Refuting the Flat-Earth theory

[FlatAssembler]

really?   you can’t tell the changes in apparent size of planes or birds as they move from zenith to horizon?    how many airplanes or flocks of birds in the sky have you seen?    did you in punishment of your own trollish stupidity pierce your own eyes with sharp objects before casting your sightless gaze upwards?

Why would you expect them to change their sizes... if the Earth is round? I can understand why somebody would expect them to change their sizes if the Earth is flat (in fact, one probably should expect that), but if the Earth is round... I mean, they are a few kilometers up in the sky, and the horizon is a few kilometers away from us, so their actual distance from us doesn't change much depending on whether they are in zenith or at the horizon.