This photo of falling snow was taken during the "thundersnow" storm that blanketed Huntsville, Ala., and much of the Deep South. Taken on Jan. 10, 2011, at 10 p.m. CST, the image shows a reverse -- or negative -- images of snowflakes, meaning the white is background and the the black portions represent snow. Many of the particles are aggregates of "branched" and "needle" crystals. There are also "lumpier" particles with small spikes extending outward. In physics terms these shapes are named graupel or "graupel-like" snow.
Credit: NASA/MSFCWalt Petersen