Monday, January 19, 2009

Meteorology 101

Okay, basic physics: Hot air rises, and cold air falls. Typically, the higher in elevation you go, the colder the air gets, right? To escape the heat of a hot summer day, you head to the mountains, where it's cooler, right?

So, in a typical environment, the hot air near the surface of the planet rises, and as it does, it cools, which in turn makes the air fall (colder air is denser, but we've been over this already), so you get this stirring action (called convection) that keeps the air, shall we say, "fresh."

Well here in our high mountain valleys, it snows in the winter, which tends to keep the air around the ground area cold. Cold air falls, as we've discussed, but this air is already on the ground... so as warmer air aloft moves over us thanks to a nice "ridge" of high pressure, the cold air is trapped, because it's colder than the air above it, instead of warmer like it usually is (hence the term "inversion"). That was a long run on sentence, but if you read it a few times, you'll get what I mean -- if you're still awake at this point, that is.

Anyway, in this nice layer of colder air near the ground that's not going anywhere because it's colder than the air above it exist all the cars, factories, oil refineries, furnaces, fireplaces, etc. (and sublimating snow, which adds to the visibility issues), and since the usual convection isn't happening, all the particulates, pollution, water vapor from the snow, etc., just hangs in the air, and all of a sudden you have Salt Lake City doing its best Los Angeles impersonation, like this:

My point? You really don't want to be out running in that gunk if you value your lungs. So, I'm relegated to this:

*Sigh* 5 miles today. Here goes nothin'.

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