Ice only falls from the sky in the form of hail stones following supercooling of recirculated precipitation within major cumulo-nimbus formations. The taller the cumulo-nimbus (controlled by the level of the tropopause), the greater the probability of hail. The level of the tropopause near the poles is considerably lower than the tropopause near the equator.
I think the ice was formed by compression of accreted snowfall over several hundred millenia.
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When in Woking do as the Wokes do.
"I do not wish to form my opinions by thoughtlessly quoting others; I wish others to support their opinions by sensibly quoting me." Paul Wesson (Aardvark) 13th April 2008
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