Thursday, November 20, 2014

Welcome back to the prolonged inversions and poor air quality

Air quality along the Wasatch Front has been getting worse the last few days. Salt Lake City is the winter home of temperature inversions and bad air. And this is just be beginning of the season. Below are shown measurements of PM 2.5 (Particulate Matter smaller 2.5 micrometers in size).
The air is not super unhealthy yet, but the pollution concentration is increasing. You may have noticed the decreased visibility last time you tried looking at the mountains across the valley. This weekend a storm should blow all this gunk away before it gets much worse, but be prepared for more days like this and try to drive less during these inversion periods if you can.
November 19, 2014 @ 2:50 PM
Photo: kbkb
November 20, 2014 @3:30 PM
Source: WBB webcam
Above is another look at the smog today. The sun is beginning to set. The concentration of the smog actually looks worse due to the fact that we are looking in the direction of the sun. When particles scatter light, they always scatter with constructive interference in the forward direction, toward your eyes if you are looking toward the sun. This optical phenomenon makes the haze look brighter, making it seem there is more stuff in the air. But still, the air is dirty.
source: atmospheric radiation course notes

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