Cirrocumulus stratiformis
Cc str
Cirrocumulus stratiformis
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Description
The name "stratiformis" (Latin: spread out in a layer) describes a cloud that appears as an extensive, flat layer or large field in the sky. Cirrocumulus stratiformis consists of tiny, regularly arranged cloud granules or platelets made of ice crystals, which form a continuous layer at high altitude, often covering large portions of the sky. This cloud type produces the classic "mackerel sky" pattern, in which numerous small, white cloud elements lie close together, creating a rippled or granular structure. The individual elements have an apparent diameter of less than one degree (roughly smaller than a little finger held at arm's length). Cirrocumulus stratiformis is the most common species of cirrocumulus and can be notable for iridescence or faint halo phenomena.
Identification Features
- Extensive, sheet-like field of very small, white cloud elements at high altitude
- Individual cloud elements have an apparent diameter of less than 1 degree
- Regular, granular or rippled pattern, typical "mackerel sky"
- Clouds are thin and largely translucent, with the sun shining through
- No significant shading on the undersides of the cloud elements
- Distinction from altocumulus: Cc elements are noticeably smaller and located at higher altitudes
- Occasional iridescence (shimmering colours) visible at the cloud edges
- Composed predominantly of ice crystals, but may also contain supercooled water droplets
Occurrence by genus
Highlighted: all genera with which stratiformis occurs.
Meteorological Significance
Cirrocumulus stratiformis indicates moisture and instability in the upper troposphere. Its appearance can be a precursor to an approaching frontal system, especially when cloud cover increases and transitions into lower clouds such as altostratus. When occurring in isolation and short-lived, however, cirrocumulus stratiformis has little prognostic significance and often indicates fair weather. In tropical regions, this cloud form can occasionally indicate the development of convective activity at altitude. As a pure ice cloud at high altitude, it produces no precipitation that reaches the ground.
Facts
- WMO-Code
- Cc str
- Height layer
- High clouds
- Typical height
- 5.5 - 12.0 km
- Genus
- CIRROCUMULUS