Describe the formation and characteristics of anticyclones
Answers
anticyclone, region of high atmospheric pressure; anticyclones are commonly referred to as "highs." The pressure gradient, or change between the core of the anticyclone and its surroundings, combined with the Coriolis effect, causes air to circulate about the core in a clockwise direction in the Northern Hemisphere and a counterclockwise direction in the Southern Hemisphere. Near the surface of the earth the frictional drag of the surface on the moving air causes it to spiral outward gradually toward lower pressures while still maintaining the rotational direction. This outward movement of air is fed by descending currents near the center of the anticyclone that are warmed by compression as they encounter higher pressures at lower altitudes.
The warming, in turn, greatly reduces the relative humidity, so that anticyclones, or "highs," are generally characterized by few clouds and low humidity. Such weather characteristics may extend over an area from a few hundred to a few thousand miles wide. Many low-level anticyclones are swept generally eastward by the prevailing west-to-east flow of the upper atmosphere, usually traversing some 500 to 1,000 mi (800–1,600 km) per day. Other anticyclones are permanent or seasonal features of particular geographic regions. The term anticyclone is derived from the fact that the associated rotational direction and general weather characteristics of an anticylone are opposite to those of a cyclone.
cyclone is a storm or system of winds that rotates around a center of low atmospheric pressure. An anticyclone is a system of winds that rotates around a center of high atmospheric pressure. Distinctive weather patterns tend to be associated with both cyclones and anticyclones. Cyclones (commonly known as lows) generally are indicators of rain, clouds, and other forms of bad weather. Anticyclones (commonly known as highs) are predictors of fair weather.
Winds in a cyclone blow counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere. Winds in an anticyclone blow just the opposite. Vertical air movements are associated with both cyclones and anticyclones. In cyclones, air close to the ground is forced inward toward the center of the cyclone, where pressure is lowest. It then begins to rise upward, expanding and cooling in the process. This cooling increases the humidity of the rising air, which results in cloudiness and high humidity in the cyclone.