Wind Chill and Freezing Water
If it is 2oC outside (air temp) but the wind chill
feels like -5oC, can a puddle of water freeze?
The wind chill is a measure of the apparent temperature
that your skin feels as air blows over it and cools your
skin temperature. Wind can help reduce the temperature of
water by taking energy away from it (by evaporation or
by removal of heat) but it cannot cool the water to much
below the air temperature. Therefore, in the
situation that you have suggested, the water will not freeze.
David R. Cook
Climate Research Section
Environmental Science Division
Argonne National Laboratory
I do not know about those particular numbers, but it IS possible for
water to freeze at a temperature just slightly above 0 C, if it is
open so that some of it can evaporate. Evaporation of just a little
water takes enough thermal energy away from the remaining water that
its temperature can drop below the temperature of the surroundings.
Yes, freezing, on the other hand, releases heat energy, but that is
a much smaller effect than the energy loss by evaporation.
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Update: June 2012