430 FIRST TEAR SCIENCE 



passes through all the changes in climate which one would 

 pass in going from the equator toward the poles. 



As already stated, high mountains also affect the climate 

 of the country near them. The windward side of moun- 

 tains is moist, since the moisture in the air is condensed in 

 rising over them. On the lee side the country is dry, as 

 the air which moves over it has already been deprived of 

 its moisture. 



POPOCATEPETL. 

 A snow-covered mountain in the tropics. 



The country on the lee side will also be subject to hot, 

 dry winds like the chinook winds of the eastern Rockies 

 and the foehn in Switzerland. As the moist winds pass 

 over the mountains their moisture is condensed. This 

 raises their temperature so that it is above what it would 

 normally be at the altitude reached. As they come- down 

 on the lee side of the mountain, the air is compressed and 

 thus heated so that on this side it is considerably warmer 



