8.40 Turbulence

Turbulence is irregular motion of the air caused by eddies, vertical currents, wind shear, or disturbed airflow.

It may range from light bumps to severe turbulence capable of causing:

• loss of control
• injury to occupants
• structural damage
• large airspeed or altitude changes

Turbulence is commonly associated with:

• fronts
• thunderstorms
• convective cloud
• wind shear
• mountain waves
• mechanical disturbance from terrain or obstacles
• wake turbulence from other aircraft

8.40.2 Define the term ‘wind shear’.

Wind shear is a change in wind speed and/or wind direction over a short distance.

It may occur vertically, horizontally, or both.

The area between the two different wind flows is called the shear zone. This area may contain turbulent, rolling, or twisting air.