Albedo

Geographic and Seasonal Variations

Because Earth's surface is varied with regard to its composition, the amount of solar radiation that is reflected and absorbed varies by location and by season. Albedo for natural surfaces ranges from ∼0.03 to 0.95 (Table 1). Generally, dark-colored surfaces (e.g., dark soils) have low albedos, and light-colored surfaces (e.g., snow and white sand) have high albedos. Albedo is also influenced by the solar zenith angle. Water generally has a relatively low albedo (<0.10), except when the sun is near the horizon. The albedo of snow also varies greatly. Freshly fallen snow initially has a high albedo, but as the snow ages and dust and soot are deposited on top of the snow surface, its albedo decreases. The presence of snow can significantly lower the albedo of the land surface, which in turn leads to colder temperatures that support further expansion/accumulation of snow (e.g., a positive feedback).

Many of the changes in albedo take place naturally due to the changing of the seasons, which can lead to changes in vegetation or snow cover, or variations in the weather, which can influence the density and health of vegetation and soil saturation. However, human activities can also have a major influence on albedo. Deforestation and urbanization are two examples of how human activities can change the albedo of the land surface, which then modifies the local and regional climate.

Source: Created using data from Oke (1987).