Work Step by Step
Ice is less dense than water. If, hypothetically, cooling were to occur at the bottom of ponds, any ice that was initially formed at the bottom would float to the surface. Ponds would not freeze from the bottom up. Water in a real pond does not cool from the bottom up. However, if your town has an indoor ice skating rink, you can perform an experiment. In such a rink, cooling coils buried in the floor DO cool the water from the bottom up. You will observe that the water freezes from the top down in the usual way. In other words, partway through the freezing process, when the top is solid ice, there is liquid water underneath it.