Question of the week: Arctic smoke

Q:What causes arctic smoke along the North Shore?

A: Arctic smoke occurs when the air is colder than Lake Superior’s water temperature. Lake Superior surface water is about 40 degrees at this time, but the air above the lake often plummets to well below zero. On most winter mornings, you can see steam from the warmer water rising and quickly cooling, creating the effect of smoke hanging above the water.

A rarer sight is spiraling columns known as steam devils, which occur when there is a large difference between the air temperature and the lake temperature. As the air coming off the lake cools rapidly, it creates updrafts that cause the spirals to form. You need very cold air temperatures and a slight wind to see them, but as we commonly have minus 20-degree days, you can usually catch them a couple times each winter.

Kelsey Olson, Gooseberry Falls State Park naturalist

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