Re: Which freezes faster, warm water or cold?

There were a few articles that appeared in the Amateur Scientist series by 
Jearl Walker and other sources that showed that if you had two vessels, 
filled to the top with 90 degree and 80 degree water, that the ninety degree
water would form a layer of ice first. I did the experiment with 60 degree
water and 90 degree water and the 60 degree water definitely froze first, by
either the definition of first to form a thin layer or fully frozen. There
is a science.answers FAQ on the Internet that gives the citations, but I
do not believe the people who wrote the FAQ have read them. I have and the
Jearl Walker article is not so categorical. There are many variables that
affect the outcome: shape of vessel, degree of fullness, temperatures of the
water. Ideas that I have seen that make the most sense are that in some
instances the evaporation of the hotter liquid will reduce its volume to
the point that it has less volume and then freezes faster. My experiments
lead me to believe that only particular combinations of factors will allow
this paradox to come about.

Regard,
David Winsemius, MD