totally absent. The temperature curve follows more nearly that 

 of insolation, and April is as warm as October. In the interior 

 of Canada the same characteristics are evident, but since the area 

 is not comparable to the vastness of the Siberian continent, the 

 feature is less pronounced. 



The Siberian winter is by no means as unpleasant as its ex- 

 treme temperatures might suggest. The air is often calm and the 

 skies clear. Danger to man or beast occurs only when the wild 

 buran or purga blows. These fearful blizzards also occur in the 

 interior of Canada. 



As has already been noted, average temperatures near the cen- 

 tral polar basin are higher than in the interior. That the mari- 

 time effect of the ice-covered sea could produce the large differ- 

 ences observed is not logical and the explanation lies in the physical 

 characteristics of the land. With no hills or trees of any conse- 

 quence to act as frictional resistance to the wind, more freedom of 

 movement is allowed. This produces a greater degree of mixing 

 in the surface layers which transport warmer air to the surface. 



Irregularities of the winter isotherms in the polar sea are pro- 

 duced by the influence of the Atlantic and Pacific Oceans. In the 

 North Atlantic the isotherms are pushed far northward and here 

 is found the greatest positive anomaly of temperature in the world 

 (the greatest departure from the latitudinal average). The win- 

 ter temperatures in the vicinity of Bering Strait are influenced 

 by the open waters of the Bering Sea. North of the Strait the 

 influence is limited to a rather small area with large local differ- 

 ences occurring with different wind directions. Northerly and 

 especially northeasterly winds bring temperatures characteristic 

 of the ice-covered sea, while southeasterly winds transport air 

 with a much higher temperature. 



The temperature inversions noted in all arctic regions are es- 

 pecially prominent over the pack ice in the polar sea. The diurnal 

 variation during the dark season is, as would be expected, rather 

 irregular. From the available data it is discovered that the max- 

 imum occurs at night hours and the minimum in the middle of 

 the day. Again it is the wind which accounts for the irregularity. 

 Any slight increase in wind, regardless of direction, will produce 

 a considerable rise in temperature by the process of mixing. Since 

 the diurnal variation of wind is largely dependent on the diurnal 

 variation of pressure it is possible to set up definite relations which 

 exist among temperature, wind, and pressure. 



Small temperature variability in summer is a characteristic 



125 



