THERMAL CONDUCTIVITY 



2 3 4- 5>i W-3 



^50 

 111 



%too 



ISO 



Figure 56. The thermal conductivity of sea ice 

 according to Malmgren, as deter- 

 mined by observations from October 

 1922 to August 1923 (- -), and from 

 November 1923 to May 1924 (— ). 



Considering the coefficient of thermal conductivity of pure ice as being 0.0054 and neglecting 

 the thermal conductivity of the air bubbles, I have computed the coefficients of thermal conduc- 

 tivity and temperature conductivity of pure ice with varying densities (table 43). 



TABLE 43. THE COEFFICIENTS OF THERMAL CONDUCTIVITY AND TEMPERATURE 



coNDUCTivrry of ice as a function of its density (multiplied 



BY 104) 



Density of Ice 0.92 



Thermal Conductivity 54 



Temperature Conductivity 117 



The values in table 43 considerably exceed the thermal conductivity values obtained by 

 Malmgren by the indirect method. However, it should be remembered that the thermal conduc- 

 tivity of sea ice is determined not only by the thermal conductivity of pure ice and the amount of 

 air bubbles within the ice, but also by the amount of brine contained in the cells. 



During this, it is necessary to take into consideration the molecular thermal conductivity of 

 brine since the turbulence processes in the brine cells and the capillaries have no place here. 



The molecular thermal conductivity of pure water at 0° is 14 x 10"* g-cals/sec deg cm, for 

 water with salinity of 40 o/oo at the same temperature, it is about 13 x 10~4 g-cal/sec/cm, i. e. , 

 approximately four times less than the thermal conductivity of pure ice. Therefore it is clear 

 that the saltier and more porous the ice, the less its thermal conductivity. 



As for the thermal conductivity of snow, Abel's careful Investigations have shown that it de- 

 pends on the density of the snow and is expressed by the formula 



where 63 is the density of snow. 



The thermal conductivity coefficients of snow at different densities computed according to 

 this formula are shown on table 44. 



161 



