In this work, it shows that nuclear reactions in lightning channel, which are produced by the deuterium-deuterium (D-D) and deuterium-tritium (D-T) nuclear reactions, represent a plausible mechanism for gamma-ray burs...In this work, it shows that nuclear reactions in lightning channel, which are produced by the deuterium-deuterium (D-D) and deuterium-tritium (D-T) nuclear reactions, represent a plausible mechanism for gamma-ray bursts observed at ground. Gamma-ray emissions from lightning can be explained by neutron inelastic scattering in the air. Neutrons (produced in lightning channel) will delay a definitive time (~33 ms) to cover the atmosphere before hitting a molecule and producing gamma rays, which is somewhat longer than the gamma-ray time delay (~20 ms) observed at ground.展开更多
We present a comparison of data obtained during testing of lightning protective system of a residential structure in rocket-triggered lightning experiment at the International Center for Lightning Research and Testing...We present a comparison of data obtained during testing of lightning protective system of a residential structure in rocket-triggered lightning experiment at the International Center for Lightning Research and Testing(ICLRT)at Camp Blanding,Florida,and current surge generator experiment at Rzeszow University of Technology in Poland.Three different configurations of LPS were tested in Poland with the dc grounding resistances of the entire system 4.09 Ω(LPS 1a),1.65 Ω(LPS 1b),and 2.88 Ω(LPS 2).For LPS 1a with three ground rods the value of the peak current entering the electrical circuit neutral was about 56% of the injected current peak,and for LPS 1b with two additional ground rods and two 5 m long buried horizontal conductors it was about 16%.For LPS 2 with five ground rods interconnected by a buried loop conductor this ratio was 21%.The current waveshapes in the ground rods differed from the injected current waveshapes and the current waveshapes in other parts of the test system,especially,for poorer-grounding LPS 1a.The surge-generator results are consistent with those of triggered-lightning experiments at Camp Blanding,Florida(DeCarlo et al.,2008 [2]).展开更多
Through the use of the independently developed Thunderstorm Energetic Radiation Observation System(TEROS),observation experiments of rocket-triggered lightning energetic radiation(RLER)were conducted for the first tim...Through the use of the independently developed Thunderstorm Energetic Radiation Observation System(TEROS),observation experiments of rocket-triggered lightning energetic radiation(RLER)were conducted for the first time at the Field Experiment Base on Lightning Sciences,China Meteorological Administration from May 2021 to July 2021.A total of 17 X-ray bursts were detected during all of the 22 leader/return strokes.In this study,the energy,time,and direction characteristics of Xray burst and its relationships with the corresponding discharge parameters,such as the return stroke peak current,half-peak width,rise time,and interstroke time interval,as well as the associated physical processes,are analyzed and discussed.Results showed that energetic radiation is ubiquitous in triggered lightning and is closely related to the last downward leader phase before the return stroke.The photon energies were concentrated in tens to hundreds of ke V,and the average duration of RLER was approximately 27μs.Moreover,RLER exhibited directional property inconsistent with a vertical downward beam,which may be related to the development orientation of the lightning leader.The intensity of RLER was positively correlated with the return stroke peak current,indicating that it directly depends on the lightning intensity,but it would be modulated by the lightning channel conditions.The 17 RLER events showed 3 different time distribution patterns,namely,discrete,continuous,and discrete/continuous pulses,of which the discharge parameters were also different.The discrete pulse event had the longest duration,a small half-peak width,and a long interstroke time interval.Furthermore,all of these events occurred during the last several leader/return strokes.The continuous pulse event had a short duration and a small peak current.The discrete/continuous pulse event had a moderate duration and a large half-peak width and peak current.These three distinct time distribution patterns may be determined by different development types of lightning leaders.Our observations support the leader high-field runaway mechanism.展开更多
Currently,the number of lightning casualties and casualty rates have significantly reduced in developed countries,but there has been no significant reduction in developing countries.On the one hand,this is due to the ...Currently,the number of lightning casualties and casualty rates have significantly reduced in developed countries,but there has been no significant reduction in developing countries.On the one hand,this is due to the high frequency of lightning;on the other hand,the vulnerability of people in developing countries is also an influencing factor.Through case analysis and summary,this paper expounds on lightning injury s mechanism and clinical manifestations.It points out that lightning injury is mainly related to heart problems and the impact on the nervous system,rather than burns,which usually cause fewer consequences.Medical treatment needs to pay attention to the order and principles of treatment.Implementing CPR and auxiliary AED is the most effective way to save lives.Attention should be paid to the practical and effective treatment and nursing of lightning stroke sequelae.Finally,combined with the situation of lightning casualties in China,the existing problems are put forward during the process of early treatment,post-hospital treatment,and nursing observation,which provides an objective basis for the cognition of the scientific nature of the lightning injury.展开更多
This study utilizes data from a 3D lightning location system,polarimetric radar,and current measurements from channels of triggered lightning flashes(TLFs)to analyze the structural characteristics of the parent thunde...This study utilizes data from a 3D lightning location system,polarimetric radar,and current measurements from channels of triggered lightning flashes(TLFs)to analyze the structural characteristics of the parent thunderstorms associated with negative TLFs in South China.The triggered-flash region(TFR)displays distinct stratiform cloud characteristics,including lower radar reflectivity heights and a predominance of ice crystals and dry snow above the 0℃ layer.In contrast,the thunderstorm convection core region(CCR)tends to have more graupel particles in the mixed-phase layers and exhibits an ice-water content peak approximately 3.4 times that of the TFR.The charge regions involved in discharges in TFRs exhibit a dipolar charge structure,with the-5℃ layer roughly dividing the upper positive and lower negative charge regions.Conversely,the CCRs feature a typical tripolar charge structure.The dominant dipole charge structure in the TFR results in an increase in the negative charge field below the negative charge region with height,providing a necessary condition for successfully triggering negative TLFs.Furthermore,the horizontal extent of TLFs is positively correlated with their duration and charge transfer.Regions where TLF channels with larger charge transfers propagate tend to have greater maximum radar reflectivity but lower average radar reflectivity compared to regions with TLFs with smaller charge transfer.展开更多
Based on the site investigation of a lightning stroke accident in a coal mine in Weiyuan County during a strong thunderstorm process on the night of August 10,2024,combined with the investigation data of the accident ...Based on the site investigation of a lightning stroke accident in a coal mine in Weiyuan County during a strong thunderstorm process on the night of August 10,2024,combined with the investigation data of the accident site,the causes of the lightning stroke accident were analyzed,and the corresponding rectification suggestions were put forward.展开更多
Activity 1 Think about the following questions and write down your answers before reading the text.1.What are some common factors that usually cause damage to trees when they are struck by lightning?2.How might the un...Activity 1 Think about the following questions and write down your answers before reading the text.1.What are some common factors that usually cause damage to trees when they are struck by lightning?2.How might the unique characteristics of a tree contribute to its ability to survive a lightning strike?展开更多
The protection effectiveness of traditional Lightning Strike Protection(LSP)for composite rotor blade of helicopter can be diminished due to the explosion risk in overlapping attachment under lightning strike,so a new...The protection effectiveness of traditional Lightning Strike Protection(LSP)for composite rotor blade of helicopter can be diminished due to the explosion risk in overlapping attachment under lightning strike,so a new protection method based on Air Breakdown and insulating adhesive layer(AB-LSP method)was designed to avoid it.In this study,a numerical method was developed to simulate the electrical breakdown,and verified by experiment results.Based on this method,a Finite Element Model(FEM)was established to investigate the effect of two factors(breakdown strength and initial ablation temperature of adhesive layer)on the LSP effectiveness.The results show that the breakdown strength impacts more to the ablation damage in composite than that of high-temperature resistance.Then,another FEM was established to predict the ablation damage by lightning strike in the AB-LSP method protected composite rotor blade.The mechanisms and potential key parameters(magnitude of lightning current,discharge channel location,adhesive layer thickness,and air gap width)that could affect the protection effectiveness were analyzed.The introduction of air breakdown changes the current conduction path and reduces explosion risk.After rational design,this method can offer effective lightning protection for composite helicopter rotor blade and other composite structures.展开更多
The Van Allen radiation belts are doughnut-shaped zones surrounding Earth, filled with highly energetic charged particles whose sources or loss mechanisms have been investigated for decades. As for the inner belt, cos...The Van Allen radiation belts are doughnut-shaped zones surrounding Earth, filled with highly energetic charged particles whose sources or loss mechanisms have been investigated for decades. As for the inner belt, cosmic ray albedo neutron decay(CRAND),radial diffusion, and local acceleration have been considered principal sources of electrons, whereas protons are predominantly from CRAND and solar protons. In this article, lightning-induced neutrons from Earth's upper atmosphere are suggested as a possible source of protons and electrons in the inner radiation belt. These terrestrial neutrons can contribute to the inner belt population by undergoing nuclear decay. Several approaches are proposed and discussed to evaluate the potential contribution of lightning-induced neutrons to the inner belt, including magnitude estimation, Monte Carlo simulations, and in situ observations. This article discusses some avenues of further study to determine the contribution of lightning-induced neutrons to the inner radiation belt.展开更多
In the past,the lightning strike risk assessment of wind farms mainly referred to the Lightning Protection Part 2:Risk Management(IEC 62305-2-2010)and the Lightning Protection of Wind Energy System(IEC 61400-24-2019)b...In the past,the lightning strike risk assessment of wind farms mainly referred to the Lightning Protection Part 2:Risk Management(IEC 62305-2-2010)and the Lightning Protection of Wind Energy System(IEC 61400-24-2019)based on protection angle method.In fact,the basic idea of the two is the same,that is,the source of the lightning fan is replaced by S1-S4 of the former lightning building with the latter ND-NDJ.According to the above method of wind farm evaluation,it has been proved that the practice can not achieve good results.Taking offshore wind farm as an example,this paper introduces a new method of establishing six evaluation indicators to determine the risk level according to the new technology and compliance principle of regional lightning protection(semi-circular method),which can be used for reference by wind farm technicians.展开更多
By using the reported data of lightning disaster and the data of lightning monitoring network in Shandong Province since its establishment,the lightning activities and the disaster climate characteristics in Shandong ...By using the reported data of lightning disaster and the data of lightning monitoring network in Shandong Province since its establishment,the lightning activities and the disaster climate characteristics in Shandong Province were analyzed.The data were processed by lattice formulation,and the spatial and temporal distribution characteristics of positive and negative CG flashes were given.The parameter characteristics of positive and negative ground lightning and its relationship with the lightning disasters were analyzed.And the lightning parameter characteristics of lightning in major cities of Shandong Province were analyzed.展开更多
Based on the special landscape and regional characteristics,the lightning location information from 1999 to 2008 and conventional observation data from 1971 to 2000 provided by electricity departments in Hebei Provinc...Based on the special landscape and regional characteristics,the lightning location information from 1999 to 2008 and conventional observation data from 1971 to 2000 provided by electricity departments in Hebei Province were applied to analyze spatial and temporal distribution of lightning.With lighting disaster data since 2000 provided by meteorological department,and records from civil affair,statistics,insurance,and other departments,the lighting disaster distribution of Hebei Province was studied from aspects of economic and people losses,and some countermeasures for several lightning disasters industries were put forward.展开更多
Based on the radar data and lightning position indicator data of strong thunderstorm weather which happened in Fuxin on July 8,2007,the relationship between the lightning activity and the radar echo was analyzed.The r...Based on the radar data and lightning position indicator data of strong thunderstorm weather which happened in Fuxin on July 8,2007,the relationship between the lightning activity and the radar echo was analyzed.The results showed that Fuxin area located in the cross position of T-shaped trough and was affected by the cold air which continuously glided down.The corresponding warm front on the ground advanced southward and arrived here.It was the weather background of this thunderstorm weather.The position variation of lightning occurrence was closely related to the strong echo movement of squall line,and the velocity echo clearly reflected and predicted the movement tendency of the radar echo.展开更多
The cloud-to-ground lightning data between 2007 and 2008 were collected by lightning detection and location system,which was composed of four lightning detectors in four different sites of Dalian area.The spatio-tempo...The cloud-to-ground lightning data between 2007 and 2008 were collected by lightning detection and location system,which was composed of four lightning detectors in four different sites of Dalian area.The spatio-temporal distribution of cloud-to-ground lightning in surrounding areas of Dalian was analyzed from several aspects of polarity distribution,diurnal variation,lightning intensity and lightning density.The results showed that the number of negative lightning accounted for 93.9% of the total number of lightning,and its average lightning intensity was 27.99 kA.The number of positive lightning accounted for 6.1% of the total number of lightning,and its average lightning intensity was 35.56 kA.The diurnal variation of lightning frequency showed an obvious structure of two peaks (17:00-18:00 and 04:00-05:00) and two valleys (09:00-10:00 and 00:00-01:00).The number of lightning between May and September was 91.5% of the annual number,and the lightning occurred the most frequently between June and August.Most of positive and negative lightning was at the intensity of 15-35 kA,80.0% lower than 40 kA,and 99.3% lower than 100 kA.The lightning density had obvious regional differences in distribution,high in the Liaodong Bay and the Dalian Bay and low in inland areas.Therefore,coastal areas should attract more attention in lightning disaster defense in the surrounding areas of Dalian.展开更多
According to structure function and lightning damage of a cable car, a feasible method of lightning strike risk evaluation for a cable car was put forward based on the evaluation model and evaluation method in the sta...According to structure function and lightning damage of a cable car, a feasible method of lightning strike risk evaluation for a cable car was put forward based on the evaluation model and evaluation method in the standard IEC62305-2. According to the difference between common buildings and cable cars, problems of height non-uniformity of equivalent section caused by inclination of the cable car and diversity of lightning activity regularity caused by the large area were resolved, and expected annual average frequency of lightning strike was calculated using three dimensional graphic approach and regional lightning characteristic analysis. Based on different types of damage process and loss consequences, according to interception effect against lightning invasion of the lightning protection measures and the method of probability selection proposed in the standard, the probability of casu- alty caused by direct lightning strike in a cable car and a waiting area as well as probabilities of casualty caused by failure of electronic information systems were cal- culated.展开更多
A low-frequency magnetic lightning mapping system(LFM-LMS)was built during the SHAndong Triggered Lightning Experiment(SHATLE),based on continuous measurements of magnetic field radiation from lightning.The hardware a...A low-frequency magnetic lightning mapping system(LFM-LMS)was built during the SHAndong Triggered Lightning Experiment(SHATLE),based on continuous measurements of magnetic field radiation from lightning.The hardware and source-mapping techniques used by the LFM-LMS were introduced;both Monte Carlo simulations and the observation of rocket-triggered lightning examples were employed to examine the location accuracy and detection effectiveness of the LFM-LMS.We estimated that the system’s location accuracy about 100−200 m horizontally and~200 m vertically.A natural intra-cloud lightning flash and a rocket-triggered lightning flash,both with intricate structures and discharging processes,were examined using the three-dimensional mapping results.The progressing path of negative lightning leaders is usually well-defined,and its propagation speed is estimated to be(0.5−1.4)×10^(6)m/s.In summary,the LFM-LMS can reconstruct the three-dimensional morphology of lightning flashes;this technology provides a efficient method for investigating the characteristics of lightning development,as well as the overall electrical strucuture of thunderstorms.展开更多
The role played by equipotential connection in lightning protection was summarized in terms of lightning protection,static electricity,electromagnetic shielding,protection from electric shocks,and earth fault protecti...The role played by equipotential connection in lightning protection was summarized in terms of lightning protection,static electricity,electromagnetic shielding,protection from electric shocks,and earth fault protection.In addition,drawbacks of independent grounding and common grounding were concluded.According to standards and researches,such as Building Lightning Protection Design Standard （GB50057-2010）,further demands and rules of equipotential connection in lightning protection engineering were proposed,providing references for lightning prevention design,construction and examination by related scientific workers and staffs.展开更多
ABSTRACT Data from the World Wide Lightning Location Network （WWLLN） were used to analyze the lightning activity and the relationship between maximum sustained wind and lightning rate in 69 tropical cyclones over t...ABSTRACT Data from the World Wide Lightning Location Network （WWLLN） were used to analyze the lightning activity and the relationship between maximum sustained wind and lightning rate in 69 tropical cyclones over the Northwest Pacific Ocean from 2005 to 2009. The minimum lightning density was observed in the category 2 typhoon Kong-Rey （2007）, with a value of only 1.15 d-1 （100 kin）-2. The maximum lightning density occurred in the category 2 typhoon Mitag （2007）, with a value of 510.42 d-1 （100 km）-2. The average lightning density decreased with radius from the typhoon center in both weak （categories 1-3） and super （categories 4-5） typhoons. The average lightning density in the inner core of super typhoons was more than twice as large as that for weak typhoons. Both groups of typhoons showed a near-monotonic decrease in lightning density with radius. Results also showed that lightning activity was more active in typhoons that made landfall than in those that did not. The mean correlation coefficient between the accumulated flashes within a 600-kin radius and the maximum wind speed in the weak typhoons and super typhoons was 0.81 and 0.74, respectively. For more than 78% （56%） of the super （weak） typhoons, the lightning activity peaked before the maximum sustained wind speed, with the most common leading time being 30 （60） h. The results suggest that, for the Northwest Pacific Ocean, lightning activity might be used as a measurement of the intensification of typhoons.展开更多
Data from the Beijing SAFIR 3000 lightning detection system and Doppler radar provided some insights into the three-dimensional lightning structure and evolution of a leading-line and trailing-stratiform （LLTS） meso...Data from the Beijing SAFIR 3000 lightning detection system and Doppler radar provided some insights into the three-dimensional lightning structure and evolution of a leading-line and trailing-stratiform （LLTS） mesoscale convective system （MCS） over Beijing on 31 July 2007. Most of the lightning in the LLTS-MCS was intracloud （IC） lightning, while the mean ratio of positive cloud-to-ground （＋CG） lightning to –CG lightning was 1：4, which was higher than the average value from previous studies. The majority of CG lightning occurred in the convective region of the radar echo, particularly at the leading edge of the front. Little IC lightning and little ＋CG lightning occurred in the stratiform region. The distribution of the CG lightning indicated that the storm had a tilted dipole structure given the wind shear or the tripole charge structure. During the storm’s development, most of the IC lightning occurred at an altitude of ～9.5 km; the lightning rate reached its maximum at 10.5 km, the altitude of IC lightning in the mature stage of the storm. When the thunderstorm began to dissipate, the altitude of the IC lightning decreased gradually. The spatial distribution of lightning was well correlated with the rainfall on the ground, although the peak value of rainfall appeared 75 min later than the peak lightning rate.展开更多
文摘In this work, it shows that nuclear reactions in lightning channel, which are produced by the deuterium-deuterium (D-D) and deuterium-tritium (D-T) nuclear reactions, represent a plausible mechanism for gamma-ray bursts observed at ground. Gamma-ray emissions from lightning can be explained by neutron inelastic scattering in the air. Neutrons (produced in lightning channel) will delay a definitive time (~33 ms) to cover the atmosphere before hitting a molecule and producing gamma rays, which is somewhat longer than the gamma-ray time delay (~20 ms) observed at ground.
文摘We present a comparison of data obtained during testing of lightning protective system of a residential structure in rocket-triggered lightning experiment at the International Center for Lightning Research and Testing(ICLRT)at Camp Blanding,Florida,and current surge generator experiment at Rzeszow University of Technology in Poland.Three different configurations of LPS were tested in Poland with the dc grounding resistances of the entire system 4.09 Ω(LPS 1a),1.65 Ω(LPS 1b),and 2.88 Ω(LPS 2).For LPS 1a with three ground rods the value of the peak current entering the electrical circuit neutral was about 56% of the injected current peak,and for LPS 1b with two additional ground rods and two 5 m long buried horizontal conductors it was about 16%.For LPS 2 with five ground rods interconnected by a buried loop conductor this ratio was 21%.The current waveshapes in the ground rods differed from the injected current waveshapes and the current waveshapes in other parts of the test system,especially,for poorer-grounding LPS 1a.The surge-generator results are consistent with those of triggered-lightning experiments at Camp Blanding,Florida(DeCarlo et al.,2008 [2]).
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDA17040503)the Basic Research Fund of the Chinese Academy of Meteorological Sciences(Grant No.2021Z011)。
文摘Through the use of the independently developed Thunderstorm Energetic Radiation Observation System(TEROS),observation experiments of rocket-triggered lightning energetic radiation(RLER)were conducted for the first time at the Field Experiment Base on Lightning Sciences,China Meteorological Administration from May 2021 to July 2021.A total of 17 X-ray bursts were detected during all of the 22 leader/return strokes.In this study,the energy,time,and direction characteristics of Xray burst and its relationships with the corresponding discharge parameters,such as the return stroke peak current,half-peak width,rise time,and interstroke time interval,as well as the associated physical processes,are analyzed and discussed.Results showed that energetic radiation is ubiquitous in triggered lightning and is closely related to the last downward leader phase before the return stroke.The photon energies were concentrated in tens to hundreds of ke V,and the average duration of RLER was approximately 27μs.Moreover,RLER exhibited directional property inconsistent with a vertical downward beam,which may be related to the development orientation of the lightning leader.The intensity of RLER was positively correlated with the return stroke peak current,indicating that it directly depends on the lightning intensity,but it would be modulated by the lightning channel conditions.The 17 RLER events showed 3 different time distribution patterns,namely,discrete,continuous,and discrete/continuous pulses,of which the discharge parameters were also different.The discrete pulse event had the longest duration,a small half-peak width,and a long interstroke time interval.Furthermore,all of these events occurred during the last several leader/return strokes.The continuous pulse event had a short duration and a small peak current.The discrete/continuous pulse event had a moderate duration and a large half-peak width and peak current.These three distinct time distribution patterns may be determined by different development types of lightning leaders.Our observations support the leader high-field runaway mechanism.
文摘Currently,the number of lightning casualties and casualty rates have significantly reduced in developed countries,but there has been no significant reduction in developing countries.On the one hand,this is due to the high frequency of lightning;on the other hand,the vulnerability of people in developing countries is also an influencing factor.Through case analysis and summary,this paper expounds on lightning injury s mechanism and clinical manifestations.It points out that lightning injury is mainly related to heart problems and the impact on the nervous system,rather than burns,which usually cause fewer consequences.Medical treatment needs to pay attention to the order and principles of treatment.Implementing CPR and auxiliary AED is the most effective way to save lives.Attention should be paid to the practical and effective treatment and nursing of lightning stroke sequelae.Finally,combined with the situation of lightning casualties in China,the existing problems are put forward during the process of early treatment,post-hospital treatment,and nursing observation,which provides an objective basis for the cognition of the scientific nature of the lightning injury.
基金funded by the Natural Science Foundation of China(Grant No.U2342215)Key Laboratory of South China Sea Meteorological Disaster Prevention and Mitigation of Hainan Province(Grant No.SCSF202302)。
文摘This study utilizes data from a 3D lightning location system,polarimetric radar,and current measurements from channels of triggered lightning flashes(TLFs)to analyze the structural characteristics of the parent thunderstorms associated with negative TLFs in South China.The triggered-flash region(TFR)displays distinct stratiform cloud characteristics,including lower radar reflectivity heights and a predominance of ice crystals and dry snow above the 0℃ layer.In contrast,the thunderstorm convection core region(CCR)tends to have more graupel particles in the mixed-phase layers and exhibits an ice-water content peak approximately 3.4 times that of the TFR.The charge regions involved in discharges in TFRs exhibit a dipolar charge structure,with the-5℃ layer roughly dividing the upper positive and lower negative charge regions.Conversely,the CCRs feature a typical tripolar charge structure.The dominant dipole charge structure in the TFR results in an increase in the negative charge field below the negative charge region with height,providing a necessary condition for successfully triggering negative TLFs.Furthermore,the horizontal extent of TLFs is positively correlated with their duration and charge transfer.Regions where TLF channels with larger charge transfers propagate tend to have greater maximum radar reflectivity but lower average radar reflectivity compared to regions with TLFs with smaller charge transfer.
文摘Based on the site investigation of a lightning stroke accident in a coal mine in Weiyuan County during a strong thunderstorm process on the night of August 10,2024,combined with the investigation data of the accident site,the causes of the lightning stroke accident were analyzed,and the corresponding rectification suggestions were put forward.
文摘Activity 1 Think about the following questions and write down your answers before reading the text.1.What are some common factors that usually cause damage to trees when they are struck by lightning?2.How might the unique characteristics of a tree contribute to its ability to survive a lightning strike?
文摘The protection effectiveness of traditional Lightning Strike Protection(LSP)for composite rotor blade of helicopter can be diminished due to the explosion risk in overlapping attachment under lightning strike,so a new protection method based on Air Breakdown and insulating adhesive layer(AB-LSP method)was designed to avoid it.In this study,a numerical method was developed to simulate the electrical breakdown,and verified by experiment results.Based on this method,a Finite Element Model(FEM)was established to investigate the effect of two factors(breakdown strength and initial ablation temperature of adhesive layer)on the LSP effectiveness.The results show that the breakdown strength impacts more to the ablation damage in composite than that of high-temperature resistance.Then,another FEM was established to predict the ablation damage by lightning strike in the AB-LSP method protected composite rotor blade.The mechanisms and potential key parameters(magnitude of lightning current,discharge channel location,adhesive layer thickness,and air gap width)that could affect the protection effectiveness were analyzed.The introduction of air breakdown changes the current conduction path and reduces explosion risk.After rational design,this method can offer effective lightning protection for composite helicopter rotor blade and other composite structures.
基金supported by the National Natural Science Foundation of China (No. 42225405 and No. 42350710200)。
文摘The Van Allen radiation belts are doughnut-shaped zones surrounding Earth, filled with highly energetic charged particles whose sources or loss mechanisms have been investigated for decades. As for the inner belt, cosmic ray albedo neutron decay(CRAND),radial diffusion, and local acceleration have been considered principal sources of electrons, whereas protons are predominantly from CRAND and solar protons. In this article, lightning-induced neutrons from Earth's upper atmosphere are suggested as a possible source of protons and electrons in the inner radiation belt. These terrestrial neutrons can contribute to the inner belt population by undergoing nuclear decay. Several approaches are proposed and discussed to evaluate the potential contribution of lightning-induced neutrons to the inner belt, including magnitude estimation, Monte Carlo simulations, and in situ observations. This article discusses some avenues of further study to determine the contribution of lightning-induced neutrons to the inner radiation belt.
基金Supported by Research on Key Technologies of Lightning Intelligent Protection System for Guangdong Energy Hehe Sea Wind Farm(SFC/QZW-ZX-XF-24-020).
文摘In the past,the lightning strike risk assessment of wind farms mainly referred to the Lightning Protection Part 2:Risk Management(IEC 62305-2-2010)and the Lightning Protection of Wind Energy System(IEC 61400-24-2019)based on protection angle method.In fact,the basic idea of the two is the same,that is,the source of the lightning fan is replaced by S1-S4 of the former lightning building with the latter ND-NDJ.According to the above method of wind farm evaluation,it has been proved that the practice can not achieve good results.Taking offshore wind farm as an example,this paper introduces a new method of establishing six evaluation indicators to determine the risk level according to the new technology and compliance principle of regional lightning protection(semi-circular method),which can be used for reference by wind farm technicians.
基金Supported by Shandong Meteorology Bureau (2005sdqxj01)Shandong Metrological Observatory (Preliminary Study on Forecast of Lightning Disasters in Shandong Province)
文摘By using the reported data of lightning disaster and the data of lightning monitoring network in Shandong Province since its establishment,the lightning activities and the disaster climate characteristics in Shandong Province were analyzed.The data were processed by lattice formulation,and the spatial and temporal distribution characteristics of positive and negative CG flashes were given.The parameter characteristics of positive and negative ground lightning and its relationship with the lightning disasters were analyzed.And the lightning parameter characteristics of lightning in major cities of Shandong Province were analyzed.
基金Supported by Scientific Research Special Fund for Public Welfare Industry(Meteorology)[GYHY200806014]
文摘Based on the special landscape and regional characteristics,the lightning location information from 1999 to 2008 and conventional observation data from 1971 to 2000 provided by electricity departments in Hebei Province were applied to analyze spatial and temporal distribution of lightning.With lighting disaster data since 2000 provided by meteorological department,and records from civil affair,statistics,insurance,and other departments,the lighting disaster distribution of Hebei Province was studied from aspects of economic and people losses,and some countermeasures for several lightning disasters industries were put forward.
基金Supported by The Special Project of Public Welfare Industry Scientific Research(GYHY200806014)Nanjing University of Information Science & Technology Project(E30JG0730)
文摘Based on the radar data and lightning position indicator data of strong thunderstorm weather which happened in Fuxin on July 8,2007,the relationship between the lightning activity and the radar echo was analyzed.The results showed that Fuxin area located in the cross position of T-shaped trough and was affected by the cold air which continuously glided down.The corresponding warm front on the ground advanced southward and arrived here.It was the weather background of this thunderstorm weather.The position variation of lightning occurrence was closely related to the strong echo movement of squall line,and the velocity echo clearly reflected and predicted the movement tendency of the radar echo.
文摘The cloud-to-ground lightning data between 2007 and 2008 were collected by lightning detection and location system,which was composed of four lightning detectors in four different sites of Dalian area.The spatio-temporal distribution of cloud-to-ground lightning in surrounding areas of Dalian was analyzed from several aspects of polarity distribution,diurnal variation,lightning intensity and lightning density.The results showed that the number of negative lightning accounted for 93.9% of the total number of lightning,and its average lightning intensity was 27.99 kA.The number of positive lightning accounted for 6.1% of the total number of lightning,and its average lightning intensity was 35.56 kA.The diurnal variation of lightning frequency showed an obvious structure of two peaks (17:00-18:00 and 04:00-05:00) and two valleys (09:00-10:00 and 00:00-01:00).The number of lightning between May and September was 91.5% of the annual number,and the lightning occurred the most frequently between June and August.Most of positive and negative lightning was at the intensity of 15-35 kA,80.0% lower than 40 kA,and 99.3% lower than 100 kA.The lightning density had obvious regional differences in distribution,high in the Liaodong Bay and the Dalian Bay and low in inland areas.Therefore,coastal areas should attract more attention in lightning disaster defense in the surrounding areas of Dalian.
基金Supported by the Scientific Research Project of Hebei Meteorological Bureau in 2014(14ky20)~~
文摘According to structure function and lightning damage of a cable car, a feasible method of lightning strike risk evaluation for a cable car was put forward based on the evaluation model and evaluation method in the standard IEC62305-2. According to the difference between common buildings and cable cars, problems of height non-uniformity of equivalent section caused by inclination of the cable car and diversity of lightning activity regularity caused by the large area were resolved, and expected annual average frequency of lightning strike was calculated using three dimensional graphic approach and regional lightning characteristic analysis. Based on different types of damage process and loss consequences, according to interception effect against lightning invasion of the lightning protection measures and the method of probability selection proposed in the standard, the probability of casu- alty caused by direct lightning strike in a cable car and a waiting area as well as probabilities of casualty caused by failure of electronic information systems were cal- culated.
基金the National Key R&D Program of China(2017YFC1501501)the CAS Project of Stable Support for Youth Team in Basic Research Field(YSRR-018)+3 种基金the Youth Innovation Fund project of the university(WK2080000172)the National Natural Science Foundation of China(41875006,U1938115)the Chinese Meridian Projectthe International Partnership Program of Chinese Academy of Sciences(183311KYSB20200003).
文摘A low-frequency magnetic lightning mapping system(LFM-LMS)was built during the SHAndong Triggered Lightning Experiment(SHATLE),based on continuous measurements of magnetic field radiation from lightning.The hardware and source-mapping techniques used by the LFM-LMS were introduced;both Monte Carlo simulations and the observation of rocket-triggered lightning examples were employed to examine the location accuracy and detection effectiveness of the LFM-LMS.We estimated that the system’s location accuracy about 100−200 m horizontally and~200 m vertically.A natural intra-cloud lightning flash and a rocket-triggered lightning flash,both with intricate structures and discharging processes,were examined using the three-dimensional mapping results.The progressing path of negative lightning leaders is usually well-defined,and its propagation speed is estimated to be(0.5−1.4)×10^(6)m/s.In summary,the LFM-LMS can reconstruct the three-dimensional morphology of lightning flashes;this technology provides a efficient method for investigating the characteristics of lightning development,as well as the overall electrical strucuture of thunderstorms.
文摘The role played by equipotential connection in lightning protection was summarized in terms of lightning protection,static electricity,electromagnetic shielding,protection from electric shocks,and earth fault protection.In addition,drawbacks of independent grounding and common grounding were concluded.According to standards and researches,such as Building Lightning Protection Design Standard （GB50057-2010）,further demands and rules of equipotential connection in lightning protection engineering were proposed,providing references for lightning prevention design,construction and examination by related scientific workers and staffs.
基金supported by the National Natural Science Foundation of China (Grant Nos.41005004 and 40930949)the "One-Hundred Talents Project" of the Chinese Academy of Sciences
文摘ABSTRACT Data from the World Wide Lightning Location Network （WWLLN） were used to analyze the lightning activity and the relationship between maximum sustained wind and lightning rate in 69 tropical cyclones over the Northwest Pacific Ocean from 2005 to 2009. The minimum lightning density was observed in the category 2 typhoon Kong-Rey （2007）, with a value of only 1.15 d-1 （100 kin）-2. The maximum lightning density occurred in the category 2 typhoon Mitag （2007）, with a value of 510.42 d-1 （100 km）-2. The average lightning density decreased with radius from the typhoon center in both weak （categories 1-3） and super （categories 4-5） typhoons. The average lightning density in the inner core of super typhoons was more than twice as large as that for weak typhoons. Both groups of typhoons showed a near-monotonic decrease in lightning density with radius. Results also showed that lightning activity was more active in typhoons that made landfall than in those that did not. The mean correlation coefficient between the accumulated flashes within a 600-kin radius and the maximum wind speed in the weak typhoons and super typhoons was 0.81 and 0.74, respectively. For more than 78% （56%） of the super （weak） typhoons, the lightning activity peaked before the maximum sustained wind speed, with the most common leading time being 30 （60） h. The results suggest that, for the Northwest Pacific Ocean, lightning activity might be used as a measurement of the intensification of typhoons.
基金supported by the National Natural Science Foundation of China(Grant No. 40930949)Key Subject Project of Beijing Atmospheric Physics and Environment,the One Hundred Person Project of the Chinese Academy of Sciences
文摘Data from the Beijing SAFIR 3000 lightning detection system and Doppler radar provided some insights into the three-dimensional lightning structure and evolution of a leading-line and trailing-stratiform （LLTS） mesoscale convective system （MCS） over Beijing on 31 July 2007. Most of the lightning in the LLTS-MCS was intracloud （IC） lightning, while the mean ratio of positive cloud-to-ground （＋CG） lightning to –CG lightning was 1：4, which was higher than the average value from previous studies. The majority of CG lightning occurred in the convective region of the radar echo, particularly at the leading edge of the front. Little IC lightning and little ＋CG lightning occurred in the stratiform region. The distribution of the CG lightning indicated that the storm had a tilted dipole structure given the wind shear or the tripole charge structure. During the storm’s development, most of the IC lightning occurred at an altitude of ～9.5 km; the lightning rate reached its maximum at 10.5 km, the altitude of IC lightning in the mature stage of the storm. When the thunderstorm began to dissipate, the altitude of the IC lightning decreased gradually. The spatial distribution of lightning was well correlated with the rainfall on the ground, although the peak value of rainfall appeared 75 min later than the peak lightning rate.
