↑ What is the difference between the Greyline and the Solar Terminator?

This page is part of the project "Understanding HF Propagation."
by Doron Tal, 4X4XM

Gray line
Figure 1: Earth terminator as seen by Apollo 11 Mission

The "terminator" and "greyline" separate the daylight and dark sides of a planetary body, but their definitions differ.

The grayline is the twilight zone, while the terminator is a line tangent to the parent star.


Why is radio propagation better along the greyline?
Propagation is ehanced along the "greyline" because there is no absorbing D-region there. Read a reasoned explanation.

Gray line illustration
Figure 2: Ionospheric Regions and Gray Line
The height of the F and D regions
is exaggerated in comparison to Earth dimensions.


The project "Understanding HF Propagation" provides a detailed overview and tutorials on HF propagation.

Total visits to site pages since 17 August 2022.
Flag counter site maybe down!

Repeat visitors counted as new after 24 hours.