Cyclone Tauktae

• 18 May 2021

Why in News

Recently, Cyclone Tauktae made landfall in Gujarat.

• The cyclone has left a trail of destruction as it swept through the coastal states of Kerala, Karnataka, Goa and Maharashtra.

Key Points

• About:
  
  • Named by:
    
    • It is a tropical cyclone, named by Myanmar. It means 'gecko', a highly vocal lizard, in the Burmese language.
    • Typically, tropical cyclones in the North Indian Ocean region (Bay of Bengal and Arabian Sea) develop during the pre-monsoon (April to June) and post-monsoon (October to December) periods.
      
      • May-June and October-November are known to produce cyclones of severe intensity that affect the Indian coasts.
  • Classification:
    
    • It has weakened into a "very severe cyclonic storm" from the "extremely severe cyclonic storm".
    • The India Meteorological Department (IMD) classifies cyclones on the basis of the maximum sustained surface wind speed (MSW) they generate.
    • The cyclones are classified as severe (MSW of 48-63 knots), very severe (MSW of 64-89 knots), extremely severe (MSW of 90-119 knots) and super cyclonic storm (MSW of 120 knots or more). One knot is equal to 1.8 kmph (kilometers per hour).
  • Developed in Arabian Sea:
    
    • Tauktae is the fourth cyclone in consecutive years to have developed in the Arabian Sea, that too in the pre-monsoon period (April to June).
    • After Cyclone Mekanu in 2018, which struck Oman, Cyclone Vayu in 2019 struck Gujarat, followed by Cyclone Nisarga in 2020 that struck Maharashtra.
    • All these cyclones since 2018 have been categorised either ‘Severe Cyclone’ or above.
• Arabian Sea becoming Hotbed of Cyclones:
  
  • Annually, five cyclones on average form in the Bay of Bengal and the Arabian Sea combined. Of these, four develop in the Bay of Bengal, which is warmer than the Arabian Sea.
  • In 2018, while the Bay of Bengal maintained its average of four cyclones a year, the Arabian Sea produced three cyclonic storms. In 2019, the Arabian Sea overtook the Bay of Bengal with five cyclones to three.
  • In 2020, the Bay of Bengal produced three cyclonic storms while the Arabian Sea generated two.
  • In recent years, meteorologists have observed that the Arabian Sea, too, has been warming. This is a phenomenon associated with global warming.
  • It has been observed that the sea surface temperature in the Arabian Sea has been rising for about 40 years. The increase in temperature is in the zone of 1.2-1.4 degree Celsius.
• Tropical Cyclone:
  
  • A tropical cyclone is an intense circular storm that originates over warm tropical oceans and is characterized by low atmospheric pressure, high winds, and heavy rain.
  • A characteristic feature of tropical cyclones is the eye, a central region of clear skies, warm temperatures, and low atmospheric pressure.
  • Storms of this type are called hurricanes in the North Atlantic and eastern Pacific and typhoons in SouthEast Asia and China. They are called tropical cyclones in the southwest Pacific and Indian Ocean region and Willy-willies in north-western Australia.
  • Storms rotate counterclockwise in the northern hemisphere and clockwise in the southern hemisphere.
  • The conditions favourable for the formation and intensification of tropical storms are:
    
    • Large sea surface with temperature higher than 27° C.
    • Presence of the Coriolis force.
    • Small variations in the vertical wind speed.
    • A pre-existing weak low- pressure area or low-level-cyclonic circulation.
    • Upper divergence above the sea level system.
• Naming of Tropical Cyclones:
  
  • According to WMO (World Meteorological Organization) guidelines, countries in every region are supposed to give names for cyclones.
  • The North Indian Ocean Region covers tropical cyclones formed over Bay of Bengal and Arabian Sea.
  • The 13 members, which come under the region, are Bangladesh, India, Maldives, Myanmar, Oman, Pakistan, Sri Lanka, Thailand, Iran, Qatar, Saudi Arabia, the UAE and Yemen.
  • India Meteorological Department (IMD), one of the six Regional Specialised Meteorological Centres (RSMC) in the world, is mandated to issue advisories and name tropical cyclones in the north Indian Ocean Region.
    
    • It is an agency of the Ministry of Earth Sciences.

Source: IE