CLIMATIC CYCLES. 



331 



be drawn in the manner of isotherms (figs. 27, 28). The areas of excess are 

 termed pleions, those of deficiency, antipleions. Arctowski has found that a 

 pleion may last for several years, its center moving back and forth in irregular 

 curves; it may grow less, tend to divide into two or more sections and practi- 

 cally disappear, or it may increase and gather into marked local areas of great 

 intensity. It appears certain that they are a pronounced feature of conti- 



1 









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M^h^^ 



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Fig. 27. — An antipleion, or "lean year," as shown by the com crop of United States. 



After Arctowski. 



Fig. 28.— a pleion, or "fat year," as shown by the corn crop of United States. 



After Arctowski. 



