devine@asgb.UUCP (Robert J. Devine) (05/22/85)
I hope this ends this discussion whether hot water freezes faster than colder. My posting of a week or so ago told of the real story of a chem TA winning a bet from a professor on this. Here is the truth. The following is from Jearl Walker's book "The Flying Circus of Physics" (he is now a columnist for Scientific American magazine). "In cold regions like Canada or Iceland, it is common knowledge that water left outside will freeze faster if it is originally hot. While this may seem completely wrong to you, it is not just an old wives' tale, for even Francis Bacon noticed it." "The critical feature is the increased evaporation from the initially warmer water. If equal masses of warmer and cooler water are set outside in freezing weather and in open-topped containers, the evaporation from the warmer water will reduce the mass remaining in that container. With less mass to cool, the water in that container can overtake the cooling of the initally cooler water and reach the freezing point sooner. The actual cooling rate can depend somewhat on the composition of the containers, the circulation above the containers and the circulation in the water. Although Bacon commented on the effect and although the result is wll known in Canada, people in warmer countries find it mysterious." Bob Devine