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Author Topic: Why does Ice form on the top of a lake  (Read 3110 times)

Offline Lex

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Why does Ice form on the top of a lake
« on: 01/08/2005 03:10:47 »
Why does ice form only on the top of a lake?


 

Offline neilep

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Re: Why does Ice form on the top of a lake
« Reply #1 on: 01/08/2005 03:55:55 »
I would have thought that it may be because it's in direct contact with the atmosphere, and that when the ice forms it creates a seal that insulates below the top...or something like that. Movement of the water may also be a contributing factor !

Lets hope a passing ice-on-lake expert drop's in with the answer.

welcome to the site Lex.



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Offline ukmicky

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Re: Why does Ice form on the top of a lake
« Reply #2 on: 01/08/2005 04:13:00 »
I maybe stating the obvious but maybe its because its cold.
WOW 100 posts, Neil it wont belong before i've caught up to you
« Last Edit: 01/08/2005 04:16:36 by ukmicky »
 

Offline finchbeak

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Re: Why does Ice form on the top of a lake
« Reply #3 on: 01/08/2005 04:15:46 »
Firstly, it's because water has a very unusual property - it is denser as a liquid than as a solid (thus, ice floats).  In fact, water is densest at 4degC.  As a large sample of water cools toward freezing, there forms a zone of 4 degree water at the bottom.  If it's cold enough for long enough, it is possible for an entire sample of water to freeze entirely.  Puddles and small ponds typically do freeze all the way through.  Neilep is right that the solid ice does act as a thermal insulator; this has the effect of protecting deeper water from freezing.  Most lakes are deep enough that it would take an impossibly cold and/or long winter to freeze them completely.
By the way - I have seen this property (denser liquid than solid) described as "virtually unique" to water.  Does anybody know of other such substances?
 

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Re: Why does Ice form on the top of a lake
« Reply #3 on: 01/08/2005 04:15:46 »

 

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