From airplane window why do distant lights appear to be "up" higher than closer lights?

Question

I keep noticing this and want the optical illusion explained.
i know the land is flat-no major hills or mountains, so it is an illusion.

Answer 1

Simply the curvature of the earth. From the plane's height,
distant lights appear higher up due to the curve, nearer lights appear to be lower down.

Answer 2

Actually, it's probably caused by the curvature and refraction in the windows rather than an 'optical' illusion.

Optically, your brain gets confused and processes the image of the more distant lights different than the closer ones, because the closer objects are moving more rapidly than the distant ones. This would be true IF there was no glass between you and the images.

However, aircraft windows are made out of two coated panes of glass, with a vacumn between the panes (for insulation, because it's COLD at 33,000 ft.!). The coating removes some of the UV-A and UV-B, and the glass is slightly curved, and both panes are curved differently...

The result is a 'bent' image where the far-away lights are HIGHER in the window BECAUSE they are further away. Then your brain gets into the way, and confuses the distances...