- noun a discharge of electricity between clouds and the earth, seen as a bright flash and accompanied by the sound of thunder which is heard after a short delay
- A luminous electrical discharge between a cloud and the ground, between clouds, or within the same cloud, due to potential differences which become strong enough to break down the insulation that the intervening air provides. A lightning discharge may consist of multiple strokes, each of which is preceded by a leader. The current in a typical discharge is about 10,000 to 20,000 amperes, with peaks which can exceed 100,000 amperes. The burst of heat which accompanies a lightning discharge forces the surrounding air to expand explosively, producing shock waves heard as thunder. Also called lightning discharge.
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