From Cyril Aydon's book Scientific Curiosity - I learn that Albedo is the Reflecting Power. The Albedo of the moon is 7% - just 7% of the sunlight hiting the moon is reflected - but even a quarter of a million miles away it's enough to see your way home by, when its full Moon.
Albedo is a ratio of scattered to incident electromagnetic radiation power. It is a unitless measure of a surface or body's reflectivity. The word is derived from albus, a Latin word for "white". It is in climatology that reflectivity is called albedo.
Albedos of typical materials in visible light range from up to 90% for fresh snow, to about 4% for charcoal, one of the darkest substances. An exception are deeply shadowed cavities whose effective albedo may approach the zero of a blackbody. When seen from a distance, the ocean surface has a low albedo, as do most forests, while desert areas have some of the highest albedos among landforms. Most land areas are in an albedo range of 10 to 40%. The average albedo of the Earth is about 30%. This is far higher than for the ocean primarily because of the contribution of clouds.
Human activities have changed the albedo (via forest clearance and farming, for example) of various areas around the globe. However, quantification of this effect is difficult on the global scale: it is not clear whether the changes have tended to increase or decrease global warming.
An example of the albedo effect is the snow-temperature feedback. If a snow covered area (albedo 40-85%) warms the snow melts then earth appears (albedo 20%) so the earth warms up causing global warming.
5 years ago
