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Field trip grants make fourth grade so much better
Great Lakes Echo (2/11)
Pictured Rocks National Lakeshore, in Mich., is one of 186 federal parks to receive a portion of the $1.1 million National Park Foundation grant to set up field trip programs.

State awards $3.6 million in grants to combat invasive species
WLUC-TV, Marquette, MI (2/11)
The Michigan departments of Natural Resources, Environmental Quality and Agriculture and Rural Development announced the award of 19 grant projects totaling $3.6 million, under the Michigan Invasive Species Grant Program.

UT dedicates lab to analyze wide range of research jobs
The Toledo Blade (1/29)
A laboratory that opened in mid-2015 at Ohio's University of Toledo allows monitoring of water quality and detection of dangerous algal toxins in Lake Erie more accurately and faster.

TEACH Calendar of Events
What's going on in your neighborhood this month? Meet other people and learn together at recreational and educational events! Our new dynamic calendar is updated daily with current educational events.
TEACH Questions & Answers

Do the Great Lakes freeze in the winter?
from Debbie in Olyphant, Penn., Michael in Kenosha, Wisc., and Jim in St. Clair Shores, Mich.

The Great Lakes do freeze, but not completely. According to Ray Assel of the Great Lakes Environmental Research Laboratory, ice cover on the Great Lakes varies from lake to lake and year to year. For example, in a year with normal temperatures, 25 percent of Lake Ontario will be frozen over, while up to 90 percent of Lake Erie will be frozen. However, wind and water movement over bodies of water as large and deep as the Great Lakes make it unlikely the lakes have ever frozen over completely for any significant length of time.

The Great Lakes have come close to freezing over completely during the extremely cold winters of 1976-77, 1977-78 and 1978-79, with up to 90 percent ice coverage. However, Assel says that severe winter air temperatures are not necessary for large ice cover on the lakes. A cool summer and fall can result in below normal water temperatures by late fall. Extensive ice cover can then form with only average winter temperatures.

Old Ice bridge As for the Niagara Falls, the volume and speed of the water flowing over the falls prevents them from freezing, as does the ice-boom at the mouth of Lake Erie. The ice-boom is a series of floating steel pontoons extending across the river from Buffalo, New York to Fort Erie, Ontario. It prevents ice from clogging the river and hydroelectric intakes by helping an "ice bridge" (a stable ice cover) to form at the mouth of Lake Erie. Before the installation of the ice-boom in 1964, the American side of the falls froze over in 1909, 1938 and 1949 because ice jams upstream reduced the water flow. Ice bridges can also form below the falls when ice goes over the falls and freezes to the edges of the gorge, resulting in a buildup of ice (as thick as fifty feet in some places) stretching across the entire river. For photographs of historical ice bridges on the falls, go to Edsen Breyer's Postcard Museum.

For a look at current and historical Great Lakes surface and ice cover, go to GLERL's Great Lakes Surface Environmental Analysis pages.

Thank you for your questions!

References
Nilsson, Matt. Not Easy to Freeze. Earthwatch Radio, 1/25/00.
Niagara Falls, Thunder Alley.


Answered on January 8, 2001

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