398 CLIMATE 



On December 22, the circle of illumination extends beyond the 

 south pole, but does not reach the north pole, and people living 

 in the northern hemisphere have short days and long nights ; 

 people living in the southern hemisphere have long days and 

 short nights. In this position of the earth the north pole 

 receives no illumination by day or night and lies in complete 

 darkness ; the south pole, on the other hand, is illuminated all 

 the time and has perpetual day. 



In the northern hemisphere the days are longest in June and 

 shortest in December; in the southern hemisphere they are 

 shortest in June and longest in December. At the equator, 

 the days and nights are always equal, because the circle of 

 illumination always covers one half of the equator. At the 

 north pole there is a six-month period of perpetual light 

 followed by a six-month period of perpetual darkness ; at the 

 south pole just the reverse is true. At the approach of the 

 long periods of darkness in the far north and south, the Es- 

 kimos betake themselves to their snow houses, and pass the 

 long winter in idleness and misery. Stefansson in his book 

 My Life with the Eskimo gives a wonderful picture of the 

 Eskimos and their intense labors during the long day and their 

 equally intense idleness during the long night. 



In temperate regions where there is darkness every twenty- 

 four hours, work and rest are better divided and greater prog- 

 ress in civilization is possible. 



Summer and winter. The amount of heat we receive from 

 the sun depends upon how the rays strike us ; the more nearly 

 overhead the sun is, the more heat we receive ; the farther the 

 sun is from being overhead, the more slanting are the rays, and 

 the less heat we receive. In December (Fig. 265) the northern 

 hemisphere is turned away from the sun ; a portion of it re- 

 ceives rays more slantingly than the southern hemisphere which 

 is turned toward the sun. Because the northern hemisphere 



