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Feb23-12, 12:35 PM
P: 50
Interesting question and I can only speculate on the answer. Note that there is little difference between the emissivity of ice & water; this is possibly due to there always being a monomolecular layer of water on the surface of ice until the temperature drops to minus 100C or less (that's why ice skates glide so well on ice). Since this layer is so thin it can't capture enough microwave energy whose free-space wavelength is 12.2 cm, and whose wavelength in water is on the order of 1.3 cm. So the microwaves are free to travel thru the ice after having past the surface.