4.2.4 Dust

New event: Dust

Six days after the initial snowfall, a dust storm sweeps across the region. Dust storms are created by very strong low-level winds moving across arid regions. The dust moves downstream in the atmosphere and resettles on snowpack when the wind speed decreases or the dust particles are scoured out by precipitation. Scouring is a process in which precipitating ice or water particles collide with other airborne particles, such as dust. These particles are carried along with the precipitation down to the ground.

Dust deposition evident on the snowpack near Fremont Pass, Colorado, May 2009

As you can see, dust discolors the top of snowpack. What impact would you expect this to have on the albedo of the pack? Select the correct answer, then click Done.

The correct answer is c.

If the dust is not covered by additional clean snow, it will significantly reduce the albedo of the snowpack, causing the top of the pack to melt significantly during daytime. In fact, general springtime snowmelt speeds up significantly when “dirty” snow is present.