Ice in the sea is of particular interest to the Soviet Union. Ice is a common occurrence in all 

 the seas of the Union. The Gulf of Finland freezes over every year. In the coastal part of the 

 Black Sea ice appears almost every year. The Sea of Azov freezes over solid in certain years. 

 The northern part of the Caspian Sea freezes over every year. On the Soviet shores of the Pacific, 

 down to the most southerly, ice likewise is found every year. All the border seas of the Soviet 

 sector of the arctic become so covered with ice that in winter and early summer navigation here is 

 impossible for even the strongest icebreakers in existence today. 



Sea ice has acquired particular importance for the USSR in connection with the discovery of 

 the Northern Sea Route and in connection with the flights from Moscow over the North Pole to 

 America, initiating the Northern Air Route. Sea ice is the greatest obstacle ui mastering the 

 Northern Sea Route. In mastering the Northern Air Route the greatest obstacles are the meteoro- 

 logical conditions over the ice fields of the arctic; these conditions are strongly dependent on the 

 state of these ice fields. Meanwhile, our knowledge of sea ice and of the laws which regulate its 

 behavior, its movements and its spread, is extremely scanty, although it is increasing every year. 

 To assist in the solution of the problem of sea ice is the modest but basic purpose of the present 

 book. 



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