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# 2.5: Surfaces - Normal Albedo

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If a lossless (conservative) Lambertian reflector (ϖ0 = 1) is irradiated normally with flux density $$F$$, then its radiance in any direction will be $$F/π$$. The normal albedo $$p_n$$ of a point on a surface is the ratio of the normally observed radiance to that of the Lambertian surface, so that

$p_n = \pi f_r \left( \mu = \mu_0 = 1 \right).$

The author has found two definitions of normal albedo in the literature. In one, the surface must be radiated normally and observed normally ($$μ = μ_0 = 1$$) and the other in which it can be irradiated from any direction, in which case $$p_n$$ is a function of $$μ_0$$.

This page titled 2.5: Surfaces - Normal Albedo is shared under a CC BY-NC 4.0 license and was authored, remixed, and/or curated by Max Fairbairn & Jeremy Tatum via source content that was edited to the style and standards of the LibreTexts platform; a detailed edit history is available upon request.

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