Not long ago someone asked me about Lake Turnover and quite honestly I did not have a good scientific answer for them. However there was a very good article in our Grindstone Lake Association newsletter which explains this affect in language that even I can understand. I have taken the liberty to paraphrase some of what was written.
Essentially “Turnover” is the term used to describe the mixing of the contents of the entire lake.
Reminds me of my stomach after dinner last night! Not long after ice-out, in early spring, winds create the wave action needed for considerable turbulence all the way to the bottom of the lake. At that time of year the water temperature and the water density is fairly uniform throughout the lake making it easier for the mixing to happen.
As springtime progresses and the spring winds decrease, (well, most of the time!) the sun’s radiation eventually causes the surface water of the lake to become significantly warmer (and less dense) as compared to the deeper water. The point where the temperature difference between the warmer and colder water is greatest is called the “thermocline”. Now there’s a word to put into your everyday vocabulary!
In many lakes, the thermocline is between 10 to 20 feet below the surface of the lake. Because of the density difference between cold and warm water, the thermocline acts like a barrier to prevent further mixing of the lake’s water.
As we approach fall the surface water cools to the point where its temperature and density once again is similar to the waters below resulting in the same mixing process that occurred in the spring. And yes we are beginning to see signs of fall and cooling, sunsets are much earlier!
Water is most dense at around 39 degrees Fahrenheit; because of this the lake water in the winter is actually warmer at the bottom of the lake as compared to the water immediately below the surface of the ice which is just above 32 degrees Fahrenheit. Essentially the warmer water of the lake shifts to the bottom in the winter and to the top in the summer. And there you have it!
Local News: Don’t forget that the Seeley Lions Club is hosting the Pre-Fat off road bicycle race this weekend and Rib and Brew Fest is next weekend. Come up and take in the fun!
Life is good….Enjoy!
Gary Nathan
Amanda Mavis
Woodland Dev & Realty
Hayward, WI
715-699-4040
nathan@cheqnet.net
http://www.garynathan.com/
http://www.haywardwaterfront.com/
