January 25, 2013

Image of the Week: Lake-Effect Snow Buries the Midwest

by Julia Rosen

This image was captured by the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument aboard NASA’s Terra satellite. Source: NASA.


If you live in Michigan, this photo may not surprise you. You are probably hunkered down, patiently waiting while the bitter Arctic wind tears across the state, leaving behind a deep wake of snow. If you live in Wisconsin, however, you might feel a twinge of relief: your side looks high and dry. In any case, you are probably wondering what’s happening up there on the north shore of Lake Superior where ferocious stormy ribbons seem to materialize out of thin air. And why the east coast of Lake Michigan has been blurred beyond recognition like half-erased chalk. This image from NASA’s Terra satellite has captured a phenomenon well-known to lakeside residents around the world: the powerful fury of lake-effect snow storms.

Lake effects occur when a cold, dry air mass moves over a body of open water. Even if you might consider that water far too cold for a dip, it’s still much warmer than the frigid air aloft. The air close to the surface absorbs the lake’s heat and rises, bringing with it a fresh supply of water vapor evaporated from the lake’s vast surface area. Inevitably, though, the air cools as it climbs until the water condenses out and falls again as snow.

In this case, winds have come swooping down out of the Canadian Arctic and haven’t encountered a drop of liquid water in hundreds of miles. When this air reaches the northern shorelines, it’s bone dry and brutally cold. But as it hits the Great Lakes, it takes up all the water it can hold, the extra heat from the lake allowing it to absorb even a little bit more. It has barely blown ashore again when that water comes dumping right back out, smothering the west coasts of Michigan, Ontario and New York with infamous lake-effect snows.


Read more from NOAA about the science behind lake-effect snow.

Learn how advances in weather forecasting can help predict storms like this.

Learn how water moves through different reservoirs on Earth in our module about the hydrologic cycle.

Julia Rosen

Written by

Julia Rosen is a freelance science writer and PhD student at Oregon State University. She received a Bachelor’s degree in Geological and Environmental Sciences from Stanford University before beginning her doctoral research on polar ice cores and climate change. In between, she did her “Master's” in backpacking around the world and skiing. Julia is a periodic contributor to Oregon State’s research magazine, Terra, and helps write blog content and develop learning modules for Visionlearning.