8.40 Turbulence

Turbulence is one of the most unpredictable of all the weather phenomena that are of significance to pilots.

Turbulence is an irregular motion of the air resulting from eddies and vertical currents.

It may be as insignificant as a few annoying bumps or severe enough to momentarily throw an airplane out of control, to stall or to cause structural damage.  

Turbulence is associated with fronts, wind shear, thunderstorms, etc.

8.40.2 Define the term ‘wind shear’.

Wind shear is a difference in wind speed and/or direction over a relatively short distance in the atmosphere.

Between the two layers of air is what is known as the shear zone. This zone consists of tumbling and twisting air particles which cause turbulence.

It is usually associated with the following weather conditions occurring close to the ground.:

• jet streams,
• mountain waves
• temperature inversion layers,
• frontal surfaces,
• thunderstorms and
• convective clouds or microbursts,