(Click image to enlarge) (Image © Gill and Peter Smith)
Most clouds are happy to coexist within the lower region of the atmosphere, known as the ‘troposphere’. Nacreous clouds, however, like to be a little different. They form in the rarefied heights of the stratosphere, and look down on the troposphere – what an obvious place it is for a cloud to exist.
Also known as mother-of-pearl clouds, Nacreous usually appear between 10 and 20 miles up, in the higher-latitude parts of the world. They are the most colourful-looking clouds, exhibiting refined and delicate pastel hues*, just as one would expect from such lofty individuals.
It seems these clouds are caused by waves of air penetrating the stratosphere, due to the effect of mountain ranges all the way down on the surface. They only tend to be spotted just before dawn and after dusk, when the lower sky is in shadow and the stratosphere is still lit up.
‘Let those common clouds jostle for people’s attention during the day,’ they no doubt whisper to each other.‘We would never lower ourselves to compete on such a overcrowded stage.’
Current Cloud of the Month:
‘Asperatus’ (June 09)
Previous Clouds of the Month:
Clouds at Night (May 09)
Sundogs (April 09)
Diamond Dust (March 09)
Cloud Streets (February 09)
Crepuscular Rays (Jan 09)
Valley Fog (December 08)
Cloud Shadows (November 08)
Contrails (October 08)
Mamma (September 08)
Kármán Vortex (August 08)
The Summertime Halo (July 08)
The Nor’west Arch (June 08)
Microbursts (May 08)
Irridescent Clouds (April 08)
Northern Lights – Aurora Borealis (March 08)
Ice halos (February 08)
Lightning (January 08)
Roll Cloud (December 07)
Banner Cloud (November 07)
Stratocumulus (October 07)
The Unclassified Cloud (September 07)
Alexander’s Dark Band (August 07)
Fumulus Snail (July 07)
Distrail (June 07)
Altocumulus undulatus (May 07)
Cumulonimbus capillatus (April 07)
Lacunosus (March 07)
Horseshoe Vortex Cloud (February 07)
Jet-Stream Cirrus (Janurary 07)
Altostratus/Altocumulus/Altowhateveritis (December 06)
Anti-Crepuscular Rays (November 06)
Stratocumulus (October 06)
Altocumulus (September ’06)
The Kelvin-Helmholtz Wave Cloud (August ’06)
The ‘Brocken Spectre’ (July ’06)
‘Whale’s Mouth’ (June ’06)
Noctilucent (May ’06)
Cirrus (April ’06)
Cap Cloud (March ’06)
Fallstreak Holes (February ’06)
Nacreous (January ’06)
Cirrostratus (December ’05)
Tuba (November ’05)
Virga (October ’05)
Cirrocumulus (September ’05)
Altostratus (August ’05)
Cumulus (July ’05)
Mamma (June ’05)
Pileus (May ’05)
Lenticularis (April ’05)
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