northern hemisphere carries ice towards the shore and creates an accumulation of floes and a 

 compression. Conversely, a current which washes a left coast carries the ice from the shore and 

 sets up a thinning action forming polynyas. In open parts of the sea, due also to Coriolis force, in 

 the center of the anticyclonic currents where the water masses descend, accumulation of ice occurs 

 with resulting compression. In the center of the cyclonic currents we observe sparse ice and on the 

 periphery, close ice. 



Regions of sinking and rising of water masses, causing corresponding accumulations or thin- 

 ning of ice, are also formed along the lines of contact of sea currents of opposite direction. Sink- 

 ing results from meeting of these currents , rising from separation or moving away from each 

 other. The formation of many ice massifs and their appearance even in the summer months of 

 years of little ice is explained by precisely these existent systems of sea currents. 



Examples of such massifs are the Spitzbergen massif in the northwestern part of the Barents 

 Sea, the Nova Zemlya massif in the southwestern part of the Kara Sea, the Taimyr massif which 

 extends to the south along the axis of the deep hollow from the north into the Laptev Sea, the Yanski 

 massif which blocks the western entrance to Laptev Straits at the start of summer navigation, and 

 others. In regions of calm the ice also lasts very long in the summer time, but here the typical 

 mark of the ice massif — compactness of ice — is usually less clearly noticed. In the melting and 

 destruction process the percentage of ice decreases at more or less an equal rate. 



COMPACTED ICE 



COMPACTED 



y//y>///////>^^////////!/////. 



WM/y///////yyA 



Figure 125. Thinning of ice behind shoals. 



Figure 125, borrowed from Burke, shows the formation of thinned areas and polynyas 

 behind shoals which lie in the path of permanent currents. Even more sharply noticeable are the 

 thinnii^s and polynyas behind islands which lie in the path of the currents. 



Of great interest is the formation of thinned areas and polynyas in the regions where the 

 speed of permanent currents is increased for one reason or another. For example, here is what 

 Badigin notes in his diary during the drift on the Sed ou. The ship was at that time at 86°09' 

 north, 96°00' east. "To our west a clear area opened up of unprecedented proportions. This 



was a whole lake over a kilometer in width. Its length extended to the limits of visibility 



The clear area appeared a few days ago Now the width of the clear area has reached 2 



kilometers. " 



This clear area, first decreasing in size and then increasing, remained near the Sedov 

 until the end of the drift. Such a phenomenon in the drift region of the Sedov was not accidental. 

 According to observations of the /ram , the quantity of polynyas and clear areas also increased in 



350 



