A blanket of white snow is extremely efficient at reflecting the sun's energy right back into space.
When soot and other dirt mixes with the snow, the sun's energy is soaked up by these tiny dark particles, melting snowpack quicker as compared to 'snowy white' snow.
According to Tom Painter from NASA's Jet Propulsion Laboratory and the University of California, Los Angeles "Dust on the snowpack of the Colorado River Basin can shorten the duration of snow cover by 21 to 51 days. Here's another way of thinking about this: if you want to get the same amount of sunlight absorbed by the clean snowpack, you would have to move that snow closer to the Sun than Venus."
Slow snowmelt is essential for the water resources of the western United States, including the Colorado River.
A slower melting process means more recharge for the aquifers as water soaks into the ground and the resulting runoff is more controlled.
Read more about this topic at Dusting the Virtues of Snow.
Also check out this story on how soot from the Industrial Revolution led to the quick retreat of glaciers in Europe.
7831 N. Business Park Drive