A very simple overturning experiment for outreach and teaching

Overturning experiment. By Mirjam S. Glessmer

For one of my side-projects I needed higher-resolution photos of the overturning experiment, so I had to redo it. Figured I’d share them with you, too.

You know the experiment: gel pads for sports injuries, one hot (here on the left), one cold (here on the right). Blue dye on the cold pad to mark the cold water, red dye on the warm pad as a tracer for warm water.

Thermally-driven overturning circulation: Warm water flowing near the surface from the warm pad on the left towards the right, cold flow from the cool pad at the bottom right to left.

A circulation develops. If you drop dye crystals in the tank, the ribbon that formed gets deformed by the currents for yet another visualization of the flow field.

Thermally-driven overturning circulation. In the middle of the tank you see a ribbon of dye, caused by falling dye crystals, being transformed by the currents in the tank.

Lighting is a problem this time of year. I chose natural light over artificial, and it came out ok, I think.

And here is the video:

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