It is my understanding that within a given medium warmer substances tend to rise and cooler substances fall, i.e. warmer air above cooler.
Assuming the same is true with water then in a lake the cooler water should fall to the bottom while warmer water rises to the top, correct? If so, I would expect that lakes would freeze from the bottom up. Can you please explain why this isn’t the case?
Thanks for your explanation.
In: 23
Most of the answers focus on how ice floats. However the other very important factor is that air above the lake is far colder than the sand or sludge at the bottom of the lake. So as the colder water sinks, it gets warmed up by the bottom of the lake. So ice crystals first form at the surface, and since ice floats, they stay there.
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