General circulation of the atmosphere

Japanese: 大気大循環 - たいきだいじゅんかん（英語表記）general circulation of the atmosphere

A large-scale circulation of the atmosphere on Earth. It occurs between the poles and the equator, and between the oceans and continents. The air surrounding the Earth (atmosphere) has a three-dimensional structure with the Arctic and Antarctic regions as cold sources and the equator and tropics as hot sources due to the difference in the amount of thermal energy it receives from the sun, and the Coriolis force caused by the Earth's rotation (to the right of the direction of travel in the Northern Hemisphere and to the left in the Southern Hemisphere), which transports thermal energy near the equator to the poles. There are three basic flows in thermal circulation. The first is the Hadley circulation, a vertical meridian circulation at low latitudes that transports thermal energy to high latitudes between the Intertropical Convergence Zone and the subtropical high pressure zone around 30° north latitude, and near the ground, it blows as trade winds (northeasterly winds in the Northern Hemisphere and southeasterly winds in the Southern Hemisphere) from the subtropical high pressure zone toward the equator. The second is the transport of thermal energy by the westerly winds that blow from west to east in the mid-latitudes and circle the Earth. In the westerly winds, when the north-south temperature gradient becomes stronger, the current begins to meander north-south, generating low pressure systems, which exchange heat to eliminate the north-south temperature gradient. In this way, heat energy is transported from the subtropical high pressure zone to the subpolar low pressure zone. The third type is the polar circulation around 60° north latitude and the poles, where cold air flows from the polar regions to the subpolar low pressure zone at 60° north latitude as easterly winds, and then returns to the poles in the upper atmosphere to exchange heat.

Source: Encyclopaedia Britannica Concise Encyclopedia About Encyclopaedia Britannica Concise Encyclopedia Information

Japanese:

地球上における大気の大規模な循環運動。極と赤道，海洋と大陸の間などで起こる。地球を取り巻く空気（大気）は，太陽から受ける熱エネルギー量の違いから北極や南極地方を冷源，赤道や熱帯を熱源とする三次元構造と，地球の自転によるコリオリの力（北半球では進行方向に右向き，南半球では左向き）によって，赤道付近の熱エネルギーを極地方へ運んでいる。熱循環の基本的な流れには三つある。一つめは，ハドレー循環といわれる低緯度の鉛直子午面循環で，熱帯収束帯と北緯 30°付近の亜熱帯高圧帯の間で熱エネルギーを高緯度に運び，地上付近では亜熱帯高圧帯から赤道方面へ貿易風（北半球では北東風，南半球では南東風）となって吹く。二つめは，中緯度を西から東へ吹き地球を一周している偏西風による熱エネルギーの輸送である。偏西風帯では，南北の温度傾度が強まると流れが南北へ蛇行を始め低気圧が発生し，南北の温度傾度を解消させる熱交換をする。こうして，熱エネルギーは亜熱帯高圧帯方面から亜寒帯低圧帯方面へ運ばれる。三つめは，北緯 60°付近と極方面の極循環で，寒気が極地方から北緯 60°帯の亜寒帯低圧帯に偏東風となって流れ，上空では極向きに戻って熱交換を行なう。

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