Snow Insulation and Talik Formation in Permafrost

This simulation runs a full annual freeze-thaw cycle through a permafrost soil column using the Stefan equation for a moving phase-change front. In summer the thaw front descends from the surface, driven by cumulative thawing degree-days. In winter a separate freeze front pushes back down from the surface — but its progress is throttled by an n-factor that represents how effectively a snow blanket insulates the ground from cold air. When the snow is deep enough that the winter freeze front cannot catch up to how far summer's thaw reached, a wedge of unfrozen ground — a talik — is left trapped between the new ice cap and the permafrost table below, a real and closely monitored sign of permafrost degradation.