UPSC Exam Preparation: Topic of the Day – Cyclones
Cyclones are large scale air masses that rotates around a strong center of low atmospheric pressure. It is the chief natural disaster that affects India’s coastal regions. Since India has a long coastline running up to 7516 km, it suffers almost 10% of the tropical cyclones that happen in the world. Almost 71% of this region lies in the ten states of Kerala, Karnataka, Goa, Maharashtra, Gujarat, West Bengal, Odisha, Andhra Pradesh and Tamil Nadu. The UTs of Lakshadweep, Puducherry and Andaman and Nicobar Islands are also prone to cyclones. Out of the 5-6 tropical cyclones that form in the Arabian Sea and the Bay of Bengal each year and hit the coasts, 2-3 are severe.
When a cyclone approaches to coast, a risk of serious loss or damage arises from severe winds, heavy rainfall, storm surges and river floods. The effect of a storm surge is most pronounced in wide and shallow bays exposed to cyclones such as in the northern part of Bay of Bengal. Most cyclones occur in the Bay of Bengal followed by those in the Arabian Sea and the ratio is approximately 4:1. The incidence of cyclonic storms, with wind speeds between 65 Km/h and 117 Km/h and severe cyclonic storm with wind speeds between 119 Km/h and 164 Km/h, reaching Tamil Nadu and Andhra Pradesh is high during the north east monsoon season ie. October – December, whereas the highest annual number of storms, severe storms occur in the Orissa – West Bengal coast.
More than 8000 km of coastline in the east and the west face the hazards of tropical cyclones, and associated storm surges and heavy rainfall, before and after the monsoon. Post monsoon cyclones are usually more intense both in numbers and intensity. It has been estimated that over 58 per cent of the cyclonic storms that develop in the Bay of Bengal approach or cross the east coast in October and November. Only 25 per cent of the storms that develop over the Arabian Sea hit the west coast.
The Machilipatnam Cyclone of 1990, Orissa Super cyclone of 1999, Cyclone Hudhud of 2014, Gujarat Cyclone of 2015 are some of the deadliest cyclones that have hit India.
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