Definition
A general term for a low-pressure weather system that forms over warm tropical or subtropical ocean waters, with organized thunderstorms rotating around a defined center. Tropical cyclones are classified by sustained wind speed: tropical depression (up to 33 knots), tropical storm (34 to 63 knots), and hurricane or typhoon (64 knots or more).
Plain English
A spinning storm system that forms over warm ocean water. Depending on how strong its winds are, it gets called a tropical depression, a tropical storm, or a hurricane.
Context Anchor
Pilots encounter this term in weather briefings, route planning, and forecasts for coastal or oceanic areas.
Derivation
From the Greek 'kyklos' meaning 'circle' or 'wheel.' The name reflects the circular, rotating wind pattern around the storm's low-pressure center. 'Tropical' specifies that it forms in the warm latitudes near the equator, where ocean heat fuels the system.
Why Pilots Care
These systems produce severe turbulence, icing, low ceilings, and hurricane-force winds that make flight through or near them unsafe.
Grounding Statement
Picture a wide mass of clouds and rain spinning around a center over warm ocean water, with the worst weather spreading far beyond the middle.
Intuition Check
A tropical cyclone is not just any storm in the tropics, and it is not the same as a tornado. It is a large ocean-born rotating storm system that can affect entire regions and many airports.
Example Sentence 1
The dispatcher re-routed the flight several hundred miles north to stay clear of a tropical cyclone developing in the Gulf.
Example Sentence 2
Preflight planning showed that the tropical cyclone would bring 50-knot surface winds and heavy rain to the destination airport.