text: The average albedo of the Earth from the upper atmosphere, its planetary albedo, is 30–35% because of cloud cover, but widely varies locally across the surface because of different geological and environmental features.Terrestrial albedo Any albedo in visible light falls within a range of about 0.9 for fresh snow to about 0.04 for charcoal, one of the darkest substances.Deeply shadowed cavities can achieve an effective albedo approaching the zero of a black body.When seen from a distance, the ocean surface has a low albedo, as do most forests, whereas desert areas have some of the highest albedos among landforms.Most land areas are in an albedo range of 0.1 to 0.4.The average albedo of Earth is about 0.3.This is far higher than for the ocean primarily because of the contribution of clouds.Earth's surface albedo is regularly estimated via Earth observation satellite sensors such as NASA's MODIS instruments on board the Terra and Aqua satellites, and the CERES instrument on the Suomi NPP and JPSS.As the amount of reflected radiation is only measured for a single direction by satellite, not all directions, a mathematical model is used to translate a sample set of satellite reflectance measurements into estimates of directional-hemispherical reflectance and bi-hemispherical reflectance (e.g.,).These calculations are based on the bidirectional reflectance distribution function (BRDF), which describes how the reflectance of a given surface depends on the view angle of the observer and the solar angle.BDRF can facilitate translations of observations of reflectance into albedo.Earth's average surface temperature due to its albedo and the greenhouse effect is currently about .If Earth were frozen entirely (and hence be more reflective), the average temperature of the planet would drop below .If only the continental land masses became covered by glaciers, the mean temperature of the planet would drop to about .