Albedo 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 15 °C. If Earth were frozen entirely (and hence be more reflective), the average temperature of the planet would drop below −40 °C. If only the continental land masses became covered by glaciers, the mean temperature of the
Bearing surface the top or bottom surface of the spring in contact with the constraining part. The ways of machine tools, such as dovetail slides, box ways, prismatic ways, and other types of machine slides are also bearing surfaces. Bearing surface A bearing surface in mechanical engineering is the area of contact between two objects. It usually is used in reference to bolted joints and bearings, but can be applied to a wide variety of engineering applications. On a screw the bearing area loosely refers to the underside of the head. Strictly speaking, the bearing area refers to the area of the