightning strike is on the corner and the edges of the building structure.

Electromagnetic screening is the usual approach for protecting sensitive electronic equipment against powerful electromagnetic disturbances. Applied for this purpose real-world metallic enclosures usually contain various structural irregularities, such as apertures or chinks, which complicate the assessment of the shielding effectiveness of such electromagnetic screens even in the quasi-stationary approximation. This is mainly due to the lack of appropriate theoretical models as well as accurate and efficient practical methods for simulating temporal and spatial field distribution of lightning electromagnetic pulses (LEMP) inside metallic enclosures with apertures. In this article we introduce generic mathematical models and a novel Hybrid method based on these models, which enable simulation of spatio-temporal distribution of electromagnetic fields, induced by distant or direct lightning strikes, inside metallic enclosures with apertures. We also carry out comparative performance analysis of the Hybrid method with respect to the Finite Element Method. Finally, we assess our theoretical results by comparing them with the experimental data acquired for a dummy rocket part. Three different cases are investigated: enclosure irradiated by quasi-static electric field of LEMP, enclosure irradiated by quasi-stationary magnetic field of LEMP, and enclosure struck by a lightning directly.

This paper presents analyses of the finescale structure of convection in the comma head of two continental winter cyclones and a 16-storm climatology analyzing the distribution of lightning within the comma head. A case study of a deep cyclone is presented illustrating how upper-tropospheric dry air associated with the dry slot can intrude over moist Gulf air, creating two zones of precipitation within the comma head: a northern zone characterized by deep stratiform clouds topped by generating cells and a southern zone marked by elevated convection. Lightning, when it occurred, originated from the elevated convection. A second case study of a cutoff low is presented to examine the relationship between lightning flashes and wintertime convection. Updrafts within convective cells in both storms approached 6–8 m s−1, and convective available potential energy in the cell environment reached approximately 50–250 J kg−1. Radar measurements obtained in convective updraft regions showed enhanced spectral width within the temperature range from −10° to −20°C, while microphysical measurements showed the simultaneous presence of graupel, ice particles, and supercooled water at the same temperatures, together supporting noninductive charging as an important charging mechanism in these storms. A climatology of lightning flashes across the comma head of 16 winter cyclones shows that lightning flashes commonly occur on the southern side of the comma head where dry-slot air is more likely to overrun lower-level moist air. Over 90% of the cloud-to-ground flashes had negative polarity, suggesting the cells were not strongly sheared aloft. About 55% of the flashes were associated with cloud-to-ground flashes while 45% were in-cloud flashes.

A 10-year statistics (2002–2011) of the Nordic Lightning Information System (NORDLIS) are presented. NORDLIS is a joined lightning location network between Norway, Sweden, Finland, and Estonia, comprising in 2011 of 32 lightning location sensors. Our data set contains a total of 4,121,649 cloud-to-ground (CG) flashes. We show the regional and temporal distribution of lightning in Northern Europe during the study period. Our results indicate that the average annual ground flash density values are greatest in Southern Sweden, Baltic countries and Western Finland. The average number of thunderstorm days is largest in the Baltic countries and Southwestern Sweden, and the annual number of ground flashes has varied during the study period from 250,000 to 620,000. The largest observed daily number of ground flashes is 51,500, and the largest daily ground flash density is about 5 CGs km − 2 ; this has occurred in southern Sweden in July 2003. The average daily number of ground flashes peaks in mid-July–early-August. Cold season (October–April) thunderstorms occur frequently over the North Sea west of Norway and in the west coast of Denmark. Our results also show that an intense thunderstorm may occur practically anywhere in the Northern Europe except for certain maritime and mountain areas.

EnglishLightning climatology in the Congo Basin is analyzed using data from the World Wide Lightning Location Network (WWLLN) from 2005 to 2013. A comparison with data from the optical space sensor LIS shows that the relative detection efficiency of the WWLLN increased from approximately 1.7% at the beginning of the period to 5.9% in 2013. These mean values over the entire area are low but related to all lightning flashes (intracloud and cloud-to-ground) and allow, however, obtaining a good representation of thunderstorm activity particularly strong in the study area. The average flash rate describes an annual cycle with high monthly proportions from October to March from 9 to 11%, and values at least 2 times lower from June to August. The meridian distribution of lightning shows a reinforcement between 5° S and 5° N with a maximum between 1° S and 2° S. The geographical distribution shows a very strong maximum in the East of the Democratic Republic of Congo (DRC), whatever the reference year and the period of the year. In 2013, the estimated annual lightning density taking into account DE and the number of thunderstorm days, calculated with a resolution of 0.1° x 0.1°, reached 218 flashes km-2 year-1 and 189 days, respectively. The maximum number of flashes per thunderstorm is in the same area, which means that thunderstorms are there, either more numerous, or more intense, or more stationary, or several of the three characteristics. This region is located west of the Virunga mountain range at an altitude that reaches 3 000 meters and plays a role in the initiation of thunderstorms during the year. In addition, the presence of the South African Easterly Jet (AEJ-S) at low altitude produces the instability necessary to the local development of Mesoscale Convective Systems (MCS) at the origin of this strong activity. These MCS can then propagate or regenerate to the west over a distance related to the influence of the phase of Kelvin waves propagating eastward. francaisLa climatologie des eclairs dans le bassin du Congo est analysee a l'aide des donnees du reseau World Wide Lightning Location Network (WWLLN) de 2005 a 2013. Une comparaison avec les donnees du capteur optique spatial LIS montre que l'efficacite de detection relative du reseau WWLLN passe d'environ 1,7 % au debut de la periode a 5,9 % en 2013. Ces valeurs moyennes sur l'ensemble de la zone sont faibles, mais concernent la totalite des eclairs (intranuage et nuage-sol) et permettent d'avoir une bonne representativite de l'activite orageuse particulierement forte dans la zone d'etude. Le taux d'eclair moyen decrit un cycle annuel avec de fortes proportions mensuelles d'octobre a mars de l'ordre de 9 a 11 % et des valeurs au moins deux fois plus faibles de juin a aout. La distribution meridienne des eclairs montre un renforcement entre 5° S et 5° N avec un maximum entre 1° S et 2° S. La repartition geographique montre un maximum tres marque dans l'est de la Republique democratique du Congo (RDC), quelles que soient l'annee de reference et la periode de l'annee. En 2013, la densite annuelle d'eclairs estimee en tenant compte de l'efficacite de detection et du nombre de jours d'orages, calcules avec une resolution de 0,1° x 0,1°, y atteignent respectivement 218 eclairs km-2 an-1 et 189 jours. Le nombre maximum d'eclairs par jour d'orage se situe dans la meme region, ce qui signifie que les orages y sont, soit plus nombreux, soit plus intenses, soit plus stationnaires, soit plusieurs des trois caracteristiques a la fois. Cette region se situe a l'ouest de la chaine de montagnes des Virunga qui presente une altitude superieure a 3 000 metres et qui joue un role dans l'initialisation des orages au cours de l'annee. De plus, la presence du courant jet africain oriental de basse altitude produit l'instabilite necessaire au developpement local de systemes convectifs de moyenne echelle (MCS) a l'origine de cette forte activite. Ces MCS peuvent ensuite se propager ou se regenerer vers l'ouest sur une distance liee a l'influence de la phase des ondes de Kelvin se propageant vers l'est.

Storm severity in the mid-Atlantic region of the United States is examined using lightning, radar, and model-derived information. Automated Warning Decision Support System (WDSS) procedures are developed to create grids of lightning and radar parameters, cluster individual storm features, and data mine the lightning and radar attributes of 1252 severe and nonsevere storms. The study first examines the influence of serial correlation and uses autocorrelation functions to document the persistence of lightning and radar parameters. Decorrelation times are found to vary by parameter, storm severity, and mathematical operator, but the great majority are between three and six lags, suggesting that consecutive 2-min storm samples (following a storm) are effectively independent after only 6–12 min. The study next describes the distribution of lightning jumps in severe and nonsevere storms, differences between various types of severe storms (e.g., severe wind only), and relationships between lightning and radar parameters. The 2σ lightning jump algorithm (with a 10 flashes min−1 activation threshold) yields 0.92 jumps h−1 for nonsevere storms and 1.44 jumps h−1 in severe storms. Applying a 10-mm maximum expected size of hail (MESH) threshold to the 2σ lightning jump algorithm reduces the frequency of lightning jumps in nonsevere storms to 0.61 jumps h−1. Although radar-derived parameters are comparable between storms that produce severe wind plus hail and those that produce tornadoes, tornadic storms exhibit much greater intracloud (IC) and cloud-to-ground (CG) flash rates. Correlations further illustrate that lightning data provide complementary storm-scale information to radar-derived measures of storm intensity.

Optimal route selection of a transmission line is significantly beneficial to reduce its lightning trip-out rate. This paper proposes a method, considering the minimal annual flash number to transmission lines, to select the optimal route from the initial point to the destination based on the lightning location system. First, the ground flash density and distribution of lightning peak current maps are drawn via the improved grid method. The flash grid and flash node are proposed based on these maps. The objective function is expressed as the summation of the grid distance of the flash node, and solved via the Dijkstra algorithm. The conditional minimum transit cost is also provided to find the optimal corridor. Five 500-kV transmission lines are used to validate the effectiveness of the proposed method. The results indicate that the annual expected flash numbers of all lines are markedly reduced.

When we examine the lightning frequency and the lightning shielding effect of the electro-geometric model (EGM), we need the current distribution of all lightning to the ground. The distribution of lightning current to structures is different from this distribution, but it has been used in EGM conventionally. We assumed the lightning striking distance coefficient related to the height of structures in order to obtain a result which corresponds to the observed frequency of lightning to structures, and estimated the current distribution of all lightning to the ground from data listed in the IEC 62305 series of EGM. The estimated distribution adjusted by the LLS detection efficiency agreed well with the distribution observed by LLS. © 2013 Wiley Periodicals, Inc. Electr Eng Jpn, 184(3): 14–26, 2013; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.22356

The number of home electric appliances, such as personal computers and telephones, has been rapidly increasing. Lightning damage to these home electric appliances has a great impact on a highly sophisticated information society. There are cases in which lightning overvoltages in low-voltage distribution lines cause malfunctions in them, even though they are equipped with surge protective devices to protect against lightning overvoltages. Therefore, for lightning protection of low-voltage equipment including home electric appliances, it is important to understand the phenomenon of lightning overvoltages in low-voltage power distribution lines. However, many aspects of this problem are not entirely clear, in particular how they are generated. The Tokyo Electric Power Company carried out lightning observations on low-voltage distribution lines. The observation results provide a statistical distribution of lightning overvoltages in low-voltage distribution lines. A mechanism for generating lightning overvoltages in low-voltage distribution lines is inferred from the observed waveforms and facilities data. © 2013 Wiley Periodicals, Inc. Electr Eng Jpn, 183(2): 12–21, 2013; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.21299

The paper investigates lightning activity in the region of tropical cyclones (TC), its structure and changeability during the process of TC development and attenuation according to the data of the World Wide Lightning Location Network (WWLLN) as well as the relation with ocean surface wind fields according to the ASCAT scatterometer data. Distribution of lightning discharges in TC regions and discharge density fields drawn up from them allowed us to detect TC structure elements, such as mesovortexes, eyewalls, cloud bands and spirals, and to trace their change in space and time.