dark sky by mammatus clouds in pouch-like s

above abstract atmosphere atmospheric background baggy bags blanket canopy cloud clouds clumping cluster colorless colourless cover covering cumulus dark darkening darkness dense distinctive dramatic drooping eerie firmament fluffy formation gray grey hanging harbingers layer lowangle lumpy mammary mammatocumulus mammatus meteorological monochrome mood natural nature ominous opaque oppressive overcast overhang pattern phenomena pouched pouches pressure rare scary scenery sky storm stormy structure texture thick thundercloud thunderhead thunderstorm turbulence twilight underside undulating unicolored vertical wallpaper weather horizon beyond celestial sphere brewing pouch-like