\VIXDS AND STORMS 



the abundant sunshine, luxuriant crops can then be 

 grown in these otherwise arid regions. 



Winds are important factors in the distribution of 

 the rainfall. Air becomes filled with moisture over 

 surfaces where water is evaporating. This moisture 

 laden air is carried along until it comes to a region 

 of lower temperature or higher pressure, where the 

 vapor condenses and falls as rain. 



Photograph by Henry G. Peabody. 

 FIG. 54. Columbia River Valley in Washington. 

 The ranches on this plain are irrigated by streams which come 

 down from the mountains in the distance. The land in the fore- 

 ground has not been reclaimed and is covered with sagebrush. 



Since the prevailing windsin the United States are 

 for the - most part from the southwest, those which 

 blow toward the land along the western coast are 

 filled with moisture from the Pacific Ocean. In the 

 summer the land is warmer than the ocean, and the 

 winds blowing over the lowlands along the coast do 

 not deposit their moisture until they reach the nioun- 



