The Flat Earth Theory – Questions for those accepting it?

I was very surprised to hear from a few people recently that they believe that the earth is flat, or shaped something like a disc. One lady challenged me to prove that it wasn’t. Since “proven” is a personal matter—a conclusion that a person makes after considering available details, I wondered what this person would consider as proof. After much pondering, some questions have come to my attention I’d like to share with anyone who is seriously entertaining the theory: 

 

1. Sunrise/sunset. Why does the sun “rise” and “set” in Ohio about 2 hours before it does in Arizona?
2. Clouds. Why do the distant clouds of the same type and altitude appear to be lower in the sky than those which are closer?
3. The North Star. Why does the North Star remain in the same position in the sky all night, while other stars (including those of the Big Dipper) appear to slowly rotate around it?

 (Time exposure images of the visual paths of stars that appear near the North Star.)

4. Vapor Trails. Why do vapor trails of high-flying jets before passing nearly overhead, appear to be flying nearly straight up?

Kings Peak, Utah     Longs Peak, Colorado

5. Mountains. Why can’t someone at the top of Kings Peak (elevation 13,534 feet, in eastern Utah) see Longs Peak (elevation 14,259 feet in northern Colorado) even with a powerful telescope on a clear day? The two massive mountains are about 260 miles apart, with no mountains with elevations as high between them?

6. Boats. Why do boats sailing out to sea disappear over the horizon sooner from the view of one standing on the shore than from someone at the same distance, but 60 feet above the other observer?

7. In the autumn of 2018, I noticed a couple of curious vapor trails from high flying aircraft. They were flying from east to west. They appeared to merge as one of the aircraft turned in the same direction as the other, and from my vantage point, it almost appeared as though their vapor trails merged. I quickly found my camera, and took some photos.

In each of the photos, the vapor trail of the closer of the two aircraft (not as low in the image) appears to be just a bit lagging and making the trail of the other appear to be wider and brighter. In the 5th photo, a third vapor trail (from a plane coming from west to east) can be seen approaching the merged trail of the two traveling west. In the 6th photo, the three appear to be headed for impact. In the remaining images, it becomes obvious that they did not collide, but the one coming up in the image (from west to east) was at a different altitude than the other two.

I’ve been intrigued with the vapor trails of high-flying aircraft since learning that some people are reverting back to the old theory that the earth is flat. If the earth was really flat, how could these vapor trails from the two high-flying aircraft traveling west appear to be diving almost straight down and the one traveling east, almost straight up? In reality they were cruising along, not diving or traveling vertically. Their paths were nearly overhead of my position.