where n = the iciness in points, 



Ai = the total increase in ice, 



Ai. 



the increase in ice under the ice, 



Aijy = the increase of ice in clear water. 



Dobrovolskii transposes formula (5) for convenience thusly 



^i=M^~n (M^-~ Mi). 



(6) 



Dobrovolskii also computes the sizes for Ai,^ and Ai f according to the formula proposed 



by me, 



Ai = — (25+r„) + y (25+i„)2 + 8;?. 



(7) 



For illustration of his conclusions, Dobrovolskii solves the following individual example. At 

 the initial moment, the thickness of a layer of water, attracted into a vertical circulation by the 

 salt increase during ice formation, is equal to 25 m; the initial salinity of this layer is equal 

 30 o/oo, the number of degree-days of frost for the examined region is 5000. 



In table 85 Dobrovolskii's computations are quoted for the following three cases: 



1. 5000 degree-days of frost are realized in 20 series (each gradually at the rate of 250 

 degree days); after each series, hummocking occurs. 



2. 5000 degree-days of frost are realized in 10 series at the rate of 500 degree days. 



3. 5000 degree-days of frost are realized in series of 5 at the rate of 1000 degree days. 



Examining table 85, we see that the less the iciness and the more often hummocking occurs, 

 the stronger the increase in salt. 



As Dobrovolskii correctly notes, the examined phenomenon can give some indications for 

 the explanation of comparatively high salinity in the sub- surface (to 100 m depth) of the layers 

 of part of the Arctic Basin during extremely low temperatures. 



TABLE 85. THE SALT INCREASE IN THE ALYER 25 M THICK WHEN 

 THICKENING OF ICE TO 150 CM WITH 5000 DEGREE- 

 DAYS OF FROST AND WITH ICE OF VARIOUS POINTS 



LITERATURE: 45, 164, 165. 



294 



