Chapter 13 — CIRCULATION OF THE ATMOSPHERE 



Due to the rotation of the earth, the Coriolis 

 effect causes a deflection of the winds to the 

 right in the Northern Hemisphere and to the 

 left in the Southern Hemisphere. (See fig. 13-3.) 

 The complex circulation resulting from the 

 interplay of the Coriolis effect with the flow of 

 air is known- as the 3-cell theory. (See fig. 

 13-4.) 



THE 3-CELL THEORY 



The rotation of the earth exerts a tremen- 

 dous influence on the circulation of the earth's 

 atmosphere. The 3-cell theory of the circulation 

 offers an explanation of the effect of the earth's 

 rotation. 



According to the 3-cell theory, the earth is 

 divided into six circulation belts — three in the 

 Northern Hemisphere and three in the Southern 

 Hemisphere. The dividing lines are the Equator, 

 30°N and S lat, and 60°N and S lat. The three 

 cells of general circulation of the Northern 

 Hemisphere are similar to those of the Southern 

 Hemisphere. 



209.36 



Figure 13-3. — Coriolis effect on windflow. 



POLAR HIGH 



WINDS EASTERLY AT SURFAC 

 WESTERLY ALOFT 



WINDS WESTERLY 

 AT ALL ELEVATIONS 



WINDS EASTERLY TO 5,000 FT. + 

 THEN WESTERLY 



WINDS EASTERLY 

 TO 25,000 FT 

 THEN WESTERLY 



WINDS VARIA8LE 



CUMULONIMBUS 

 TOPS AS HIGH AS 

 60,000 FT CEILING 

 BELOW 1,000 FT. 



60,000 FT. 





25,000 FT. 



Figure 13-4. — Idealized pattern of the general circulation. 



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209.87 



