The classic 1964 surfing documentary, The Endless Summer, followed the adventures of three surfers traveling from Malibu to Ghana, via Nigeria, Australia, New Zealand, Tahiti, and Hawaii in search of the perfect wave. Cloudspotters can experience their own perfect wave too, without ever having to leave home – all they need is a lot of patience. The only down side to the ultimate aerial breaker, is that it has the particularly un-hip name of the ‘Kelvin-Helmholtz cloud’.

The breaking waveforms of ‘Kelv-Helmz’ (as they aren’t known) are the result of shearing winds up at cloud level. A particular type of turbulence can develop in a layer of Cirrus cloud, which happens to form below an inversion* between air currents of differing speeds and/or directions. Sea waves break as their bases are slowed down upon reaching shallow water and their crests surge ahead. Cloud waves break in the same way: when their crests are pushed ahead of their troughs by the difference in air currents.

Though spotter-dudes won’t have to cross the world to see this formation, those in search of the perfect Kelvin-Helmholtz will have to wait a while. This most beautiful and transient of formations may appear over most regions of the world but it only ever does so on the rarest of occasions.

*An inversion is a region where air temperatures change with altitude in such a way as to act as an invisible ‘ceiling’ that stops clouds from rising through it.

Current Cloud of the Month:
September 2010

Previous Clouds of the Month:
August 2010
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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