Each row is 50 pixels wide

For most of the rows, if not noted otherwise:
pixels on the left are used when the sun/moon is 90 degrees up, directly overhead
pixels on the right are used when the sun/moon is directly at the horizon
practically the sun/moon does not reach directly overhead

Every time 2 rows together form first the alpha value and then the color value (for easier editing)
Not every value type may use the alpha row

0:  Night Ambient Color -> Ambient light color, alpha is used for sky-baked-ambient
2:  Night Fog Color -> Color of fog, alpha multiplies strength. Unused as fog is set to 0
4:  Night Cloud Color -> Color of the clouds, alpha multiplies strength
6:  Night Sky Color -> Color of the light that hits the atmosphere. RGB applies to moon halo color, alpha multiplies strength
8:  Night Ray Color -> Unused, no god rays
10: Night Light Color -> Color of the light that hits the ground. Alpha used for moon-visibility-ambient-lighting, multiplies strength
12: Night Moon Color -> Color of the moon mesh, alpha multiplies strength

same uses as night above
14: Day Ambient Color
16: Day Fog Color
18: Day Cloud Color
20: Day Sky Color
22: Day Ray Color;
24: Day Light Color
26: Day Sun Color

28: Atmosphere RayleighMultiplierGradient -> sun angle based, makes the sky blue at noon and red at sunset
30 - Height Fog Strength, left = 0.0, right = 24.0, day night cycle. Only color R channel is read

Not all of them may be actively used, but hey they're there
Currently this is client-side and not server-side

