i know this had something to do with vality before i opened it.
so he can help you:
http://i621.photobucket.com/albums/tt297/Vality7_2/Elder%20Scrolls/Random/morrowind_ini_weather.png
thats a chart of sky textures from vanilla MW, the settings are in the MW ini file in number form.
you have to use a paint program to get the desired colours:
http://planetelderscrolls.gamespy.com/View.php?view=Utilities.Detail&id=75
vurt made that to show people what each setting can do.
a few tips that vality told me:
(1:43:36 PM) Vality: exactly
(1:43:55 PM) Vality: just look at where the ambient colours are
(1:44:09 PM) Vality: or the shadowed side of an object
(1:44:15 PM) Vality: find the brightest part of it
(1:44:18 PM) Vality: and use that colour
(1:44:29 PM) Vality: like if i posted a picture of a scene
(1:44:33 PM) Vality: that had fully white textures
(1:44:38 PM) Vality: it would be easiest to get them from
(1:44:58 PM) Wolli: cause they're the closets to the actually settings..?
(1:45:03 PM) Wolli: st*
(1:45:05 PM) Vality: yes
(1:45:31 PM) Wolli: nice
(1:45:33 PM) Vality: http://images.uesp.net/f/fd/SR-prerelease-2011-04-01-4.jpg
(1:45:38 PM) Vality: take this for example
(1:45:44 PM) Vality: you can easily get the fog colours from that
(1:45:48 PM) Vality: and the sun/sky stuff
(1:46:01 PM) Vality: for the ambient just find a shadowed bit of rock
(1:46:11 PM) Vality: like on the far left theres a white patch
(1:46:19 PM) Vality: above that werid green rock
(1:46:22 PM) Wolli: I see it
(1:46:24 PM) Vality: use that
(1:46:31 PM) Vality: and for the sun colour
(1:46:37 PM) Vality: find a bit of rock thats facing the sun
(1:46:41 PM) Vality: and find the whitest bit of it
(1:46:56 PM) Wolli: damn smart
it makes sense... a bit, when you know what it means