MadSci Network: Environment & Ecology

Re: What kinds of light from the sun are involved in the greenhouse effect?

Date: Sat Jul 14 13:36:24 2001
Posted By: Richard Kingsley, Science teacher
Area of science: Environment & Ecology
ID: 991322082.En

Hi Carissa,

Like all bodies, the sun emits a range of light wavelengths. They are typically referred to as "short-wave radiation" because the earth emits longer wavelengths. You must always apply caution when interpreting the phrase "short-wave radiation" because it is used for different parts of the electromagnetic spectrum. Atmospheric scientists typically use it in place of "solar radiation" whereas a physicist may only use it to mean ultraviolet (UV) light (or shorter).

According to Barry and Chorley (1998), solar radiation consists of: 39% visible (0.4 - 0.7 micrometres); 53% near-infrared (or longer); and 8% UV (or shorter). Thus, nearly all of the radiation that your figures refer to are in just a small part of the electromagnetic spectrum.

The figures you provide do not match what I have (Trenberth et al 1996, in Barry and Chorley, 1998).

3% absorption by stratosphere
(ozone layer dealing with harmful UV)
15% absorption by aerosols and water vapour in troposphere
3% absorption by clouds
48% absorption by earth's surface
20% reflection by clouds back to space
3% scattered back to space
6% reflected by earth's surface back to space

Hope this helps

Richard Kingsley

A good general text on the atmosphere is Atmosphere, Weather and Climate by Roger Barry and Richard Chorley.

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