Albedo distribution of solar radiation reaching the Earth's surface. These factors vary with atmospheric composition, geographic location and time (see position of the Sun). While bi-hemispherical reflectance is calculated for a single angle of incidence (i.e., for a given position of the Sun), albedo is the directional integration of reflectance over all solar angles in a given period. The temporal resolution may range from seconds (as obtained from flux measurements) to daily, monthly, or annual averages. Unless given for a specific wavelength (spectral albedo), albedo refers to the entire spectrum of solar radiation. Due to measurement constraints, it is often given
Bond albedo phase angles from the Earth, the only reliable data for measuring their Bond albedo comes from spacecraft. The Bond albedo ("A") is related to the geometric albedo ("p") by the expression where "q" is termed the "phase integral" and is given in terms of the directional scattered flux "I"("α") into phase angle "α" (averaged over all wavelengths and azimuthal angles) as The phase angle "α" is the angle between the source of the radiation (usually the Sun) and the observing direction, and varies from zero for light scattered back towards the source, to 180° for observations looking towards the source.