Air turbulence describes any irregular movement of air masses that disturbs an aircraft in flight. There are five distinct types — each with different causes, locations, and predictability. Here's the complete picture.
Clear-air turbulence is the most notorious type because it is completely invisible — no clouds, no precipitation, no radar return. CAT occurs primarily near the jet stream, at altitudes of 25,000–45,000 feet, where fast-moving air meets slower surrounding air masses. The resulting wind shear creates eddies and waves that can violently shake even large aircraft. CAT is the leading cause of turbulence-related injuries at altitude. Research from the University of Reading found CAT over the North Atlantic increased 55% between 1979 and 2020, driven by climate change strengthening the jet stream. Prediction requires specialized atmospheric models — standard weather radar is useless against CAT.
Mechanical turbulence is caused by physical obstacles disrupting airflow — specifically, mountains and terrain. When wind flows over a mountain range (Alps, Rockies, Andes, Himalayas), it creates lee waves — alternating bands of ascending and descending air that extend hundreds of kilometers downwind and up to the stratosphere. The ascending part of the wave can be smooth enough for gliders to soar; the descending part creates severe chop. The Rotor Zone directly behind and below mountain peaks is the most violent area of mechanical turbulence, with chaotic, unpredictable air movement. Routes crossing mountain ranges at relatively low altitudes are particularly susceptible.
Thermal turbulence occurs when the sun heats the ground unevenly, creating rising columns of warm air (thermals) and compensating downdrafts. At altitude, convective turbulence is generated by thunderstorms — the intense vertical air motion inside a cumulonimbus cloud can extend 10–15 km upward and generate severe-to-extreme turbulence in and near the cloud. Pilots avoid thunderstorms by 10–20 nautical miles laterally. Convective turbulence is most common in summer afternoons over continental areas and year-round in the tropics. Unlike CAT, convective turbulence is visible and radar-detectable.
Frontal turbulence occurs along weather fronts, where warm and cold air masses meet at different altitudes and speeds. The turbulence zone can extend 50–100 miles on either side of the front. More predictable than CAT, frontal turbulence shows up clearly on weather models and is routinely in flight plans. Wake turbulence is the rotating air left behind by preceding aircraft — powerful wingtip vortices that can roll a following aircraft. Air traffic control manages this through minimum separation standards. At altitude over busy airways, wake turbulence encounters are brief and usually light; the serious risk is at low altitude during approach and departure.
Ranked by historical turbulence score — click any route for details