Chapter 12 — THE GOVERNING FUNDAMENTALS OF METEOROLOGY 



Figure 12-3, — Revolution of the earth around the sun. 



209.3 



Hemisphere is inclined 23 1/2° TOWARD the 

 sun. This inclination results in more of the 

 sun's rays reaching the Northern Hemisphere 

 than the Southern Hemisphere. On or about 

 June 21, the sun shines OVER the North Pole 

 down the other side to latitude 66 l/2°N (the 

 ARCTIC CIRCLE), and the most perpendicular 

 rays of the sun are received at 23 l/2°N lat 

 (the TROPIC OF CANCER). The Southern 

 Hemisphere is tilted AWAY from the sun at 

 this time, and the sun's rays reach only to 

 66 1/2°S lat (the ANTARCTIC CIRCLE) and do 

 not go beyond this latitude. The area between 

 the Antarctic Circle and the South Pole is in 

 darkness; the area between the Arctic Circle 

 and the North Pole is receiving the sun's rays 



for 24 hours each day. Note carefully the shaded 

 and unshaded area of the earth in figure 12-3 

 for all four positions. 



At the equinoxes in March and September, 

 the tilt of the earth's axis is neither toward 

 nor away from the sun. For this reason, the 

 earth receives equal numbers of the sun's rays 

 in both the Northern Hemisphere and the 

 Southern Hemisphere, and the sun's rays shine 

 most perpendicularly at the Equator. 



In December, the situation is exactly reversed 

 from that in June, The Southern Hemisphere 

 now receives more of the sun's rays. The most 

 perpendicular rays of the sun are received at 

 23 1/2°S lat (the TROPIC OF CAPRICORN). The 



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