Liquid Water Absorbs a Lot of Heat as It Vaporizes into Steam

Appears in
On Food and Cooking

By Harold McGee

Published 2004

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Hydrogen bonding also gives water an unusually high “latent heat of vaporization,” or the amount of energy that water absorbs without a rise in temperature as it changes from a liquid to a gas. This is how sweating cools us: as the water on the skin of our overheated body evaporates, it absorbs large amounts of energy and carries it away into the air. Ancient cultures used the same principle to cool their drinking water and wine, storing them in porous clay vessels that evaporate moisture continuously. Cooks take advantage of it when they bake delicate preparations like custards gently by partly immersing the containers in an open water bath, or oven-roast meats slowly at low temperatures, or simmer stock in an open pot. In each case, evaporation removes energy from the food or its surroundings and causes it to cook more gently.