This is a really useful visual if one has contacts or meetings in other world cities. The left edge of the light hump is roughly 6am, the center is noon, and the right edge is roughly 6pm. The center of the dark hump is midnight, give or take DST.<p>Gnome2 had a map like this in its calendar/time drop-down when you add cities to it:
<a href="https://help.gnome.org/misc/release-notes/2.22/figures/rnusers-international-clock.png.fr" rel="nofollow">https://help.gnome.org/misc/release-notes/2.22/figures/rnuse...</a><p>It's one of the main reasons I still use Mate. No other desktop environment keeps it handy like this. I try them for a bit, then always go back to Mate.