You probably know the feeling: you’re sitting on a plane, happily cruising through the sky, when suddenly the seat-belt light comes on and things get a little bumpy. Most of the time, turbulence leads to nothing worse than momentary jitters.
Turbulence occurs when something disrupts this smooth flow, and the air starts to move up and down as well as horizontally. When this happens, conditions can change from moment to moment and place to place.
When pilots encounter turbulence, they will change altitude to try to avoid it. They also report the turbulence to air traffic controllers, who pass the information on.
Turbulence is usually short-lived. Modern aircraft are engineered to comfortably withstand all but the most extreme air turbulence. Among people who are injured, the great majority are those who aren’t strapped in.