Cirrus radiatus
Ci ra
Cirrus radiatus
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Description
The name "radiatus" (Latin: radiated) describes the characteristic arrangement of these cirrus clouds in nearly parallel bands or streaks that appear to converge perspectively toward one or two points on the horizon. Cirrus radiatus often forms impressive, fan-shaped patterns in the sky that can extend across large portions of the firmament. The apparent convergence of the cloud bands is a purely perspective effect, similar to the way railway tracks appear to meet in the distance. This variety frequently occurs in connection with jet stream-related airflows and consists entirely of ice crystals. Cirrus radiatus can produce particularly spectacular light displays at sunrise and sunset, when the long cloud streaks are bathed in warm colors.
Identification Features
- Long, parallel bands or streaks of cirrus clouds that appear to converge toward a point on the horizon
- Radiated, fan-like pattern that can extend across large portions of the sky
- Very high altitude, typically above 6,000 meters
- Fibrous, silky, or hair-like appearance of the individual streaks
- The cloud bands can stretch across the entire sky and diverge again on the opposite side
- Thin, translucent structure through which the blue sky remains visible
- Frequently associated with high wind speeds at great altitude
Occurrence by genus
Highlighted: all genera with which radiatus occurs.
Meteorological Significance
Cirrus radiatus is often an indicator of strong upper-level winds and may point to the proximity of a jet stream. When the bands become increasingly dense and consolidate into a closed cirrostratus layer, this can signal an approaching warm front and thus a deterioration in weather within the next 12 to 24 hours. As an isolated occurrence without any further tendency to thicken, however, cirrus radiatus has no immediate significance for surface weather. The orientation of the bands provides information about the prevailing flow direction in the upper troposphere and is therefore of interest for synoptic weather analysis.
Facts
- WMO-Code
- Ci ra
- Height layer
- High clouds
- Typical height
- 6.0 - 12.0 km
- Genus
- CIRRUS