Differentiate between between cyclone, hurricane, tornado and twister. Explain the necessary conditions for their formation. Which of these are generally observed in India and at which places?

Cyclone and Hurricane
Cyclone is weather situation characterised by a rotating organized system of clouds coupled with thunderstorms and has low pressure centre and closed low-level atmospheric circulation. Hurricane is also similar weather phenomenon. They differ in name based on location where the storm occurs. While in the Atlantic and Northeast Pacific such weather phenomenon is termed as “hurricane”, in the South Pacific and Indian Ocean the same is referred as “cyclone”.
Necessary conditions for the formation of a Cyclone and Hurricane

  • The temperature of tropical waters must be at least 26.67° for up to 165 feet below the ocean’s surface.
  • Cyclone is referred as hurricane when the maximum sustained wind speed reaches 74 miles per hour or higher.
  • Coriolis effect must be present for initiating and maintaining the cyclone

Tornado and Twister
Tornado is a violent storm. It is characterised by rapidly rotating column of air that is in contact with both the surface of the Earth and cumulonimbus cloud.  Tornadoes are formed over hot land surfaces. Twister is just another name for tornado.
Necessary conditions for the formation of Tornado and Twister
The recipe for tornado or twister is a combination of instability in the lower atmosphere, wind shear and weather front. Instability refers to warm and humid conditions, wind shear means difference in wind speed over short distance and weather front refers to junction of hot and cold air masses.
Cyclones as well as tornadoes both occur in India
Cyclones as well as tornadoes both occur in India. However, unlike cyclones the frequency of tornadoes outbreak is very low. Cyclones originate in the Bay of Bengal region as well as in the Arabian Sea region. Tornadoes of weak strength occur in north-western and north-eastern region of the country. (290 words)


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