No fog cheat
Note: This procedure involves editing a game file. 
Create a backup copy of the file before proceeding. 
Use a text editor to edit the "env2.dat" file in the game directory. 

Set the following:

Fog 000 00000 000 000 000
Ambient 80 80 90

DirLight 0   -1 0   255 255 255
DirLight 0.5 -1 0.5 255 255 255

TerrainSkySpeed 20
TerrainSkyScale 0.03
TerrainSkyColor 255 255 255 65