Fog lights - the truth?

[ScubyRoo]

Ok so there I was crusin around in some dense melbourne fog this morning and I thought to myself, "damn, really should have bought those fog lights a few days ago". Then I remembered why I didn't buy them - because I was confused and had to research first.

The thought was planted by a fellow named Chris who is one of the staff at Autobarn in Frankston. He's always given me good advice so when he told me that yellow fog lights worked no better - in fact often worse - than white fog lights I was a little surprised... So I bought my driving lights instead

And now I finally have a day off so I've browsed the net and found some pretty interesting articles and web pages, all mostly answered by uni academic types... and the conclusion by all of the them:

YELLOW LIGHTS ARE NO BETTER!!!!

In fact, because most of these yellow lights use filters, you actually loose light intensity and thus penetration in the first place...

Please correct me if i'm wrong, but isn't the common assumption go that yellow lights penetrate better, or that there is less reflection off the fog than if we were using white?

Some points i've taken from my reading:

• The size of the water droplets in fog are too large to cause proper dispersion of light (which is what most say is what stops white light from penetrating) Dispersion happens on a far smaller scale, and the size of the water droplets in fog are too large to be affected by the different wavelengths of colours.
• Beam pattern and spread, along with positioning, play a much more important role in penetration in fog than the colour (the reflection that happens when you put your high beams on happens because of the pattern and direction, not colour).
• Fog lights are not driving lights - they are not designed to enable you to see a long way through fog. They are designed (or should be designed) to spread a downward angled beam that illuminates to the front and side of the car that enables to you to seen when you otherwise would not. They are designed to be used at low speeds in very poor conditions.
• It is illegal to use fog lights in fair conditions*.

Certainly food for thought!



The websites I used:
Good for the conclusions: http://www.gi.alaska.edu/ScienceForum/ASF5/593.html
Dr. Karl is the best: http://www.abc.net.au/science/k2/trek/s203318.htm
sciencey stuffhttp://www.madsci.org/posts/archives/19 ... .Ph.r.html
more sciencey stuffhttp://www.newton.dep.anl.gov/askasci/p ... y99xx4.htm
Good for a chuckle: http://www.caradvice.com.au/3119/fog-light-fury/
On legality? http://www.mynrma.com.au/cps/rde/xchg/m ... lights.htm
*Apparently they're legal in victoria, if they're aimed correctly:http://www.exploroz.com/Forum/Topic/353 ... e_day.aspx


Now for some more pennies so I can go get those fog lights.....

Owen.

[steptoe]

Some good research there.I have never used fog lights. I always thought white driving lights could still pierce the fog but it is our human eye that gets the white light reflected back at us. Try a pair of yellow or orange safety specs from safety shops. I've used both colours, and reckon they are on par with each other. You'll be surprised .

The reasoning behind the yellow and orange lens is to increase the contrast , and you will note Karl Sven Kruszelnicki says that fog has low contrast light.

[AlpineRaven]

I have to agree that yellow fog lights are the worst.
Really, the idea of using fog lights in the fog is to show other drivers and minimise reflection in the fog if you're using the headlight - that is the reason.

I use fog lights at the same time with headlights all the time because fog light provides light on the surface for at least 15-20metreas at the front, after that is the headlight's job.
My 2c worth
Cheers
AP

[Alex]

yeah as AP said, the yellow is more so other people can see you in the fog as the yellow light penetrates fog better than white light.

As a side note, very blue lights like HIDs etc absolutely suck in very very heavy rain and fog, just way too much reflection(as do high powered halogen spotlights)

alex

[subaruby]

As others have said the yellow fog is for other drivers to see you better.
My understanding is the the positon of the fog lights on the drivers car is more important than the colour.
Fog doesn't fall right to the road surface, there is a gap and the fog lights are designed to shine where this gap is, which avoids the light reflecting off the moisture (fog) in the air.
If you drive in fog then flick the high beams on all you get is a wall of white and you cant see anything.

[El_Freddo]

The thing that pisses me off about fog lights on later model vehicles is that they are used in-approriately - as in ALL the time their headlights are used, fog or no fog.

These fog lights are designed to get under the fog as subaruby has said. I have a few issues with driver's mis-use of their lights:

- slow/in-attention to dimming from high beam to low beam
- driving along a freeway in on-coming traffic without dimming to low beam
- those bloody fog lights that come out on all new 'above base' model vehicles used all the time.
- The latest vehicles have very powerful lights, even their low beam is stronger than my standard high beam...

I do have a set of reasonable driving lights on the front of my L as most of you have seen. I try to use these appropriately by only using them when there is no traffic in front of me, on-coming or otherwise. Its all about attention on the road, something that's lacking these days in my opinion.

End rant

Bennie

[steptoe]

i recall a rule of fog lights must only operate with park light circuit, but gues that also includes headlights

[Battlewagon]

Using your fog lights all the time is illegal. It'll get you a $75.00 fine. I know, I've been done for it. (Not in the battlewagon, but in the wife's commodore) Bloody Holdens......

[clarkey]

( i know this is an old post but eh....)

i would not really bother with fog lights, concidering that they are highly illegal (in wa anyway) dont know about rest of the state, but i have been pulled over many of times and threatened with a $200 dollar fine and two points , you are only permited to have them on if it is alot of fog and you can not have your head lights on, just park lights and fog lights.

Cheers Mike.

[coxy]

In NSW the fine is these days is $175.00 and I hate the clowns who use them incorrectly.
That being said I consider the fact that the Law is rarely enforced for such a visible offence is the ultimate in stupidity when society needs the Police being respected or feared (your choice) to have an effective and safe society for all.
I have spent more time in fog than most driving down the F6 to the Southern Highlands and the biggest problem in fog is the Idiots in Prado's and Territories driving well above prudent speeds because they have fog lights and think they are safe in a big vehicle.
Statistically these heavy vehicles crush the roof when they fall over leading to the occupants having spinal or neck injuries and the obvious that follows that,so much for being safe in a big vehicle.
Fog lights are useful in limited circumstances but for most are simply a "hey look at me factor" that guarantee's to all around you that you are truly a wanker when used inappropriately.

[tex]

yeah as AP said, the yellow is more so other people can see you in the fog as the yellow light penetrates fog better than white light.

As a side note, very blue lights like HIDs etc absolutely suck in very very heavy rain and fog, just way too much reflection(as do high powered halogen spotlights)

alex

I will testify to this I have HIDs in my outback and so use the factory fog/cornering lights with their standard (yellowish) bulbs in the fog and heavy dust!
Although at one stage there was someone down here selling bulbs with a gold fillament Apparently they provided an extra yellow light but at $50 each I don't know anyone who bought any!

But when I went to tech they had a big emphasis on colour spectrums for lighting!

[Alex]

Fog lights are useful in limited circumstances but for most are simply a "hey look at me factor" that guarantee's to all around you that you are truly a wanker when used inappropriately.

my foglights are never off. Ive never been told off and i will continue having them on until i get told otherwse by the authorities.

and shesh, theyre just lights! as long as they arent blinding then i dont see any problem with them

alex

[RSR 555]

my foglights are never off. Ive never been told off and i will continue having them on until i get told otherwse by the authorities.

and shesh, theyre just lights! as long as they arent blinding then i dont see any problem with them

alex

Ooooo.. aren't we a big rebel :D:D

But you're just lucky as the law states only 1 set of white forward lights are to be on at one time.