The amount of solar energy that reaches the surface

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The amount of solar energy that reaches the surface and is absorbed by the planet also depends on: 1) Albedo 2) Chemical composition of the atmosphere Albedo: how much power is reflected away from the earth (or any planet) as a fraction of the incident power. The albedo depends on the nature of the surface and of the atmosphere. Albedo= (power reflected) / (power received)
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High albedo more power reflected, less power absorbed Cooler (all else being equal) Clouds and ice have a high albedo; water, rocks, and forests have a low albedo. Earth’s average albedo: about 30 % Chemical composition of the atmosphere: A given gas allows light to pass through it at some frequencies but strongly absorbs light at other frequencies. Some atmospheric gases absorb strongly in the same infra-red part of the electromagnetic spectrum in which the surface of the earth re-emits received solar energy as heat. Greenhouse gases: eg. Water vapor, carbon dioxide, methane Ozone in the upper atmosphere also strongly absorbs light at ULTR-VIOLET frequencies. The greenhouse effect: without greenhouse gases the avg. surface temperature would be about 33 degrees colder than it actually is. Because of a greenhouse gases in the atmosphere the earth must raise its surface temperature by about 33 degrees to achieve a steady state. The atmosphere acts as a blanket, ensuring a warmer temperature than would otherwise be the case. This is what is called the greenhouse effect.
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