Hey if you are inhabitant of earth then you must be well acqainted with the phenomenon called lightening.

Lightning is an electric current that are produced by cloud. The separation of positive and negative charges within cloud is the main reason for lightning to take place.

Clouds are formed [ Read : Why rain clouds are Grey in Color ] by the air around us. When air get warm it rises to the sky where it cools down and forms cloud. When air continues to rise, the cloud gets bigger and bigger. The temperature of top layer of the clouds fell below freezing point and the water vapour turns into ice. Lots of small bits of ice bump into each other as they move around. All these collisions cause a build up of electrical charge.

Eventually, the whole cloud fills up with electrical charges. Since similar charges repel each-other and opposite charges attract each other, Lighter, negative charges generally gather near the base of the cloud, while heavier, positive charges build in the upper reaches of the cloud. This allows electric fields to form and grow between the cloud and the ground and within the cloud itself. When the positive and negative charges grow large enough, a giant spark - lightning - occurs between the two charges within the cloud.

Most lightning happens inside a cloud, but when the potential difference between the clouds and the ground become too large it happens between the cloud and the ground. A build up of positive charge builds up on the ground beneath the cloud, attracted to the negative charge in the bottom of the cloud. The ground's positive charge concentrates around anything that sticks up - trees, lightning conductors, even people! The positive charge from the ground connects with the negative charge from the clouds and a spark of lightning strikes.

The temperature of lightening that strikes the ground is around 27,000 oC, which is six times hotter than the surface of sun.