Does snow allow ice to melt?

It has to be really cold to freeze the surface of the rivers in my area. We just got a little over a foot of snow, and I have noticed that in areas where the water stills and has frozen; after the snow it is breaking up and clearing.

Does the insulation from a thick coat of snow allow the water underneath the ice to erode the ice from the bottom, or is the weight of the snow breaking up the thin ice?

Yes, maybe
Water freezes from the top down.

It does so by losing heat to the air (convection) and to the sky (radiation).

The not frozen water underneath the ice adds heat trying to melt the ice (again convection).

If the heat loss is greater than the heat gain then the ice gets thicker.

If the heat gain is greater than the heat loss then the ice melts.

The snow can act as insulation, so yes, the blanket of snow could be responsible for the melt and break-up you are seeing.

All that is true. Along the same lines, open water within cracks in the ice will stay unfrozen for very long periods if covered by snow, and ice-fishing holes can be “saved” for several hours or until the next day if covered with a pile of snow, even in weather that would cause them to freeze shut in less than an hour if left uncovered.

Partly but ice melts from the bottom up
The bottom sediments on your river may still be generating heat. Moving water is hard to get to freezing to any great thickness.

People on snowmachines who tourist here are always getting into river accidents. Snow disguises weak ice underneath that is not frozen as thick as they think. A couple of years ago a Maine Wardens ATV went through…an embarrasing lapse.

Slightly off topic,
but I’ve noticed, when cross-country skiing on snow covered frozen lakes, that there is often water where the snow and ice intersect. This makes for tough skiing as the skiis ice up and drag. I believe the weight of the snow, pressing down on the ice, forces water up through cracks in the ice.


its called overflow
and can be quite dangerous

What so you mean,
losing heat to the air and to the sky? Could you please clarify that? I had thought that they were essentially the same medium.

Not the same, and this is conveyed by…
… the words he used. That is, convection and radiation are not the same. From Wikipedia:


The transfer of energy between an object and its environment, due to fluid motion.


The transfer of energy to or from a body by means of the emission or absorption of electromagnetic radiation.”

Air is the fluid medium carrying energy by convection in this case, and radiation requires no medium at all.

You can see the difference between these two processes very often, in terms of how cold it gets on cloudy nights compared to clear nights. Cloud cover blocks radiative heat loss to the sky and space beyond. Actually, it doesn’t stop radiative heat loss from occurring (that’s a constant, proportional to the square of the temperature (if I remember correctly)), but the clouds which absorb that energy simply radiate much of it back to earth (since it radiates in all directions, some is lost to space).

In summary, one process of heat loss involves direct contact with air, and motion of that air, while the other is completely independent of air.

for the link. Sure enough, snow weight forces the water up. My response has mostly been to stay off of snow covered lakes after a couple of instances of badly iced skiis.


Thank you very much.