Fog lamps are extra lights on a vehicle, usually below the headlights, which are designed to make the road more visible in foggy conditions. They are rarely angled like the headlights; the lens being angled would make the fog lamps less effective. Some fog lights are set inward on the body, and some are mounted completely externally. The design that keeps the fog light lens flush with the body is the most common type produced on modern passenger cars, but the inset lights are also found on some models. Externally mounted fog lights are typically aftermarket additions, especially for extra bright versions that need to be cooled by passing air.
Fog Light Color
Optimally, fog lights will have a yellow tint, because it is the legal-for-public-road-use color that fog reflects off of water vapor the least. Blue tint and white lights are less effective, but are sometimes used anyway for aesthetic reasons. Having fog lights that emit a different color light than the headlights also helps light up objects ahead that the headlights haven't.
Fog Lights in Motorsports
Some racing cars, most frequently rally cars, have extra fog lights, which are above the headlights. This is because of the frequency of high-speed altitude changes they encounter. Some of the extras are also sometimes pointed away from the center, so the driver can see better around sharp corners, which have to be driven around quickly to remain competitive.
LED Fog Lights
LED fog lights are becoming more common and replacing incandescent fog light bulbs with LEDs is a common upgrade for older vehicles in need of improved lighting.