Originally Posted by
theprestige
Clouds appear to be parallel to a flat earth, even in the distance. Why?
I assume the answer is that the human eye isn't calibrated to detect curvature at that scale. Nor even estimate distance.
It's worse than that. The human eye is curved, so everything projected onto the nerves gets curved. The brain can sort some of this out, based on how important it was to our survival as a species.
So, if you are standing on train tracks, looking straight down the track, the rails will appear to grow closer and meet in the far distance. We may insist that they're parallel to each other but only because: a) we know they are; and b) our experience has conferred on us the general understanding that lines like that are really parallel.
The ocean doesn't appear to fall away, nor do the clouds. They just eventually meet because that's how we perceive them, even though this is not reality.
This gives rise to all sorts of crazy optical illusions like that window thing that spins around and makes you question everything you think you know to the entryway in Willy Wonka that appears to be a long hallway and is just a little box with a tiny door.