An anticyclone is a weather

Weather

Weather is the state of the atmosphere, to the degree that it is hot or cold, wet or dry, calm or stormy, clear or cloudy. Most weather phenomena occur in the troposphere, just below the stratosphere. Weather refers, generally, to day-to-day temperature and precipitation activity, whereas climate...

 phenomenon

Meteorological phenomenon

A meteorological phenomenon is a weather event that can be explained by the principles of meteorology. Such events include:* Air mass* Anticyclone* Arctic cyclone* Clouds* Crow Instability* Derecho* Diamond dust* Drought* Dust devil* Dust storm...

 defined by the United States' National Weather Service

National Weather Service

The National Weather Service , once known as the Weather Bureau, is one of the six scientific agencies that make up the National Oceanic and Atmospheric Administration of the United States government...

's glossary as "[a] large-scale circulation of winds around a central region of high atmospheric pressure, clockwise in the Northern Hemisphere, counterclockwise in the Southern Hemisphere". Effects of surface-based anticyclones include clearing skies as well as cooler, drier air. Fog can also form overnight within a region of higher pressure.