tropical cyclone

A warm-core, nonfrontal, synoptic-scale cyclone originating over tropical or subtropical waters, with organized deep convection and a closed surface wind circulation around a well-defined center.

Once formed, a tropical cyclone is maintained by the extraction of heat energy from the warm ocean surface, predominantly via wind-driven evaporation of water, and the export of heat into the much colder upper troposphere. In this they fundamentally differ from extratropical cyclones, which derive their energy from horizontal temperature contrasts in the atmosphere (baroclinic effects). The term tropical cyclone encompasses tropical depressions, tropical storms, and hurricanes in the North Atlantic, central North Pacific, and eastern North Pacific, and typhoons in the western North Pacific. Tropical cyclones in the South Pacific and Indian Oceans are locally referred to as “cyclones.”

See also tropical depression, tropical storm, hurricane, typhoon.

Term edited 15 June 2026.