Polar stratospheric cloud | |
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![]() Antarctic stratospheric cloud (nacreous clouds) | |
Abbreviation | PSC |
Altitude | 15,000–25,000 m (49,000–82,000 ft) |
Classification | Other |
Appearance | Glowing brightly with vivid iridescent colors |
Precipitation | No |
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).
AAD
was invoked but never defined (see the help page).