CLIMATE IN SOME OF ITS RELATIONS TO MAN 251 



ate zones lies a debatable belt, shifting seasonally. Within it, stormy 

 westerlies and drying trades alternately hold sway. It is known as the 

 " subtropical belt." With prevailingly fair skies, even temperature and 

 moderate rainfall, the subtropical belt is a favored climatic region, 

 where invalids seek health, and an escape from the rigors of a cold 

 winter is found by many who have the time, and the means, to leave 

 their northern homes. The long list of well-known health resorts on 

 the Mediterranean, and the shorter list for southern California — " the 

 American Riviera " — bear witness to the popularity of this subtropical 

 belt. 



Seasons in most of the temperate zones are classified according 

 to temperature — not, as in the tropics, by rainfall. The four seasons 

 are important characteristics, especially of the middle latitudes of the 

 north temperate zone. These seasonal changes are of the greatest im- 

 portance in the life of man. They control his occupations, his crops, 

 his place of residence, to a considerable extent his health. 



The north temperate zone embraces so great a variety of climates 

 that no single district can be taken as typical of the whole. Its climate 

 has been called " a crazy quilt of patches." The south temperate zone, 

 on the other hand, may be described as a piece of fairly uniform tex- 

 ture and appearance throughout. This is the effect of the large ocean 

 surface. The whole climatic regime is more uniform than that of the 

 northern zone. The south temperate zone may truly be called " tem- 

 perate," but our own zone is certainly in the highest degree " intem- 

 perate." 



Characteristics of the Polar Zones. — The climate of the polar zones 

 gains a peculiar character by reason of the longer or shorter absence 

 of the sun. At the poles themselves, the day and the year are alike. 

 In the Arctic climate, plants must make rapid growth in the short, 

 cool summer. They grow and blossom with great rapidity and luxuri- 

 ance where the exposure is favorable, and where the water from the 

 melting snow can run off. Over great stretches of the northern plains 

 the surface only is thawed out in the warmer months, and swamps, 

 mosses and lichens are found above eternally frozen ground. In high 

 latitudes, where the exposure is good, snow melts in the sun even when 

 the temperature of the air in the shade is far below freezing. It has 

 been reported that at Assistance Bay, latitude 74.5° north, in March, 

 when the air temperature was about — 25°, snow near stones and 

 other dark objects melted in the sun. The temperature in the immedi- 

 ate vicinity of the North Pole is probably a little below — 40° in Jan- 

 uary; below 32° in July and a few degrees below 0° for the average 

 of the year. It may be noted, however, that northeastern Siberia has 

 a January mean temperature which is 20° lower than that at the 

 North Pole in the same month. 



For the Antarctic our knowledge is still very fragmentary. The 



