Climate of Southern California 



377 



plays any important part in modifying the climate of 

 the Pacific coast. The active factors are, as said above, 

 the prevailing easterly drift of the atmosphere and the 

 proximity of the mass of water, a great natural conserv- 

 ator of heat. . . . It is probable that if one of 

 these conditions (the easterly drift of the air and 

 the proximity of the ocean in modifying climate) could 

 be reversed and the general movement of the air in 

 these latitudes lie from east to west, marked differences 

 in climatic conditions would result, and the Pacific 

 coast might then have a rigorous climate." 



The cause of rains why some reach Southern Cali- 

 fornia and others pass east in the latitude of Oregon or 

 San Francisco, and why it does not rain in Southern 

 California from May to November is often a puzzle to 

 the stranger. Very briefly, the facts are as follows: 

 What is known to meteorologists as the North Pacific 

 cyclone belt is an important factor in producing storms 

 in Southern California, which are cyclonic disturbances 

 that rise or are created far to the west on the great Jap- 

 anese current. The North Pacific cyclone belt, influ- 

 enced by the sun, moves north in summer and follows 

 the sun south in winter; hence in summer it is well 

 north, and the storms which come in from the Pacific pass 

 east without coming below San Francisco ; but as 

 winter approaches and the sun retreats to the south the 

 cyclone belt comes farther south, and passing storms im- 

 pinge on Southern California ; singularly enough, coming 

 from the south-east or east, cloud banks creeping along 



