3 ms·

You'll find this sort of visualization on a lot of ham radio websites, since skywave propagation between two points varies based on the amount of sunlight among

You'll find this sort of visualization on a lot of ham radio websites, since skywave propagation between two points varies based on the amount of sunlight among other things. For instance, https://www.pskreporter.info/pskmap.html https://www.pskreporter.info/pskmap.html The Geochron (https://www.geochron.com/about/what-is-it/ https://www.geochron.com/about/what-is-it/) is a mechanical map+clock created in 1965 that shows it.

MichaelApproved 7y ago
Does more sunlight help or hurt skywave propagation?
- bityard 7y ago
  It's complicated. There are various "layers" of the ionosphere that "bounce back" radio waves in different bands of frequencies depending on the time of day. It's a fun topic to learn about.
- Tempest1981 7y ago
  "Because the lower-altitude layers (the E-layer in particular) of the ionosphere largely disappear at night, the refractive layer of the ionosphere is much higher above the surface of the Earth at night. This leads to an increase in the "skip" or "hop" distance of the skywave at night." https://en.wikipedia.org/wiki/Skywave#Other_considerations https://en.wikipedia.org/wiki/Skywave#Other_considerations
- teraflop 7y ago
  It's not quite as simple as that, because there are multiple ionospheric layers with different physical properties that affect RF propagation. An over-simplified explanation is that the outer layers of the atmosphere persist continuously, and can be used for very long distance communication, but only reflect radio waves at relatively low frequencies (<10MHz). The lower layers that become ionized during the day absorb some of the radio waves, reducing overall efficiency and range, but also allow operation at higher frequencies which would be unusable at night. And you can get very efficient long-distance propagation along the terminator at dawn and dusk: https://www.qsl.net/w2vtm/grayline.html https://www.qsl.net/w2vtm/grayline.html

MichaelApproved 7y ago

Does more sunlight help or hurt skywave propagation?

bityard 7y ago
It's complicated. There are various "layers" of the ionosphere that "bounce back" radio waves in different bands of frequencies depending on the time of day. It's a fun topic to learn about.
Tempest1981 7y ago
"Because the lower-altitude layers (the E-layer in particular) of the ionosphere largely disappear at night, the refractive layer of the ionosphere is much higher above the surface of the Earth at night. This leads to an increase in the "skip" or "hop" distance of the skywave at night." https://en.wikipedia.org/wiki/Skywave#Other_considerations https://en.wikipedia.org/wiki/Skywave#Other_considerations
teraflop 7y ago
It's not quite as simple as that, because there are multiple ionospheric layers with different physical properties that affect RF propagation. An over-simplified explanation is that the outer layers of the atmosphere persist continuously, and can be used for very long distance communication, but only reflect radio waves at relatively low frequencies (<10MHz). The lower layers that become ionized during the day absorb some of the radio waves, reducing overall efficiency and range, but also allow operation at higher frequencies which would be unusable at night. And you can get very efficient long-distance propagation along the terminator at dawn and dusk: https://www.qsl.net/w2vtm/grayline.html https://www.qsl.net/w2vtm/grayline.html