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Lake Effect Snow

Image Credit: SeaWiFS Project, NASA

Here's the basic explanation for this image offered by NASA on November 30, 2004 (go to their webpage for links to much more information about lake effect snow). Also see this page for some very nice animations and descriptions assembled by the National Center for Atmospheric Research at the University of Colorado-Boulder (

Those strange clouds stretching out from the Great Lakes are caused by cold air moving over the relatively warm water (at least a lot warmer than the air). This results in rising bands of moistened, warmed air that drop "lake-effect snow" alternating with clear bands of falling cold air. During winter, such bands can create hundreds of centimeters of snow more than upwind areas only a hundred kilometers away. Just ask the folks that live on the Keweenaw Peninsula on the southshore of Lake Superior or the folks in Buffalo, New York. Here in Duluth, our "Mega Storm" from Halloween night on 1991 that dumped more than 3 feet on us in a couple of days was in part due to lake effect snow. This image from November 30, 2004 was caused by a cold northwesterly wind over Lakes Superior and Michigan and was taken with NASA's SeaWiFS satellite.