CHAPTER IX 

 CLIMATOLOGY OF THE PERUVIAN ANDES 



CLIMATIC BELTS 



The noble proportions of the Peruvian Andes and their posi- 

 tion in tropical latitudes have given them climatic conditions of 

 great diversity. Moreover, their great breadth and continuously 

 lofty summits have distributed the various climatic types over 

 spaces sufficiently ample to affect large and important groups of 

 people. When we add to this the fact that the topographic types 

 developed on a large scale are distributed at varying elevations, 

 and that upon them depend to a large degree the chief character- 

 istics of the soil, another great factor in human distribution, we 

 are prepared to see that the Peruvian Andes afford some strik- 

 ing illustrations of combined climatic and topographic control 

 over man. 



The topographic features in their relations to the people have 

 been discussed in preceding chapters. We shall now examine the 

 corresponding effects of climate. It goes without saying that the 

 topographic and climatic controls cannot and need not be kept 

 rigidly apart. Yet it seems desirable, for all their natural inter- 

 dependence, to give them separate treatment, since the physical 

 laws upon which their explanations depend are of course entirely 

 distinct. Further, there is an independent group of human re- 

 sponses to detailed climatic features that have little or no connec- 

 tion with either topography or soil. 



The chief climatic belts of Peru run roughly from north to 

 south in the direction of the main features of the topography. Be- 

 tween 13° and 18° S., however, the Andes run from northwest to 

 southeast, and in short stretches nearly west-east, with the result 

 that the climatic belts likewise trend westward, a condition 

 well illustrated on the seventy-third meridian. Here are devel- 



121 



