Each of these terms applies to a disturbance of intense severity. Technically, a cyclone is a large-scale wind and pressure system characterized by circular wind motion with low pressure at its center. In the Southern Hemisphere, motion of the wind in a cyclone is clockwise; in the Northern Hemisphere it is counterclockwise. A hurricane is a violent tropical storm occurring mainly in the western North Atlantic, with wind speeds in excess of 70 miles an hour. The term hurricane is applied loosely to any storm accompanied by high winds. A tornado is a violently destructive and usually localized windstorm occurring over land. The most visible part of a tornado is its long funnel-shaped cloud, filled with debris, that extends toward the ground.
Dictionary of problem words and expressions. Harry Shaw. 1975.