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TEACH Questions & Answers

Do the Great Lakes create their own weather systems?
from Heidi of St. Bernard School in Brantford, Ontario, Age 12

The Great Lakes themselves do affect the hydrologic cycle. The large surface area of the Great Lakes causes quite a bit of evaporation, which contributes to much of the moisture in the region. This moisture will either stay in the air and create those hot, humid days of summer, or condense and form clouds and, eventually, precipitation. This precipitation (rain, snow, sleet) will either fall back into lakes or will be absorbed by soil and become groundwater*. And some groundwater eventually enters back into the lakes, starting the cycle all over again.

Great Lakes weather is also affected by air masses from other regions. While the prevailing winds in this region are from the west, cold, dry weather from the Arctic region as well as the hot, humid weather from the Gulf of Mexico can also affect the Great Lakes weather system, causing quick and sometimes drastic changes in the weather (have you ever heard the saying, "If you don't like the weather in Michigan, wait five minutes!"). Autumn and spring are especially affected by clashes of warm and cold air that can produce strong winds and storms.

*Water that is not absorbed by the soil is called surface runoff, which can contribute to water pollution. For more information on surface runoff, see the second page of the TEACH Great Lakes Areas of Concern topic.

Natural Processes in the Great Lakes Region, Great Lakes Atlas, Environment Canada

Thank you for your question!

Answered on July 17, 2000

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