Tropical cyclones are called hurricanes in the Atlantic and Caribbean; in the Pacific they are known as typhoons. They may be 50-500 miles in diameter, and sustained winds in excess of 100 mph are common.

If a tropical cyclone moves outside the tropics, it becomes known as an extratropical cyclone, an occurrence that causes air masses to move and influences the weather. An extratropical cyclone often weakens and becomes a cold front or a warm front.

Cyclones have an eye, an area like a hole, where the winds can be nearly still. This may recall the one-eyed Cyclops of Greek mythology, but there's no proven association between the two words. In fact, cyclone was a modification of the Greek kykoma, meaning "wheel" or "coil." The term was coined by Henry Piddington, an Englishman in Calcutta who named the storm after its characteristic highly circular winds and defined his coinage in his 1848 Sailor's Hornbook for the Law of Storms.