Fog in Pleasanton today lowered visibility to less then 500 feet. I was amazed at the number of cars that were driving the city streets without their headlights on (just having the "parking" lights on doesn't count). What was even more amazing was people driving white cars in white fog without their headlights on (invisible car?).
There was an accident on Valley near the Mormon church area where a vehicle struck a child on a bicycle. I do not know how much the weather played a part in this accident, but obviously if the driver were more visible with the car headlights on, and bicylist wore a brightly colored overcoat, at least the changes of an accident would be lowered.
Responding to this accident, going down Valley, were a police motorcycle and a fire engine. The policeman had to tell a motorist to move out of the left lane so the fire engine could get through. The motorist had panicked and completely stopped with the rear wheels in the left lane and the front wheels in the right lane.
Good thing it doesn't snow here.