Tag Archives: grey line

Ham Radio Realtime Gray Line

Current Gray-Line Position

Courtesy of http://www.fourmilab.ch/, this is the current real-time position of the Gray

Line, as utilised by Ham Radio operators over the world.

For those who don’t know, the”grey line” is a band around the Earth that separates daylight from darkness as the earth rotates.  Propagation along this line can be very efficient.  One 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.

Interesting? Well, I’ve spoken to people on the other side of the planet during this 30 minute phenomenon. It certainly gives you a buzz.

[Later: This damned map can takes ages to load.. Grrr]