What is Cyclone?

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.



 


What is El Nino?

The El Nino is a narrow current of warm water that appears off the coast of Peru sometime in December-January and which lasts till March. The name literally means ‘The Child’ and refers to the Child Christ, apt because the appearance of the current coincides with Christmas. As it flows southward along the west coast of South America, it warms the cold waters of the coast of Ecuador and Peru.



El Nino was first recorded as early as in 1726 and it has returned on an average of once every four years. El Nino is believed to be related to a shift in air movements over the tropical Pacific Ocean. Changes in wind direction bring about changes in the circulation and temperature of the oceans. This in turn further disrupts ocean currents and air movements.



A powerful El Nino in 1982 and 1983 caused severe drought in Australia and Indonesia. It also caused storms in California and rains and floods in Ecuador and Peru. The El Nino effect also profoundly affects the Indian monsoons.