Dear Tom,

Waves on Lake Michigan seem higher in the winter than in the summer. Why is that? —

Mary Rasche

Dear Mary,

It has to do with air/water temperature differences between winter and summer. When the air is colder than the water (the winter situation), more wind energy transfers to the water and builds higher waves. Warm air over colder water (the summer situation) transfers less wind energy to the water. When cold air blows over warmer water (winter), it heats and lifts off the water surface and is replaced by stronger wind from above. Stronger winds are constantly sinking to the lake surface. Warmer air blowing over colder water (summer) is cooled, hugs the lake surface and slows because of friction. Stronger winds higher up do not build down to the lake surface.