Anticyclonic rotation, or anticyclonic circulation, is
atmospheric
An atmosphere () is a layer of gases that envelop an astronomical object, held in place by the gravity of the object. A planet retains an atmosphere when the gravity is great and the temperature of the atmosphere is low. A stellar atmosphere ...
motion in the direction opposite to a
cyclonic rotation. For cyclonic rotation, this motion is in a counter-clockwise direction in the
Northern Hemisphere
The Northern Hemisphere is the half of Earth that is north of the equator. For other planets in the Solar System, north is defined by humans as being in the same celestial sphere, celestial hemisphere relative to the invariable plane of the Solar ...
and clockwise in the
Southern Hemisphere. Thus, just anticyclonic rotation would mean clockwise in the Northern Hemisphere and counter-clockwise in the Southern. For
large-scale weather systems, greater than approximately , anticyclonic rotation only occurs for
high-pressure systems. This is due to how the
Coriolis effect
In physics, the Coriolis force is a pseudo force that acts on objects in motion within a frame of reference that rotates with respect to an inertial frame. In a reference frame with clockwise rotation, the force acts to the left of the moti ...
acts on high-pressure systems. Large,
low-pressure systems, such as
tropical cyclone
A tropical cyclone is a rapidly rotating storm system with a low-pressure area, a closed low-level atmospheric circulation, strong winds, and a spiral arrangement of thunderstorms that produce heavy rain and squalls. Depending on its locat ...
s, have
cyclonic rotation. Small scale rotating atmospheric features, such as
tornado
A tornado is a violently rotating column of air that is in contact with the surface of Earth and a cumulonimbus cloud or, in rare cases, the base of a cumulus cloud. It is often referred to as a twister, whirlwind or cyclone, although the ...
es,
water spouts, and
dust devil
A dust devil (also known regionally as a dirt devil) is a strong, well-formed, and relatively short-lived whirlwind. Its size ranges from small (18 in/half a metre wide and a few yards/metres tall) to large (more than 30 ft/10 m ...
s can have either anticyclonic or cyclonic rotation, since the direction of their spin depends on local forces rather than the Coriolis effect.
External links
Anticyclonic Rotation- AMS Glossary of Meteorology
Climate patterns
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