![]() ![]() Terrestrial albedo Sample albedosĪny albedo in visible light falls within a range of about 0.9 for fresh snow to about 0.04 for charcoal, one of the darkest substances. The average albedo of the Earth from the upper atmosphere, its planetary albedo, is 30–35% because of cloud cover, but widely varies locally across the surface because of different geological and environmental features. Īlbedo is an important concept in climatology, astronomy, and environmental management. Ice–albedo feedback plays an important role in global climate change. Ice is very reflective, therefore it reflects far more solar energy back to space than the other types of land area or open water. Ice–albedo feedback is a positive feedback climate process where a change in the area of ice caps, glaciers, and sea ice alters the albedo and surface temperature of a planet. This spectrum includes visible light (0.4–0.7 μm), which explains why surfaces with a low albedo appear dark (e.g., trees absorb most radiation), whereas surfaces with a high albedo appear bright (e.g., snow reflects most radiation). Due to measurement constraints, it is often given for the spectrum in which most solar energy reaches the surface (between 0.3 and 3 μm). Unless given for a specific wavelength (spectral albedo), albedo refers to the entire spectrum of solar radiation. ![]() ![]() The temporal resolution may range from seconds (as obtained from flux measurements) to daily, monthly, or annual averages. While bi-hemispherical reflectance is calculated for a single angle of incidence (i.e., for a given position of the Sun), albedo is the directional integration of reflectance over all solar angles in a given period. These factors vary with atmospheric composition, geographic location, and time (see position of the Sun). The proportion reflected is not only determined by properties of the surface itself, but also by the spectral and angular distribution of solar radiation reaching the Earth's surface. Surface albedo is defined as the ratio of radiosity J e to the irradiance E e (flux per unit area) received by a surface. It is measured on a scale from 0 (corresponding to a black body that absorbs all incident radiation) to 1 (corresponding to a body that reflects all incident radiation). Īlbedo ( / æ l ˈ b iː d oʊ/ from Latin albedo 'whiteness') is the fraction of sunlight that is diffusely reflected by a body. Some areas reflecting close to 20 percent less light than a decade ago. For other uses, see Albedo (disambiguation).Īlbedo change in Greenland: The map shows the difference between the amount of sunlight Greenland reflected in the summer of 2011 versus the average percent it reflected between 2000 to 2006. ![]()
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