نتایج جستجو برای: lightning
تعداد نتایج: 6387 فیلتر نتایج به سال:
To appropriately infer the correlation between lightning events and flashovers/voltage dips on real distribution networks, data coming from lightning location systems are certainly needed, but need to complemented on the one hand by data coming from distributed measurement systems able to record both protection manoeuvres and lightning-originated transients, and on the other hand by accurate ca...
Ball lightning, a fireball sometimes observed during lightnings, has remained unexplained. Here we present a comprehensive theory for the phenomenon: At the tip of a lightning stroke reaching the ground, a relativistic electron bunch can be produced, which in turn excites intense microwave radiation. The latter ionizes the local air and the radiation pressure evacuates the resulting plasma, for...
Charge moment change and lightning-driven electric fields associated with negative sprites and halos
[1] Sprites are structured high altitude optical emissions produced by lightning-driven electric fields. Both strong positive and negative cloud to ground flashes (CGs) are capable of initiating sprites. However, reported sprites are almost exclusively produced by +CGs. The very limited number of negative polarity sprites makes it difficult to reveal their morphologies and mechanisms. Since 200...
Lightning incidence analysis is required for the design of adequate lightning protection systems for wind turbines. We present a method to estimate the number of upward flashes for multiple wind turbines located in mountainous areas. The proposed method is applied to the case of the Mont Crosin wind turbine park located in the Jura mountains in the Northwestern part of Switzerland. A significan...
A 48-year-old-woman was struck dead by lightning on October 24, 2010, in Pretoria, South Africa. The cause of death was due to direct lightning strike. Examination showed secondary missile injury on her legs. This secondary missile (shrapnel) injury was caused by the lightning striking the concrete pavement next to her. Small pieces of concrete were located embedded within the shrapnel wounds. ...
Five mechanisms have been described in the literature regarding lightning injury mechanisms. A sixth mechanism is proposed in this article, namely, lightning barotrauma. A simple laboratory experiment was conducted using ordnance gelatin for ballistic studies. Lightning was simulated in a high-voltage laboratory using an 8/20-microsecond current impulse generator and discharged through ballisti...
An experimental VLF WorldWide Lightning Location (WWLL) network is being developed to provide realtime locations of cloud to ground lightning discharges occurring throughout the globe. This network has expanded from a limited number of stations in the Western Pacific to its current state of 11 stations, in most longitude sectors, with additional stations planned in the near future. As part of t...
The rapid expansion of wind power generation has brought problems involving lightning strikes to the fore. Many such incidents have damaged not only the wind turbine that was actually struck, but also other turbines that were not. The phenomenon of surge invasion to the distribution line is categorized as “back-flow surge”. It has been reported that this back-flow surge sometimes burns out surg...
Lightning measurements from the Geostationary Lightning Mapper (GLM) that will be aboard the Geostationary Operational Environmental Satellite – R Series will bring new information that can have the potential for improving the initialization of numerical weather prediction models by assisting in the detection of clouds and convection through data assimilation. In this study we focus on investig...
Seven-year measurements of precipitation, lightning flashes, and visibility from 2000 to 2006 have been analyzed in the Pearl River Delta (PRD) region, China, with a focus on the Guangzhou megacity area. Statistical analysis shows that the occurrence of heavy rainfall (>25 mm per day) and frequency of lightning strikes are reversely correlated to visibility during this period. To elucidate the ...
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