A tropical cyclone is essentially a rotating storm (an individual low pressure disturbance, complete with winds, clouds and precipitation) in the tropical oceans. The life span of a tropical cyclone is, on average, about six to nine days until it enters land or recurves into cooler latitudes, but this may vary from a few hours to as much as three to four weeks. No two tropical cyclones are identical. The movement of a tropical cyclone is generally 12 knots or less.

The associated storm surge is a long gravity wave with a length scale similar to the size of the generating tropical cyclone, its life span similar to that of the cyclone. In many major tropical cyclone disasters, storm surges frequently occur and are a key factor. As the cyclone approaches the coastal area, strong on-shore winds can cause a rise of several meters in sea level; the result is water crossing the coast and flooding large areas of the coast. The factors that combine to cause a storm surge are partly meteorological and partly hydrographic, including the state and nature of the tide and the topography of the seabed in the vicinity of the coast.

Tropical cyclones, storm surges and their associated phenomena (high winds, torrential rains, floods, etc.) cause tremendous damage to life and property in the countries bordering the Northern Indian Ocean and particularly the Bay of Bengal leading to disastrous effects on population, economic and social life.

URL: Click here for data extracted from "Extreme sea level variability along the
coast of India. Vol. 2 Published in 2004 by NIO. For further details,
contact: unni@nio.org