Long term propagation?

[WA9SVD]

Keep in mind that while the SUN is the primary source of ionization, there has to be something there to ionize in the first place! Ease of ionization is very sensitive to atmospheric pressure, which has changed radically in human history

We can guestimate the propagation quality in times past, but since Radio itself a little over a century old, there's no way to prove (or disprove) what sort of propagation occurred much in the past, even though we have sunspot records that far precede the development of radio. Sunspot numbers alone are not the sole predictor of propagation at HF; not then, and not now. Other solar activities can affect propagation, even with a "high" sunspot number.

[KA3JLW]

We can guestimate the propagation quality in times past, but since Radio itself a little over a century old, there's no way to prove (or disprove) what sort of propagation occurred much in the past, even though we have sunspot records that far precede the development of radio. Sunspot numbers alone are not the sole predictor of propagation at HF; not then, and not now. Other solar activities can affect propagation, even with a "high" sunspot number.

Well, despite the negative attitude against learning for learning's sake...but we might be able to prove certain things and we might be able to say certain things with high probability.

So for instance, if there was ever a time when the earth had NO atmosphere - that will have certain propagation characteristics. We can certainly model certain aspects (like a higher pressure) and then speculate against a range of sunspots.

Eh, its just something to think about...to wonder what, if any, more exotic propagation possibilities might have existed.

[KL7AJ]

As we all know the inventor of the pneumatic tyre John Boyd Dunlop was British and as such I am declaring any reference to tires as null and void.
JEEZ! just noticed that this site has the temerity to flag tyre as a spelling mistake. What is the world coming to?

Y don't know whi you Brytysh Folks Spell Tyre wyth a Y.

[VK2AKG]

http://pubs.acs.org/subscribe/archiv...l/12learn.html

Here's the most reasonable treatise I've seen on the topic of atmospheric pressure.

Thank you.

[G8ADD]

I think that atmospheric pressure is a red herring. Look at it like this, if we have a higher surface pressure than today, the height at which the atmosphere becomes rare enough to allow ionisation will increase proportionally, and if we have a lower surface pressure then that height will decrease proportionally. If the pressure is higher, then, the height of the various layers will be higher leading to longer ranges and wider skip zones. It would be interesting to learn how the ionosphere on Mars behaves: atmospheric pressure is low but the gravity field is weaker than Earth's which will allow what atmosphere there is to extend higher, and solar ionising radiation will be weaker because of the greater distance (inverse square law).

73

Brian G8ADD

[KY5U]

Propagation? Sounds like propositioning the congregation down at the Baptist Church.

[N0NB]

As we all know the inventor of the pneumatic tyre John Boyd Dunlop was British and as such I am declaring any reference to tires as null and void.
JEEZ! just noticed that this site has the temerity to flag tyre as a spelling mistake. What is the world coming to?

Yt's probably your browser and not the syte. Check your spell checker settyngs.