Dear Tom,
As an avid recreational boater on Lake Michigan for many years, I have noticed the lake's waves are higher in the winter than in the summer. What is the explanation?
Bill Roberts, Waukegan
Dear Bill,
Any given wind speed, say 15 knots, will build higher waves in the winter than in the summer. Cold air over warm water (the winter situation) transfers more wind energy to the water than does warm air over cold water (the summer situation). When cold air blows over warm water, the air heats, lifts off the water and is replaced by stronger winds from above. Strong winds are constantly sinking to the lake surface. In summer, it's just the opposite. Cool, calm air hugs the water and strong winds remain aloft. The net effect is that wind speeds over the surface of Lake Michigan are higher during the winter than in the summer.
