250 TEE POPULAR SCIENCE MONTHLY 



be made here of a peculiar relation between climate and man in the 

 case of certain tropical mountains which are high enough to receive 

 snow instead of rain on their upper slopes. These mountains furnish 

 a supply of snow and ice for refrigerating purposes in the towns below 

 them. Thus, in Ecuador, snow is carried to Quito from the upper 

 slopes of Pichincha; to Eiobamba and Ambato from the slopes of 

 Chimborazo. Guayaquil was formerly supplied with ice in the same 

 way. In Colombia, Popayan, in the department of Cauca, is also sup- 

 plied with ice and snow from the neighboring mountains. In Mexico, 

 snow is carried from the summit of Colima to the towns on the hot 

 plains below. The occupation of the Indians who bring down this ice 

 from their tropical mountain tops is a curious example of climatic 

 control. 



Characteristics of the Temperate Zones. — The so-called " temperate 

 zones " occupy about one half of the earth's surface. The north tem- 

 perate zone includes the greatest known extremes of temperature, and 

 if the word " temperate " were not so firmly established it would be 

 well to change the name to " intermediate." A marked changeableness 

 of the weather is a striking characteristic of these zones. For most of 

 the year, and most of the temperate zones, settled weather is un- 

 known. Climate and weather are here by no means synonymous. 

 The changeableness of the weather suggests our never-failing subject 

 of conversation. In the tropics no one talks about the weather, for it is 

 monotonously the same, day after day. 



In the north temperate zone the differences in temperature between 

 the warmest and coldest months reach 120° at their maximum, in 

 northeastern Siberia. An average January temperature of — 60° and 

 an average July temperature of 95°, with maxima of over 120° and 

 minima lower than — 90°, occur in this same zone. 



The prevailing winds of the " temperate zones " are the westerlies, 

 which occupy about as much of the earth's surface as do the easterly 

 trades. The westerlies are, however, less regular than the trades, 

 being much confused and interrupted by storms. So common are such 

 interruptions that the prevailing westerly wind direction is often 

 difficult to discern without careful observation. The south temperate 

 zone is chiefly water. Hence the westerly winds are there but little 

 interfered with by land. " Eoaring forties " is a well-known designa- 

 tion for the southern middle latitudes, and between latitudes 40° and 

 60° south the well-named "brave west winds" blow with a constancy 

 and a velocity hardly known in the northern hemisphere. Storms, fre- 

 quent and severe, characterize these southern hemisphere westerlies. 

 Voyages to the west around Cape Horn against head gales, and in 

 cold, wet weather, are much dreaded, and are apt to be long and dan- 

 gerous. 



Between the trades of the tropics and the westerlies of the temper- 



