Albedo

the albedo (lat. albedo = „whiteness “; lat. albus =) a measure for the reflecting ability of vaguely reflecting (reemittierenden) is white, thus not reflecting and not even bright surfaces.

The albedo is particularly in the meteorology ofMeaning, where it makes statements possible about it, how strongly air over different surfaces warms up. She finds also in the 3D-Computergrafik application, where she serves the volume dispersion as measure for the vague strewing strength of different materials for the simulation.

kinds of albedo

it are differentiated different kinds of the albedo:

• The geometrical albedo (also visual geometrical albedo called) is vague from a perpendicularly illuminated ball half surface inthe semi-infinite space strewn fraction of the remarkable quantity of light, in relation to the Rückstrahlung of a white, vaguely reflecting hemisphere with the same size and at the same distance with the phase angle 0° to the observer.

• The spherical albedo (also Bond albedo called) is thatRelationship of the quantity of light strewn by a Kugeloberfläche after all directions to the parallel irradiated quantity of light.

• The hemispherical albedo is the portion of the incident light, which is strewn by the surface as a function of the angle of incidence.

The relationship of the Rückstrahlung to the irradiation can take theoretically values from 0 to 1. The larger the portion of the reflected radiation is, the more brightly is the surface and all the more highly is the albedo. The spherical albedo is usually somewhat larger with same material than the geometrical.The connection between them is obtained mathematically by the so-called Phasenintegral. In the astronomy the comparison with the albedo values of terrestrial substances makes possible to draw conclusions on the condition of other planetary surfaces. In accordance with the definition of the spherical albedo is the conditiongiven of parallel breaking in light because of the large distances of the reflecting heavenly bodies of the sun as source of light very well.

influences

one supplies if to warmth by radiation and mainly by other processes one exhausts, reach surfaces with smallerAlbedo higher temperatures (see. Bitumen and snow). If warmth mainly by other processes is supplied and (and. A.) by radiation is exhausted, reaches surfaces with smaller albedo smaller temperatures (that is also the reason, why the radiator boxes of electronic devices mostlyare black).

Smooth surfaces such as water, sand, snow have a relatively high portion of reflecting reflection, their albedo depend therefore strongly on the angle of incidence of the solar radiation (see table).

middle albedo in the solar system

the Venus possesses with onea middle spherical albedo of 0,39 has middle spherical albedo of 0,76 a very high, the moon with on the average 0.12 a very small reflecting ability and the earth. The highest measured value falls with 0,99 on the Saturnmond Enceladus andthe lowest average value was determined with only 0.03 at the comet Borrelly.

measurement

the measurement of the albedo is made by albedo meters.

literature

Joachim Gürtler and Johannes Dorschner: The solar system., Barth (1993), ISBN 3335002814

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Wiktionary: Albedo - word origin, synonyms and translations

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