Asked by: Tina Hanson, Littlehampton
Water turns to ice when its molecules move slowly enough to form rigid bonds. Normally, the molecules in the waterfall move under the influence of both the flow and thermal agitation. But if it gets cold enough, the heat effect becomes so low that not even the waterfall’s motion can stop ice forming, gradually at first but then ever more rapidly.
Robert is a science writer and visiting professor of science at Aston University.