Have you ever looked down the road and seen a car in the distance with two yellow lights shining out of its bumper? Have you wondered what they are? Ever had the impression with some kits that it’s a UFO landing? 

It’s not. Those are fog lights – some built-in, some custom. Fog lights have been around for a long time, and many cars have them. But why do we use yellow fog lights instead of white ones? We’ll explain below.

So… What Are Fog Lights?

If you read any of our articles from our Fog Lights series, you know the drill: fog lights aren’t just used in foggy weather. They’re also valuable for snowstorms, rainstorms, and even misty night drives. 

These tiny yet efficient fog lamps are helpful when you want to see the road ahead but have low visibility conditions. The most common color for your typical fog light is yellow because it’s a more visible color in low lighting conditions.

Standard Yellow Lights for Standard Eyes

Why yellow? Yellow is the best color to be seen through the fog. This may sound like a no-brainer, but it actually isn’t. White light—the sort that may come from standard headlights -is less effective than yellow light in fog for several reasons. However, there’s more to the story than just having better visibility.

  • Yellow light is more visible to other drivers and pedestrians who might be in your path when driving through heavy fog on the road. 
  • Yellow lights are better for seeing animals that could dart out into traffic at any moment (think deer). 
  • White light reflects off of water vapor more easily than other colors do (red being an exception), if you’re driving behind someone with a white headlight setup instead of a yellow one, it’s harder for you to see what’s ahead of them without resorting to using your high beams or turning on emergency flashers yourself.
  • Fog lights tend to be yellow because they produce less glare than headlights do—and this helps reduce the risk of dazzling other drivers, keeping them from crashing into your car during poor weather conditions.

Some people may be surprised by this conclusion—after all, it’s counterintuitive to think that yellow light would be any brighter than white light—but the science behind it is sound: we perceive brightness first through our eyes’ rods (which detect black-and-white shades) rather than cones (which detect color). 

The more intense the stimulation of our rods by light waves hitting them from all directions at once will result in a brighter image being formed on our retinas; therefore, a yellow light source creates an impression of greater brightness and visibility compared with another color such as blue or green which stimulates fewer rods per unit area due to its narrower spectrum.

Don’t Shine Bright Like a Diamond

Fog lights are designed to be used in low visibility conditions, so they don’t need to be as bright as headlights. In fact, they shouldn’t be—fog lights can actually blind other drivers if they’re too bright! 

In addition to being brighter than regular headlights, fog lights are also typically yellow instead of white because yellow light has a shorter wavelength (and therefore higher energy), which makes it more visible in low-visibility conditions where your eyes have trouble picking out details.

If you ever find yourself wondering why most cars have yellow fog lights, this is why!

How Our Eyes Process Yellow

The reason why yellow fog lights are so popular is because of the way our eyes process light. The human retina contains three color-sensitive photoreceptor cells called cones, representing red, green, and blue. 

For clear weather conditions, each type of cone responds to a different part of the light spectrum: red at around 620 – 750 nm, green in the middle of that range at 550 nm, and blue at 450 – 495 nm. When it’s foggy out, or you’re driving through rain or snow (known as “zero visibility” conditions), some colors become impossible to see because they don’t reflect back towards your eye as much as others—which is why it looks like everything has turned grayish-white when there’s not enough light around you!

When it comes down to it, though… Yellow is just one color in this group with good visibility properties: dimmer lights such as orange and purple won’t look nearly as bright due to their lower energy efficiency; brighter ones like white or blue can hurt your eyes more easily than yellow does so again there’s less contrast between objects.

The Wavelength of Yellow Light

If you’re wondering why fog lights are usually yellow, that’s because they are the shortest wavelength visible to the human eye. If you recall from your high school science class, there are many different types of light and a bunch of different spectrums in which those types fall. 

Different colors have different wavelengths, with red having the longest and violet having the shortest. White light has all colors mixed together; blue has a shorter wavelength than red; yellow is somewhere in between—and it turns out that this is especially helpful when trying to see through foggy weather conditions.

Fog lights do their job by emitting more visible light than other kinds of headlights—and since yellow is at one end of this spectrum (with longer reds and violets on either side), it produces brighter visibility for drivers who need it most: folks driving through thick pea soup fog before sunrise or after sunset during winter months when low temperatures cause moisture droplets from clouds called aerial aerosols to condense into water droplets along with dust particles from roadsides.

The Most Visible Color in Foggy Weather

Yellow light is the shortest wavelength visible to the human eye. It has a wavelength of 580 nanometers (a nanometer is one-billionth of a meter), compared to 450 nanometers for blue and between 400 – 700 mm for white. This means that yellow light can be seen better than other colors or combinations of colors.

Moreover, according to some studies, yellow and amber are two of the most effective colors to use on vehicles when visibility is poor and you need to be seen by oncoming traffic.

What’s Better, White or Yellow Fog Lights?

It’s a common misconception that white fog lights are better than yellow ones. In fact, as we talked about already, yellow is much more visible because of its brightness and contrast against dark conditions. White light reflects off water droplets and fog before it reaches your eyes, which can make it harder to see than if you were looking at the same headlights through the clear air.

Still not convinced? Try this simple test: If you look down a straight road with a pair of white headlights shining toward your eyes, then look at a row of trees a few miles away with their leaves blowing in the wind…you’ll notice that it’s really hard to see them through those trees!

Conclusion

Fog lights are usually yellow because they are the most visible color in any weather. Why? Because if you’ve ever been driving behind someone with their headlights on, you may have noticed that the yellow light from their vehicle looks like it’s reflecting off of something in front of them—you know what I’m talking about. And now you know why most cars have yellow fog lights.