Natural Disasters-Cyclones

Natural Disasters-Cyclones

Natural Disasters – Cyclones

Tropical Cyclones

  • Tropical cyclones are violent storms which have a diameter of about 320kms.
  • They originate over oceans in tropical areas and move over to the coastal areas.
  • The direction of rotation of cyclones is influenced by Coriolis Force.
  • Hence cyclones in the Northern Hemisphere rotate in a counter clockwise direction while in the Southern Hemisphere they rotate in a clockwise direction.
  • The passage of a tropical cyclone over the ocean results in the substantial cooling of upper layers of the ocean, which can reduce subsequent cyclone formation.
  • Cyclones formed in the oceans around the world are given names by the Regional Specialized Meteorological Centres (RSMCs) and Tropical Cyclone Warning Centres (TCWCs).
  • There are six RSMCs present in the world including the Indian Meteorological Department (IMD), and five TCWCs.
  • The IMD is given the mandate to name of cyclones as well as issuing advisories to 13 countries in the region namely Bangladesh, India, Maldives, Myanmar, Oman, Pakistan, Sri Lanka, Thailand, Iran, Qatar, Saudi Arabia, United Arab Emirates and Yemen.

What causes formation of Cyclone

The trigger mechanisms required for the formation of tropical cyclones are:

  • Sea surface temperatures normally in the region of, or in excess, of 27 °C which will provide a source of warm, moist air derived from tropical oceans with.
  • Winds near the ocean surface blowing from different directions converging and causing air to rise and forming storm clouds.
  • Low wind shear which means that Winds which do not vary greatly with height allowing the storm clouds to rise vertically to high levels.
  • Sufficient distance from the equator to provide spin or twist (presence of Coriolis Force).

Synonyms of Cyclones

Cyclones are called different names in different regions such as

  • North Atlantic Ocean (including Caribbean and Gulf of Mexico): Hurricanes
  • Eastern and North Central Pacific Ocean: Hurricanes
  • North Western Pacific Ocean: Typhoons
  • Arabian Sea/Northern Indian Ocean: Tropical Cyclones
  • South Indian Ocean: Tropical Cyclones
  • Southwest Australia: Willy-Willy
  • Coral Sea/South Pacific Ocean: Tropical Cyclone