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Stratfield Mortimer, near Reading, Berkshire RG7, United Kingdom of Great Britain and Northern Ireland

Latitude: 51° 22' 12'' N

Longitude: 1° 2' 24'' W

02 December 2009 1011 (Local Time)
Camera direction: towards SE

Image P/S code: P.3.2

Image I.D.: 5491

C_L = 0, C_M = 0, C_H = 8

Cirrostratus fibratus undulatus with 22° halo
The double layer of Cirrostratus is identified by the alignment of fibratus striations. In the lower layer, the fibratus is aligned north-east to south-west; the higher layer is at a right angle to the lower layer; that is, south-east to north-west.
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© Stephen Burt
Stratfield Mortimer, near Reading, Berkshire RG7, United Kingdom of Great Britain and Northern Ireland
Latitude: 51° 22' 12'' N
Longitude: 1° 2' 24'' W
02 December 2009 1011 (Local Time)

Camera direction: towards SE
C_L = 0, C_M = 0, C_H = 8
Image P/S code: P.3.2
Image I.D.: 5491
A large depression lay to the west of the British Isles. An occluded front, followed by a trough, passed over southern England, UK in the early hours of the morning.
© Crown Copyright
Infrared image showing frontal structure and Cirrostratus band over the site four hours before the photo was taken
© EUMETSAT, 2009
Parhelic circle and 120° parhelion
This picture shows Cirrostratus fibratus and Cirrus spissatus clouds, together with some aircraft condensation trails (Cirrus homogenitus) at 3 and 4. However, there are also two photometeors of particular interest.

The first is the bright spot near the centre of the photograph; this is a 120° parhelion, caused by at least two internal ice crystal reflections of sunlight. Rays entering the top face of plate crystals reflect internally off two adjacent side faces and then exit through the lower face. The second 120° parhelion was not visible on this occasion. At the time of the photograph, the Sun’s azimuth was 274° and the azimuth of the parhelion was 034° (an azimuthal distance of 120° from the Sun).

The second photometeor is a white band which passes through the 120° parhelion; this is a parhelic circle. The parhelic circle is a white horizontal band circling the sky at the same angular elevation above the horizon as the Sun. The vertical faces of many ice crystals each mirror the Sun around the sky to form the circle. Only part of the circle was visible on this day. The elevation of the horizontal band was 020° above the horizon. At the time of these phenomena, a bright circumhorizontal arc was also visible but is not shown in this photograph.
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© Frank Le Blancq
Jersey Airport, Jersey
Latitude: 49° 12' 27'' N
Longitude: 2° 11' 43'' W
02 August 2010 1836 (Local Time)

Camera direction: towards NNE
C_L = 0, C_M = 0, C_H = 6
Image P/S code: S.13.1.6
Image I.D.: 4702
Cirrostratus fibratus and Altocumulus floccus
An overcast layer of Cirrostratus near the horizon can be mistaken for Altostratus. Cirrostratus is never thick enough to prevent objects on the ground from casting shadows, at least when the Sun is high above the horizon. When the Sun is low (less than about 30°), the greater slant depth of the atmosphere reduces the light intensity such that shadows may not be cast on the ground. In this photo the Sun was below 10°. An observer would have noted this “absence of shadows” by the presence of shading in thicker parts of the Cirrostratus fibratus veil.

Lower tufts of Altocumulus floccus and a small line of Altocumulus castellanus are also present. By the following morning, the cloud had thickened into Altostratus and possibly Nimbostratus; light rain was reported in the area. The location was ahead of a warm front and a series of cold fronts.
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© Stefan Kämpfe
Weimar, Thuringia, Germany
Latitude: 51° 0' 0'' N
Longitude: 11° 0' 0'' E
08 November 2015 1530 (Local Time)

Camera direction: towards SW
C_L = 0, C_M = 8, C_H = 7
Image P/S code: S.3.2
Image I.D.: 4798
Cirrostratus fibratus, circumzenithal arc and supralateral arc
The transparent white cloud is a thin veil of Cirrostratus, which only partly covered the sky. The presence of striations in the cloud suggest the species fibratus. Cirrostratus is composed of ice crystals which often produce halo phenomena, as in this case. The main feature is a strong circumzenithal arc with red colouration on the outside. Below and to the left of this arc is a much fainter supralateral arc extending towards the lower left of the photograph.

A circumzenithal arc will occur only when the light source (for example, the Sun) is at an elevation of less than 32° above the horizon. The circumzenithal arc appears high in the sky and is centred on the zenith, the point of the sky directly above the observer.

A supralateral arc is a rarer and fainter arc of spectral colour that also forms only when the light source is below 32° elevation. The supralateral arc may be mistaken for the 46° halo, but can be distinguished from it by the somewhat brighter and more coloured appearance of the supralateral arc. The apex of the arc is near to or touching the circumzenithal arc.
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© Frank Le Blancq
Noirmont Common, St. Brelade, Jersey
Latitude: 49° 10' 18'' N
Longitude: 2° 10' 8'' W
18 September 2010 1739 (Local Time)

Camera direction: towards SW
C_L = 0, C_M = 0, C_H = 6
Image P/S code: S.13.1.5.1
Image I.D.: 4994
22° halo and Cirrostratus fibratus
The 22° halo appears as a white or mostly white luminous ring of 22° radius with the light source at its centre. The cloud in this picture is mainly Cirrostratus fibratus.
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© Kam Hoo Man
Tuen Mun, Hong Kong, China
Latitude: 22° 23' 27'' N
Longitude: 113° 58' 21'' E
11 July 2015 0724 (Local Time)

C_L = 0, C_M = 0, C_H = 6
Image P/S code: S.13.1.1 3
Image I.D.: 5088
Cirrostratus fibratus with impressive halo phenomena
The slow northward movement of a warm front produced a shield of high cloud over southern England, UK on the morning of 7 October 2010. The first Cirrus appeared before dawn, followed by variable and beautiful Cirrus and Cirrostratus during the morning – at one point a large shield of Cirrostratus with a sharp edge spread in quickly from the south-east. Later in the morning and into the afternoon, with more general Cirrus/ Cirrostratus, there was a fine and prolonged halo display, including two very bright 22° parhelia, segments of the parhelic circle, an upper tangent arc to the 22° halo (suncave with the Sun at 33° elevation at noon) with pronounced Parry arc and, for part of the afternoon, a very bright circumzenithal arc as well (not shown in the picture). Altocumulus spread in very rapidly from the south after 1500 UTC and the rest of the day and evening remained cloudy, with rain commencing at 1730 UTC.
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© Stephen Burt
Stratfield Mortimer, near Reading, Berkshire RG7, United Kingdom of Great Britain and Northern Ireland
Latitude: 51° 22' 12'' N
Longitude: 1° 2' 24'' W
07 October 2010 1211 (Local Time)

Camera direction: towards S
C_L = 0, C_M = 0, C_H = 6
Image P/S code: S.3.2
Image I.D.: 5684
Cirrostratus translucidus fibratus
A uniformly thin veil of Cirrostratus covers the sky. It is sufficiently thin to show the sun's position, but illustrates its existence distinctly by the 22° halo surrounding the sun. Around 1, the fibrous nature of the cloud layer is shown faintly by an irregular pattern of curved filaments. The light of the sun is strong enough to cause shading variations in the Cumulus fractus at 2. The photo was taken in an area of extensive cloudiness to the east of a low-level vortex that had passed to the west-north-west across Dakar during the previous night.
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© R.L. Holle
Dakar, Senegal
Latitude: 14° 45' 52'' N
Longitude: 17° 21' 58'' W
08 August 1974 1000 (Local Time)

C_L = 1, C_M = 0, C_H = 7
Cirrostratus fibratus with Altocumulus castellanus undulatus
After the passage of an occlusion the Cirrostratus fibratus, which covers the greater part of the sky, is decreasing, which calls for the coding C_H = 8. Under the main cloud layer, there are patches of Altocumulus at (1, 2, 3, 4) of elongated form and broadly parallel to one another. The bulges at 5 and 6 indicate a convective character and presumably (note the shading) more such bulges are arranged on the common, slightly ragged bases, so that the clouds are properly called castellanus.

The occlusion was to the east of the point of observation, and had given rise to an intensive thunderstorm one hour before the photograph was taken.
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© A. Viaut
Bruges, Belgium
Latitude: 51° 12' 33'' N
Longitude: 3° 13' 29'' E
26 August 1951 1616 (Local Time)

Camera direction: towards NW
C_L = 0, C_M = 8, C_H = 8

Cirrostratus fibratus undulatus with 22° halo

Parhelic circle and 120° parhelion

Cirrostratus fibratus and Altocumulus floccus

Cirrostratus fibratus, circumzenithal arc and supralateral arc

22° halo and Cirrostratus fibratus

Cirrostratus fibratus with impressive halo phenomena

Cirrostratus translucidus fibratus

Cirrostratus fibratus with Altocumulus castellanus undulatus