Friday, January 7, 2011

Fog, Stratus, and Smog. Oh My!

Living in Utah is quite a privilege, most of the time. But experiencing cold air pools like the present one is not the best of times. Everyone down in the Salt Lake Valley has been exposed to a mystery brew of fog, stratus, and smog for the past 24 hours. The composite image above was taken from the Suncrest development at the south end of the valley this evening. It's impossible to see anything down in the Valley, but the the Oquirrhs are in the distance to the left and Lone Peak is to the right.

We're now in day 7 of IOP-5 with ~30 hours to go. This event has had a number of unexpected features, but we're now locked into the most intense part of the event in terms of one measure of cold-air pools: the deficit in temperature air from a particular level would have if it was lifted upwards without exchanging heat to the level of the top of the Wasatch (~3000 m). The larger the deficit, the more negatively buoyant the air is, and the greater tendency for the air to sink back to its original level. The observed temperature deficits this morning of over 25 C are pretty impressive (the purple shades in the accompanying figure). These deficits and the cold air pool won't be wiped out until the next push of cold air begins to move in aloft Saturday night.

That'll usher in a welcome breath of fresh air.

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