Is there any truth in the claim that warm or hot water freezes faster than cold water?
• YES, boiling water will freeze faster than room temperature water if evaporation is allowed (eg with open containers), because sufficient mass is lost from the increased evaporation to compensate for the higher starting temperature. For further information, see http://www.urbanlegends.com/science and scientific references therein. (Dr) Richard Balthazor, Upper Atmosphere Modelling Group, School of Mathematics and Statistics, University of Sheffield (r.balthazor@sheffield.ac.uk) • IT SEEMS impossible, but the answer is yes This is the Mpemba effect, discovered by an African school boy (of that name) who was not taken seriously by his teachers when he insisted on telling them this: a visiting team from Britain listened to him and discovered he had done experimental work on this effect and it did really happen. A man who will give you a first hand account is John Lewis of Malvern School. I am reporting this fourth-hand; he will explain it from first hand. I have tried this experiment, a
