Lightning is a form of electrical discharge between clouds or between a cloud and the ground.
The discharge may take place between two parts of the same cloud, between two clouds, or between a cloud and the ground. Lightning may appear as a jagged streak, a flash in the sky, or in the rarer form of a brilliant ball. Thunder is the sound waves produced by the explosive heating of the air in the lightning channel during the return. Most lightning strikes occur either at the beginning or end of a storm. The average lightning strike is six miles long.