Pressure belts influencing climate of cameroon
Published on: Mar 4, 2016
Transcripts - Pressure belts influencing climate of cameroon
Pressure Belts influencing climate of CameroonBy George Ngang, Douala, CameroonAzores HighThe Azores High (also known as the Azores anticyclone) is a semi-permanent anticyclonicregion with relatively consistent high pressure and subsiding air over the Atlantic Ocean ataround 30°N latitude in winter (i.e. south of the Azores). The Azores High is part of a belt ofsubtropical anticyclones on the northern hemisphere and an important so called centre of actionin the global climate system. (like its sisters the Bermuda High and California high) Movement of the system poleward in summer has a major impact upon the climate of Europe. In summer the pressure centre shifts towards 35°N across the Iberian peninsula and a ridge might build across France, northern Germany and even the south-eastern UK. This is when the typical mid- to late summer heatwaves arrive, with very hot temperatures and persistent dry weather. Temperatures will easily climb into the 30ies °C (90ies degF).In both winter and summer the central pressure lies around 1024 mbar (hPa), but conditions aremore variable in winter. The aridity of the Sahara Desert and the adjacent Mediterranean regionis due to the subsidence of air in this high-pressure system.AnticycloneAn anticyclone is a region of high atmospheric pressure relative to the surrounding air, generallythousands of kilometres in diameter and also known as a high or high-pressure system.Anticyclones appear on weather charts as a series of concentric, widely spaced isobars of 1000mbs and above. The roughly circular closed isobar at its central region indicates the area ofhighest pressure. The centre of an anticyclone has a characteristic pattern of air circulation, with subsiding air and horizontal divergence of the air near the surface. The name anticyclone comes from the circulatory flow of air within the system; anticyclonic circulation has a local circulation that is opposed to the Earths rotation. Winds, generally light, circulate
around the high pressure centre in a clockwise direction in the Northern Hemisphere andanticlockwise in the Southern Hemisphere. The subsiding air compresses as it descends, causing adiabatic warming. The eventually warmer and drier air suppresses cloud formation and thus anticyclones are usually associated with fine weather in the summer and dry, cold, and sometimes foggy weather in the winter. Calm settled weather is usually synonymous with anticyclones in temperate latitudes. Anticyclones are typically relatively slow moving features. However, mid-latitude anticyclones can be divided into warm andcold anticyclones (continental highs). Subtropical anticyclones are usually warm and quasipermanent features of the Earths general circulation (e.g. the Azores high). In mid-latitudesanticyclones are often located beneath the leading edge of ridges in the upper-air westerlies,where they may be associated with blocking weather patterns.