Appleton layer

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Ionospheric layers as a function of the time of day

The Appleton layer (after the British physicist Edward Victor Appleton ), also known as the F layer , is the highest ionospheric layer on earth. Short-wave radio signals are reflected in the ionosphere , so it is most important for the propagation of the sky wave of radio signals.

The F-layer is divided into two sub-layers:

  • The lower F1 layer ranges from 150 to 220 km and is only available during the day. It consists of a mixture of positively charged O + -, O 2 + - and NO + - ions .
  • The F2 layer, which primarily consists of positively charged, atomic oxygen O + , spreads over the F1 layer between 220 and 800 km in altitude .

At noon, the F1 layer has approx. 5 × 10 5 free electrons per cm 3 with minimal solar activity ; With increased solar activity, the charge carrier density can reach up to 2 × 10 6 electrons per cm 3 . At night, the electron density of the F1 layer drops to below 10 4  electrons per cm 3 .

→ Main article: Ionosphere # F-layer

See also