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Re: Spikes growing from ice cubes



Bill,

I don't think that happens. Ice will never freeze from the bottom up
because convection will prevent it from doing so. The other reason I
suspect it doesn't happen is that I've also seen it happen outdoors
in a plastic bucket.

I think it likely that a surface skim of ice forms with a tiny hole
remaining. As water cools toward freezing it expands, and the water
below the surface skim is extruded through the hole. The outer water
in contact with the cold air freezes, but the central water cannot
as readily dissipate its latent heat. Thus the "upsicle" continues
to grow at its center until it finally freezes shut somewhere in the
pipe.

I have no data to support my picture, and I think it would be a
really nice project to videotape the process. The principal obstacle
will be keeping the video camera warm, I think. It doesn't happen
every time, but videotape is reuseable, and it is now easy to edit
any interesting result down to just the interesting bits.

Leigh