I thought it would be more appropriate to find an existing topic thread and inject some information into this well-worn topic, but when I tried I received a caution that due to the age and dormancy of the old topic, I might be advised to start a new one. But seeing as this is my first post on this board, I hope I'm not breaking any rules by starting a new topic is a post count of 0. (I've been posting recently as "Yib" on another flat earth community's forum.)
I've been intrigued by what I would expect the sun to look like as it traversed the sky if the current flat earth visualization was a good model. Like most skeptics of the flat earth model, I feel that I should be able to see a marked difference in the sun's apparent size (width/diameter) from when it is at the highest point of elevation compared to when it is receded into the distance, low in elevation.
There's a video (who's source I can't identify) on YouTube showing a sunset, presumably in the Middle East, that DOES give the appearance I would expect of a diminishing sun as it recedes toward a horizon. But I've never personally seen a sunset like that. By my unmeasured eye, I feel like I see a sun sphere that's basically the same at low altitude as it is at high altitude, and it doesn't diminish to a vanishing point but becomes an obscured circle/sphere, as if over an edge.
So, "is that an illusion?" I ask myself. I've read the wiki(s) that propose a magnification explanation for why the sun doesn't diminish in apparent size as it sets towards the "conversion zone" of the horizon. Yet there are also videos by defenders of the current flat earth model attempting to verify that the sun DOES diminish in size as it "sets" into a vanishing plane/convergence zone. So, does it or doesn't it?
Yesterday (Sunday, April 22nd 2018) I took some photographs of the sun and tried to be as careful as possible to avoid introducing aspects that would change the angular perspective of the sun. I included a solar filter and exposure settings to reduce the glare of the sun so that I could see its boundary. Using the same focal length for all photographs throughout the day, same resolution, same field of view, and without altering the photographs, it didn't matter whether the sun was at its closest point to my location (San Diego at 69° elevation due south) or 10 minutes to scheduled sunset (1½° elevation to the west). My measurements of the sun's pixel size from every test point was 605px +/- 5 pixels, the variance being due to precision error in where to choose the edge from which to measure.
The consistent size can't be akin to glare or lost focus since I accounted for that. The atmosphere, itself, acts as a filter as the sun's elevation drops and the intensity of the light is diminished. But if that's where magnification due to water vapor begins to take effect, it didn't seem to have a magnifying effect, unless it is perfectly synchronized to maintain a constant angular diameter of the sun until refractive elements take hold at around 1-2°. Only then, at less than 2°, did the circle of the sun start to become distorted, as it got "squashed" and its edge boundaries more irregular. However, it's horizontal width didn't change.
Even with some magnification, I would only expect it to reduce the rate of change, maybe, so that the evening sun might be larger than expected, but nevertheless smaller than the sun at solar noon. But that didn't happen.
I posted this on another forum, but didn't receive any feedback other than from those inclined to already agree with me. I'd appreciate a critical, contrary review. I can either re-post my data and observations, or provide a link to where they are posted.