and western Soviet coasts. In the channels, fiords, and inlets the 

 tides may reach heights of 30 feet owing to the waters piling up 

 in the restricting narrows. The spring range is frequently two to 

 three times greater than the mean range. 



ICE 



The ice conditions of the Arctic Sea vary from year to year. On 

 the average, about 90 percent of its surface is ice-covered in winter. 

 Most of this ice is true sea-ice and not land derived. Its forms are 

 many and diverse, depending on its age, the influence of winds, 

 waves, currents, and the weather. See HO 551. 



MAXIMUM 

 THICKNESS 



8 FT. 



Figure 2-10. — Growth of ice. 



Ice begins to form on sea water of average salinity (35°/00) 

 when the temperature reaches about 29° F. Polar seas have lower 

 salinity and therefore freeze at higher temperatures. The first ice 

 formed may be salt free, but the salt becomes trapped between the 

 crystals and new ice is very salty. During the summer the surface 

 of the ice melts and the water percolates down through the ice, 

 carrying with it much of the salt so that ice a year old is not 

 especially salty to the taste. On the surface of the ice, pools of 



36 



