Posted: Jun 20, 2017 5:38 am
If water ice were more dense than liquid water, the pond would freeze from the bottom up
Only if it was cold enough to freeze the whole pond, since this doesn't happen now it wouldn't under those circumstances either. What would happen is that ice would start to form at the surface, then sink, and melt before it got to the bottom. This circulation may make a bit more heat transfer happen, but it wouldn't likely make the difference between ponds/lakes that only freeze a few inches deep now getting so much colder that ice crystals sinking as soon as they can break surface tension would reach the bottom intact and stay that way.