albedo

albedo , reflectivity of the surface of a planet, moon, asteroid, or other celestial body that does not shine by its own light. Albedo is measured as the fraction of incident light that the surface reflects back in all directions. A perfect reflector by definition has an albedo of unity, i.e., all the incident light is reflected; a body that reflects no light at all would have an albedo of zero. Real surfaces have albedos between these values. The albedos of planets, moons, and asteroids provide valuable information about the structure and composition of their surfaces. The dark regions on the earth's moon give it the very low average albedo of 0.07, while highly reflective clouds give Venus an albedo of 0.85, the highest of any body in the solar system.

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%, 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% (over 30% for yellowing deciduous forest in autumn); for cities and rock surfaces, 12–18% (over 40% for chalk and light-coloured rock and buildings); for sand up to 40%; for fresh, flat snow up to 90%; and for calm water only 2% in the case of vertically incident radiation but up to 78% where there is a low angle of incidence. The albedo for cloud surfaces averages 55%, but can be up to 80% for thick stratocumulus.

albedo Fraction of light or other radiation that is reflected from a surface. An ideal reflector has an albedo of 1; those of real reflectors are less; that of the Earth, viewed from satellites, is 0.35.