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Published byJoy Hawkins Modified over 8 years ago
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Lightning
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Lightning Polarization of + and – charges within a storm cloud by frictional charging and freezing. + charges carried to upper portions of cloud and – portions gravitate to bottom of clouds. –Electric field from cloud induces movement of electrons upon Earth Buildings, trees and people can experience a build up of static charge as electrons are repelled by the cloud’s bottom.
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Anatomy of Lightning As static charge buildup increases, the electric field becomes stronger Ionization of surrounding air makes it more conductive Begins with development of a step leader. Why zigzag? Induces a strong positive charge on earth surface. This charge begins migrating upward (streamer) through buildings, trees and people into the air. When step leader meets streamer, a complete conductive pathway is mapped out and lightning begins.
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Lightning Rods Pointed metal pole which extends upward above the building, is attached by a copper cable to a grounding rod buried in the Earth below. “leaks off” excess charges in the atmosphere, thus reducing the likelihood of a sudden and explosive discharge.
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Myths about Lightning Never strikes the same place twice Only strikes very tall objects Does not strike water Could be used as a power source Rubber shoes or boots insulate and protect against a lightning strike A metal vehicle is safe because of rubber tires “Heat lightning” is a strange phenomenon caused by hot water or occurs after very hot summer days and poses no threat. Lightning victims are electrified
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Facts about Lightning The average flash could light a 100-Watt light bulb for more than three months Chances of being struck are estimated to be 1 in 600,000 Temperature of a flash is 5x hotter than sun’s surface Can travel over and through the Earth’s surface ~20 million cloud to ground lightning strikes occur in the US per year ~2,000 thunderstorms active throughout the world at any given time, producing more than 100 flashes/second ~26,400 lightning-induced fires/year in the US 80% of livestock deaths attributed to lightning strikes Second largest storm killer in the US (#1 floods) The Guinness Book of World Records lists Roy Sullivan of Virginia as the human being struck by lightning the most times: seven. This is one record you don't want to beat!
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