Cumulus fractus
Cu fra
Cumulus fractus
© Wetterkurs.ch
Description
The name "fractus" (Latin: broken, torn) describes the characteristic appearance of this cloud: irregular, ragged cloud shreds with constantly changing shapes. Cumulus fractus are small, torn heap cloud fragments that frequently appear beneath larger cloud formations. They typically form through turbulent air movements near the ground or through evaporation processes at the edges of larger cumulus clouds. In contrast to stratus fractus, they have a clearly recognisable, albeit irregular, vertical extent and appear brighter and more billowy. They often occur during the dissipation phase of convective clouds or in freshening winds beneath rain clouds.
Identification Features
- Small, torn and ragged cloud fragments with irregular edges
- Constantly and rapidly changing shape due to wind influence and turbulence
- Noticeable, if limited, vertical extent (distinguishing feature from stratus fractus)
- Appear brighter and whiter than stratus fractus
- Frequently occur beneath larger cumulus or cumulonimbus clouds
- Often move quickly across the sky
- Can merge into larger cumulus forms as convection increases
- Individual shreds dissipate rapidly and reform elsewhere
Occurrence by genus
Highlighted: all genera with which fractus occurs.
Meteorological Significance
Cumulus fractus carry different meteorological significance depending on context. When they appear in the morning during fair weather, they are often harbingers of stronger convective development during the course of the day and can develop further into cumulus humilis or mediocris. When they appear beneath nimbostratus or cumulonimbus, known as "scud clouds" or cloud shreds, they indicate already present precipitation and strong turbulence in the lower layers. During the dissipation phase in the evening, they signal the end of convection and a calming of the weather. Their rapid movement also provides insight into wind conditions at low altitudes.
Facts
- WMO-Code
- Cu fra
- Height layer
- Vertical clouds
- Typical height
- 0.3 - 2.0 km
- Genus
- CUMULUS