Friday, January 22, 2010

Fog, Smog and Haze

For the past week, as I'm driving into school in the morning, when it hasn't been raining, it's been foggy. Now, I've driven through plenty of fog in the last 16 years, so if you'd asked me before this morning, I would have considered myself pretty fog savvy.

I'd have told you:

Fog is thick, dense-- pretty much clouds sitting on your road. So it comes in two colors: white, and gray. Right?

Smog, though I've never actually been in any that I can recall, is much like Fog, but man-made and made up from car exhaust and other air pollution. And somehow, I'm not seeing having avoided this particular phenomenon as a bad thing....

And Haze is like Fog, but thin. Not clouds on the road, but maybe just huge puddles evaporating-- you can see through that stuff, where Fog might mean you don't see the red light until you're slamming your breaks on (not that I've ever had to do that, but it's a great example.)

So today, I hop in my truck and start heading to school, and begin my traditional, "Oh. It's foggy." driving prep.

Head lights on: Check.
(Now that I know my truck has it) Fog lights on: Check.
Paying attention to my peripheral vision: Check.
Watching the "fog horizons" (That's the name I've given the furthest point you can see things. There are three. 1: the furthest you can ACTUALLY, clearly, see things. 2. the furthest you can still make things out. 3. the furthest you can see large shapes-- read "trees, buildings, etc." in the distance.) : Check

Now, as a side note on "fog horizons" I'd also like to mention the "vicarious fog horizon". This one can only be employed when there are other drivers on the road with you-- who are a) heading the same direction you are, and b) in front of you. When they're at the furthest edge of your ACTUAL fog horizon-- their actions and tail lights will give you advance warning for crap you just can't see yet-- but they can.

So, all my fog safety requirements taken care of, I begin the arduous, semi-tedious 45 minute drive north.

Not 5 minutes into it, I'm out of my mental fog (you know-- where your auto-pilot is starting to take over because you drive this road so often) like lightning and sitting up straighter in my seat actually looking AT the fog: I passed from fog being the traditional blue grey fog that I've known all my life-- to a lighter fog, that was peach orange in color! You can see farther in it. You can tell the sun was up and coming through it a little bit. I was fascinated!

During the entire drive to school, patches of fog alternated on the drive between the traditional dense blue gray fog, the also traditional white fog, and the new peach orange fog. It was almost surreal!

Wondering about it, I spent over an hour attempting to search fog color-- turns out there's a wealth of them.  (Particularly with the help of photoshop).

Anyway, after finding no real "This is why the fog outside was three different colors" answers, what I did find suggested that it was caused by a couple of things. First-- the density of the fog-- denser = gray blue. Not as dense, but still harder to see through= white. Hazy (and therefore really not dense at all, and why it was easier to see through) = the peach orange. Because the sun heating up the air is what makes the fog appear to lift, and the reflection of the light on the water particles that make up the fog/haze is what determines the color.

As to why I passed through multiple fields of each on the drive, I believe the explanation comes down to land vs. water. Where there was water-- be it lakes, streams, etc. would be the peach haze, as they were like the water evaporating off the the bodies of water. But the real fog was over the 'land' portions of my drive. All of this based on information from Argonne National Laboratory and USA Today.

The end result, of course, was a short lived, multi-colored fog that made my otherwise hum-drum drive a lot more interesting.

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