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After reading your article:"Why is it that water freezes on the surface of a lake but not below it?" here I found this very interesting and gave me one more question which should be interesting to others too, I hope.

Question: If warmer water was to be sent from lower down, where it is warmer, to the surface in the form of agitated turbulence, so the water is moving, would this stop the ice forming, so long as the volume of water was great enough to keep ahead of the cold air?

I'm looking at ways to keep breathing holes open for mammals trapped beneath ice during mid winter freezes after seeing the movie "Big Miracle." I'm sure there must be a better way of keeping the ice from freezing up. Even an outboard motor should work better. So far I have thought of lowering a grid of pipes down low and pumping air through the pipes which are full of small holes. The thought was that the air bubbles would bring warmer water to the surface and therefore keep the ice from freezing over. I still haven't been able to find out if the water is warmer at the bottom or half way up yet. I also thought about vertical pipes suspended in the water, going down deep and ending about 10 feet below the surface to insulate the water on its way up but whales and Orcas are likely to break the pipes and hurt themselves. Maybe soft pipes would work? I'm not in the areas you normally answer questions for, I'm in New Zealand, but if someone has time to give me some advice I would really appreciate it, so will the whales who get trapped and die.

Question Date: 2014-05-06
Answer 1:

Interesting question! Conceptually, this idea would work. In fact, a chemical engineer’s job is to do such modeling! You could model the body of water as a system such as a tank or a reactor where there is a heat input and output. At the surface of the water there is a heat drain where heat is escaping with some rate that is related to the surface properties of water and air. At the bottom of the tank you have some heat input at some rate. Turbulence would be a little difficult to account for, but you could simplify and figure out the necessary rate that heat needs to be inputted to keep the temperature at the surface of the water above freezing temperatures. A simple temperature gradient can be assumed that goes from hot to cold from the bottom to the top.

Considering the scope of a real project, however, practical costs may outweigh the benefits. If these analysis techniques are applied to a huge body of water like the ocean, you can start to see the difficulties in laying deep-water pipes that provide enough heat to prevent the surface from cooling. Some alternative solutions may be more cost-effective. For instance, it might be more practical to have icebreaker ships fragment the ice as they pass through, and also apply a layer of salt to aid in melting of the ice. Perhaps using some sort of solar concentrator might be able to do the trick as well, though this would depend on the solar intensity around the area of interest (generally, icy areas would imply lower solar intensity).

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