From Glossary of Meteorology


A cyclone's direction of rotation (counterclockwise in the Northern Hemisphere) is opposite to that of an anticyclone. While modern meteorology restricts the use of the term cyclone to the so-called cyclonic-scale circulations, it is popularly still applied to the more or less violent, small- scale circulations such as tornadoes, waterspouts, dust devils, etc. (which may in fact exhibit anticyclonic rotation), and even, very loosely, to any strong wind. The first use of this term was in the very general sense as the generic term for all circular or highly curved wind systems. Because cyclonic circulation and relative low atmospheric pressure usually coexist, in common practice the terms cyclone and low are used interchangeably. Also, because cyclones are nearly always accompanied by inclement (often destructive) weather, they are frequently referred to simply as storms.
See tropical cyclone, extratropical cyclone;
compare trough.