I encountered some pretty heavy fog this past weekend while skiing, and my fog lights did not help a bit. Therefore, I will be purchasing a different set.

I know the purpose of fog lights are to illuminate the road in foggy conditions, but is the purpose to
1. Cut through the fog
2. or, to illuminate the road UNDER the fog.
If the latter, I gather it would be best to mount the fog lights as low as possible.

Any other insight on the placement would be appreciated. Thanks.

yeah, you want them to be mounted as low as possible to shoot out under the fog. here's a pic of the patternn mine put out, i'm assuming your current ones (are they stock?) don't provide this kind of pattern/illumination

Yes, they are the stock ones. I noticed in some of the other threads that yours were the PIAA 90's. I really like them, but a bit out of my price range. I presently have mine mounted on a push bar that I recently installed. I think with the new ones, I will place back under the bumper.

Do you have fog lights or offroad lights? There is a difference.

Fog lights, like was said, are designed to shoot under the fog to give a better view of the road. Offroad lights are designed to give better lighting in offroad conditions than would be allowable on the street, and they are just as bad in fog/snow as normal headlights.

The purpose of fogs is to light the road and cut through the fog. The reason fogs are yellow is because the wavelength of yellow light allows the light to go around the fog particles. If you are driving down a dark foggy road and switch from driving lights to fogs you may not really notice a difference in visibility but the yellow light will travel further and therefore drivers coming the opposite way will see you earlier. Also, if you were to come upon a vehicle in front of you, you would see it earlier with fogs than with driving lights. Hope this helps.

Well, around here the fog is _on_ the road, there is no way you are going to shoot the light under it...so you got to get a light that will cut through it.

Also, I think the key is putting the fogs at the proper angle...they should be aimed a degree or two down toward the road; if they are angled flat or up too high, they will just spread the light around into the fog, and that won't do any good. A lot of stocker fog lights are just aimed flat and that's no good; they may be placed low on the truck to compensate, but there's no substitute for a fog that's both positioned low and angled down a little.

I bought some cheapo $17 fogs (because I have a tendency to get them broken all the time) and they cut through the fog just fine.

Yes, they are stock fog lights from Ford, but I have placed them in a non stock location on the push bar. I have them presently aimed slightly under my headlights at 25 ft from a garage door or wall, so as not to blind any oncoming drivers.

They really need to be as low as possible.

Good luck......

I think there's some confusion.
Fog lights don't literally shine under the fog.
Your normal lights are designed with a pretty broad pattern.
Because of this a lot of the light gets reflected off the fog and shines back into your eyes reducing your visibility.
Good fog lights are not only mount farther below your line of sight but are designed with a very sharp cutoff along the top edge of the light beam reducing glare.

The yellow light would help for the same reason the sky is blue.;)
Blue light is the shortest wavelength and so is more affected by refraction, meaning of all the light coming from the sun the blue gets bent around more and so appears to come from everywhere.
The same happens with light in fog but on a much smaller scale.
The yellow lights have less blue in them to scatter.
Using red lights would reduce glare even more.
But not only are red lights on the front of a vehicle illegal, you would see a lot less color and less detail.

The yellow may help you be seen. The yellow light does not help you see any better.
The projector fog lights are best for allowing the least light to be reflected back into the drivers eyes. Because of that they also dont light up as much of an area as the non-projectors. If you have such thick fog that you cant see the road you need projectors. Most any other conditions the wide/thin beam of standard fog lights will produce more useable light. The clear lensed multi surface reflectors usually put out more light than the ribbed lense fog lights. Assuming the same watt bulbs.
It just depends on your driving conditions and what you want the lights to do. No one set of lights is going to be right for everyone.