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Meteorology

This is called dew, and in freezing weather, it is rime.

- If the wind is calm, dew or frost forms.

- If the wind is weak (1 to 5 kt), radiation fog forms.

- If the wind is above 5 kt, the fog lifts and becomes stratus clouds.

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3.6.8 Visibility – concepts and terminology

Visibility is extremely important for flying, and reduced visibility can have

catastrophic consequences if one ventures out into it.

Fog poses a problem during takeoff and landing due to reduced visibility. Since

fog is defined as visibility at the ground level of less than 1000 meters, it is not

a problem for VFR flight, as it cannot take place under these values.

Mist and Haze, however, can cause problems for VFR flight, as visibility can

extend up to 5 km.

The extent of visibility depends on several factors:

- The number of water droplets and pollution particles in the air
- The color, contour, and size of the target

- Background color and lighting

- The observer’s eyesight

3.6.8.1 Cloud height / cloud base

On a day with clearly defined clouds, the

height is given from the earth’s surface to

the bottom of the clouds.

Cloud base = bottom of the clouds.

Flight Theory PPL(A)(UL)/LAPL Henning Andersen, Midtjysk Flyveskole© 2025 292