WEATHER CONDITIONS ON THE PACIFIC COAST 

 in controlling the temperature along the coast is 

 the general and steady drift of the surface air from 

 west to east, that is, from a water surface to a land 

 surface. The specific heat of air at constant pres- 

 sure is about one-fourth that of water, which means 

 that it requires four times as much heat to raise 

 a given volume of water one degree as for air. 



83* A 

 fSO'F) 



Figure 3 

 Temperature chart for California, showing mean annual 



isotherms and direction of prevailing winds. 

 The specific heat of water vapor, however, is twice 

 that of air, or half that of water. The water vapor 

 is free to move and does move in the form of 

 invisible vapor or in the visible form of condensed 

 vapor which we call fog. This is a matter of much 

 importance, but to it little attention has been 

 given heretofore in explaining temperature control in 

 coast regions. If, as is the case on the Pacific Coast, 

 the prevailing winds are from the water surface 

 to the land, and the circulation is strong and steady, 



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