Title text:
While weather control is typically thought of as a superpower, the unconscious ability of astronomers and astrophotographers to summon clouds is more properly classified as a curse.
Transcript:
Transcript will show once it’s been added to explainxkcd.com
Source: https://xkcd.com/3253/
A superpower that requires that you remember which hemisphere* of the planet you're on.
In Australia, a window with such a sunbeam is north-facing, not south. The westward moving sun thus takes the sunbeam to the far table.
* Things get real funky if you're on a planet with a severe axial tilt relative to the perpendicular of its orbital plane.