### 2.12.5.6. Heat Capacities[¶](#heat-capacities "Permalink to this headline")

The vertically-integrated heat capacity for each lake layer, \\(\\text{c}\_{v,i}\\) (J m\-2) is determined by the mass-weighted average over the heat capacities for the water and ice fractions:

(2.12.47)[¶](#equation-12-42 "Permalink to this equation")\\\[c\_{v,i} =\\Delta z\_{i} \\rho \_{liq} \\left\[c\_{liq} \\left(1-I\_{i} \\right)+c\_{ice} I\_{i} \\right\] .\\\]

Note that the density of water is used for both ice and water fractions, as the thickness of the layer is fixed.

The total heat capacity \\(c\_{v,i}\\) for each soil, snow, and bedrock layer (J m\-2) is determined as for vegetated land units (Chapter [2.6](https://escomp.github.io/ctsm-docs/versions/master/html/tech_note/Soil_Snow_Temperatures/CLM50_Tech_Note_Soil_Snow_Temperatures.html#rst-soil-and-snow-temperatures)), as the sum of the heat capacities for the water, ice, and mineral constituents.

