Layering and Turn Over in Webb Lake
I want you all to take a little trip with me. Close your eyes, picture yourself floating out in the middle of Webb Lake on a beautiful day in July. The water is nice and warm (can you feel it?); now let your toes tangle down a little deeper, I bet your toes are a little chillier. So what is the point of my request? I want to tell you about layering and over turn in our favorite lake. In July the lake is stratified into layers as shown in the diagram.
In the summer, Webb Lake remains stratified, with the epiliminon containing warmer less dense water, the thermocline is a zone of changing temperature and the hypoliminon contains the densest cooler water. In the fall, the sun gets lower in the sky, the leaves turn wonderful colors and the temperature drops. The dropping tempertures cause the surface waters to cool, as they cool they become more dense and sink, this process continues into the fall until the entire lake becomes the same temperature. Once the lake is all the same temperature, it is also the same density; then when the wind blows, the whole lake mixes. This process bring oxygen rich waters from the surface down to the lower reaches of the lake and brings nutrient rich water from the bottom up to the surface waters.
Stay tuned for the next installment of the yearly life of our favorite lake. Winter and spring information coming in the next newsletter.
Article Credit: Lise Bofinger
Photo credit: http://www.islandnet.com/~see/weather/elements/turnlakes.htm