(Click image to enlarge)
Photographed over Limekilns, Fife, Scotland © Dennis Cowan (see it in the gallery)
All clouds with ‘undulatus’ in their name have wave-like features to them. The name is derived from unda, the Latin word for a wave. Sometimes, they are in the form of a continuous layer with an undulating surface. Other times, they are like lines of cloud with gaps in between, as in this fine Altocumulus undulatus, spotted over Fife in Scotland.
It is the way the winds vary with altitude that tends to cause these formations. When blowing at different speeds above and below the cloud layer, the wind can cause the cloud to bunch up into ridges, which curve, join and divide, like the lines on your finger.
Of course, the shearing winds that cause undulatus clouds are never visible. You have to be a cloudspotter to know that they are there. Who else would recognise the enormous fingerprints they’ve left across the sky?
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)
To
contribute a Cloud of the Month,
go to our Photograph Submissions
page.
