POLAR INFLUENCES ON WORLD WEATHER 



35 



Fig. 8 — The departures from normal air pressure over the earth's surface in July, rgio, when the 

 solar radiation was two per cent below normal. (From Fig. 31 in Clayton, second work cited in 

 footnote 13.) 



Fig. 9 — The departures from normal air pressure over the earth's surface in July, 1917, when the 

 solar radiation was two per cent above normal. From Fig. 28 in Clayton, same source as Fig. 8.) 



abnormal distribution of pressure brought about by other causes. 

 The researches of Helland-Hansen and Nansen^^ indicate that the 

 abnormal distribution of pressure is the primary cause and not the 



12 Bjorn Helland-Hansen and Fridtjof Nansen: Temperatur-Schwankungen des Nordatlantischen 

 Ozeans und in der Atmosphare: Einleitende Studien iiber die Ursachen der klimatologischen Schwank- 

 ungen, Videnskapsselskapels Skrifter: I, Mat.-nalurv. Klasse, 1916, No. 9, Christiania, 1917. [An 

 English translation, with additions by the authors and by Dr. C. G. Abbot, has appeared under the 

 title: Temperature Variations in the North Atlantic Ocean and in the Atmosphere: Introductory 

 Studies on the Cause of Climatological Variations, Smithsonian Misc. Colls., Vol. 70, No. 4, Washing- 

 ton, 1920.] 



