Interesting study —

Why yellow

The use of yellow or amber light in fog lights is based on the belief that yellow light is less likely to cause glare in foggy conditions and can improve visibility compared to white or blue light. Here’s why:

1. Reduced Glare: The main reason for choosing yellow light is its perceived ability to reduce glare. In foggy conditions, light can be scattered by the water droplets in the air. Yellow light, with its longer wavelength, is thought to scatter less than blue or white light, which have shorter wavelengths. This reduced scattering can result in less glare, making it easier for drivers to see.
2. Better Contrast: Some people believe that yellow light can enhance contrast in certain weather conditions, making it easier to discern objects and obstacles on the road. This is partly due to the fact that the human eye can sometimes process contrasts and outlines more effectively under yellow light.
3. Historical Preference: The preference for yellow fog lights also has historical roots. In the past, when headlight technology was less advanced, yellow light was more effective under foggy conditions. Although modern lighting technology has reduced this advantage, the preference for yellow in fog lights has persisted in some regions and brands.

However, it’s important to note that recent studies and advancements in lighting technology have challenged the superiority of yellow light for fog lights. Modern white LED lights, for instance, are highly effective in cutting through fog while minimizing glare, leading to a shift away from yellow fog lights in many newer vehicles. The effectiveness of yellow versus white light in fog is an area where technology and preferences continue to evolve.

What do fog lights do?

Fog lights are effective in poor visibility conditions due to their unique design and placement on the vehicle:

1. Low Mounting Position: Fog lights are mounted lower on the vehicle, often near the bumper. This positioning is crucial because fog tends to hover above the ground. By shining light from a lower point, these lights illuminate the road beneath the fog, rather than the fog itself.
2. Beam Shape and Direction: Fog lights emit a wide, flat beam of light that is directed towards the ground at a sharp angle. This beam pattern is designed to avoid shining light directly into the fog, which would cause reflection and glare, impairing visibility. Instead, the light is directed downward to illuminate the road.
3. Light Color: Often, fog lights emit a yellow or amber light, which is believed to reduce glare and improve contrast in foggy conditions compared to the white light used in standard headlights. However, many modern vehicles also use white LED fog lights which are effective as well.
4. Intensity and Range: While they are bright, fog lights are not designed to illuminate as far as regular headlights. Their intensity and range are calibrated to provide enough light to see the immediate road ahead without creating a strong reflection off the fog.

These features combine to help drivers see the road surface and markings more clearly in challenging conditions, improving safety. However, it’s important to use fog lights correctly, only in low-visibility situations, as their intensity can be blinding to other drivers in clear conditions.