albedo
albedo The proportion of insolation that is reflected back from the Earth, from the tops of the clouds, and from the atmosphere, without heating the receiving surface. It averages about 30 per cent, but varies widely according to the substance and texture of the surface, and the angle and wavelength of the incident radiation. The value for green grass and forest is 8–27 per cent (over 30 per cent for yellowing deciduous forest in autumn); for cities and rock surfaces 12–18 per cent (over 40 per cent for chalk and light-coloured rock and buildings); for sand up to 40 per cent; for fresh, flat snow up to 90 per cent; and for calm water only 2 per cent in the case of vertically incident radiation but up to 78 per cent where there is a low angle of incidence. The albedo for cloud surfaces averages 55 per cent, but can be up to 80 per cent for thick stratocumulus.
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albedo