Cirrus duplicatus
Ci du
Cirrus duplicatus
© wetterkurs.ch
Description
The name "duplicatus" (Latin: doubled) refers to a variety in which cirrus clouds appear in at least two clearly superimposed layers. These delicate, ice-formed cloud bands or veils occur at slightly different altitudes and may partially overlap. The individual layers consist of ice crystals and appear as fine, fibrous, or hair-like structures in the sky. Cirrus duplicatus commonly forms when different wind currents prevail at various levels of the upper troposphere, each generating their own cirrus layer. This multi-layered arrangement is an indication of a complex vertical wind structure at high altitude.
Identification Features
- At least two clearly distinguishable, superimposed layers of cirrus clouds
- Fine, fibrous, or hair-like structure within each individual layer
- The layers may partially overlap, but remain recognizable as separate sheets
- White to silvery shimmering appearance, typical of ice clouds
- Individual layers may display different fiber orientations, caused by varying wind directions
- Best observed when the viewing angle is oblique to the cloud plane
- Frequently observed in combination with other cirrus species such as fibratus or uncinus
Occurrence by genus
Highlighted: all genera with which duplicatus occurs.
Meteorological Significance
Cirrus duplicatus indicates a layered structure of the upper troposphere, in which different air masses with varying wind speeds and directions glide above one another. This configuration can be an early sign of an approaching warm front or an advancing low-pressure system. If cloud cover increases over the following hours and thickens into cirrostratus, a deterioration in weather conditions can be expected within 12 to 24 hours. If, however, the cloud appears in isolation and subsequently dissipates, the weather often remains stable. The multi-layered arrangement also provides valuable information about jet stream activity and wind shear at altitude.
Facts
- WMO-Code
- Ci du
- Height layer
- High clouds
- Typical height
- 6.0 - 12.0 km
- Genus
- CIRRUS