defrosting windscreen
 

On Wed, 18 Jan 2006 22:49:44 GMT, Roger wrote:

AIUI water is at its most dense at 4C so ice forms on the surface.
However given a severe enough frost you fish pond would freeze
solid.

It would have to be a pretty hard and long frost to freeze a decent
fish pond solid in this country.

As you say water is most dense at 4C, so it sinks to the bottom of the
pond. As the surface of the pond gets colder it gets *less* dense and
floats on the 4C water below. Convection stops and the only way the
lower water is going to freeze is by conduction, ice is a pretty poor
conductor of heat and the lower levels are in the relatively warm
ground as well.

--
Cheers
Dave. pam is missing e-mail

defrosting windscreen
 

wrote:

erm, no it won't - think about the chemistry first.

Ice is a lattice structure (like a diamond), and it takes energy for
the molecules to move into the lattice. ...

Hey - that's physics, not chemistry.

"All science is either physics or stamp collecting" (Ernest Rutherford;
I think nowadays we'd say maths or stamp collecting given much of modern
physics).

But in a different thread, has recently written

I stumbled across this while looking for the coefficient of expansion
of water...

http://www.lsbu.ac.uk/water/anmlies.html

Chris.

which discusses this and 40 other interesting properties of water.

Douglas de Lacey

defrosting windscreen
 

"Douglas de Lacey" wrote in message
...
wrote:

erm, no it won't - think about the chemistry first.

Ice is a lattice structure (like a diamond), and it takes energy for
the molecules to move into the lattice. ...

Hey - that's physics, not chemistry.

"All science is either physics or stamp collecting" (Ernest Rutherford; I
think nowadays we'd say maths or stamp collecting given much of modern
physics).

But in a different thread, has recently written

I stumbled across this while looking for the coefficient of expansion
of water...

http://www.lsbu.ac.uk/water/anmlies.html

Chris.

which discusses this and 40 other interesting properties of water.

Douglas de Lacey

I thank you for that link, it brought back a few memories.

I used to work in the Fire Brigade and, as you would expect, water plays a
major part in their activities. During lectures I often asked my class "why
cold water could be lifted (sooked up) from a greater lift than warmer
water" and "if heat rises, why does ice form on the surface of a pond and
not at the bottom".

This link explained it technically but would go over the head of most of the
students. The samples were only used as a point of interest.

Sorry for going OT a bit

Bill