Turbulence
Turbulence is one of the most operationally significant weather hazards tested on the Aviation Weather knowledge exam, and understanding its causes — from convective lift and wind shear to mountain waves and clear-air turbulence — is essential for sound preflight decision-making. The exam expects you to interpret pilot reports, forecast products, and atmospheric conditions to anticipate where turbulence is likely and how severe it may be. Work through our 5 in-depth, ACS-aligned turbulence articles below, or return to the Aviation Weather library.
Four Causes of Turbulence: Convective, Mechanical, Wind Shear, and Wake
Turbulence has four main causes — convective currents, mechanical obstructions, wind shear, and wake turbulence — each with distinct triggers, locations, and hazard levels every pilot must recognize.
Mechanical Turbulence from Terrain, Buildings, and Surface Friction
Mechanical turbulence forms when wind flows over terrain, trees, buildings, and other obstructions, creating irregular eddies that can produce hazardous bumps at any altitude — understanding its causes and intensity factors is essential for safe low-altitude operations.
Low-Level Wind Shear: Convective and Non-Convective Sources
Low-level wind shear from both convective and non-convective sources creates sudden, violent changes in wind speed and direction that threaten aircraft during approach, departure, and cruise — understanding each source is critical to safe flight operations.
Turbulence Intensity Categories and How Pilots Report Them
Turbulence is classified into four intensity categories—light, moderate, severe, and extreme—based on aircraft reaction and occupant experience, and pilots are expected to report it using standardized PIREP terminology grounded in FAA-H-8083-28B.
Clear-Air Turbulence Near the Jet Stream and Tropopause
Clear-air turbulence (CAT) near the jet stream and tropopause is a severe, invisible hazard most common above 15,000 ft where wind shear between the jet core and surrounding air causes sudden, violent aircraft buffeting.
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Articles are original summaries grounded in the public-domain FAA handbooks and cite their source. ACS-aligned study aids — not a substitute for the official handbooks or regulations.