Hey guys I've been looking into buying some driving/fog lights and everywhere I go it gives me the option of Yellow len or White len. Which is the best? What advantages/disadvantages does each have? I live in Indiana so we don't really have too much fog, I'm just going to use them for offroading and driving in the country. Would appreciate some info.

 

Supposedly yellow lights are better in fog. I've never had yellow lights though, so I can't vouch for that. We have A LOT of fog around here and I've never had a problem with white lights.
Since you don't have much fog I wouldn't be too worried about it. Go with your personal preference. I'd recommend the white ones if you're just using them for the trail. It will provide better light when out in the back country.

 

The yellow means nothing. The old adage that yellow lights cut the fog is false.
Get what ever you like better. I would suggest a clear lens for the best lighting.

 

In skiing, I found my amber lenses would give MUCH better definition to the surface than my clear lenses in both day and night skiing. At night, it would depend on where we were (lighting color differences slope to slope).

In fog/driving lights, I have found the same to be true. Yellow light does not cut through the fog better, rather, it does not refract off the fog as much as light with more of a blue hue.

Blue light is known to reflect/refract off of things more. It will tend to glare back at you from any reflective surface and serve to obscure said surface, hiding detail.

As with anything, it is all up to what you like.

 

swartlkk is correct. the yellow (sometimes even amber) lenses don't refract light as severe as the blue spectrum of light (white light). this is why "fog" lights have traditionally been yellow. but with newer lens technology, the use of clear lenses, is becoming more popular.
if you're using them for mostly trail lighting, go with a "flood" patterened light. either way, it sounds like you're looking for a clear lens on whatever light you buy.

 

First I'll give you the wrong explanation, which you can find here and there. It goes something like this. As everyone knows, scattering (by anything) is always greater at the shortwavelength end of the visible spectrum than at the longwavelength end. Lord Rayleigh showed this, didn't he? Thus to obtain the greatest penentration of light through fog, you should use the longest wavelength possible. Red is obviously unsuitable because it is used for stop lights. So you compromise and use yellow instead.


This explanation is flawed for more than one reason. Fog droplets are, on average, smaller than cloud droplets, but they still are huge compared with the wavelengths of visible light. Thus scattering of such light by fog is essentially wavelength independent. Unfortunately, many people learn (without caveats) Rayleigh's scattering law and then assume that it applies to everything. They did not learn that this law is limited to scatterers small compared with the wavelength and at wavelengths far from strong absorption.


The second flaw is that in order to get yellow light in the first place you need a filter. Note that yellow fog lights were in use when the only available headlights were incandescent lamps. If you place a filter over a white headlight, you get less transmitted light, and there goes your increased penetration down the drain.


There are two possible explanations for yellow fog lights. One is that the first designers of such lights were mislead because they did not understand the limitations of Rayleigh's scattering law and did not know the size distribution of fog droplets. The other explanation is that someone deemed it desirable to make fog lights yellow as a way of signalling to other drivers that visibility is poor and thus caution is in order.


Designers of headlights have known for a long time that there is no magic color that gives great penetration. I have an article from the Journal of Scientific Instruments published in October 1938 (Vol. XV, pp. 317-322). The article is by J. H. Nelson and is entitled "Optics of headlights". The penultimate section in this paper is on "fog lamps". Nelson notes that "there is almost complete agreement among designers of fog lamps, and this agreement is in most cases extended to the colour of the light to be used. Although there are still many lamps on the road using yellow light, it seems to be becoming recognized that there is no filter, which, when placed in front of a lamp, will improve the penetration power of that lamp."


This was written 60 some years ago. Its author uses a few words ("seem", "becoming recognized") indicating that perhaps at one time lamp designers thought that yellow lights had greater penetrating power. And it may be that because of this the first fog lamps were yellow. Once the practice of making such lamps yellow began it just continued because of custom.

 

So, what does that "explanation" actually explain? For the first part, it assumes that filters are used instead of light color being manipulated by the design of the filament. True, the author is asking about white vs yellow lenses. For this, I would stick with the clear lens since halogen output is a lower color temperature (more of a yellow hue) anyway. White light using regular incandescent bulbs is produced by way of a filter so in that thought, your quoted text above would favor true unfiltered halogen output over the "white" halogen bulbs.

Now, lets look at the second part. Look back at my reasoning for choosing a lower color temperature. This comes down to what you have in terms of bulbs to choose from. With HID bulbs, the color temperature is controlled by the bulb itself and is modified without the use of filters. In this case, for driving/fog lights, for better definition on the road surface in these inclement conditions, a lower color temperature would be more appropriate.

My explanation was based on my direct experiences on the subject which are collaborated by many people regardless of what theory states. I never stated that yellow light cuts through fog better than while or blue light, actually quite the contrary. When you are dealing with road surfaces during inclement weather, in my experience, a lower color temperature light will give better surface definition (provided that the overall lumen output is the same bulb to bulb). That is where the whole wavelength thing comes in.

 

I was not zeroing in on any one members post here, the explanation was aimed at what is known about the technology that has been common in automotive usage. With the emerging HID scene, things are changing rapidly.
I apologize if it seemed that way. We all know how well the internet conveys ideas... sometimes it is clear as mud.
I am with you guys completely on the fact that the color has everything to do with making the correct choice of lighting for a particular use. Like mentioned by most here, a whiter light is probably best for the OP's situation. Especially since he stated that they rarely have fog.

 

wow! and my wife thinks i make long winded explanations Brent. i'm refering to the author of the article you quoted of course, not yourself.

by the way, luv your new sig.

 

i have yellow fogs along with blue hids and i don't notice a difference with better visibility with the yellow vs the white/reg bulb