Albedo their reflectivities. Fresh 'black' ice exhibits Fresnel reflection. Snow on top of this sea ice increases the albedo to 0.9. Cloud albedo has substantial influence over atmospheric temperatures. Different types of clouds exhibit different reflectivity, theoretically ranging in albedo from a minimum of near 0 to a maximum approaching 0.8. "On any given day, about half of Earth is covered by clouds, which reflect more sunlight than land and water. Clouds keep Earth cool by reflecting sunlight, but they can also serve as blankets to trap warmth." Albedo and climate in some areas are affected by artificial clouds, such as
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