FORECAST SOL: Moderate yellow MAG: Normal green ION: Normal green
Space Weather

Glossary of Solar Terrestrial Terms

Obliquity Factor

The factor that relates the vertical critical frequency to the MUF for an HF circuit. It is denoted by M(D)layer, where D is the path length of the circuit and layer indicates which ionospheric region is being considered, i.e., E, F1 or F2. This factor increases with increasing path length so longer circuits will normally use higher frequencies.

Optimum Working Frequency

This is a statistical prediction of the highest frequency for HF sky wave propagation. If the prediction is correct, this frequency should be refracted by the ionosphere 90% of the time. See Maximum Usable Frequency and Upper Decile MUF.

Ordinary Wave

The radio wave that follows the laws of refraction when propagating in a plasma containing a magnetic field. For the ordinary wave, the electric vector rotates in the opposite direction to that of an electron gyrating in the field when propagation is along the direction of the magnetic field. For propagation perpendicular to the magnetic field, the electric vector oscillates parallel to the magnetic field.


See Optimum Working Frequency.

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