ARCTIC INFLUENCES ON AMERICAN CLIMATE 49 



winters the cyclonic areas from the Pacific are deep and in other 

 winters shallow, why in some years they are farther north than in 

 others. When they are deep, together with an abnormally northward 

 movement, they force their way into sub-Arctic America, and the 

 normal anticyclonic conditions of the continent do not develop. In 

 other years the Pacific lows enter the continent farther south, and 

 great anticyclones appear over the Polar Regions and enter Arctic 

 America and sweep down over western and central Canada. 



These facts indicate much variation in atmospheric circulation, 

 and it seems not improbable that this variation may be largely re- 

 sponsible for the difference in the character of corresponding seasons 

 in different years in northern North America. 



Some years ago the Canadian Meteorological Service equipped 

 four of the ships of the Canadian Pacific Steamship Company with 

 thermographs for recording the temperature of the surface water 

 between Vancouver and Yokohama and also had all water tempera- 

 ture records in possession of the company copied out and meaned for 

 the various months and years, and we now possess certain data which 

 may prove valuable in determining to what extent the varying tem- 

 perature of the Pacific Ocean affects cyclonic development and 

 atmospheric circulation. It is conceivable that a varying solar radia- 

 tion may so affect the tropics and equatorial regions that the trade 

 winds will vary in strength and affect the strength of ocean currents 

 sufficiently to cause the variation in water temperatures which are 

 recorded in our survey work. The data so far available appear to 

 indicate an intimate relationship between water temperature and the 

 intensity of cyclonic development. 



Factors Leading to the Development of 

 Anticyclonic Areas 



While some of the factors leading to the development of cyclonic 

 areas seem to be fairly apparent, the causes leading to the develop- 

 ment of northern anticyclones are perhaps more obscure. It has been 

 suggested that the high domelike interior of Greenland may be the 

 pole of anticyclonic energy, but in the writer's opinion the weather 

 maps show that this is not the case. The general appearance of the 

 weather map in winter points rather to the poles of greatest refrigera- 

 tion being located in Siberia and northeastern America, where there 

 is probably as low a temperature as at the high altitudes of Greenland 

 and certainly, being at low altitudes, a much greater mass of air. 



A study of the weather charts for the summer of 1926, this being 

 the only summer with reports from Greenland, indicates a prevalence 

 of high pressure within the Arctic Regions with no definite preference 

 for any particular portion of these regions. 



