Why doesn moving water (such as rivers) freeze?
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.
I thought this was interesting: “Kinetic energy is certainly a factor in how rivers freeze. Ambient air temperature is another. Rivers begin freezing at the banks, in pools or eddies. As the ice sheets there grow out into the water, they break off and float downstream. Along with the colder weather both at your location and at the head of the river, this has the effect of cooling the water, regardless of its speed, to near freezing. This accelerates the growth and thickening of ice near the bank, allowing it to reach farther into the moving water, and it also allows any unmelted floes to grow. Most rivers have shallow regions or islands, and floes can become grounded on these. As the floes ground, they provide not only seeds for more stationary ice to form, but blockages which catch other loose ice.
