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Earth's energy budget accounts for how much energy comes into the Earth's climate system from the Sun, how much energy is lost to space and accounting for the remainder on Earth and its atmosphere.〔 ("energy budget (of the earth)" )〕 Quantifying changes in these amounts is required to accurately model climate. Received radiation is unevenly distributed over the planet, because the Sun heats equatorial regions more than polar regions. Energy is absorbed by the atmosphere and hydrosphere and, in a process informally described as Earth's heat engine, the solar heating is distributed through evaporation of surface water, convection, rainfall, winds and ocean circulation. When incoming solar energy is balanced by an equal flow of heat to space, Earth is in radiative equilibrium and global temperatures stabilize. Disturbances of Earth's radiative equilibrium, such as an increase of greenhouse gases, change global temperatures in response. However, Earth's energy balance and heat fluxes depend on many factors, such as atmospheric composition (mainly aerosols and greenhouse gases), the albedo (reflectivity) of surface properties, cloud cover and vegetation and land use patterns. Changes in surface temperature due to Earth's energy budget do not occur instantaneously, due to the inertia of the oceans and the cryosphere. The net heat flux is buffered primarily in the ocean's heat content, until a new equilibrium state is established between radiative forcings and climate response. ==Energy budget== The earth receives a certain amount of Insolation (short waves or ultraviolet radiation) and gives back heat into space by terrestrial radiation (infrared or long wave radiation). Through this give and take, or the heat budget, the earth maintains a constant temperature. The earth as a whole does not accumulate or lose heat. It maintains its temperature. This can happen only if the amount of heat received in the form of insolation equals the amount lost by the earth through terrestrial radiation. Consider that the insolation received at the top of the atmosphere is 100 per cent. While passing through the atmosphere some amount of energy is reflected, scattered and absorbed. Only the remaining part reaches the earth surface. Roughly 35 units are reflected back to space even before reaching the earth’s surface. Of these, 27 units are reflected back from the top of the clouds and 8 units from the snow and ice-covered areas of the earth. The reflected amount of radiation is called the albedo of the earth. The remaining 65 units are absorbed, 14 units within the atmosphere and 51 units by the earth’s surface. The earth radiates back 51 units in the form of terrestrial radiation. Of these, 17 units are radiated to space directly and the remaining 34 units are absorbed by the atmosphere (6 units absorbed directly by the atmosphere, 9 units through convection and turbulence and 19 units through latent heat of condensation). 48 units absorbed by the atmosphere (14 units from insolation +34 units from terrestrial radiation) are also radiated back into space. Thus, the total radiation returning from the earth and the atmosphere respectively is 17+48=65 units which balance the total of 65 units received from the sun. This is termed the heat budget or heat balance of the earth. This explains, why the earth neither warms up nor cools down despite the huge transfer of heat that takes place. (Heat Budget )〔http://www.pmfias.com/2015/08/climatology-heat-balance.html〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Earth's energy budget」の詳細全文を読む スポンサード リンク
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