Besides this, the ice crystals which form when it is extremely cold are very small. Because 

 they have a large specific surface, the crystals retain a large amount of brine around themselves. 

 Table 29 shows the corresponding observations of Malmgren. 



TABLE 29. ICE SALINITY VS. AIR TEMPERATURE 



Air Temperature in °C -16 -23 -30 -40 



Salinity of new ice in o/oo 5.64 8.01 8.77 10.16 



The rate of ice accretion from below by means of heat conduction is generally lower than 

 the rate of ice formation of surface ice layers which are in direct contact with the cold air. Thus, 

 on an average, while the rate of brine seepage is not great, the ice salinity decreases from the 

 upper surface to the lower. Malmgren's corresponding observations are given in table 30. 



TABLE 30. ICE SALINITY VS. LAYER DEPTH 



Depth of the layer in cm 13 55 95 



Salinity in o/oo 6.74 5.31 4.37 3.17 



3. The state of the sea during ice formation. When any of the processes that mix water are 

 absent, ice forms in comparatively regular needle shapes; on the other hand, the ice which formed 

 during strong mixing resembles a spongy mass saturated with sea water. This is saltier than 

 needle ice. * 



It should be kept in mind that ice formation in the open sea, even after the sea surface is 

 covered with the solid ice cover, seldom takes place as undisturbed ice accretion from below. The 

 initial ice structures are broken by one water movement or another, are carried from place to 

 place, collide and leaf up on one another and fuse together. When this happens, they break up 

 again and once more fuse. Sea water, which freezes in turn along with all the salts found in it, 

 splashes on the ice structures which arose, thus there are precipitates, etc. All this taken to- 

 gether creates an extremely complex picture of salinity distribution in ice vertically and spatially 

 and of its changes with respect to time. 



4. The age of the ice. The older the ice, the lower its salinity is. This is explained by the 

 constant seepage of the saline solution between the ice crystals . 



The vertical distribution of salinity in ice, according to We5fprecht's determinations, is 

 given below (table 3 1) . 



TABLE 31. ICE SALENITY VS. LAYER DEPTH 

 Depth of the layer in cm . . 0-5 5-14 14-19 

 Salinity in o/oo 25 13 12 



*Samoilenko, in 1932, determined the salinity of ice formed from sea water with a salinity of 

 33.64 o/oo under conditions of rest and artificial mixing. 



In spite of the small amounts of ice obtained (about 7 o/o in all, the experiments were not 

 completed), the salinity of the ice formed under conditions of rest was 19.3 o/oo and the ice 

 formed during mixing was about 23.8 o/oo. 



140 



