why rivers only rarely freeze, even in subzero temperatures

Question

why rivers only rarely freeze, even in subzero temperatures

In: Earth Science

Answer 1

The flowing of the water creates friction which creates heat. Not a lot but some. This is sometimes enough to keep it from freezing. Also water is very dense and takes alot of coldness to turn that much water to ice. You will sometimes see the edges ice up where water can stagnate or is shallow. Eventually you will see a river freeze if it is cold enough for long enough.