CHAPTER X 

 WATER SOULPTUKE 



149. Rainfall. The water of the earth's surface is con- 

 stantly evaporating, rising into the air and being dis- 

 tributed by the winds. Much of this water is blown over 

 the land, where it is condensed and falls as rain. Some 



A HOT SPRING IN THE YELLOWSTONE. 



portions of the land receive much and some little of this 

 aerial water circulation. When winds from warm seas, 

 where the evaporation is great, strike lofty mountain 

 ranges, the land upon the windward side has a large rain- 

 fall, but that upon the lee side comparatively little. This 

 is particularly well shown in the northwestern part of the 

 United States. Since continents, as a rule, have their 



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