Sunshine, which supplies the energy needed for life on Earth, plays a key role in energy and water balance by heating the earth's surface, evaporating water and generating weather. It influences critical local factors such as air and soil temperature, humidity, moisture and snow melt. Solar radiation affects global climate patterns and local crop growth conditions. Topography, vegetation, human structures and atmospheric conditions affect insolation at the local level. Insolation maps, which show local effects, are valuable for agriculture, forestry and resource management.
Insolation is difficult to measure due to variations in time and spatial location.
Typically, insolation is measured using sensors at monitoring stations. However, for most other locations these measurements are unavailable. Sensor measurement interpolation and extrapolation cannot account for spatial and temporal variation. Models measure up Solarflux, developed in 1992 by Paul Rich and William Hetrick of the University of Kansas, and similar models that simulate shadow pattern influence on insolation, has been used by researchers to produce insolation maps. However, these models are available only for use with high-end GIS software and computers.