(c) 



20' 



20° 



Figure 8c. --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 tlie tluee decades 1926-35 (open arrows), 1936-45 

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



Figure 8d. --Decade moans, averaged by seasons, for the principal regional indices described in te.Kt. 

 (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 sliown for Uie tluee decades 1926-35 (open arrows), 1936-45 

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



i": 



