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[citation needed] Earth's average surface temperature due to its albedo and the greenhouse effect is currently about 15 °C (59 °F). If Earth were frozen entirely (and hence be more reflective), the average temperature of the planet would drop below −40 °C (−40 °F). [17]
For layered and finite media, according to the CIE, [citation needed] reflectivity is distinguished from reflectance by the fact that reflectivity is a value that applies to thick reflecting objects. [6] When reflection occurs from thin layers of material, internal reflection effects can cause the reflectance to vary with surface thickness.
In geophysics, shortwave flux is a result of specular and diffuse reflection of incident shortwave radiation by the underlying surface. [3] This shortwave radiation, as solar radiation, can have a profound impact on certain biophysical processes of vegetation, such as canopy photosynthesis and land surface energy budgets, by being absorbed into the soil and canopies. [4]
The Earth has an albedo of 0.3, meaning that 30% of the solar radiation that hits the planet gets scattered back into space without absorption. The effect of albedo on temperature can be approximated by assuming that the energy absorbed is multiplied by 0.7, but that the planet still radiates as a black body (the latter by definition of ...
The albedo of several types of roofs (lower values means higher temperatures). Reflective surfaces, or ground-based albedo modification (GBAM), is a solar radiation management method of enhancing Earth's albedo (the ability to reflect the visible, infrared, and ultraviolet wavelengths of the Sun, reducing heat transfer to the surface).
The planet absorbs the radiation that isn't reflected by the albedo, and heats up. One may assume that the planet radiates energy like a blackbody at some temperature according to the Stefan–Boltzmann law. Thermal equilibrium exists when the power supplied by the star is equal to the power emitted by the planet.
[citation needed] Radians and steradians are, of course, dimensionless and so "rad" and "sr" are included only for clarity. Example: A surface with a luminance of say 100 cd/m 2 (= 100 nits, typical PC monitor) will, if it is a perfect Lambert emitter, have a luminous emittance of 100π lm/m 2 .
Planetlight is the diffuse reflection of sunlight from a planet, whose albedo can be measured. The most observed and familiar example of planetshine is earthshine on the Moon , which is most visible from the night side of Earth when the lunar phase is crescent or nearly new , [ 1 ] without the atmospheric brightness of the daytime sky.