EARTH SCIENCE > ATMOSPHERE > ATMOSPHERIC PHENOMENA > CYCLONES
Definition:
A weather system charcterised by relatively low surface air pressure at a given level and a closed cyclonic wind circulation. Also the regional name for a severe tropical cyclone with sustained surface wind speeds greater than 64 knots (74 mph) in the western South Pacific and Indian Oceans, equivalent of a hurricane or typhoon.
Reference:
Glossary of Weather and Climate, American Meteorological Society, 1996.
