RT @SciencePorn: One of the rarest weather phenomena, Mammatus Clouds. Photo taken by John C. Olsen in Hastings, NE http://t.co/vdHGefOt4P
RT @SciencePorn: One of the rarest weather phenomena, Mammatus Clouds. Photo taken by John C. Olsen in Hastings, NE http://t.co/vdHGefOt4P