Saturday, June 30, 2007

Electrostatic induction theory:

Another theory is that opposite charges are driven apart by the above mechanism and power is stored in the electric field between them. Cloud electrification appears to necessitate strong updrafts which hold water droplets upward, supercooling them to -10 to -20 C. These have a collision with ice crystals to form a soft ice-water mixture called graupel. The collisions result in a slight positive charge being transferred to ice crystals, and a slight negative charge to the graupel. Updrafts drive lighter ice crystals upwards, causing the cloud top to accumulate increasing positive charge. The heavier negatively charged graupel falls towards the middle and lower portions of the cloud, building up an increasing negative charge. Charge separation and accumulation continue until the electrical potential becomes sufficient to initiate lightning discharges, which occurs when the gathering of positive and negative charges forms a adequately strong electric field.


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