Nacreous clouds form when ozone depleting gasses freeze in the stratosphere.
From Ice Abstracts
Movie Poster "Spring"
Antarctica: A Year On Ice feature film.MoviePosterSpring27x40AntarcticaA Year On Icefeaturefilmnacreous
Nacreous or Polar Stratospheric Clouds being illuminated by the moon over McMurdo Sound Antarctica.
MoonPolarStratosphericcloudsnacreousstarsantarcticamcmurdoAnthonyPowell