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Re: Density of water.



doesn't matter -- just as the conductivity of air is considerably less than most (all?) solids no one uses it for insulation!!  It must be contained by orders of magnitude more conductive solids to make use of its insulating value. It's preventing convection that counts.

bc

Ps. ice has only ~ four times the conductivity of water

Brian Whatcott wrote:

Is there anyone else who thinks the thermal conductivity of ice
  is less than that of water?   <grin>

Brian W

At 10:35 AM 12/3/01, you wrote:
>I don't think (in this unconscionably long thread) anyone has mentioned the
>importance of the insulating quality of ice in protecting aquatic
>life.  This I
>think is the difference between freezing from the bottom up or the reverse.
>However, what ever the conditions (already stated on this thread?) no ocean is
>going to freeze, unless we have an ice age much more intense than the earth's
>ever experienced (barring the creation of the earth before the sun)..
>
>bc
>
>Rick Tarara wrote:
>
> > But once the whole body of water has cooled and mixed to a nice uniform 0.1
> > degree C and then cools a little more----one big ice cube!  Somewhat
> > devastating to temperate (and artic) zone aquatic life and therefore to the
> > diversity of aquatic life, but unless one can cite evidence of
> sustained sub
> > zero global temperatures during the past 2 billion years, then life itself
> > is not necessarily threatened.
> >
> > Rick
> >
> > **********************************************
> > Richard W. Tarara
> > Professor of Physics
> > Saint Mary's College
> > Notre Dame, IN 46556
> > rtarara@saintmarys.edu
> >
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> > www.saintmarys.edu/~rtarara/
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> >
> > ----- Original Message -----
> > From: "Brian Whatcott" <inet@INTELLISYS.NET>
> > To: <PHYS-L@lists.nau.edu>
> > Sent: Sunday, December 02, 2001 9:18 PM
> > Subject: Re: Density of water.
> >
> > > At 12:25 PM 12/2/01, Jim Green wrote:
> > > >At 23:51 01 12 2001 , Bernard C wrote:
> > > > >Right, Hewitt plots (ordinate) the volume of one gram of water instead
> > > > of the
> > > > >inverse.  No matter, he's plotting water not ice.  Ice (normal near
> > zero C
> > > > >[ice I]) 917 kg / m^3 or sg ~ .92  Water @ 100 C is 1.04 mL / g or sg
> > > > 0.96 So
> > > > >ice floats as per your experience (and mine).
> > > >
> > > >Bernard, you seem  to be missing the essential point -- the fact
> > > >that  makes life possible!  Water at freezing is less dense than
> water at
> > > >4C therefore water freezes on the _surface_ of the body of water.
> > > >
> > > >Jim Green
> > > >mailto:JMGreen@sisna.com
> > > >http://users.sisna.com/jmgreen
> > >
> > >
> > > This gee whiz item is a favorite of the divine design folks.
> > >
> > > If water density uniformly decreased above freezing point,
> > > it would cool at the surface of cooler air as usual  - and becoming
> denser
> > > when cooler then sink, until it reached it reached its density level.
> > >   Relatively warmer water at the bottom would rise, and so I suppose,
> > > there might be a vigorous circulation while a temperature gradient
> exists.
> > > And quite possibly on significant bodies of water, there would always
> be a
> > > gradient, and a circulation, so that icing would be postponed perhaps
> > > banished from significant bodies of water....
> > >
> > > This does not seem specially lethal to life, when I consider the life
> that
> > > thrives
> > > in sulphide springs at great depths.

Brian Whatcott
   Altus OK                      Eureka!