Why Minnesota’s lakes love blustery April weather

You may cringe at the blustery wind and bracing chill in the air these days.

But in the Land of 10,000 Lakes the winds of April are critical in renewing the health of Minnesota's favorite resource.

Water.

Turnover

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April is the time of year when our lakes in Minnesota "turn over." Water has the unique property of having its highest density at 39.2 degrees. That means the heavier waters in winter settle down to the oxygen-starved lake bottom. Above that layer temperatures rise until you hit ice at 32 degrees. That's why ice floats, it is essentially less dense than liquid water at 39 degrees.

The ice melts in spring. Soon the surface water warms to around 39 degrees. Now the water density is relatively similar from top to bottom.

Cue the winds of April.

Gusty winds start mixing the water in our lakes. The lake water essentially "turns over" from top to bottom. Now oxygen-rich water near the surface returns to the bottom feeding aquatic life. Oxygen-depleted water from below rises to the surface for renewal.

The process repeats in fall as fresh water is once again returned to the lake bottom.

LakeTurnover
University of Wisconsin

The process of lake turnover is silent and invisible to us. But we see and enjoy the benefits of this physical reality every day in the Land of 10,000 Lakes.

Loon In Thursday

Speaking of our lakes, I'm looking forward to hosting the Freshwater Society's annual Ice Out Loon In event Thursday evening at the brand new CHS (St. Paul Saints) Stadium in St. Paul.

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Stadium tours will be offered prior to the event. Hope to see you there.