Lightning protection - HUBER+SUHNER - #9

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Introduction HUBER+SUHNER 5 Creation and threat of lightning Strokes of lightning kill more people in Europe and North America each year than floods or tornados, causing billions of dollars in damage. The number of lightning-induced forest fires throughout the world alone runs to more than 10'000 annually. Since the experiments performed by B. Franklin, Romas and other lightning researchers we know that lightning is a physical phenomenon. It is created in thunderstorm cells. The cold storm front, which penetrates a hot area, forces the warm and humid air to rise. Temperature decreases with altitude and the water vapor condenses to small water droplets. This process is accompanied by the creation of heat which accelerates the air current. Reaching altitudes with subzero temperature, the water drops freeze to ice crystals. Again heat is produced simultaneously. The air speed increases once more – reaching a velocity of several hundred km/h – and propels the small ice particles to higher altitudes of up to 12 km. The growing ice crystals convert to hail stones which fall down due to their weight or remain in certain balanced positions. This causes electrons being stripped from the ice crystals. As a result of this process, charges are separated across a wide surface area. With field strengths of several 100 kV/m, discharges may be triggered in the form of cloud-to-cloud or cloud-to-earth lightning strokes, and in rare cases even as earth-to-cloud lightning. Mechanism of thunderstorms - 20 °C - 10 °C 0 °C cold storm front sun-heated air Lightning basics