| Cirrocumulus lacunosus | |
| Image Location: | File:2023-07-22 - Cirrocumulus lacunosus - solitary cloud - zenith - DSG1929-11 - crop mid right.jpg |
| Image Name: | Cirrocumulus lacunosus cloud 07/2023 (view explanatory annotations) (view image of whole cloud, with further annotations) |
| Abbreviation: | Cc la |
| Symbol: | Clouds CH 9.svg |
| Genus: | Cirro- (curl) -cumulus (heaped) |
| Variety: | lacunosus (full of gaps) |
| Altitude M: | Above 6,000 |
| Altitude Ft: | Above 20,000 |
| Appearance: | Perforated with round, frayed holes[1] [2] |
| Precipitation: | Virga only |
Cirrocumulus lacunosus, also known as Cirrocumulus lacunar or Cirrocumulus lacunaris,[3] is a variety of cirrocumulus cloud. The term lacunosus is from Latin, meaning "full of hollows".[4]
Cirrocumulus lacunosus is a relatively rare cloud form that occurs as a cloud layer with circular gaps or holes in it. Formation is commonly attributed to a cool layer of air mixing with an overlying, warmer atmospheric layer, with each downflow of air creating an individual gap.[5] [6] These gaps normally have frayed edges, and are often arranged in a manner that resembles a net or a honeycomb.[7] [8]
Lacunosus must not be confused with the superficially similar cloud form cavum, a supplementary cloud feature also known as a fallstreak hole or as a hole punch. A fallstreak hole usually consists of one very large hole in a cloud layer combined with visible downdraft filaments in the centre, as opposed to 'lacunosus', which consists of a compact lattice or honeycomb of small to tiny holes.