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Page 2
The process is greatest in June and July when the difference between the lake's surface water temperature and the tropical Gulf air's dew point is smallest and thus the condensation potential is greatest. Researchers have calculated that the condensed water, or dewfall, forming on the surface of Lake Superior can add several centimetres/inches of water per month to the lake during the summer. The total amount of dewfall may be equivalent to the water gained through precipitation at this time of year: around 80 mm (3.1 inches) each summer month. If we assume 25 mm (an inch) of condensed moisture uniformly deposited over the whole 82,880 square kilometres (32,000 square miles) of lake surface, the water gain amounts to over 2 trillion liters (550 billion gallons). Now that is a Superior moisture gain!
A similar process, of course, will occur over the other Great Lakes. particularly Lakes Huron and Michigan, but not to the amount deposited on Lake Superior. Because of the unique geography of eastern North America, the contribution of dewfall to lake water balances is likely the highest here, but the process can occur anywhere in the world where humid air flows over cold lakes. And if you don't think an inch of water means much on large lakes such as the Great Lakes, the United States Great Lakes Shipping Association has reported that for every inch of lost clearance due to low water in certain areas of the waterway, an international vessel can lose from 90-115 metric tons of cargo-carrying capacity, which can amount to revenue losses to $11,000 per day of operation. Copyright 2005, Keith C. Heidorn, All Rights Reserved. (Illustrations, unless otherwise specified, ©Keith C. Heidorn, All Rights Reserved.) Go To Page: 1 2
The copyright of the article Superior Moisture Gain - Page 2 in Meteorology is owned by . Permission to republish Superior Moisture Gain - Page 2 in print or online must be granted by the author in writing.
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