RE: [Paddlewise] POST SCRIPT to: Into Winter Mode -- water/air temperatures and clothing

From: Matt Broze <mkayaks_at_oz.net>
Date: Wed, 11 Dec 2002 01:30:49 -0800
Ralph wrote:
>>>>>My entire original posting should be read as supporting the
NYCKayaker's
caution regarding current water temperatures, bearing in mind that some open
and "paddlable" water is actually already near or at the freezing point, NOT
still at 40 deg F!!!<<<<<<<<<

I think that 40 degrees F and freezing of a waters surface are very close
together in nature. If I understand this correctly (and it may be much more
complicated than this) the surface of water can't freeze when in contact
with freezing air until it reaches 40 degrees F. because water is at its
greatest density at 40 degrees. Below that temperature the water expands
again until freezing (where it expands a lot more). Therefore, the warmer
(less dense water) at the surface no longer floats to the top once the
surface temperature reaches 40 degrees. The water "turns" and the colder
water, lower than 40 degrees F., that had been below floats to the surface
as the denser 40 degree water sank below it. Water colder than 40 degrees
that had been lower down now rises to the surface and the icy air can bring
down the temperature to freezing at the surface rather quickly since warmer
water is sinking rather than rising below 40 degrees F.
Thank you Ralph for both your recent posts.

Matt Broze
http://www.marinerkayaks.com

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Received on Wed Dec 11 2002 - 01:31:53 PST

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