Weather Conditions on the Pacific Coast 

 the reason why the temperature is comparatively 

 uniform is plain. There is little doubt but that 

 if our surface circulation were to be reversed and 

 the air moved from land to sea, there would be 

 decided changes in temperature; and the isotherms 

 would run east and west instead of north and south 

 as they now do (fig. 3). 



It IS the practice of meteorologists to regard the 

 weather of the coast section of California, Oregon 

 and Washington as irregular and to try to account 

 for the irregularity by ocean currents, up-welling 

 waters, etc. A more rational view, it seems to us, 

 is to regard the weather of this section as regular 

 and of a simple type; and consider the weather 

 of other sections, especially our Atlantic Coast, as 

 irregular. 



The first control, then, of weather on this coast 

 is the quantity of water vapor brought in by the 

 prevailing west winds. Other factors are, distance 

 from storm tracKs of maximum frequency, and 

 the orography of the coast. For detailed informa- 

 tion regarding the first of these factors the reader 

 may consult various Weather Bureau publications 

 showing average storm-tracks; and particularly 

 Climatology of California (McAdie, 1903). Regard- 

 ing the other factor, one may refer to the physio- 

 graphic features of the coast as discussed elsewnere 

 in this volume. 



Two conspicuous illustrations of a direct con- 

 nection between weather and physiographic fea- 

 tures may be found in California; first, the forced 

 draft through the Golden Gate and the deflection 

 of the surface air northward through the Sacra- 

 mento and northern bay valleys, also southward 

 through the Santa Clara and the San Joaquin val- 

 leys; and second, the draft through El Cajon Pass. 

 Through the latter, under certain pressure distri- 

 bution, the dry, sand-laden air pours into the 

 Colton-Riverside-Ontario section. Known locally as 

 Santa Anas, these wind storms constitute the most 

 disagreeable feature of the weather in the great 

 valley of the south. They are trying to man, beast 

 and vegetation, and at times interfere with traffic. 



The last weather control of importance is the 

 location of the particular hyperbar or infrabar de- 

 termining the general surface circulation. These 

 more or less permanent pressure areas have been 

 called "centers of action;'* but the newer names are 

 more appropriate. The best known of the infrabars 

 is the Aleutian low, which in a normal winter ex- 

 tends from latitude 40* N to 60* N and from 

 longitude 130*W to 140** E. In the summer this 



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