Long term propagation?
Is there any known method to measure propagation in the distant past?
We know of solar cycles and maunder minimums and such...but do we know of any past propagation "ice ages" where there was little or no propagation at all for 100s or 1000s of years? Or the opposite? It would seem that there are more than a few similarities with weather, so this would stand to reason as a possibility.
If so, what is the equivalent of the propagation 'fossil record' - what is considered evidence of past propagation? Are sunspot trackings our only connection to measure past propagation effectiveness, thus we only have 100, maybe 150 years of data?
As humans we have only just begun watching the Sun in earnest, in the past 300 years or so. Some of the largest sunspots were recording as far back as 300 BC. The Chinese started making records of the Sun's activity around the time of Christ. The cycle of the activity has only been known for a short time but there have been some indications of Sunspot activity around 11-12 thousand years ago. It wasn't until the twentieth century that a link was established that some type of relationship between Sunspot activity and radio propagation was found. It is still not entirely understood exactly what that relationship is and there appears to be evidence that higher ultraviolet emissions account for some of the connection. It's still a work in progress. The early predictions for this cycle were that it was going to be a whopper but we now know it as a dud. Predicting solar activity in a reliable way is still in it's infancy and scientist are still exploring how the Sun works and what bad things can or cannot happen. There has been a lot of speculation on the possibility of a massive solar ejection like the one that occurred on September 1, 1859. With our reliance on technology that can be disabled by such an event there are a lot of "What if's" circulating.
The fact is we rely on the Sun for many things, we just don't want it to turn on us. Maybe some voodoo sacrifice is in order.
In the event the Sun had a massive blowout there isn't much we could do about it but watch and hope.
Have fun (while you can).
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
"The more you know, the less you don't know."
If you have the time I would like to hear more about the long variation of atmospheric pressure.
Originally Posted by KL7AJ
When ever the US Congress is in session, the amount of hot air, noxious gases, and frankly a whole lot of huffing and puffing can and often does increase the atmospheric pressure.
Originally Posted by VK2AKG
Then it goes away for summer recess.
FCC Section 97.313(a) “At all times, an amateur station must use the minimum transmitter power necessary to carry out the desired communications.”
Flying Pig -57 NAQCC 18 ARCI 10223 SKCC 2076T FISTS 5695 CC 764 SOC 400
I'll explore a bit more. I imagine there are 'fossils' of changing atmospheric pressure of some kind - maybe evidence in ice or in the animal types or something else. That could then trace back to a very rough history of propagation.
From there, I wonder how strong the correlation is between our relatively recent (last few 100 years) technological advances and propagation. How might we be different had we 'gotten smart' during a period where there was no propagation? Or much better propagation - or different propagation? Granted, radio is only a part of technology and has only mattered in the last 150 years or so. But what if?
I don't believe that there is any way of ascertaining any information regarding propagation from centuries past, the reason being, they hadn't invented radio ! Astromers saw spots on the sun and some recorded what they saw, but like today, despite all the comments which scientists make at various intervals, they don't really understand what is happening on the sun from one day to the next.
You might be interested to know that it was only during WW2 that the effects of a solar disturbance, causing radio blackouts, was experienced which caused concern to the military commanders in Germany and Britain. An important part of war is mis-information and there had been intelligence reports that Britain was testing a ray which could affect communications.
A solar disturbance caused a blackout which had never been experienced before and the German High Command were convinced when their soldiers were unable to communicate that this was caused by the British using their secret ray.
You can just imagine the panic this would have caused for at least a day, and that was the first known event of a solar blackout. Sixty nine years, in the life of the sun, just a millisecond.
Well, we know of ice ages in the distant past, well before thermometers were invented. But i think you're pointing out that 'propagation' is the actual journey of the radio signals, while what I'm really seeking is the atmosphere's potential for propagation....no?
Originally Posted by G0GQK
I'm asking if there's some indirect way to tell. Maybe not on the scale of a single solar cycle, but on the scale of an 'age' - like...there was no chance of propagation, even if radios existed, during the pleziazoic era because of X. What's X look like, how would we know this, and what are the top and bottom end of potential propagation in the very long term?
Is the atmospheric pressure lower now than at any time since such values have been recorded? If so, consider the cubic feet of atmosphere current trapped in pneumatic tires around the world. No, I'm not being flippant or silly. I genuinely wonder what the effect on our climate is from the percentage of the atmosphere that's not there.
Originally Posted by KL7AJ
Well, let's do a little back of the envelope calculation.
The guy on this site seems to know what he's talking about (from my cursory glance), and he says that the air in a car tire weighs something like 26 grams.
There are about 7 x 10^9 people in the world. Many of them don't own any tires, but let's assume that each person has 100 tires, all filled with air. That's probably a worst-case scenario, but perhaps the old tire I discarded is still sitting in the tire dump with its 26 grams of air held captive. (I can only think of about 30 tires attributable to my family, but I bet if I looked around the garage, I would find more, so 100 probably isn't unreasonable.) So the earth contains 7 x 10 ^ 11 tires. = 1.8 x 10 ^ 13 grams of air.
According to Wikipedia, the total mass of the atmosphere is approximately 5 x 10^ 18 kg, or 5 x 10 ^ 21 grams.
So the portion of the atmosphere currently trapped in tires is 1.8 x 10^13 / 5 x 10^21 = 0.0000000036 = 0.00000036%.
It doesn't seem like enough to make a difference, although I didn't know for sure until I crunched the numbers.