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Meteorology

3.11.4 Weather – abbreviations and symbols

3.11.4.1 Abbreviations and symbols on Significant Weather Chart

When there are widespread areas with visibility under 5000 meters and/or

cloud base below 1000 feet, it is marked with yellow lines.

Such a line indicates a trough line.

Along such a line, there is a risk of convective clouds. ISOL CB should be

expected. TS (thunderstorms) may occur locally.

Lines like these indicate a convergence line.

These are most commonly found in warm unstable air masses.

Convergence at low levels can sometimes form CB systems with

embedded CB and TS.

When you see this symbol, interpret the small "v"s as TURN BACK.

This indicates an active squall line (severe Squall Line). It is about EMBD

CB and FRQ CB.

You need to go up to 2500 feet before the temperature drops to 0°C.
0° :025
This number also indicates at which height icing in clouds can be
expected.

Flight Theory PPL(A)(UL)/LAPL Henning Andersen, Midtjysk Flyveskole© 2025 351