Am radio tower power [video]
youtube.com
youtube.com
A long time ago I was a part time overnight radio engineer for a faith based radio operation in the Portland, Or area. Literally the only reason they needed a person like me to be there was because sundown happens at a slightly different time every night and someone has to manually lower the power of the AM antenna and log that they did it and when they did it at sundown. If an AM antenna is broadcasting at full power on the dark side of the earth it reflects all the way around and causes very interesting chaos. I frequently muse about AM and the solar wavefront and how it could be used as a lens. No one cares. lol.
They had one kind of cool old guy that paid to run a late night AM/FM radio show, real theater of the mind shit. It was cool to run his show. Brother Jacob. I'm not religious or anything. But 100% of why they paid me $15/hr 3 days a week to show up and overnight be the ONLY person in the building managing six radio stations was about AM and it's insane power.
I really mean it when I say this is one of the best videos I've ever seen. There is something so fundamental on display here and I love it.
As a result, the peak of the voltage on the tower is changing with rise and fall of the audio signal. And that peak voltage change is changing the spark in some way that makes it get hotter or cooler really fast (or something), which causes the air that is getting zapped to expand and contract, resulting in an air pressure wave that is relative to the original audio.
There's probably a pile of distortion due to all of the physics of the arc (high frequencies seem louder), but humans are pretty good at hearing the human voice through all of that anyways.