ARCT0W8KI, CHANGES IN DISTRIBUTION OF TEMPERATURE 75 



est and lowest annual means. The geographical distribution of these 

 figures is most interesting. The highest differences are those of Bis- 

 marck, Duluth, St. Paul and Marquette. The figures are respectively 

 9°.8, 9°. 7, 9°. 5, and 9°.4 F. In Xorth Dakota and the Lake Superior 

 region the range of possible variation of the annual means is therefore 

 above 9°F. From that region, the values diminish progressively towards 

 the east, south and west. The line limiting the region where the differ- 

 ences are above 5° goes from Portland, Ore., towards Salt Lake City, 

 North Platte, Hannibal. Lynchburg and from there northeast, along the 

 Atlantic coast. The difference 7°. 2 for Portland, Me., is too high. The 

 series of observations taken in Portland, Me., is evidently not homo- 

 geneous. The values of 5°. 5 for Los Angeles, 5°.8 for El Paso and 

 San Antonio are also probably too high, since the line of 4° goes from 

 Eureka southward over Sacramento toward San Diego, then eastward 

 towards Little Rock, Memphis, Atlanta and Wilmington. 



The lowest value. P)°.l for San Francisco, and the value 2°. 8 for the 

 shorter series of observations of Corpus Christi and Jupiter, are not very 

 much higher than the differences 2°.l and 2°. 6 of the pleionian crests 

 and antipleionian depressions of the consecutive curves of Arequipa and 

 Bulawayo. It follows that if, all over the United States, the varia- 

 tions are primarily due to pleions, having the same cause as the equa- 

 torial pleions, the phenomenon would be four times more pronounced 

 at the center of the ISTorth American continent — in Winnipeg, let us 

 say — than under the equator. Of course, in the case of the brachypleions, 

 the difference would probably be very much greater, and if the results 

 obtained from the study of the interdiurnal mean variabilities of temper- 

 ature-* are taken into account we must be impressed by the similarity 

 of the results obtained. Evidently, the continentality must have the 

 same exaggerating effect on climatic variations that it has on the cold 

 and warm waves characterizing the changes of weather. 



I will pass now to the study of the annual departure maps. ' 



The figures utilized have been taken from the Annual Reports of the 

 Weather Bureau and those of the Canadian stations were copied from 

 the Summaries of the Monthly Weather Review. In Table lY, I repro- 

 duce the means of the decade 1900-1909 and the annual departures from 

 these means for all the utilized stations. These figures were inscribed on 

 maps and equideparture lines drawn. The ten maps thus obtained are 

 reproduced as figures 22-31. 



"J. Hann : "Untersuchunsen uber die Veriinderllchkelt der Tagestemperatur." Sltzi 

 Math. Nat. CI. Acad. Wlss. Wlen, Vol. 71, 11, p. 571. Wien, 187.5. 



