In the July/August 2012 issue of Weatherwise on page 7 is a statement that says that anticyclonic winds cause the warm water on the surface of Lake Erie to converge in the center of the lake. How does this happen? Why would the same condition not happen with cyclonic winds?
Staten Island, New York
The question refers to a warm-season phenomenon, when the warmest water occurs at the lake surface. The oceans and fairly large lakes have a thermocline, a layer of water that marks the transition between warm surface water and relatively cold water underneath. Within the thermocline, the temperature decreases rather quickly with depth. This leads to a stable stratification that inhibits mixing of water in the vertical direction because the density of water is greater below the thermocline than above it. (At temperatures above 39°F, the density of water decreases with increasing temperature.)
Weatherwise Contributing Editor THOMAS W. SCHLATTER is a retired meteorologist and volunteer at NOAA's Earth System Research Laboratory in Boulder, Colorado. Submit queries to the author at firstname.lastname@example.org, or by mail in care of Weatherwise, Taylor & Francis, 530 Walnut Street, Suite 850, Philadelphia, PA 19106.