http://www.danielsternlighting.com/tech/lights/fog_lamps/fog_lamps.html
"In clear conditions, more foreground light is not a good thing, it's a bad thing. Some foreground light is necessary so you can use your peripheral vision to see where you are relative to the road edges, the lane markings and that pothole 10 feet in front of your left wheels. But foreground light is far less safety-critical than light cast well down the road into the distance, because at any significant speed (much above 30 mph), what's in the foreground is too close for you to do much about. If you increase the foreground light, your pupils react to the bright, wide pool of light by constricting, which in turn substantially reduces your distance vision—especially since there's no increase in down-the-road distance light to go along with the increased foreground light. It's insidious, because high levels of foreground light give the illusion, the subjective impression, of comfort and security and "good lighting"."
What is the point? What does this have to do with FOG LIGHTS... ALSO who ever wrote this is WRONG..... Your regular headlights DO THROW OFF a side lobe of light, to illuminate light the side, as well as the road AHEAD OF YOU... You don't drive looking out the side window. The hood, body blocks your vision for a dozens feet ahead and to the side anyway. Having a lit road, lane marker, and side of road, visible is VERY IMPORTANT at night and low visibility, especially roads with out street lights.
However you DO need to see down the road.... to see bends and turns and hazard's....
However the question is should you drive when the visibility is very low, fog lights are not.... It is true with FOG if you throw too much light at it it just reflects it. HOWEVER
FOG LIGHTS ARE NOT ONLY MADE SO THE DRIVER CAN SEE, BUT SO OTHER DRIVERS CAN SEE THEM (and not run into them). The idea of fog lights is to be more visible to others. NO ONE CAN SEE IN THICK FOG REGARDLESS OF LIGHTS, not with standing artificial vision or FLIR (fwd looking infrared). This is why some jet aircraft (and military) have FLIR.
NO ONE IS SAYING DRIVE WITH JUST FOG LIGHTS.... THAT IS DUMB, DANGEROUS and PROBABLY ILLEGAL. FOG LIGHTS ARE AN ADJUNCT TO YOUR LOW BEAMS. HIGH BEAMS IN FOG, IS A VERY BAD IDEA. IT JUST REFLECTS LIGHT BACK AT YOU, AND MAKES IT HARDER TO SEE OTHER ONCOMING CARS.
I can tell you on DARK nights, back roads THERE IS NO PERIPHERAL VISION EXCEPT BY THE HEADLIGHTS.... The longer and further I can throw light the better on dark back roads (thus high beams) ..... Fog lights are LOW and short range, not made for this reason (
unless you have them aimed improperly). You should avoid driving in REAL FOG and park the car. Other wise slow way down.
HERE IS THE TRUTH.... DON'T DRIVE IN FOG IF YOU CAN HELP IT.... Fog lights are of LIMITED use in fog or other wise, since all light reflects off the water vapor.... Take it from me, I land +200,000lb jets in very low visibility, in all light conditions, at +130 kts (150 mph). The ONLY thing that saves the day (or night) are RUNWAY LIGHTS, approach, threshold, center-line and runway lights. Same with cars; for most of us, we never drive at night even an hour after the sunset (when it is dark), because the streets are lit up all over suburbia. If you live in rural areas that is a different story. Do fog lights help when there is no fog and it is just dark? That is opinion, but I would rather my high beams. Of course HIGH beams need to be turned off for oncoming traffic.... However high beams + fog why not, if no one else is coming at you.
From California:
"Driving In The Fog
The best advice for driving in the fog is DON’T. You should consider postponing your trip until the fog clears. However, if you must drive, then drive slowly, turn on your windshield wipers, and use your low beam headlights. The light from the high beam headlights will reflect back and cause glare.
Never drive with just your parking or fog lights.
Increase your following distance and be prepared to stop "
Fog lights can help a LITTLE but are MORE so OTHERS can see you. If you can't see well down the road, as well along the side of the road.... you should get off the road and park. Some states have LAWS that govern FOG LIGHTS, and require FOG LIGHTS only be used on unlit roadways and in inclement weather.... Obviously common sense says if you have on coming traffic, conditions don't warrant the use of extra lights, turn them off. Some states have laws that say FOG LIGHTS should be treated some what like HIGH BEAMS. However if aimed low and down it should not be a big issue. HIGH BEAMS ARE A BIGGER ISSUE.
BOTTOM LINE IS FOG LIGHTS SPREAD A LOW LIGHT CLOSE TO THE GROUND, SO IN THEORY IT DOES NOT REFLECT OFF THE WATER VAPOR (FOG)..... They can't work miracles.
Here is another article from Volkswagen that explains when you should use fog lights:
"Fog lights are very useful to keep the road safe from vehicular accidents. As thick fogs dominate the road, high speed driving is very dangerous while low speed could subject other vehicles to collide on your rear.
To keep accidents from happening, the vehicles should be visible at all times. Fog lights should be turned on.
When is the right time to use the fog lights? Normal road visibility
should entitle you to see more than a hundred yard from where you are. If the road visibility drops from that, say less than a hundred, it is time to turn those additional lights on.
Rear fog lights on the other hand are used when the visibility is less than 50 yards. (AGAIN MORE BE SEEN THAN TO SEE AND YOU SHOULD NOT DRIVE IN THIS KIND OF LOW VIS IF AT ALL POSSIBLE.) But there is a main difference between the front and the rear fog light. Rear fog lights are usually a single red light as bright as a brake light. They are called fog lights because rarely does your visibility drop to such a dangerous level in normal rain or snow like it can in fog. "
I think an interesting and relevant thread drift is HOW TO AIM FOG LIGHTS!
