What’s in a name: Cyclone, Hurricane or Typhoon?
Haiyan typhoon that hit the Phillippines On Friday

New Delhi: Haiyan has been found to be the world’s most powerful typhoon of the year. It hit the Philippines on Friday and moved onwards to the South China Sea.
Do you wonder why some storms are called hurricanes, others as typhoons and still others as cyclones?
All the three names point to the same thing – tropical cyclones. They are just named differently in different parts of the world:

  • In the Atlantic Ocean, Caribbean Sea, and Central and Northeast Pacific Ocean, these tropical cyclones are called Hurricane.
  • In the Northwest Pacific Ocean, they are called Typhoons.
  • In the Arabian Sea and the Bay of Bengal, they are called Cyclones.
  • In the Southwest Indian Ocean, these storms are called Tropical Cyclones.
  • In the Southwest Pacific Ocean and Southeast Indian Ocean, they are Severe Tropical Cyclones.

Storm Strength Scales

Wind becomes a Tropical Storm when it attains the speed of 63 km per hour. It becomes cyclone, hurricane, tropical cyclone or typhoon when it attains the speed of 119 km per hour.

Typhoons are classified into five categories according to the speed of the wind. The highest and most dangerous is Category 5, which is above 252 km per hour.
Australian scale to measure storm intensity differs. There Category 1 Tropical Cyclone has a wind speed of above 91 km per hour while Category 5 Tropical Cyclone has a wind speed of above 279 km per hour.

Rotation of the Storm

Storms originating in the North of the Equator rotate clockwise while storms originating in the South of the Equator rotate counter-clockwise.

Season of Storms across the World

  • Hurricane seasons in the Atlantic Ocean and Central Pacific Ocean are from June 1 to November 30.
  • Hurricane season in the Eastern Pacific is from May 15 to November 30.
  • Hurricane season in the Northwest Pacific Ocean spans almost across the year, with most activity being from May to November.
  • Hurricane season in the South Pacific and Australia is from November to April.
  • There are two Hurricane seasons in the The Bay of Bengal –  from April to June, and again from September to November.

Place with Most Cyclones

North-west Pacific where Typhoon Haiyan has just hit is the busiest place for such activity. In a normal year, there are 27 named storms. Haiyan was the 28th this year and 29th storm has already hit the region.

On the other hand, the Atlantic Ocean sees least activity with only 11 named storms a year. This year, there have been 12 storms but none of them posed major threats to the region.

Who names the Storms?

The World Meteorological Organisation maintains the lists of the names familiar in each region. If a hurricane causes a lot of deaths or damage, the name given to it is struck off the list of that region and a new name fills up the position.Hence, in 2005, when Hurricane Katrina devastated New Orleans, the name was struck off the list.Philippines has its own storm naming system and hence, Typhoon Haiyan is also being called ‘Yolanda’.‘Haiyan’ is Chinese for ‘Pretel’ – a seabird that lives over the open sea and returns to land only when it needs to breed.

This post was written by Aditya Singhal, managing director of askIITians

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