Dust = Bad Snow and Bad Air

Yesterday's strong westerly and northwest winds ushered in the first major blowing dust event of the spring.  Here's a look at the dust accompanying the rather ill-defined cold front pushing into the Salt Lake Valley (courtesy George Wilkerson and Steve Krueger).

We will see that dust again later this spring.  It's been deposited now in the mountain snowpack and will rise to the top, along with other impurities, as the snowpack melts.  Because dust is darker than pristine snow, it absorbs more sunlight, and thus it's presence accelerates the snowmelt in the spring.  

The dust also degrades air quality.  Note the spike in hourly PM2.5 concentrations to 33.5 ug/m3 yesterday morning.  Ick.

Source: Utah Division of Air Quality

Although many believe that these dust storms are natural events, they clearly have a strong human-caused component.  The bulk of the evidence suggests that the western U.S. is a far dustier place today than it was prior to western settlement (although not as dusty as it was prior to the passage and implementation of the Taylor Grazing Act).  Most desert surfaces are very resistant to dust emissions unless they are disturbed, and many areas of the west are highly disturbed.  Thus, I view these dust storms as unnatural events, or at least human enhanced, as many dust sources are the result of land-surface disturbance.