|Mountain Meteorology Lab on the east side of University of Utah Campus|
Located at the lab is a weather station and ceilometer. Ceilometers point a laser at the sky and measure light that is scattered back to the ground. Clouds do a really good job of scattering light, so ceilometers are generally used to identify where the bottom of clouds are. Particle pollution is also really good at scattering light, so we can use them to study inversions.
Below is wind data from the weather station at the Mountain Met Lab with the ceilometer backscatter for January 1, 2014. The more red the color the more light was scattered back to the ground, so we know there was more pollution in the air. We see the most pollution in the afternoon. This increase in pollution is correlated to the winds shift. In the afternoon the winds are light (3-4 mph) and blow from the southwest. This direction blows pollution from the valley up the slope into the foothills of campus, thus causing an increase in pollution on the University of Utah campus. In the evening and morning the winds are stronger and blow from the northeast which mixes out the boundary layer and brings clean mountain air to campus.
Another example from the next day, January 2, 2014, shows the same pattern