Circulation Systems Over China :: essays research papers

Circulation Systems Over ChinaIntroduction The Earths atmosphere is in continuous motion movement which isattempting to balance the constant differences in insistence and temperaturebetween different parts of the globe. It is this motion which carries water fromthe ocean to the continents to brook precipitation and moves heat energy fromthe tropic regions toward the poles, warming the high latitudes. It is thiscirculation which plays a basic part in maintaining a steady state in theatmosphere and generating the climatic zones which characterise different partsof the earth. China, from its latitudinal location, loosely belongs to the mid-latitudes, with a small part to the low latitudes. It is located at southeast ofSiberia and the north of the tropical Pacific. At this distinctive location, thecountry is affected by the alternate seasonal expansion and contraction of thepolar continental highs and tropical maritime air masses, along with theseasonal shifts of the everywherehea d sun. These changes in the imperativeness systems oerAsia generate the unique Asian monsoon circulation which prevails everyplace China end-to-end the year.Surface Pressure Field and Winds For any fluid to initiate movements, twitchgradient must exists. Therefore, for a close understanding of the circulationsystem that operates everyplace China, we should start from discussing the seasonal twitch distribution at sea-level over the Asia-Pacific region, which is thedriving force for the air movements in China. Most clearly to be seen, thelargest difference in the atmospheric pressure occurs between winter and summer,whereby January and July contribute be considered as representative months. In January,a typical raw anticyclone with central pressure above 1,040 hectopascals (hPa)developed over mid-Siberia and Mongolia (Mongolian high gear) while a stronglyestablished cyclone over the north-western Pacific Ocean (Aleutian Low). Sinceboth pressure systems practically lie in the s ame latitude of 50 to 55N, asteep pressure gradient occurs which produces strong and persistent north-westerlies over Northeast China. A third pressure system which affects China,although limited merely to south-eastern China, is the equatorial Low overAustralia and New Guinea. The vast territory of atomic number 99 China lies in the middle ofthe path along which the Mongolian inhuman air tries to rush southward into theEquatorial Low. Northerly and north-easterly flows prevail over the eastern halfof China. As a typical feature, the Mongolian High is only a rather shallowpressure system. It disappears at the 500-hPa level. westerly China which has ahigher elevation, therefore feels little of its influence Yunnan highlands argoneven predominated by south-westerlies during most of the winter. The pressurepattern at sea-level during summer differs completely from winter conditions.