|Albedo, from Wikipedia|
The word albedo is derived from the Latin word "albus" (white). The range of possible values of albedo (whiteness) goes from 0 (darkest) to 1 (brightest).
Albedo change occurs when a surface changes in color, e.g. if a snow-covered area warms and the snow melts, the albedo decreases.
Fresh snow can have an albedo as high as 85%, but as the snow melts more, its albedo will go down, to as low as 40%. The albedo of ice is typically between 30% and 40%. As sea ice melts away, the albedo goes down dramatically, firstly because melt pools start to appear on top of the ice, and finally because it becomes open water, which has an albedo of only about 7% or 8%.
The average overall albedo of Earth is 30 to 35%. These figures are from Wikipedia.