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Old January 22nd 04, 11:27 AM
Brian Sandle
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Grant wrote:
Brian Sandle wrote:


The physics involved in a massive block forming in a clear sky through
natural causes is so mind-boggling as to be virtually inconceivable.
Probably ice meteor incidence is correlated with aircraft traffic.



A normal tiny meteor can act as a nucleus for ice to form.


You could calculate the time it takes to grow a 10kg chunk of ice under
the most extreme plausible conditions of atmospheric supersaturation.
See ch. 4 of Wallace and Hobbs.


But it would be a pointless exercise, because the answer would be
measured in weeks or months, and you could never hope to keep your chunk
of ice suspended in the atmosphere longer than a few minutes, once you
got past a few grams.


Unless there is some sort of vortex.

And you wouldn't get a clear chunk of ice anyway by this mechanism;
you'd get a big porous mass of ice crystals.


Like hoar frost? It's incredibly patterened, but quite solid, not porous, I
think.

Where are the data about upper atmosphere temperature and global warming?


Here's a factoid that might help put things into perspective: typical
water vapor concentrations in the upper atmosphere are below 4 parts per
million, relative to air. And air at, say, 50 km altitude has a density
on the order of 1 gram per cubic meter. So to grow a 10 kg chunk of ice
at that altitude would require you to figure out a way to quickly
condense onto one object *all* of the water vapor in 2.5 cubic
*kilometers* of ambient air.


Any reason for 50 km? Most of the air where vortices could do anything is in
the troposphere.

Bottom line: I tend to think the stories about chunks of ice out of the
clear sky, while possibly true in some sense, have nothing to do with
meteorology in any form, let alone global warming.


Could someone be deliberately tossing junks of ice out of passing
aircraft?


I have heard of frogs raining down. Seemed genuine.


Recall the crop circle "mystery" -- it eventually was
acknowledged to be a hoax -- by the hoaxers themselves - after countless
"experts" had been quoted as saying, "it can't be a hoax."


Ha ha, yes. It became quite a hobby of the `sceptics' or pranksters to show
how it could be done. How did they hoax the real crop circles in which the
bent over wheat is said to keep growing - it is not trampled? Enlightenment
please.


(Though I think this example, from the shape of the block has been formed in
some sort of mold. Either that or cleaved off somehow.)