Tropical Cyclone

WHY IN NEWS?

‘Statement on Climate of India during 2019’ released by the India Meteorological Department (IMD) reported that last year was dominated by tropical cyclones as the country witnessed eight cyclones formed in the Indian Ocean.

ABOUT TROPICAL CYCLONE

• Tropical cyclones are violent storms that originate over oceans in tropical areas and move over to the coastal areas bringing about large-scale destruction due to violent winds (squalls), very heavy rainfall (torrential rainfall) and storm surge.
• They are irregular wind movements involving closed circulation of air around a low-pressure center.
• The cyclonic wind movements are anti-clockwise in the northern hemisphere and clockwise in the southern hemisphere.
• A mature tropical cyclone is characterized by the strong spirally circulating wind around the centre which is called the eye.
• The eye is an area with calm weather descending air.
• It is characterized by light winds and clear skies.
• Conditions favorable 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
• They are known as:
  • Cyclones in the Indian Ocean
  • Hurricanes in the Atlantic
  • Typhoons in the Western Pacific and the South China Sea
  • Willy-willies in Western Australia

Prelims Question

Q. Regarding tropical cyclones, which of the following statements is/are correct?
1. They originate over oceans/seas and not on land
2. The eye of a cyclone is an area with calm weather descending air
3. Wind movements are anti-clockwise in the northern hemisphere
Select the correct answer using the code given below:
a. 1 and 2 only
b. 2 and 3 only
c. 1 and 3 only
d. 1,2 and 3

Answer to the Prelims Question