Submitted to: Encyclopedia of Soils in the Environment
Publication Type: Review Article
Publication Acceptance Date: March 15, 2004
Publication Date: November 1, 2004
Citation: Hatfield, J.L., Sauer, T.J., Prueger, J.H. 2004. Radiation Balance. In: Hillel, D. (ed). Encyclopedia of Soils in the Environment. Elsevier, Oxford, UK. p. 355-359. Technical Abstract: The balance of energy on the earth's surface represents the difference between incoming and outgoing radiation. There are two components in both the incoming and ongoing fractions and are separated by wavelength as shortwave (less than 5 um) and longwave (greater than 5 um). Shortwave radiation originates at the sun and impinges on the earth's surface with the amount of energy dependent upon the position on the earth's surface, slope, time of year, and time of day. Solar radiation loss from the surface is dependent upon the reflectivity of the surface with the greater the albedo (the whiter the surface) the greater the loss. Longwave radiation is a function of the temperature of the object and the higher the temperature the more energy emitted. Longwave radiation from the atmosphere can be approximated by air temperature near the surface while the amount lost from the surface depends upon the surface temperature of the object. The radiation balance for natural surfaces varies from a positive gain during the day when the sun is shining to a negative loss from the earth's surface at night. The radiation balance has a large impact on soil processes since energy input into the earth's surface is the driving force for soil temperature changes. Understanding the radiation balance in different systems helps us to understand the impact humans have had on their environment.