| Concept definition: |
The ratio, for a particular material <SURFACE>, of the flux density reflected into the hemisphere above this <SURFACE> to the flux density incident upon it from all <DIRECTION>s within this hemisphere. This quantity is also defined as the ratio A/B, where A is the integral (over the incident hemisphere) of the incident <<RADIANCE>> times the cosine of the angle between the surface normal and the incident <DIRECTION> times the <<DIRECTIONAL_HEMISPHERICAL_REFLECTIVITY>> times the unit solid incident angle and B is the same integral without the <<DIRECTIONAL_HEMISPHERICAL_REFLECTIVITY>>. This quantity may also be known as the "total" or "bi-hemispherical" reflectivity and is spectral (a distribution function in <<WAVELENGTH>>), therefore the quantity is measured in terms of inverse <<WAVELENGTH>> bin size. |
