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Cyclones, storms and hurricanes

Map of cyclone Nargis.
(UNOSAT)

One symptom of climate change is more severe tropical cyclones, hurricanes and typhoons, featuring in the headlines more often.

What is a tropical cyclone?

A tropical cyclone is a generic term for a small, intensely developed low-pressure cell that forms over warm oceans. Its diameter can range from 200km to 2,000km, with a warm centre and strong cyclonic winds, moving clockwise in the southern hemisphere.

What is a tropical depression?

Tropical cyclones with a maximum wind speed of less than 60km per hour are called tropical depressions.

What is a tropical storm?

When a tropical cyclone reaches speeds ranging from 60km per hour to 110km per hour it is called a tropical storm and given a name.

What is the difference between a hurricane, a typhoon and a tropical cyclone?

"Hurricane" and "typhoon" are regionally specific names for a strong tropical cyclone.

When wind speeds reach more than 119km per hour, a tropical cyclone is called:

- a "hurricane" over the North Atlantic Ocean, the Northeast Pacific Ocean east of the International Date Line or the South Pacific Ocean east of 160°E

- a "typhoon" over the Northwest Pacific Ocean, west of the International Date Line

- "severe tropical cyclone" over the Southwest Pacific Ocean west of 160°E or Southeast Indian Ocean east of 90°E

- "severe cyclonic storm" over the north Indian Ocean

- "tropical cyclone" over the southwest Indian Ocean

jk/he

Sources:

The Atlantic Oceanographic and Meteorological Laboratory
The South African Weather Service


This article was produced by IRIN News while it was part of the United Nations Office for the Coordination of Humanitarian Affairs. Please send queries on copyright or liability to the UN. For more information: https://shop.un.org/rights-permissions

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