Figure 8a. — Decade means, averaged by seasons, for the principal regional indices described in text, 

 (a) Winter (Dec. , Jan., Feb.), (b) Spring (Mar. , Apr., May), (c) Summer (June, July, 

 Aug.), (d) Autumn (Sept. , Oct., Nov.). Arrows represent mean magnitude of wind 

 components in the directions shown for the three decades 1926-35 (open arrows), 1936-45 

 (hatched arrows), and 1946-55 (blacked-in arrows). 



^■»- 



20' 



20° 



Figure Sb. --Decade means, averaged by seasons, for the principal regional indices described m text, 

 (a) Winter (Dec. , Jan., Feb.), (b) Spring (Mar. , Apr., May), (c) Summer (June, July, 

 Aug.), (d) Autumn (Sept. , Oct., Nov.). Arrows represent mean magnitude of wind 

 connKincnts in the directions shown for the Uiree decades 1926-35 (open arrows), 1936-45 

 (hatched arrows), and 1946-55 (blacked-in arrows). 



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