So you mean, on the ground you see the sun 'set' on the horizon, but when about 1km in the sky you will be able to see the sun again?
This is more possible on a flat earth model with a close sun than it is on a round earth model, I think, because on a flat earth model you would be shifting the angle to a higher perspective which will allow you to see further, on the flat model, the sun is merely further away and the light is localized.
Unless, you mean to say that it is night time on ground level and when you arrive to the top the tower still receives luminance from the sun?
Hmmm. Quite something if that is the case. I propose that the light of the sun on the fe model would be blocked by trees or buildings or sheer angle of convergence (sun being 30 000 miles up in fe model, comparatively a small distance)
And the tower being 1km or so high, would be in an unobstructed path from the light of the sun to the tower, accounting for daytime on top of the tower.
in the RE model, you are suggesting that from that high one would essentially be looking down the curvature, revealing the sun. I myself have skydived once at a height of roughly 4km.
I can tell you now, there was no curvature to be seen period. I was actually stunned the first moment i was out of the plane, by the sheer fact that 'the earth looks so flat from here'
Back then the flat earth theory wasn't actually a thing but as a photographer i did wonder why all the images displayed inside the paradiving building were distinctively made with extreme fishey lenses, even the video that was taken was with a fisheye lens. As a photographer this was the first thing i noticed, everything was being done with a fisheye. I almost would've asked them about it, now i wish i did just to have had the experience of their reaction to share...
But with my own eyes man, you could see flat fields for miles, the only thing that could slightly obstruct your view was forests and trees, but the horizon was flat100%