Summary of Changes from CLM4 to CLM5:

Overview of Changes:
- Thermal conductivities include additional eddy diffusivity beyond the Hostetler and Bartlein (1990) formulation to account for unresolved processes.
- Lake water is now allowed to freeze by an arbitrary fraction for each layer, releasing latent heat and changing thermal properties.
- Convective mixing occurs for all lakes, even if frozen.
- Soil and bedrock are included beneath the lake.
- The full snow model is used if the snow thickness exceeds a threshold, with radiation transfer predicted by the snow-optics submodel.
- Lakes have variable depth, with depth-dependent enhanced mixing.
- A previous sign error in the calculation of eddy diffusivity was corrected.

Key Changes:
- Improved representation of lake thermal physics, including freezing, convective mixing, and snow/ice interactions.
- Inclusion of soil and bedrock beneath lakes.
- Correction of a previous error in eddy diffusivity calculation.