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Outgoing Longwave Energy

September 16, 2017
Image of the earth

Earth absorbs energy from the Sun in the form of shortwave energy (or "radiation"), mostly in visible, near-infrared and ultraviolet forms. Energy leaving Earth is in the form of outgoing longwave radiation, mostly infrared and far-infrared. If the incoming shortwave energy matches the amount of outgoing longwave energy, the Earth's energy budget is considered to be "in balance." However, if the amount of incoming energy is greater than the amount of outgoing energy, the planet will warm (the converse is also true). Clouds, water vapor and greenhouse gases reduce the outgoing energy, leading to global warming. Monthly and yearly values of outgoing longwave energy are plotted here. The brighter orange colors indicate areas in which more energy is released into space. These areas are often associated with hot, dry regions like deserts and other low cloud-cover regions, such as the doldrums over the oceans. Darker areas highlight the abundant clouds and rainfall in the tropics, as well as regions closer to the poles with cooler temperatures.