318 PHYSIOGRAPHY 



in summer) and cold (during anticyclones in winter). They are 

 also the cause of the sudden changes of weather, and so are an 

 element of the variable climate of these zones. 



The prevailing westerly winds tend to carry the oceanic climate 

 over onto the western borders of the continents. Hence the mild 

 climate of the western coasts of both North America and Europe. 

 On both these coasts the range of temperature, like that of the 

 tropical zone, is relatively low. Blowing over the cooler land, the 

 oceanic winds give abundant moisture, and often much cloudiness 

 and fog, especially in the higher latitudes in winter. 



The continental interiors of the intermediate zones have much 

 greater ranges of temperature than the western coasts, and the 

 ranges become greater with increasing distance from the ocean, 

 and with increasing latitude. In Siberia, for example, in high lati- 

 tudes and far from a western coast, are found the greatest annual 

 ranges of temperature known. 



The climates of the eastern borders of the continents are unlike 

 those of the western borders. On the former, continental rather 

 than oceanic climates prevail. The differences are made clear if 

 the climate of Vancouver is contrasted with that of Labrador, and 

 that of England with that of Kamtchatka, .on opposite sides of a 

 continent (see Figs. 217 and 218). 



Questions. 1. How would the climate of North America be affected if 

 the mountains of the west were shifted eastward (1) to the central part of the 

 continent? (2) To the eastern border of the continent? 



2. What would have been the effect on the climate of central Europe if 

 there had been a high mountain range along the west coast of Europe? 



3. What would have been the effect on the climate of South America if 

 the Andes Mountains had been on the east side of the continent instead of 

 the west? 



Climate of the Polar Zones 



The distribution of the sun's heat is more unequal in the frigid 

 zones than in lower latitudes (p. 229). At the poles there is half 

 a year of continuous night and half a year of continuous day. Be- 

 tween the poles and the polar circles, the inequality of heat distri- 

 bution is less than at the poles, but still great. 



Though the seasonal range of insolation is greater here than in 



