How do snow layers on lake ice affect the rate of ice growth?

A layer of snow on top of lake ice acts as an insulator, offering resistance to the flow of heat from the bottom of the ice surface to the air above. Because ice growth is driven by the transfer of heat from the water through the ice cover to the atmosphere, this added resistance significantly slows the rate of incremental ice thickening.1

The impact of snow on the growth rate is determined by the snow's thickness and its thermal conductivity, the latter of which increases with the density of the snow.1

In some cases, the weight of a heavy snow cover can cause the ice to become submerged, allowing water to flow through cracks and saturate the snow. When this saturated snow freezes, it forms a distinct type of ice known as snow ice, which represents a different mode of growth than the standard thickening process.2