(Click image to enlarge) (Image © Clay Craig)
A ‘tuba’ is when a cloud extends a finger towards Earth. Young children often yearn to reach up and touch the soft mounds of a fair-weather Cumulus. So who can blame a cloud for wanting to know what the ground feels like?
It does have to get worked up into a vigorous spin, however, before it can summon the energy to do so. In and around the intense downdrafts associated with large Cumulonimbus and Cumulus congestus clouds, a vortex of swirling air can develop – like that of water draining down a plughole. The air in the center drops in pressure as a result of all the spinning, which can make it cool enough for some of its water vapour to combine into droplets.
Like the slender pair of swirling digits forming above, tuba are columns or cones of cloud extending down the middle of these vortices. They do not always end up reaching the surface, however. More often than not, the cloud loses heart before touching terra firma. Maybe it knows that, in another guise – on a different day – it will return as fog or mist, only to hug the ground until it is heartily sick of it.
Current Cloud of the Month:
March 2010
Previous Clouds of the Month:
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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