Actually what you see from satellite views is the bathtub effect, which is the high fog and inversion layer. That is the stuff that prevents any and all sunshine from coming through all day. It is a dry weather high pressure pattern that brings that. We can have that without the ground fog.
See my San Joaquin Ocean picture:
Once we descended down through that stuff, there was no ground-level fog.
RP is right, that we don't get the bad fog within the city limits like in the outlying areas. Apparently there is enough heat generated from the homes and increased traffic that less ground fog forms.
The ground-level Valley fog that causes the freeway pileups forms at night, more in the outlying areas, and clears up every day by mid-morning. It is worst the week after rain comes through.
