fog...
 

why during precipitation like rain or snow, the fog cannot came?

tks

Water droplets are already "catched".

In order to make the copilot fly the leg !

Temperature inversion.
 

The one thing you must always have for fog to form is a temperature inversion.

Usually, you get temperature inversions with clear skies. Not always, but usually.

Ciao.
M.
:cool:

Fog is simply cloud on the ground. The air is already saturated.

If there is a heavy rain,you could say it's fog..you won't see a :mad: thing,even with wipers at high speed..:}
Zero,fog is usually caused by temp inversion.Usually,but not always.:)
there are also:
radiation fog ,advection fog,evaporation fog,precipitation fog,upslope fog, valley fog (caused by inversion) ,ice fog,freezing fog,garua fog .
To learn more about those,check this: http://en.wikipedia.org/wiki/Fog