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Critical frequency of the F2 ionospheric layer

Critical frequency of the F2 ionospheric layer

Absortion maps

The Three D-RAP Charts above show Atmosphere and Ionosphere Effect from Space Weather. Top chart - always show any flare irradiance. Center chart - shows effects at radio blackout levels. The bottom chart - lights up during major events.




Aurora forecast

Aurora forecast map

Greyline map

The "grey line" is a band around the Earth that separates daylight from darkness. Propagation along the grey line is very efficient. One major reason for this is that the D layer, which absorbs HF signals, disappears rapidly on the sunset side of the grey line, and it has not yet built upon the sunrise side. Ham radio operators and shortwave listeners can optimize long distance communications to various areas of the world by monitoring this band as it moves around the globe.