gray clouds billow across angry sky

alarming altrostratus angry appear atmosphere backdrop background begin billow billowing brighter brooding brown cloud clouds color condensation cottony cover cumulonimbus cumulostratus cumulus cycle dark darkening design doom droplets fire firestorm forbidding forest gray green grey heavenly heavens hostile impending inclement low malignant mammatus mass menacing nature negative particulates patches patterns pollution portend pressure rain refraction seraphic sinister skies sky skyward smoke smokey smoky space storm stormy stratus system texture thunderstorms upward upwards visibility water wild