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世界1/3以上的陆地属于干旱和半干旱地区,这些地区普遍存在沙丘流动的问题,湖岸和海滨沙滩的流沙使问题更加严重,没有一个大陆不存在治沙问题。风蚀是沙丘形成的主要原因。在干旱和半干旱地区,不合理的垦耕、过度放牧和樵采引起风蚀。雨量不稳定的边远地区,开垦后常常旱作,容易欠收,土壤裸露,尤其夏季引起严重的风蚀。开阔地上灌丛林过度采伐,草场过度放牧,使原来保护土壤的植被层消失,造成风蚀。风蚀时,最细小的土粒在大气中呈悬浮状。现已发现,大气中的这种尘土如果密度大,会干扰成云和降雨过程。因为悬浮的尘土干扰了反照率——不同地表反射出的太阳辐射。这种太阳辐射的反射,决定大气的冷热。当热量被反射,热气团上升,遇冷空气形成云。但是当尘土悬浮在地球表面,太阳热量的下传和反射都受阻而减少。干旱区大气湿度有
One-third of the world’s land belongs to the arid and semi-arid regions. The prevalence of sand dunes in these areas is exacerbated by the quicksands on the lakeshore and seaside sandy beaches. None of the continents has the problem of sand control. Wind erosion is the main reason for the formation of sand dunes. In arid and semi-arid areas, unreasonable reclamation, overgrazing and fire-cutting cause wind erosion. Rainstorm unstable remote areas, reclamation often dry, easy to owe, soil bare, especially in the summer caused serious wind erosion. Over-shrubs in the open ground shrubs, pasture grazing, so that the original protective layer of soil vegetation disappeared, causing wind erosion. Wind erosion, the smallest soil particles in the air was suspended. It has been found that such dust in the atmosphere, if it is dense, can interfere with the formation of clouds and rainfall. Because suspended dust disrupts albedo - solar radiation reflected from different surfaces. The reflection of this solar radiation, determines the hot and cold of the atmosphere. When the heat is reflected, the hot air mass rises and clouds of cold air are formed. However, when the dust floats on the surface of the earth, the amount of solar heat transmitted and refreshed is reduced. Arid zone atmospheric humidity there