A cyclone is a low pressure area in the atmosphere in which the winds spiral inward in an anticlockwise direction. All cyclones are characterized by having an atmospheric pressure lowest at the centre and winds spiraling in towards this low pressure central zone called the ‘eye’. Cyclones are usually characterized by gusts of winds which may even go up to 250 kilometres/hour. In addition they are also accompanied by heavy rain. Along coastal areas they sometimes produce high tidal waves. In the southern hemisphere the winds blow in a clockwise direction. Cyclones are called hurricanes if they form in the West Indies and typhoons if they form in western Pacific.

In India a large number of cyclones originate in the Bay of Bengal and occasionally cause large-scale devastation on the eastern coast. The 1970 cyclone which hit the coast of Andhra Pradesh killed thousands of people and devastated property worth crores of rupees.