TROPICAL CYCLONES

TROPICAL CYCLONES

Subject: Geography

Context: Tropical cyclones across the globe, except Atlantic hurricanes, are moving closer to land in recent decades, a new study found.

Concept:

• Tropical cyclones generally have been moving westward by about 30 kilometres per decade since 1982, putting them closer to land and making them more dangerous, a study published in Science said.
• Storms generally move east to west because of trade winds in the tropics, so a greater westward shift usually puts them closer to where the land is, Study said.
• Storms that form just west of land, such as in the Pacific off the California and Mexican coasts, are usually moving away from land already, so this shift doesn’t spare more land.
• However, it’s mysterious that, unlike other areas, the Atlantic hurricane basin didn’t show any significant westward shift, but that could be because the Atlantic hurricane zone is more closely surrounded by continents.

Tropical Cyclones

• 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, very heavy rainfall and storm surge.
• They are irregular wind movements involving closed circulation of air around a low pressure center. This closed air circulation is a result of rapid upward movement of hot air which is subjected to Coriolis force.

Conditions Favourable 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.

Favorite Grounds for Tropical Cyclones

• South-east Caribbean region where they are called hurricanes.
• Philippines islands, eastern China and Japan where they are called typhoons.
• Bay of Bengal and Arabian Sea where they are called cyclones.
• Around south-east African coast and Madagascar-Mauritius islands.
• North-west Australia.