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UK diy (uk.d-i-y) For the discussion of all topics related to diy (do-it-yourself) in the UK. All levels of experience and proficency are welcome to join in to ask questions or offer solutions. |
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#41
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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 |
#43
Posted to uk.d-i-y
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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 |
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