There is a story about the origin of yellow fog lights, possibly apochryphal, but entertaining, anyway. It's rumored that a Le Mans racer back in the 1920's was having problems with fog, and pasted newspaper over his headlights to cut down on the glare. The French newspapers at the time were printed on yellow paper (the origin of the term "yellow journalism") and apparently, the yellow light cut the fog effectively. The real reason was probably the refraction of the light as it went through the paper, but who knows for sure? This story apparently influenced headlight manufacturers to begin selling yellow-lens lights for fog driving.
Jerry
