Bond albedo

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Bond albedo

Post by Kaustav »

What is the Bond albedo of a planet, as opposed to the albedo? I know that the albedo of the planet Earth is measured to be approx. 0.39 (Kaufmann, Universe 7th edition) and that the term albedo, put simply, is the overall average reflection coefficient of an object. However, I've read that the Bond albedo of the Earth is approx. 0.29. Why are the the two values different and how is Bond albedo measured?
Kaustav Bhattacharya
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Post by cowait »

The two main categories are normal albedo and Bond albedo. Normal albedo, also known as normal reflectance, is a measure of a surface’s relative brightness when illuminated and observed vertically. Within this category, visual albedo refers to radiation only in the visible part of the spectrum, whereas geometric albedo, also known as physical albedo, is the ratio between the brightness of an object as seen from the direction of the Sun, and the brightness of a hypothetical white, diffusely reflecting sphere of the same size and at the same distance. The normal albedo of a moon or asteroid, which can be calculated if the object’s apparent brightness, size, and distance are known, is an important indicator of surface composition. Bond albedo (named for the American astronomer George Bond (1826-1865)), also known as spherical albedo, is the fraction of the total incident solar radiation—the radiation at all wavelengths—that is reflected or scattered by an object in all directions; this is an important measure of a planetary body’s energy balance.

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