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Meteorology

If the conditions are right, instability can occur in the air, leading to the

formation of CB (cumulonimbus clouds).

3.6.3.3 Orographic clouds

Orographic clouds form when moist air is forced upward by mountains or other

high terrains. As the air rises along the mountains, it cools, and the water vapor

condenses, forming clouds.

This phenomenon is known as orography.

If the air is very humid, fog can form. If the water content is moderate,

stratocumulus clouds will form at the condensation level.

If the air is unstable, CB clouds can form. On the lee side of the mountain, the

clouds dissolve due to descending air.

In stable weather, mountain waves can
form on the lee side.

The clouds in these mountain waves

will be AC (altocumulus) and SC

(stratocumulus), and they will form in bands or in shadow zones.

Flying in clouds presents problems!

In addition to reduced visibility, issues include turbulence, icing, and dangerous

precipitation in the form of hail. The most dangerous are CB clouds!

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3.6.4 Cumulonimbus cloud

CB, or cumulonimbus, is the large storm cloud that contains virtually all

weather phenomena’s, such as turbulence, icing, hail, heavy rain, strong winds

from all directions, thunder, and lightning.

Flight Theory PPL(A)(UL)/LAPL Henning Andersen, Midtjysk Flyveskole© 2025 282