The captain was partially correct.
Resonance is not a factor, but electrical conductivity of the
frozen crystal is much lower than conductivity of liquid water.
Hence, water reflects radar much better than ice.
(There's a whole lot of Maxwell's Equations and boundary-value
conditions involved in that "hence", but this isn't the place for that. :-)

"Jim Macklin" wrote in message ...
Weather radar results, unlike reflections from a metal
surface, are determined by a resonance with a water
molecule. Frozen water is a crystal and the return is of a
lesser and different character, at least that is what I
remember Capt. David Gwinn telling me.