Quote Originally Posted by RobbieDB
Yellow light has a longer wavelength so it can "stretch" over obstacles and you can see better/further. Snowplows and such use them in the snow because they can see better and it doesn't reflect as bad.

My 91 Prelude came stock with yellow fogs lights, and I wouldn't have traded them for anything when I had that car. If you'll notice when you're using the yellow light, the objects you're looking at have more clarity.

I wouldn't instantly throw the "JDM" stick at the yellow fogs either. Someone above showed that Euro cars have been using them since the 60's/70's. They just produce a better light for fog lights. I almost believe that white fogs barely do much at all beyond look good.
You don't want to use yellow driving lights though unless your headlights are yellow as well...the two differant colors will really screw with your depth perception. Fog lights are generally a wider angle and close to the car so it's not a big deal.