photos by mike hollingshead in oklahoma of mammatus clouds, which are formed when air laden with big water droplets is carried to the top of a thunderstorm cloud whose altitude is cold enough to freeze the water droplets. the resulting crystals sink back down towards the earth, collecting at the base of the cloud before they have time to evaporate. mammatus clouds are usually only stable for a few minutes. (see also: previous cloud posts)

images by seb janiak, which he creates by layering several photos on top of each other. (see also: previous cloud posts)

circumhorizontal arcs photographed by (click pic) david england, andy cripe, del zane, todd sackmann and brandon rios. this atmospheric phenomenon, otherwise known as a fire rainbow, is created when light from a sun that is at least 58 degrees above the horizon passes through the hexagonal ice crystals that form cirrus clouds which, because of quick cloud formation, have become horizontally aligned. (see also: previous cloud posts)

photos by (click pic) tim kemple (previously featured) and scotty rogers of the moab monkeys slacklining three thousand feet above rio de janeiro (see also: previous brasil posts)

photos by denis budkov of the 2012 tolbachik eruption in russia’s kamchatka peninsula (see also: previous volcanology posts)

"stormscapes" by nicolaus wegner in wyoming (see also: previous extreme weather posts)

photos by jeffrey sullivan around the border of california and nevada, which include those featuring lenticular clouds (3,6,9) and a time lapse of lighting from a cumulonimbus cloud (1). (see also: previous cloud posts and lightning posts)

yield to oncoming mesocyclones. photos by caleb elliott from tornado alley. (see also: previous extreme weather posts)

photos by franz schumacher in strohgaeu, germany. (see also: previous storm posts