360What is a cyclone, and how is it different from a hurricane?
Cyclones, hurricanes and typhoons are the same kind of storm: a huge, spinning tropical storm that forms over warm seas. The name depends on where it happens. In the Atlantic they are hurricanes, in the northwest Pacific typhoons, and in the Indian Ocean and South Pacific cyclones. They bring destructive winds, heavy rain and storm surges.
Tropical cyclones form over warm ocean water, usually at least 26.5°C. Warm, moist air rises, cools and forms clouds, releasing heat that drives the storm. The Earth's rotation makes it spin: anticlockwise in the northern hemisphere and clockwise in the southern.
A mature storm has a calm 'eye' at its centre, surrounded by a wall of towering clouds with the strongest winds.
The same storm has different names in different places. Over the North Atlantic and northeast Pacific it is a hurricane. Over the northwest Pacific it is a typhoon. Over the Indian Ocean, including the Bay of Bengal and Arabian Sea, and the South Pacific, it is a cyclone.
In the North Indian Ocean, the India Meteorological Department grades storms from depressions up to 'super cyclonic storms', and names them from a list agreed by countries in the region.
The greatest danger is often the storm surge, when winds push the sea onto the land, followed by flooding from heavy rain. Better forecasts and early evacuations have greatly reduced deaths, saving many thousands of lives.
Sources: World Meteorological Organization · India Meteorological Department · NOAA.