The quantity of falling solar energy and the proportion that is absorbed by either the atmosphere or the surface varies greatly from one place to another. This results in regional variations in temperatures both for earth surface and atmosphere. The variation of temperature results in difference of atmospheric pressures.Such difference in pressure leads to the movement of air from high-pressure area to low-pressure area.Therefore， wind is the result of the conversion of solar radiation to thermal energy， and then to kinetic energy. Wind moves in both horizontal and vertical directions and is affected by the conditions of surfaces it encounters. Generally， surface wind extends to 50-100 m above the earth's surface and is dominated by strong mixing， i.e. turbulence. The surface wind influences the habitats for wildlife， the growth of crop and livestock， soil erosion， snow distribution， sand-blown and so on， and causes extreme damages when it is very strong， especially in the sandy areas with arid and semi-arid climates.Windbreak， as the word itself， can be defined as the barrier used to reduce wind speed， usually consisting of trees and shrubs， or even perennial or annual crops， wooden fences or other materials.Windbreaks when they are reasonably designed can provide large areas of reduced wind speed because they increase the roughness. The areas of wind speed reduced， especially in windy regions， are generally called sheltered zone， which are very useful for wildlife， agriculture and for the people suffering from the severe climates. In fact， there are many functions such as protection against erosion， improving crop production，filtering air and water， ameliorating climatic extremes， improving ecological environment， reducing and ameliorating potential conflicts that may arise， fulfilled by the windbreaks through altering the wind behaviors （wind speed reduction and changes in turbulence rates）.
鄂公网安备 42010302001612号 