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

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

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

In article ,
Joe Hunt writes:
It always amazes me how they say that no two snowflakes are exactly the
same. They obviously have verified this by checking every one that has
fallen from the sky, that would be ludicrous,

I thought that it was no two snow _crystals_ that were alike? Of course,
since each snowflake is an agglomeration of many crystals, it would be
even more certain that no two of those would be alike.
--
John Hall
"One half of the world cannot understand
the pleasures of the other."
From "Emma" by Jane Austen (1775-1817)

In article ,
Joe Hunt writes:
It always amazes me how they say that no two snowflakes are exactly the
same. They obviously have verified this by checking every one that has
fallen from the sky, that would be ludicrous,

I thought that it was no two snow _crystals_ that were alike? Of course,
since each snowflake is an agglomeration of many crystals, it would be
even more certain that no two of those would be alike.
--
John Hall
"One half of the world cannot understand
the pleasures of the other."
From "Emma" by Jane Austen (1775-1817)

In article ,
Joe Hunt writes:
It always amazes me how they say that no two snowflakes are exactly the
same. They obviously have verified this by checking every one that has
fallen from the sky, that would be ludicrous,

I thought that it was no two snow _crystals_ that were alike? Of course,
since each snowflake is an agglomeration of many crystals, it would be
even more certain that no two of those would be alike.
--
John Hall
"One half of the world cannot understand
the pleasures of the other."
From "Emma" by Jane Austen (1775-1817)

In article ,
Joe Hunt writes:
It always amazes me how they say that no two snowflakes are exactly the
same. They obviously have verified this by checking every one that has
fallen from the sky, that would be ludicrous,

I thought that it was no two snow _crystals_ that were alike? Of course,
since each snowflake is an agglomeration of many crystals, it would be
even more certain that no two of those would be alike.
--
John Hall
"One half of the world cannot understand
the pleasures of the other."
From "Emma" by Jane Austen (1775-1817)

"Joe Hunt" wrote:

It always amazes me how they say that no two snowflakes are exactly the
same. They obviously have verified this by checking every one that has
fallen from the sky, that would be ludicrous, however, I feel it must be
based on some mathematical theory. This has similarities to a calculation
I did at GCSE Biology which showed why no two people look alike, was to do
with genotypes and chromosomes IIRC.

Anyone have more of an idea than I seem to have !?

This might involve a calculation which I have often promised
myself that I ought to attempt, but never got round to. I am now
far too old and lazy to try. That is, how many snow-flakes are
there in a typical snowstorm. Work on the basis that the best
snowstorm we are likely to get in the UK would cover,
say, half the country with 30cm of snow, that would be
25mm x 125,000 sq km of water equivalent. And how much
water in a snowflake? No idea, but not much ... less than
a mm cubed, I guess.

Philip Eden

"Joe Hunt" wrote:

It always amazes me how they say that no two snowflakes are exactly the
same. They obviously have verified this by checking every one that has
fallen from the sky, that would be ludicrous, however, I feel it must be
based on some mathematical theory. This has similarities to a calculation
I did at GCSE Biology which showed why no two people look alike, was to do
with genotypes and chromosomes IIRC.

Anyone have more of an idea than I seem to have !?

This might involve a calculation which I have often promised
myself that I ought to attempt, but never got round to. I am now
far too old and lazy to try. That is, how many snow-flakes are
there in a typical snowstorm. Work on the basis that the best
snowstorm we are likely to get in the UK would cover,
say, half the country with 30cm of snow, that would be
25mm x 125,000 sq km of water equivalent. And how much
water in a snowflake? No idea, but not much ... less than
a mm cubed, I guess.

Philip Eden

"Joe Hunt" wrote:

It always amazes me how they say that no two snowflakes are exactly the
same. They obviously have verified this by checking every one that has
fallen from the sky, that would be ludicrous, however, I feel it must be
based on some mathematical theory. This has similarities to a calculation
I did at GCSE Biology which showed why no two people look alike, was to do
with genotypes and chromosomes IIRC.

Anyone have more of an idea than I seem to have !?

This might involve a calculation which I have often promised
myself that I ought to attempt, but never got round to. I am now
far too old and lazy to try. That is, how many snow-flakes are
there in a typical snowstorm. Work on the basis that the best
snowstorm we are likely to get in the UK would cover,
say, half the country with 30cm of snow, that would be
25mm x 125,000 sq km of water equivalent. And how much
water in a snowflake? No idea, but not much ... less than
a mm cubed, I guess.

Philip Eden