In meteorology, a cyclone can refer to one of several different meteorological phenomena. Due to ambiguity most weather forecasters avoid using the term cyclone without a qualifying term.
The term normally refers to a wind and rain storm associated with a region of atmospheric low pressure. The cyclonic winds rotate around a common center. Rotation is counter-clockwise in the northern hemisphere, or clockwise in the southern hemisphere. The rotation is caused because air moving between the tropics and the poles is affected by the rotation of the earth. The storms are termed Hurricanes, typhoons or tropical cyclones, depending where they form and how strong they are.
In North America, a tornado may also be called a cyclone. This usage has gone out of favour in recent years as professional weather forecasters have avoided using the term in this way.
Anticyclone, Arctic cyclone, Mesocyclone Severe weather, Subtropical cyclone, Tornado, Tropical storm Weather