Waves Upon Waves Upon Waves...

Photo copyrighted by Craig Johnson, Weather Briefing, LC and taken at Cedar Falls, Iowa

This dramatic sky was photographed on March 28, 2020 in Cedar Falls. This layer of altocumulus had waves coming from different directions. Gravity waves are caused by layers of air disturbed by the wind. The layers have different density and become disturbed when wind of different velocities interacts with the layers. Velocity is a combination of wind speed and wind direction. It is the difference in wind velocity (wind and speed) as air flows through adjacent layers that forms the waves. The stability of the air also determines the size and shape of the waves by setting up the vertical motion that ripples through the layer. The waves are similar to (but not exactly like) waves in water. Waves coming from different directions meet and cause complex patterns like are seen here.