posted by Mike .
What are some of the unique properties of water 0-4 centigrade?
Why are they important?
As the temperature is decreased from 4 to 0 C, while, it expands instead of contracts. Thus when water is close to turning into ice, the coldest water tends to rise above warmer water below, so that the ice forms at the top first. Once formed, the ice floats because it is even lighter than the liquid. As the ice thickens it does so from the bottom of the ice sheet, not from depths of the water below, which are warmer denser and warmer.