IAS Gyan

Daily News Analysis

Typhoon Rai            

20th December, 2021 Geography


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  • Super typhoon Rai is battering the southern Philippines, forcing thousands of people to take shelter amid warnings of widespread flooding and destruction.
  • The storm made landfall in Siargao, a popular tourist island, packing winds of about 175km/h.



  • Typhoon Rai, known in the Philippines as Typhoon Odette, is currently a powerful tropical cyclone over the South China Sea which recently passed through the Philippines.
  • Rai became the third Category 5 super typhoon to form in South China Sea after Pamela of 1954 and Rammasun of 2014.


Tropical Storms

  • Hurricanes, cyclones and typhoons are all types of tropical storms. But are given different names depending on where they appear.
  • Hurricanes are tropical storms that form over the North Atlantic Ocean and Northeast Pacific.
  • Cyclones are formed over the South Pacific and Indian Ocean.
  • Typhoons are formed over the Northwest Pacific Ocean.


Favorable Conditions for Tropical Cyclone Formation

  • Large sea surface with temperature higher than 27° C,
  • Presence of the Coriolis force enough to create a cyclonic vortex,
  • 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,