I was wondering why freshwater freezes from up to bottom and not the other way around. The reason I question this is because in a Video I came across, I discovered water freezes from top but surely with the current knowledge I would say it should be opposite because we know cool air drifts down while hot air drifts up so similarly the heat should fall down and this that the freezing should start from bottom and not up? Unless my knowledge applied is wrong and potentially stupid so I want to ask:
Why does water freeze from top to bottom?
Best Answer
The density of water rises from 0 to 4 degrees celsius. So you would have a gradient of water temperatures. On the bottom 4 degrees celsius and colder water above it. This is also the reason why fish survive in winter, they just dive to the bottom where the temperature stays warm longer. Also the density of ice is smaller than water so it will float.