Waves form as the wind’s energy is transferred to the surface of water.
A weak gusty wind can make ripples appear on smooth water. These ripples will dissipate quickly once the wind stops.
The size of a wind-generated wave depends on the following:
• The wind speed. The stronger the winds, the larger the force and, thus, the bigger the wave. The wind must also be constant, not just a wind gust here or there.
• The duration of the winds. The longer the wind blows over the open water, the larger the waves.
• The fetch. This is the distance of open water over which the wind blows. The longer the fetch, the larger the waves.
• The depth of the water also plays a role, as it is difficult to generate large waves in shallow water.
Waves in a deep lake or sea can be taller and last much longer.
Waves in the open ocean have been measured to be larger than 100 feet in height.
Waves in the Great Lakes have reached heights of 35 feet. The storm Sandy generated waves on Lake Michigan of 21.7 feet.
High sustained winds from one direction can push water up at one end of the lake, resulting in a storm surge.
Weather can also cause a seiche on the Great Lakes. In French, the word “seiche” means “to sway back and forth.”
An atmospheric disturbance causes waves to slosh back and forth between shores of the lake basin resulting in huge fluctuations of water levels in a short period of time.