Why don rivers freeze now that used to, like the Hudson River?
Well, I’m not familiar with the Hudson River particularly, but as a rule, rivers don’t freeze because they are moving bodies of water. To freeze many more hydrogen bonds have to be made between the water molecules making it solid. If the water is moving then these bonds cannot be made or are broken instantly as independently each one is very weak. The force of the water overcomes the bonds easily. So the molecules remain free moving.
