| Abstract from DBPedia | Atmospheric circulation is the large-scale movement of air and together with ocean circulation is the means by which thermal energy is redistributed on the surface of the Earth. The Earth's atmospheric circulation varies from year to year, but the large-scale structure of its circulation remains fairly constant. The smaller scale weather systems – mid-latitude depressions, or tropical convective cells – occur chaotically, and long-range weather predictions of those cannot be made beyond ten days in practice, or a month in theory (see chaos theory and the butterfly effect). The Earth's weather is a consequence of its illumination by the Sun and the laws of thermodynamics. The atmospheric circulation can be viewed as a heat engine driven by the Sun's energy and whose energy sink, ultimately, is the blackness of space. The work produced by that engine causes the motion of the masses of air, and in that process it redistributes the energy absorbed by the Earth's surface near the tropics to the latitudes nearer the poles, and thence to space. The large-scale atmospheric circulation "cells" shift polewards in warmer periods (for example, interglacials compared to glacials), but remain largely constant as they are, fundamentally, a property of the Earth's size, rotation rate, heating and atmospheric depth, all of which change little. Over very long time periods (hundreds of millions of years), a tectonic uplift can significantly alter their major elements, such as the jet stream, and plate tectonics may shift ocean currents. During the extremely hot climates of the Mesozoic, a third desert belt may have existed at the Equator.大気循環（たいきじゅんかん、英語：atmospheric circulation）とは、地球の大気の大規模な循環のことである。太陽から地球への熱の供給が原因となって発生する現象。「大気大循環」また地球表面を南北方向に割った断面（子午面）の循環であることから「平均子午面循環」「子午面循環」とも呼ばれる。 大気循環は、海洋における風成循環および熱塩循環と並ぶ、地球上の大循環の1つである。 一見、大気の流れは絶えず移り変わっているように見えるが、地球規模で数週間から数か月の長いスパンで見ると大気の流れは基本的には一貫しており、大規模な循環の構造を成している。 (Source: http://dbpedia.org/resource/Atmospheric_circulation) |
