| Cirrus | |
| Abbreviation | Ci |
| Family | A |
| Genus | Cirrus |
| Occurrence | Worldwide |
| Altitude | >5000m, in troposphere |
| Formation | Saturation of upper-level air mass |
| Precipitation | Virga may be produced |
| Potential Hazards | Indicates an approaching frontal system or decayed thunderstorm |
Cirrus (Ci; Latin for wisp of hair) is a genus of clouds characterized by occurrence in high altitudes and by appearing to consist of fibrous or wispy strands. Cirrus clouds are composed of millions of ice crystals blown into streaks by high-level winds, and they indicate the presence of moisture high in the troposphere.
Cirrus clouds were first described in 1802 by Luke Howard as "parallel, flexuous or diverging fibres extensible by increase in any or all directions."
Subtypes
- Cirrus catellanus
- Cirrus Kelvin-Helmholtz
- Cirrus with mammatus
| Clouds | |
|---|---|
| High Clouds (Family A): | Cirrus (Ci) • Cirrus aviaticus • Cirrus intortus • Cirrus radiatus • Cirrus uncinus • Cirrus Kelvin-Helmholtz • Cirrostratus (Cs) • Cirrocumulus (Cc) • Pileus • Contrail |
| Middle Clouds (Family B): | Altostratus (As) • Altostratus undulatus • Altocumulus (Ac) • Altocumulus undulatus • Altocumulus mackerel sky • Altocumulus castellanus • Altocumulus lenticularis |
| Low Clouds (Family C): | Stratus (St) • Orographic stratus • Fog • Nimbostratus (Ns) • Cumulus humilis (Cu) • Cumulus mediocris (Cu) • Stratocumulus (Sc) |
| Vertical Clouds (Family D): | Cumulonimbus (Cb) • Cumulonimbus incus • Cumulonimbus calvus • Cumulonimbus with mammatus • Cumulus congestus • Cumulus castellanus • Pyrocumulus • Pyrocumulonimbus |