Sometimes referred to as a hurricane or typhoon, a tropical cyclone refers to a revolving storm formed over tropical waters driven by heat and moisture.
Tropical cyclones start as tropical depressions and can be 300 to 500 miles across and up to five to six miles high. When the average wind speed of the storm reaches 74 mph, the tropical cyclone is classified by different names globally despite resulting from the same processes.
Tropical cyclones can develop from other cyclone systems such as subtropical cyclones and storms thousands of kilometres away. If the tropical cyclone travels polewards and becomes caught up in a front, it can become an extratropical storm.
Last updated: 14 August 2013