Directional-hemispherical reflectance is the
reflectance
The reflectance of the surface of a material is its effectiveness in reflecting radiant energy. It is the fraction of incident electromagnetic power that is reflected at the boundary. Reflectance is a component of the response of the electronic ...
of a surface under direct illumination (with no diffuse component).
Directional-hemispherical reflectance is the integral of the
bidirectional reflectance distribution function
The bidirectional reflectance distribution function (BRDF), symbol f_(\omega_,\, \omega_), is a function of four real variables that defines how light from a source is reflected off an Opacity (optics), opaque surface. It is employed in the optic ...
over all viewing directions. It is sometimes called "black-sky
albedo
Albedo ( ; ) is the fraction of sunlight that is Diffuse reflection, diffusely reflected by a body. It is measured on a scale from 0 (corresponding to a black body that absorbs all incident radiation) to 1 (corresponding to a body that reflects ...
".
References
See also
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Bi-hemispherical reflectance
Electromagnetic radiation
Climatology
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