On Mon, 06 Sep 2004 05:54 am, helmsman posted to
rec.radio.shortwave: %MM

It could also be following a 'crooked path' along the grey line,
depending upon the time of day and the frequency.

"crooked path"??

GRAYLINE PROPAGATION http://dx.qsl.net/propagation/greyline.html
The Grayline is a band around the Earth that separates Daylight from
Darkness. It is a somewhat fuzzy area because the Earth's atmosphere
tend's to defuse light into darkness. On one side of the Earth the
Grayline is coming into light [Dawn] and on the other side of the planet
it is going into darkness [Dusk]. Propagation along the Grayline is very
efficient. The Grayline runs North and South but varies as much as 23
degree's either side of the North South line. The variation is caused by
the Earth's axis relative to the Sun. The major reason for excellent
Grayline Propagation is because the D-Layer disappears quickly on the
sunset side of the Grayline and hasn't built up yet on the Sunrise side.
You have about one hour for best conditions, that's about 15 degree's.

Many thanks!!