I have solution for big square! Probably you dont need this anymore, but maybe it will help somebody. -in object window you have WorldData->Climate->BlackreachClimate. Duplicate this and rename; -edit your climate, on the left you have "Sun" and "Sun Glare", which are set on "black.dds". This black square is big lightining square on your sky, we must change it; -for change you will need extract file from Skyrim by BSAopt ( http://www.nexusmods.com/skyrim/mods/247/? ): open Skyrim->Data->Skyrim - Textures.bsa by BSAopt;navigate to Skyrim-Textures->textures->sky;find sun.dds and sunglare.dds and extract them on your desktop;from Desktop->textures cut "sky" catalog and paste it into Skyrim->Data->Textures;-now you can edit "Sun" and "Sun Glare" in your climate and choose this two dds files; -enjoy:)
