Thursday, January 31, 2013

Lake Effect Snow


If you live in the Great Lakes region of the United States, you are undoubtedly familiar with the products of lake effect snow (LES). Very simply, LES storms are localized precipitation events that occur as a result of cold air passing over relatively warm waters. However, that explanation does not do justice to the fascinating intricacies that lead to these weather events.

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.


Sources/Further Reading
-http://www.noaa.gov/features/02_monitoring/lakesnow.html
-http://www.sciencedaily.com/articles/l/lake_effect_snow.htm
-http://www.crh.noaa.gov/apx/?n=les

Radar Images/Conceptual Maps
-http://www.noaa.gov/features/02_monitoring/images/lakesnow_radar.gif
-http://www.crh.noaa.gov/apx/?n=lesConceptual

Photo
ClarabellafaireStock – deviantart.com

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