The lake effect is known to mean many things. To a Wisconsinite it is the saying “cooler by the lake”, a phrase often used as a way to explain the cooler weather often appearing near the western shores of Lake Michigan during the summer. To a meteorologist, it is a phenomenon occurring in fall and winter in which cooler atmospheric conditions create precipitation throughout the Great Lakes region. To the lake-lover, it’s the smiles, laughter and general shenanigans (scientific word) that occur in and around lakes.
In order to distinguish between these meanings further - a scientific explanation, Jessica Maier, meteorologist and friend of Lake Effect Co., is offered.
A lake breeze is actually the correct term to describe when its colder by the Great Lakes in the summer and warmer in the winter (similar to land/ocean breezes). This occurs mostly due to the Great Lakes’ water having higher heat capacity than the land. Every day when the sun heats up the Earth’s surface, think rocks and water, a localized difference in pressure across the surface. Essentially the rocks heat up faster than the water and therefore the air above the rocks becomes less dense and begins to rise. We know that air must flow from areas of high pressure to areas of low pressure-imagine about air being released from a towable tube after a long day of doughnuts behind your uncles outboard. If we imagine the space above the rocks (western shores of Lake Michigan) and the space above the water (Lake Michigan), we see air moving from east to west creating a……breeze! Boom. Science-d.
However, THE lake effect, is actually a way to explain precipitation around lake regions when no larger scale weather patterns are present. The lake effect, often called lake effect rain (LER), lake effect snow (LES) or lake effect blizzards occurs when cold air from the north travels down and over the Great Lakes. Similar to the lake breeze, cold dry air lies above and warm moist air rises below which helps water to condense and clouds form! This temperature difference between the atmosphere above and the lake below can be so drastic that air moves upward faster and makes clouds large enough to produce rain, snow or even blizzards. Often times this occurs on the eastern portion of the Great Lakes because weather generally moves east.
Lake breezes and lake effect precipitation are similar because they involve pressure gradients in the horizontal and vertical planes respectively and they are supplied by the high heat capacity of water. However, the lake effect does not only involve three dimensional planes, pressure gradients or heat capacity! It’s simply that overwhelming feeling of bliss, calm, ease, and appreciation after a long day on the lake.
Jessica M Maier, M.S.
Space Science and Engineering Center
University of Wisconsin Madison
Native of Lake Tichigan, Wisconsin