(Click image to enlarge) (Image © Chris Dolley)
Wizened mariners pay careful heed to dramatic displays of the cirrocumulus cloud, which they refered to as a mackerel sky. It can be a precursor of storms at sea, warning them to batten the hatches and stow the mainsal.
More often than not, however, this high cloud appears in less extensive patches – usually in the company of its relatives the cirrus and cirrostratus.
The term mackerel sky is often erroneously used to refer to this cloud’s lower cousin, the altocumulus, whose elements, or ‘cloudlets’, are larger. Cloudspotters can distinguish the two by a simple rule of thumb. If the cloudlets directly above appear smaller than the width of a finger held at arm’s length then they can be confident they are looking at a cirrocumulus.
Care should be taken with the use of this rule, however, for the cirrocumulus is a beautiful and uncommon cloud, to which cloudspotters wouldn’t want to give the impression that they are making a rude gesture.
Current Cloud of the Month:
Microbursts (May 08)
Previous Clouds of the Month:
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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