For anyone who doesn’t know, the grey line is a band around the Earth that separates the daylight from darkness.
This grey line is of particular interest to us radio operators. Radio propagation along the grey line is very efficient. One major reason for this is that the D layer in the atmosphere, which absorbs HF signals, disappears rapidly on the sunset side of the grey line, and it has not yet built up on the sunrise side.
Ham radio operators (and shortwave listeners) can capitalize upon this phenomenon for long distance communications to various areas of the world, and do so by monitoring this area as it moves . . .
To read the rest of this article, please click here: → Workin’ on the Grey Line…
