I might have run into a bug of some sort.
I was playing around with the Daylight system and using the world map to have the light come from various angles.
But I found when I moved the crosshairs on the world map slightly, in some instances the lighting would change dramatically.
For example, keeping the longitude the same (at -50), and moving the latitude by 1 (from -66 to -65), the lighting changed dramatically (see attachments).