Wikipedia:Reference desk/Archives/Science/2023 July 15

= July 15 =

Sky curvature at ground level
It seems that, alongside usual horizon curvature of the Earth, I also perceive sky curvature at ground level through distribution of clouds that, when looked wider, appear to be scattered in an arched pattern (as opposed to notorious flat Earth where clouds would be distributed flatly). Is it sort of a horizon curvature or another manifestation of Earth curvature? 212.180.235.46 (talk) 19:15, 15 July 2023 (UTC)
 * See Celestial sphere. If the coordinate lines of the celestial sphere were visibly painted somewhere up there (they aren't) then we would notice their arched pattern. My clouds may be more random than yours because I don't see that pattern. Philvoids (talk) 09:28, 16 July 2023 (UTC)
 * Imagine a very long straight line in front of you, higher than your point of view, say the overhead wire over a straight train track. In front of you, you have to look up. When you follow it in the distance to your left, it goes down to the horizon. But it also goes down when you follow it in the distance to your right. So if you try to capture this in a picture on a possibly panoramic flat canvas (something you can do with a fisheye lens), you get a curved line. In this fisheye photo of stair steps, you can see whether they are above or below the camera's pov by the way they are curved. --Lambiam 07:16, 17 July 2023 (UTC)