From communication prospective why can't higher frequency ranges be reflected from atmospheric layers and what is the effect of parameters (like temperature, pressure, etc) of the atmospheric layer on reflection of waves for sky wave and space wave propagation.


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Different materials reflect, absorb, and scatter different wavelengths of light. The ionized layer at the edge of earth's atmosphere happens to reflect a certain range of wavelength while transmitting others. This is due to the physics of the material.

The reason you can't use the atmosphere to reflect shorter wavelengths for the purposes of communication, is because the atmosphere doesn't reflect those wavelengths in the first place.

The primary parameters affecting the atmosphere's reflectivity is the amount of ionization and the depth of the ionized layer. That largely depends on solar activity. There is a significant difference in this layer between night and day. It is also subject to individual solar phenomena, like flares or coronal mass ejections.

  • $\begingroup$ Please provide some references. In particular, I'm skeptical that ionization strength affects all wavelengths. $\endgroup$ Jul 20, 2017 at 13:51
  • $\begingroup$ @Carl: I never said it did. Clearly it doesn't, since visible light, as just one example, is largely passed without being reflected. $\endgroup$ Jul 20, 2017 at 14:59
  • $\begingroup$ Thank you for your response. So is there a relation between reflection of certain wavelength and ionization ? ... Something like as (for longer wavelength smaller amount of ionization will guarantee the reflection of waves) $\endgroup$ Jul 20, 2017 at 22:23
  • $\begingroup$ @Kara: If I remember right from listening to shortwave radio long ago, you can get really long distances due to bounces off the ionosphere in the 10-15 MHz range. This varied by time of day. Even 1 MHz commercial AM can sometimes be picked up far away due to "skips". There is probably a graph out there somewhere showing rough reflection capability of the ionosphere as a function of wavelength (or frequency). $\endgroup$ Jul 20, 2017 at 22:50

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