[at-l] Cold weather hiking

[lubitz@alpha.fdu.edu (Richard S. Lubitz)]

Water is most dense at approximately 37* F. As a body of water cools, the 
water exposed to the cold air reaches 37 and drops to the bottom 
displacing warmer water to the top.  after all the water is below 37*, the 
water at the top can cool and become less dense as it does so.  this is 
the process that northern lakes go through known as "turning over".  The 
reverse happens in the spring after ice out.  During the winter, the 
warmest water is at the bottom of the lake at 37*.  Ask any Ice fisherman, 
this is where the fish hang out.  Turning over is an important part of 
the life cycle of a northern lake's ecology.

Now back to the water bottle (or milk bottle).  Since water becomes less 
dense below 37*, it takes up more space, (density is the ratio between 
mass and volume).  This expansion can damage a full container.  keeping 
the bottelupside down will cause the ice to form at the bottom which is 
now the top.  Assuming that the water does not freeze solid, the water 
below (above) the ice will remain liquid and, if the bottom is the cap 
end, the water will be accessable.  Damage to bottles is caused by filling
it completely and not leaving space for the expansion of the water.
Those of us old enough to remember can see in our minds a milk bottle 
with a cylinder of ice milk coming out of the top crowned by the paper 
top and the pog.
Now you know more than you ever wanted to.
Merry Xmas
Rich



 > > 
> In a message dated 12/22/01 4:10:23 PM, kahley7@ptd.net writes:
> 
> << Another good tip is to store your water container upside down.
> The thread/lid connection is less likely to freeze as quickly
> that way.  don't as me why,  you'd think that the warmer water
> would be at the top, but my experience says it doesn't work that way. >>
> 
> As Ice forms it expands and becomes lighter than the water.  It floats to the 
> top to finish its freeze. At least that's my understanding.
> 
>                                         Art
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