Page 326 - PPL-engelsk 2025

Meteorology

If there is ice in the carburetor, it will cause a drop in engine RPM. You will

notice that the engine does not run smoothly.

Be prepared for a further drop in RPM when applying carburetor heat. As the

ice melts, the RPM will rise again.

3.9.4 Thunderstorms

Thunderstorms are usually a result of strong cumulonimbus (CB) clouds. The

next page shows a diagram that indicates areas of the cloud with positive and
negative charges.

The lower part of the CB cloud is predominantly negatively charged. There is

often a positively charged center associated with heavy precipitation. The

upper part of the cloud is positively charged.

For lightning and thunder to occur within a cloud, the CB must reach a certain

size. Most lightning discharges are negative, meaning the negative charge near

the cloud base is neutralized.

The discharges can also be positive, for example, when they occur from the top

of the cloud to the ground.

Positive discharges have a higher current than negative ones, resulting in

greater damage.

A discharge between

cloud and ground

begins with a search

path down toward the

earth.

As the search path approaches the ground, countercharges are developed from

the highest point on the earth.

Flight Theory PPL(A)(UL)/LAPL Henning Andersen, Midtjysk Flyveskole© 2025 326