From: utzoo!decvax!yale-com!leichter
Newsgroups: net.physics
Title: Re: A different ice question
Article-I.D.: yale-com.1289
Posted: Wed Apr 13 14:46:36 1983
Received: Fri Apr 15 08:38:05 1983
References: floyd.1434

This topic - warm water freezing faster than cold - has been discussed
before, both here and in Scientific American's "Amateur Scientist" column
a couple of years ago.  Conclusions:

	1.  It really does work for appropriate choices of water temperatures;
	2.  The principle cause is evaporation; much of the warm water
		evaporates, taking a great deal of heat with it, while at
		the same time reducing the volume of water left to freeze.
		Thus, you quickly end up with water at the same temperature
		as the cold water is at, but there is less of it.  Since
		further cooling occurs at the surfaces, and in most containers
		the available surface area is the same for full and partially
		full containers, a smaller volume of water will freeze faster.

BTW, you CAN'T ignore convection currents, either; they probably contribute,
although not as much.
							-- Jerry
						decvax!yale-comix!leichter
							leichter@yale