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Show RAINFALL VARIES FROM ZERO TO 500 INCHES ANNUALLY Geologically the earth may be subdivided sub-divided into three spheres, the outer, gaseous, atmosphere, the watery hydrosphere, hy-drosphere, and the rigid and rocky lithosphere. Water is present In varying amounts everywhere In the lower portion of the atmosphere and nearly everywhere In the outer crust of the lithosphere. The earth's atmosphere constitutes slightly less than a millionth part of the earth's whole mass. lint the rain which falls from the atmosphere every century weighs seven times as much as the air Itself. Three-fourths of this rain falls back lito the ocean. Even so, the work of the atmosphere at-mosphere amounts to pouring all the water of the oceans over the land once In 12,000 years. Nearly three-fourths three-fourths of this rainfall again vaporizes. vapor-izes. What remains Hows back to the sea In rivers. In polar regions the snowfall represents rep-resents from S to 13 Inches of wafer, whereas on certain southern slopes of the Himalayas the rainfall may be as much as 500 Inches a year. In dry regions, such as the vast desert areas of North Africa, Central Asia. Australia, and along the coast of Peru, only a few Inches of water Is precipitated annually. Among the Canary Islands surrounded by water are localities that have very little rainfall for periods as long as three years In duration. The average rainfall for the United States varies from 70 Inches for the Gulf coast and Northwest raclflo coast region to 15 Inches over the Great Plains and less than 10 Inches In Nevada, Arizona, and southeastern California. Dr. G. A, Thiol, University Univer-sity of Minnesota. |