I call the coefficient of buoyancy the entire load in tons which forces one meter cubed of ice 

 to sink. It is not hard to see that the coefficient of buoyancy is equal to 



Po-iK-^^)- 



(7) 



It is clear that the buoyancy of an ice floe will be the product of the coefficient of buoyancy and the 

 volume of the ice flow expressed in m , or 



P=Po'<l, 



(8) 



where i is the thickness of the ice, 

 q is the area of the ice. * 



TABLE 52. THE BUOYANCY COEFFICIENT 

 OF SEA ICE IN TONS 



It follows from formulas (6) and (7) that buoyancy is greater the greater the thickness of the 

 ice and the density of the water and the less the density of the ice. 



It can be easily seen from table 52 that with ice thickness remaining constant, the possible 

 seasonal changes in the density of the water in which the ice is floating have little effect on the 

 buoyancy of ice. The matter is different with the density of the ice itself, seasonal changes of 

 which are extremely important. Because of this, if the fact that the pores of the summer ice are 

 opened to the surrounding media while the pores of winter ice are not exposed to it is not con- 

 sidered, we can by formulas (6) and (7) arrive at a false conclusion that ice of the same thickness 

 has greater buoyancy during the summer than during the winter. But we observed the reverse 

 phenomenon in nature. 



The fact that the upper surface of the ice sinks below the surface of the water under the 

 weight of the snow precipitated upon the ice, and especially under the weight of snow drifts, is ex- 

 plained by the slight buoyancy of ice. Actually, from formulas (3) and (7) it follows that the upper 

 surface of the ice field sinks below the level of the water on the condition that 



s5, = /(S,-Si), 



(9) 



where 3 is the height of the snow cover, 

 6 is the density of the snow. 



♦Formulas (6) and (7) and table 52 are derived on the proposition that the ice is homogeneous 

 in density in its upper and lower parts. 



172 



