On Thu, 03 Mar 2005 18:12:09 GMT, Sniper8052(L96A1) wrote in
.uk

This will sound just a little daft but why is snow... well snow, and not
ice?
Why is it that a snow flake is a flake rather than a pellet? What is it
that makes the water expand to form a flake rather than just freezing to
be an ice drop?
We were pondering this last night and I suggested the smart bods on here
would know the answer.

A snow flake is an aggregation of tens or hundreds of separate tiny ice
crystals. The latter grow within the colder parts of clouds and take on a
crystal structure, well illustrated on many web pages.

The growth is directly from water vapour gas to an ice crystal, with no
liquid water normally involved. As the falling crystals bump into each
other, they often join (at fairly high temperatures) to form what we see as
a snow flake, containing much air, both in and between the crystals. If
the lower air is sufficiently cold, these flakes can get all the way down
to the ground, but usually they melt to produce what we see as rain.

So your idea of "water expanding to form a flake" needs to be re-thought:-)

This page seems to have some useful information:

http://www.its.caltech.edu/~atomic/s...mer/primer.htm

--
Mike 55.13°N 6.69°W Coleraine posted to uk.sci.weather 03/03/2005 18:37:23 UTC