Translations:Advanced Config/25/en

Maximum haze used : 0 is lowest value, 10 is highest.
Max turbulence factor : 1 to 3. This value can be set from 0-3 meters per second.
Maximum wind speed : in meters per second.
Minimum haze used : minimum distant haze : 0 is lowest value, 10 is highest.
Use realistic weather (0/1) : 0 for clear skies, 1 for realistic weather

The mission will conform to the weather. You will get much more variety, in particular. lots more rain and snow. Most battle areas have upwards of 30% rainy days.
Any given weather pattern may or may not impact a given mission type. If it is overcast and rainy most of the missions are going to be pushed to low altitude.
Dive bombing missions are particularly affected. Dive bombing will be swapped for an attack mission where the Stuka will drop bombs much like a fighter or IL2. Tactical bombing will be pushed lower. Patrols will be pushed lower.
Deeper penetration missions will be scrapped in favor of lower altitude missions near the front.
If cloud cover is not overcast or heavy then you will fly the missions as usual with whatever cloud cover there may be.