Neetu Singh Geography's video: Tropical Cyclone : Climatology Hazard IMD I By Neetu Singh

The term cyclone is a Greek word meaning ‘coil of a snake’. It was first used by Henry Piddington about the middle of the last century for tropical revolving storms occurring in the Bay of Bengal and the Arabian Sea. The term ‘cyclone is applied to all tropical storms even though they are locally known as Hurricane in the Atlantic and the Eastern Pacific, Typhoon in the Western Pacific, Willy-Willy in Western Australia, Baguio in the Philippines, Taifu in Japan, Ghumi Jad in Bangladesh and Chakvat over the Indian region. These storms are confined to definite region of the earth and occur for the most part, in the portion of the western side of the great oceans. The cyclone is basically associated with low pressures and high wind speed. A low pressure system is defined as the area closed by one isobar, surface wind in the Northern Hemisphere) and wind speed less than less than 17 knots or nautical miles per hour (31.5km/hr) [1knot=1.853km/hr=0.514m/s]. When the low pressure area is covered by two or more isobars at 2mb (millibar) interval (1mb=100 Newton/meter sq or hecto-Pascal) covering an area of 5° sq, pressure gradient between the center and at a distance of 250km being 5-13mb and wind speed 17-24knots then the system is know as deep-depression. For cyclonic storm wind speed has to be 33-48 knots and when wind speed is 48-64 knots and pressure gradation greater then 5-13mb, it is known as severe cyclonic storm and for the speeds greater than 64knots (119km/hr), the system is known as sever cyclonic storm with hurricane core.