To characterize aeronautical turbulence one must specify its origin and its intensity.
Atmospheric turbulence is defined as "small-scale, irregular air motions characterized by winds that vary in speed and direction" .
In a more aeronautical field, turbulence can be defined as small-scale, short-term, random and frequent changes to the velocity of air.
The amount of turbulence depends on wind speed and obstruction size and shape.
Shear: When the direction or speed of wind changes dramatically within a short horizontal or vertical distance, an aircraft will experience turbulence when it flies through (typically a cumulonimbus).
Wake turbulence: An aircraft causes wake turbulence in its trail as it flies through the air.
Turbulence is separated into four levels of intensity.