16 RURAL CALIFORNIA 



thority that "a common feature of continental 

 climates in all latitudes is their large range of tem- 

 perature. Marine climates, on the other hand, are 

 characterized by a small annual range. . . . The 

 temperatures in a littoral or an insular climate are 

 characterized by a greater uniformity, i.e., by smaller 

 variations about the mean, than in a continental 

 climate." 1 



The practical demonstration that California shares 

 in these qualities of an insular climate is found in the 

 fact that the occurrence of a temperature below 20 

 Fahrenheit is exceedingly rare at any point in Cali- 

 fornia valleys and then only of short duration; 

 ground freezing is also rare and only superficial. In 

 the mountains, however, lower temperatures are 

 reached and a natural ice crop of considerable im- 

 portance is secured. 



2. The demarcation of a four-season year, common 

 to the temperate zones, is displaced by division into 

 two seasons, wet and dry. The wet covers fall, win- 

 ter and spring, as rains are to be expected at any 

 time from September to May, and the dry season cor- 

 responds to summer. 



3. The California wet season is the period 

 of greatest activity in vegetation. All plants ex- 

 cept those which can endure no touch of frost make 

 their chief growth then. All important grains ex- 

 cept corn and rice proceed from seed to harvest; all 

 extensively grown forage plants advance from seed 



1 "Handbook of Climate," Julius Hann (The Macraillan Com- 

 pany, New York, 1903), pp. 139, 148. 



