Much thanks for the Toronto image. It's a pretty one, though perhaps not a fit for this particular collection. I tried to find images that were clearly labeled moonrise, and for northern and southern latitudes, I was looking for lunar images that were right on the horizon. (I broke the rule for Mumbai because I could find hardly any equatorial images, and I figured close to the equator would not rotate the moon much as it moved off the horizon, unlike far north and south latitudes.) Fortunately, I think St. Petersburg is further north than Toronto, so I think I've got that latitude covered. (New York should be close enough.)
Generally speaking, you can't distinguish Flat Earth and the globe by this tilt using a qualitative argument, i.e. without exact measurements and geometry, so you'll be unable to appeal to most people.
Really? So you think most people wouldn't be able to figure out the apparent tilt of the moon on the horizon actually meant it was the horizon that was tilting--even without exact geometry? I thought the cool thing about this effect would be the obviousness of it. Perhaps I was being too optimistic.
To understand this, move to a room with a smoke detector and observe its changing tilt as you move along one wall (from North to South).
Took me a bit to realize this is probably a reference to a ceiling-mounted smoke detector. I've only had wall-mounted units (which would be the more natural analog to a moon on the horizon). But on a wall unit, the bottom stays stubbornly the bottom.
Thanks also for the links to the other threads. My keyword searches had pulled up the Moon terminator thread but that was kind-of a different topic. The other thread is much more what I was looking for, but apparently I was not using the right words to find it. And again, I can see how that kind-of works for an overhead moon, but not a moon right on the horizon.
So some flat-Earthers also believe in a flat disk moon? I did not know about this. Surely in the 150+ years that we've had stereoscopes, someone must have used the librations of the moon to produce a stereographic image. Seems like that ought to be a pretty clear and obvious demonstration. Or is that too much optimism also?