ASK TOM: Turbulence when a jet aircraft flies through layers of clouds

Dear Tom, 

What causes the turbulence when a jet aircraft is going through layers of clouds during takeoffs and landings?

—Lionel Chartier, Chicago 


Dear Lionel,

Turbulence is caused by random, continuously changing air motions that are superimposed on the wind.

A jet flying through any sharp boundary between differing air motions will experience “bumpiness.” This is most often caused by a current of air moving up adjacent to a current of air moving down. An aircraft will have a bumpy ride when it flies through the sharp boundary between opposing air motions. A sudden change in wind direction has a similar effect, as does a sudden change in wind speed.

Such sudden changes in vertical air motions, wind direction and wind speed are typical of air in clouds, especially cumulus clouds.