Height of base:

above 5000 to 15000 m (16,500 – 45,000 ft) (high-level clouds)

Description:

Small heaps

 white or bluish

 no shading

 less than 1º across (less than 1 finger wide at 30º above horizon)

Occurrence:

World-wide

Made of:

Supercooled water droplets, ice crystals

Precipitation:

None

Formation:

Transition between Ci and Cs, transient

Species:

Stratiformis, lenticularis, castellanus. floccus

Varieties:

Undulatus, lacunosus

How to distinguish from …

Altocumulus (Ac)

Ac cloudlets are larger than one finger’s width at outstretched arm 30º above horizon

Cloudlets of Cc have no shading

Cirrus and cirrostratus (Ci, Cs)

Cc elements are grain-like, not fibrous

Cirrocumulus

Morris, Feb 06

Cirrocumulus floccus

Morris, Dec07

Cirrocumulus stratiformis

(no shading!)

Morris, Jan 2008

Cirrocumulus above stratocumulus,

in advance of incoming warmfront from SW,

Morris, June2008

Same as left, 10 minutes later; notice

Undulatus edges