Why in the news?

  • Cyclone Montha formed in the Bay of Bengal region.

Tropical Cyclone

  • What is it?: A cyclone is a large-scale air system rotating around a low-pressure centre, accompanied by high winds and rainfall.
  • Direction:
    • Anticlockwise in the Northern Hemisphere.
    • Clockwise in the Southern Hemisphere.
  • Other Name:
    • Hurricanes (Atlantic and Northeast Pacific),
    • Typhoons (Northwest Pacific),
    • Tropical Cyclones (Indian Ocean & South Pacific).
  • Condition for Formation:
    • Sea surface temperature > 26°C
    • High humidity in the troposphere
    • Low vertical wind shear
    • Pre-existing low-pressure area
  • Process of Formation:
    • Warm ocean surface (temperature ≥ 26°C) → evaporation of water vapour.
    • A low-pressure zone develops due to rising warm moist air.
    • Condensation of water vapour releases latent heat, fueling the cyclone.
    • Coriolis force initiates rotation (absent near the Equator).
    • Inward spiralling winds intensify around the eye — the calm centre.
  • Why Bay of Bengal Experiences Frequent Cyclones
    • The funnel shape of the Bay concentrates atmospheric activity and amplifies storm surges.
    • Warm Sea Surface Temperatures: The Bay remains warmer than the Arabian Sea.
    • Complex coastline: Deltas, estuaries, and shallow coastal topography amplify impact.
    • Seasonal factors:
      • Post-monsoon season (October–December) is ideal for tropical cyclone formation.
      • Low-pressure systems often enter from the South China Sea and move westward.

Naming of Cyclone

  • Cyclones in the North Indian Ocean are named by the WMO/ESCAP Panel on Tropical Cyclones (PTC).
  • Members (13 countries): Bangladesh, India, Maldives, Myanmar, Oman, Pakistan, Sri Lanka, Thailand, Iran, Qatar, Saudi Arabia, UAE, and Yemen.
  • Each country suggests 13 names — total 169 names (list issued by IMD, April 2020).