Cyclones and anticyclones

Cyclones and anticyclones are weather systems that involve masses of air moving in a spiraling motion. In a cyclone, air spirals inward, whereas in anticyclone, air spirals outward. Most types of cyclones and anticyclones are large features that move slowly across the Earth's surface, bringing changes in the weather as they move. These are referred to as traveling cyclones and traveling anticyclones

The circulation of weather systems is determined by their pressure which in turn determines whether air ascends as in the case of low pressure, or descends as in the case of high pressure. Where air rises, condensation and cloud formation results as seen here in the system developing off the west coast of Alaska. In an anticyclone, outspiraling air descends and is warmed adiabatically leading to clear conditions.

For more details visit: http://www.gurukpo.com/