Terrestrial Albedo
| Surface | Typical albedo |
|---|---|
| Fresh asphalt | 0.04 |
| Worn asphalt | 0.12 |
| Conifer forest (Summer) |
0.08, 0.09 to 0.15 |
| Deciduous trees | 0.15 to 0.18 |
| Bare soil | 0.17 |
| Green grass | 0.25 |
| Desert sand | 0.40 |
| New concrete | 0.55 |
| Ocean ice | 0.5–0.7 |
| Fresh snow | 0.80–0.90 |
Albedos of typical materials in visible light range from up to 0.9 for fresh snow, to about 0.04 for charcoal, one of the darkest substances. Deeply shadowed cavities can achieve an effective albedo approaching the zero of a black body. 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 0.1 to 0.4. The average albedo of the Earth is about 0.3. 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 on the global scale is difficult.
The classic example of albedo effect is the snow-temperature feedback. If a snow-covered area warms and the snow melts, the albedo decreases, more sunlight is absorbed, and the temperature tends to increase. The converse is also true: if snow forms, a cooling cycle happens. The intensity of the albedo effect depends on the size of the change in albedo and the amount of insolation; for this reason it can be potentially very large in the tropics.
The Earth's surface albedo is regularly estimated via Earth observation satellite sensors such as NASA's MODIS instruments on board the Terra and Aqua satellites. As the total amount of reflected radiation cannot be directly measured by satellite, a mathematical model of the BRDF is used to translate a sample set of satellite reflectance measurements into estimates of directional-hemispherical reflectance and bi-hemispherical reflectance (e.g.).
The Earth's average surface temperature due to its albedo and the greenhouse effect is currently about 15 °C. If the Earth was 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 planet would drop to about 0 °C. In contrast, if all the ice on Earth were to melt—a so-called aquaplanet—the average temperature on the planet would rise to just under 27 °C.
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