98Expy5-0, as for yellow being better than white, yes, it is slightly better. It has to do with the reflection that white light has inside of the water droplets. Since white light is the summation of all colors of light, you tend to get more flection. Where the yellow light is just that, yellow light. Inside the water, the light is reflected differently due to the different wavelength of light.
As for 3000K bulbs being the brightest, that is partially true. Actually, if you look, 4300K bulbs are the brightest with 3000K and 5000K bulbs being second brightest for a given wattage bulb. So, going with 3000K bulbs is a good thing if you are looking for maximum light.
THe big thing with fog lights is to keep them as low to the ground as possible. The reasoning behind this is you are trying to shoot the light under the fog (if you look, it normally hovers just above the ground) and then you can get the light to reflect back at that point off of any object in front of you. This gives you the ability to see farther in the fog. Get the lights up too high and all you are doing is putting more light for the fog to reflect back at you, in a lot of cases, making it all the more difficult to see. You want to prove this to yourself, when in fog (and no one in front of you), turn on your high beams and see how far you can now see. You will find out that the distance will drop dramatically.
