Thermocline

[WyoChris]

Can someone explain to me what exactly the thermocline is? It is a term I hear a lot but really don't know exactly what it is. Thanks.

[sparcebag]

A depth in a body of water where there is a definate temperature difference.Cold water is heavier than warm it sinks, the difference between that cold and the sun warmed surface where they meet is the thermocline.

[Scott M]

The thermocline is an area of rapidly changing water temperatures. It has to do with water temperature and the changes in density at given temperatures. Water is most dense at 4 degrees C, or about 40 degrees F; so when water temperatures cooled at the surface reach that temperature in the fall, they sink to the bottom. When lakes stratify in the summer they form a thermocline. Eventually the water mixes as temperatures stabilize from top to bottom and you get a turnover. Minnesota lakes are monomictic, meaning they turn over once. Temperatures are relatively uniform from top to bottom in winter. When spring comes and the water heats up, they stratify, stay suspended until the fall, mix again, and then the lake freezes up.

Right now we're closing in on the fall turnover. Water temperatures range from 55-60. If we get a cold snap and the weather stays windy, we may only be a couple weeks from the fall turnover.

[YourBobersDown]

wow good to know I have always been sketchy on this topic as well

[cvanderweyst]

how long does it take for a lake to "turn over". Does it take a day or a week....

[Scott M]

A couple days. You can usually tell when it has occurred because the water clarity temporarily diminishes and there is a slight rotten eggs odor as decaying matter mixed in the stagnant hypolimnion (bottom layer) water rises to the top.