Oceanography (2+1)

Specific heat

Specific heat of ice

The specific heat of sea ice varies over a wide range and depends upon the brine or salt content and on the temperature of the ice. However, the specific heat of pure ice varies very little and depends upon its temperature. The specific heat of sea ice is higher than the specific heat of pure ice, especially just below the freezing point, since more amount of heat is required for melting or freezing of additional brine content. According to Malmgren (1927), the specific heat of pure fresh water ice (when the salinity is zero) varies between 0.48 cal/^oC-g at a temperature of -2^oC and 0.46 cal/^oC-g at a temperature of -22^oC and when salinity is two, the specific heat of sea ice varies between 2.47 cal/^oC-g, at a temperature of -2^oC and 0.52 cal/^oC-g at a temperature of -22^oC.

Latent heat of fusion and latent heat of freezing

The latent heat of fusion of pure ice i.e., the heat required to melt pure ice at 0^oC and at atmospheric pressure is 79.67 cal/g. Since the melting of sea ice does not occur at a fixed temperature due to the presence of salts, the usual definition of latent heat of fusion is not applicable to sea ice. Malmgren defined the latent heat of fusion of sea ice as the amount of heat required to melt 1g of sea ice of given salinity that was initially at the indicated temperature.