Why Yellow Light Is Used in Fog

Why Yellow Light Is Used in Fog
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Having a vehicle is crucial for many people to get from place to place during their day, especially when there is no public transportation system.

Vehicles allow you to get to your job and go where you need to go. However, they also increase the amount of danger within your life.

Being in a car in harsh weather conditions such as snow, rain, and intense fog can increase your chances of a crash due to poor visibility. In order to prevent this from happening you need the proper lights in place to help your visibility and see as far as you can.

In fog you may notice that vehicles on the road use yellow lights. Why is this and why yellow light is used in fog?

We are going to dive into the answer to that question!

So Why Yellow Lights?

When it is really foggy out, why do cars and other vehicles on the road use yellow lights? Does it really make it that much easier to see?

It is crucial that fog lights are one color and one color only (rather than a usual headlight color of white, which is a bunch of colors). The reason is different wavelengths of colors hit droplets of fog differently.

This is dispersion, simply because the various shades within a color of light will leave one another, causing the image the light is hitting to disperse.

If you light up a foggy road with a light of just one color, the images you see in front of you will be a bit blurry because of the light hitting the fog, but this is much better than dispersion getting in your way using a color like white. Colors that have shorter wavelengths have the ability to scatter more light than colors with long wavelengths.

Our eyes are very sensitive to both yellow and green lights, so a yellow light has been chosen for people driving on the road in foggy conditions; yellow lights allow you to see the best distance in front of you during fog and it hits the fog in the best way.

So Why Yellow Lights

Yellow light bulbs used in fog also give you the highest amount of illumination while using the least electricity. This saves you money on gas, and it also extends the lifespan of the bulbs. 

Many people may wonder why the color yellow was chosen over red, as red really pops in a variety of parts of the car for visibility. The main reason is that red has already been chosen for brake lights.

In heavy fog, if another vehicle sees red lights they automatically will think it is break lights, and this can cause great confusion and can lead to accidents. Yellow lights are strictly used for fog situations, and for construction, so you can tell what is what on the road.

 Yellow lights are also known to have sharper contrast at night and allow more focus for the driver. This increases the safety around the car in a heavy fog.

Another theory that is increasingly popular is that yellow light actually decreases stress during stressful situations. Whether you are driving in snowy conditions or intense fog, yellow light is calming and does not add to driver fatigue if you’ve been driving for a long time.

This is especially true during darker winter months where you might have a lot of fog in front of you. Yellow is easy on the eyes, and also creates defining outlines of obstacles that may come in front of you in fog.

Not Perfect

Now with all that being said, having a yellow light used in fog is definitely not perfect at all. When you pass light through any colorized filter it reduce the light’s intensity.

White will always be the strongest light, but with a yellow filter in front, it reduces intensity by approximately 12 percent. While this is not much and the common eye but not even notice, it does decrease the amount you can see in front of you.


So now you know why yellow lights are used in fog. But your headlights will be useless if you have not gotten them checked in a while. Headlight bulbs frequently go out, and they dim over time and you may not even know it.

In order to ensure that your car is fully safe, always have a new set of bulbs on hand (both white and yellow).