Polar stratospheric cloud

Polar stratospheric cloud
Antarctic stratospheric cloud (nacreous clouds)
AbbreviationPSC
Altitude15,000–25,000 m
(49,000–82,000 ft)
ClassificationOther
AppearanceGlowing brightly with vivid iridescent colors
PrecipitationNo
First documented appearance of a polar stratospheric cloud over Switzerland and Italy, seen from Brissago, Ticino, Switzerland
First documented appearance of a polar stratospheric cloud over Switzerland and Italy, seen from Brissago, Ticino, Switzerland on December 22, 2023

Polar stratospheric clouds (PSCs) are clouds in the winter polar stratosphere at altitudes of 15,000–25,000 m (49,000–82,000 ft). They are best observed during civil twilight, when the Sun is between 1 and 6 degrees below the horizon, as well as in winter and in more northerly latitudes.[1] One main type of PSC is made up mostly of supercooled droplets of water and nitric acid and is implicated in the formation of ozone holes.[2] The other main type consists only of ice crystals which are not harmful. This type of PSC is also referred to as nacreous (/ˈneɪkriəs/, from nacre, or mother of pearl, due to its iridescence).

  1. ^ Cite error: The named reference AAD was invoked but never defined (see the help page).
  2. ^ "Why is the ozone hole over Antarctica?". United States Environmental Protection Agency. Archived from the original on 2006-09-30.