Great Lakes tides; Ask Mr. WeatherBlogger
The WeatherBlog has received this question from Sally Ryerson, at the Saint James Academy:
Do the Great Lakes, or any bodies of fresh water, have tides?Dear Sally, Good question. Actually, everyplace on the Earth's surface is subject to tidal action. Even land. The combined gravity of the sun and moon are always pulling on the Earth's surface and tugging it out of shape like a rubber ball. But it's the oceans where we see the action most clearly. Bodies of fresh water are mostly too small to be visibly affected in the way the oceans are. But they do actually rise and fall twice a day as the Earth's crust beneath them rises and falls. The Great Lakes are an exception. They're so big that a small tidal effect - a couple of inches - has been measured in the lake waters. But it is swamped by other influences, such as wind and atmospheric pressure changes. Here is the best discussion I've found on the Great Lakes tides. It's from the National Oceanic and Atmospheric Administration. Just scroll down to the fourth item.
