From Red Orbit (Cheryl Dybas):
“More than 80 percent of sunlight falling on fresh snow is reflected back to space,” says Tom Painter, Director of the University of Utah’s Snow Optics Laboratory. “But sprinkle some dark particles on the snow and that number drops dramatically.”
That’s exactly what’s happening in Colorado’s high peaks. When the winds are right and the desert is dry, dust blows eastward from the semi-arid regions of the U.S. Southwest. In a dust-up, Western style, small dark particles of the dust fall on Colorado’s pristine white snowfields. “The darker dust absorbs sunlight, reducing the amount of reflected light and in turn warming the now ‘dirty’ snow surface,” says scientist Chris Landry, Director of the Center for Snow and Avalanche Studies (CSAS) in Silverton, Colo.
Painter’s and Landry’s research on dust-on-snow events, as they’re called, is supported by the National Science Foundation’s (NSF) division of Atmospheric and Geospace Sciences, which is part of the directorate for geosciences.