April 28, 2019

According to India Meteorological Department, a deep depression over southeast Bay of Bengal has developed into cyclonic storm ‘Fani’ which is expected to further intensify into a “severe cyclonic storm”.


  • Worldwide terminology: Cyclones are known as –
    • Typhoons in the China Sea and Pacific Ocean;

    • Hurricanes in the West Indian islands in the Caribbean Sea and Atlantic Ocean;

    • Tornados in the Guinea lands of West Africa and southern USA.;

    • Willy-willies in north-western Australia and

    • Tropical cyclones in the Indian Ocean. 

  • Cause: Cyclones are caused by atmospheric disturbances around a low-pressure area distinguished by swift and often destructive air circulation.

  • Features: Cyclones are usually accompanied by violent storms and bad weather. The air circulates inward in an anticlockwise direction in the Northern hemisphere and clockwise in the Southern hemisphere.

  • Classifications: Cyclones are classified as extra tropical cyclones (also called temperate cyclones); and tropical cyclones.

  • Tropical cyclones:
    • They develop in the regions between the Tropics of Capricorn and Cancer.

    • The World Meteorological Organisation (WMO, 1976) uses the term 'Tropical Cyclone’ to cover weather systems in which winds exceed ‘Gale Force’ (minimum of 34 knots or 63 kph). 

    • These are the result of ocean and atmosphere, powered by the heat from the sea; and driven by easterly trades and temperate westerlies, high planetary winds and their own fierce energy.

  • Extra tropical cyclones (temperate cyclones): They occur in temperate zones and high latitude regions, though they are known to originate in the Polar Regions.

Source : The Hindu