Dear folks, it is awesome how radio waves travel. I have studied such, having been a Ham radio operator and radio listener for so, so many years...and it is still a wonder! In speaking with Steve Morris ("Steve Scott") awhile back, I believe that I mentioned doing the math and realizing that I listened to Steve when he was on The Mighty 1090! I'd also mentioned a time or two that within thirty minutes of sundown, I could hear KAAY starting to fade in. Granted, this was while still on their daytime pattern, which was more or less roughly circular to cover the state of Arkansas and not switched over to their figure-eight nighttime pattern yet.
In the nighttime pattern above, the coverage was HUGE...and we can see how all of Cuba, parts of Central and South America were covered, as well as literally over half of Canada, up to Alaska...and no telling where else...I wish we had access to all the mail KAAY got!
In the past, I'd mentioned the "grey line" a phenomenon where it is not day, nor night...just that half-light pattern between the two. In the "old days", radio stations would sign off at sunset and sign back on at sunrise (some few still do). During this time, it was possible to tune to frequencies and momentarily, for a few minutes, hear other radio stations that were blocked by a local station, before THOSE stations signed off. In some instances, it was mere minutes, others it was maybe longer, due to the difference of a time zone. We radio enthusiasts of all types still use the "grey line" to communicate or to listen for otherwise elusive radio stations not "there" in daylight or dark. It is a fascinating phenomenon, as things happen during the "grey line" that do not happen any other times. Here is the link to the "grey line" map; it refreshes ever five minutes or so:
Because radio propagation is an ongoing study, some things are constant- others are constantly changing! A lot has to do with weather and sunspots. Nonetheless, I believe this "grey line effect" was responsible for my hearing KAAY before dark and the changeover to the nighttime "flame-thrower" figure-eight pattern. Give the dial a whirl before sunset sometime, you may be pleasantly surprised! Do it for a week, or two weeks and there may be more there than you realized!
Bud S. (firstname.lastname@example.org)