|"The Fog" (1980)|
|Downtown from the Avenues Foothills @ 3:15 PM MST 2 January 2013|
The decline is not only visually apparent, but also evident as a very dramatic and large increase in PM2.5 concentrations at the real-time sensor at Hawthorne Elementary School.
The reason why the air pollution won't die appears to be fairly simple: The Great Salt Lake. During the day, the lake is relatively cold and the air over the lake is relatively cold. As a result, the inversion tends to be strongest and mixing tends to be weakest over the lake. During the day, the airmass over the lake typically penetrates into the Salt Lake Valley, bringing along with it all that nastiness. The leading edge of this airmass is called a lake-breeze front. Today, the lake breeze front was accompanied by the huge spike in PM2.5 and, as shown below, a slight drop in temperature, shift in wind to WNW, and an increase in wind speed to about 5 miles per hour.
|Source: Utah Division of Air Quality|
|Temperature, humidity, and wind traces at Hawthorne Elementary|