In fact using 3000 K for fogs is erroneous as well. You may think you see better with yellow light, but this is likely an illusion. See this thread and the posts by
PMD for more information:
Link. That poor man tried so hard to get the point across.
There are pros and cons to using yellow lights for fogs.... The bright side to yellow is that it is reflected more uniformly than a white light which is actually a combination of several different colors on the spectrum, well more so than yellow at least. Yellow is also good for high contrasting, however, you are reducing your light. Still, yellow has its uses in reduced visibility situations like fog. Any other time, it is completely useless and reducing the amount of visible light a light is producing, plus it adds to eye strain. Though, I will note that I tend to disagree with some of what he has said.... my understanding of optics leads me to a very slightly different conclusion.... Though, I will admit, he is probably on to something when he is talking about the cones/rods and our perception of light.... biology is not my strong suit, so while I can do the physics of optics, I am generally working on considerations that are under an ideal, and not accounting for the shift in human perception that accompanies night vision.... However, I still believe yellow is better for fog because of how water droplets can diffuse and reflect light. Same reason our sky is blue. Light in different wavelengths is reflected/diffused differently by water.
Either way, silly to use HIDs in fogs, because a fog is by nature not supposed to produce incredibly silly amounts of light.
On to another statement. I have nothing against HIDs, I just hate cheap HID retros that just replace the stock bulb in a housing that is not designed for that amount of lumens. I also hate when people are using a bulb that produces light in a different location than the reflector is designed for. Reflectors aren't just a bowl to point light forward. Serious engineering goes into these optics. Manufacturers determine the candela (brightness in specific directions) of a bulb and design reflectors that put certain amounts of light in the direction they need it. Fluting to the back of the reflector or to the lens aids in directing or diffusing light in whatever direction they want it to go.
When you use an HID, you are putting something into the housing that creates an insane amount of lumens compared to the original bulb. Plus, every candela the bulb creates is of a higher magnitude and in a completely different location and direction (unless you find an HID that is creating light at the exact same position as a stock bulb, which, well you cannot). A housing designed for a halogen bulb can NEVER properly direct the light produced because the light is not being distributed in the same directions or intensity. No amount of aiming your headlight can correct this, and, as I have told you before, if you disagree, I welcome you to post up pics of your beam pattern on a wall from 25 feet away. HIDs only kinda work in some aftermarket clear housings even because most aftermarket housings are not designed with correct optics in mind, therefore they primarily function as a spotlight with a little spread (usually side to side), which gives a half passable (but nowhere near good) pattern when using an HID bulb since the HID can produce enough light to compensate for bad optics.
The only thing an improper retrofit tells me when I see them is that the owner is too poor to afford a proper retrofit, or lacks the skills to do the work himself. I put HID retrofit bulbs approximately on the same level as those whistlers you can put in your exhaust pipe to make the turbo sound, edelbrock stickers on a Hyundai with a body kit, big chrome intakes or tiny factory drum brakes that are exposed by large lightweight "racing" wheels. It also tells me that the owner is ONLY concerned with the appearance of their vehicle and damn the other drivers.
Using light in a color other than 4100-4500k also shows that you are only concerned with appearance and not light output, since anything above or below that color temperature is reducing the amount of light just to give a "better" color to your lights. By the way, I'd LOVE to compare your white lights to white lights some time.....
By the way, I have been all over long island.... nowhere in long island is THAT dark. I'm not saying it is lit well enough you can drive around with headlights, but there is a TON of ambient light there. Come out to the northern plains some time and I will show you what dark is. Trust me, you will be amazed at the number of stars you can see in the sky when it gets this dark.