When dressing up for the evening, there is always the danger of overdoing things. Tonight, Washington’s Mount Rainer – clearly eager to make an impression – has decided that the classic mountain look of a single ‘cap cloud’ perched upon her summit is not dramatic enough. She’s gone and made the fashion faux-pas of opting for a pair of them.

Cap clouds, like their lenticularis cousins (see Cloud of the Month for April ’05), are known as ‘orographic clouds’. This means that they form when air cools as it rises to pass over an obstruction such a mountain. If the airstream is moist enough, such cooling can cause droplets to form and appear as a cloud – it is much like breath becoming visible as it mixes with the air on a cold morning. Two cap clouds can appear, one above the other, when the airstream consists of layers of moist air, separated by a drier one.

Mount Rainer’s sense of restraint will surely have returned by tomorrow. And in time, like the rest of us, she’ll doubtless muse upon the sartorial choices of days gone by, and gently blush in the honeyed rays of the setting sun.

Current Cloud of the Month:
August 2010

Previous Clouds of the Month:
July 2010
June 2010
May 2010
April 2010
March 2010
February 2010
January 2010
Cloud Reflections (December 09)
Numbers in the Clouds (November 09)
Sun Pillar (October 09)
Convection Clouds (September 09)
‘Pile d’Assiettes’ (August 09)
Cumulus congestus (July 09)
‘Asperatus’ (June 09)
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)
Stratus (March ’05)
Cumulonimbus (February ’05)
Contrails (January ’05)


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