Re: [Paddlewise] Taking Water Temps

From: Joe Pylka <pylka_at_castle.net>
Date: Sat, 6 Jul 2002 12:29:49 -0400
>>>OK. I've taken the bait. What's a "lake turn" ? And why would a lake want
to do


that sort of thing ?


regards,


David





  It's part of the annual cycle of water in a large, mostly deep, lake.  The
word is "Turnover".  As the weather warms and winds blow, the upper surface of
a lake gets moved and heated.  Sooner or later currents will set up in the
upper layers from one side of the lake to another.  This circulation tends to
keep the accumulated heat and sediments, plankton, oxygen, etc. in that upper
layer.  The transition between the upper and lower layer is called the
"Thermocline", a stratum where the temperature drops abruptly.  Ever swim in a
lake in nice warm temps then tread water and get your feet into something
really cold?  You just punched through the thermocline.  


    The upper water cools as autumn/winter approaches, and at some point this
thermocline barrier breaks down and the upper and lower layers mix; fairly
abruptly and thoroughly.  That's the Turnover.  


    Check out a couple of texts on Limnology -- that's the science of water
ecosystems.  Much better descriptions than mine are available.  Some general
Ecology textbooks describe this as well.





Joe P.

















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Received on Sat Jul 06 2002 - 09:30:33 PDT

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