Large bodies of water such as the Great Lakes take longer to warm up than the air (due to waters higher specific heat). As a result, the temperature of the lakes are still warm during fall and some of winter. When cold air moves down from Canada, the warmth of the lakes heats up the bottom layers of the cold air mass, evaporating moisture from the lake into the air. The warm air below begins to rise (since it is less dense), begins to cool, and condenses the evaporated moisture, forming clouds. These clouds cause severe localized snow storms (and sometimes thunder and lightning as well) often exceeding 5 inches (12.7 cm) per hour. The storm bands typically range from 1-25 miles (1.6-40.2 km) wide, appearing as a thin strip on a radar map.
While those who live in LES regions have to adapt to a severe routine weather event, those who don’t can appreciate the power of Earth’s climate under unique geographic circumstances.
Radar Images/Conceptual Maps
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