Page 333 - PPL-engelsk 2025
P. 333
Meteorology
3.9.5.6 Mechanical and thermal turbulence in connection with thunderstorm
Mechanical turbulence is not a direct consequence of thunderstorms, but it can
be intensified near thunderstorms, especially when the wind is very strong or
stormy, and there are geographical obstacles.
Thermal turbulence can be a direct result of thunderstorms, as the strong
updrafts in thunderstorms create thermal turbulence.
In thunderstorms, there are intense updrafts of warm, humid air that rise
quickly and create turbulence, which can lead to both thermal turbulence and
the powerful upward air currents that create thunder.
Definitions of turbulence
- Light – FBL: Turbulence is noticeable.
- Moderate – MOD: The aircraft remains under control at all time; it is
difficult to move in the cabin; loose objects move.
- Severe – SEV: The aircraft is out of control for brief periods; loose
objects are thrown around; passengers are thrown into their seatbelts.
3.9.6 Flying over mountain areas
Flying in mountainous areas is incredibly beautiful and an amazing flying
experience. As beautiful and pleasant as it is, it can also be very dangerous. It
requires extensive knowledge of the area being flown over.
The dangerous phenomena include:
- Mountain waves
- Downdrafts
3.9.6.1 Mountain waves
The next page shows an example of how mountain waves forms.
Flight Theory PPL(A)(UL)/LAPL Henning Andersen, Midtjysk Flyveskole© 2025 333
