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
Albedo (alchemy) Albedo (alchemy) In alchemy, albedo is one of the four major stages of the magnum opus; along with nigredo, citrinitas and rubedo. It is a Latinicized term meaning "whiteness". Following the chaos or "massa confusa" of the nigredo stage, the alchemist undertakes a purification in albedo, which is literally referred to as "ablutio" – the washing away of impurities. In this process, the subject is divided into two opposing principles to be later coagulated to form a unity of opposites or "coincidentia oppositorum" during rubedo. Titus Burckhardt interprets the albedo as the end of the lesser work, corresponding to a