It was about 17 - 18 years ago. I was with a group of friends headed to Moab, Utah. We were in Utah and just turned East onto Interstate 70 off of Interstate 15 north bound.
Our group had started the climb up the hill. We were taking on our CB radios. I heard a Beaker call over the radio. I said “go breaker”. He returned with where are you? I said headed up the hill just turned off of the I-15. He said repeat again, and I did with the added part of 1 mile off of the 15 going east.
My thought was it was probably a trucker down on the I-15 (This was a clear line of sight shot a mile or so behind us.) I asked where he was? His next sentence was “South Sacramento!” I said I knew the area well and exactly where? He said off of Florin Blvd. I lived for a while in Orangevale. We chatted for a bout 2 minutes and I mentioned I would probably loose him as I crest the hill, and I did about 15 seconds later.
This was one of the rear occasions when the Ionosphere conditions were just right the short height of the radio waves bounced back to the earth. So line of sight (if I could see around the earth was 480 miles over the earths surface between locations.
It was very clear as if the person was a 1/4 mile away. So yes there are conditions where the radio waves can bounce around and get through. This is not the normal distance for signals to be heard. Normally it is line of sight.
I have had many transmissions where I have had conversations of over 25 miles away when one or the other was on a mountain and the other 5,000 feet below with a clear line of sight.
These are all with a standard and not a side band channel or a buster of any kind. Where we can not control the terrine the CB and FRS frequencies and power limits there are better solutions.
I have not even mentioned the people which you can have on the CB frequencies.
As the snow falls, the world goes quiet just to listen!