This phenomenon results from the accumulation of electrical charges in cumulonimbus clouds
While straight-line winds called derechos occur less frequently and result in ... 
Thunderstorms are produced by cumulonimbus clouds, which are tall, dark, and 
.... by which excess electrical charges in one object causes the accumulation by... [DOC] [TLE] The Physics of lightning - Hong Kong Observatory [PAR] Lightning is an atmospheric electric discharge phenomenon.