Washington Post: Also critical is the snow's "albedo,' or reflective quality, which dictates how much sunlight it absorbs and helps determine how quickly it will turn to water. Albedo varies considerably; freshly fallen snow reflects 90 percent of the sunlight that hits it, while older snow, which forms larger crystals, reflects only 60 percent. Dust and black carbon carried to the snowpack by winds also can change the percentage. The spectrometer measures that as well.
The information is fed into powerful computers...