Atmospheric electricity

Lightning is a dazzling  bluish white light light produced in the clouds. It is followed by a loud noise called thunder.

Till 1752 nobody really knows about the cause of lightning. Benjamin Franklin by a brilliant experiment proved that it was caused by static electric charges in the clouds. He proved that clouds build up charges by sending up kite during a thunder storm with a key attached to the other end of the string. He got an electric shock when he touched the key. This happened as charges had flowed from the clouds down the wet string to the key.