© Michael C. Hanna

Wayland, New York, United States of America

Latitude: 42° 34' 4'' N

Longitude: 77° 35' 24'' W

12 October 2015 1733 (Local Time)
Camera direction: towards SE

Image P/S code: P.1.2

Image I.D.: 5996

C_L = 0, C_M = 0, C_H = 1

• Images & related info Other Images Images of 1987 edition
• 

  Cirrus uncinus, floccus, castellanus, fibratus and spissatus

  This quite amazing image has captured five species of Cirrus in the same sky. The predominate species is uncinus, filaments often shaped like a comma, terminating at the top in a hook or a tuft but not in the form of a rounded protuberance.

  The other species, in no specific order, are:

  fibratus of which there are a few filaments on the lower right; castellanus, a solitary line left of centre on the horizon; floccus in several places, particulary here and here; and lastly spissatus of which there are a few patches with a silky sheen near the right edge.

  The Cirrus was the first visible sign of an approaching cold front 900 km to the west. However, this Cirrus is not classified as invading as it developed in situ and did not extend down to the upwind horizon.

  The Cirrus cleared to the NE and the leading edge of the frontal cloud band was on the western horizon 4 to 6 hours later. Light rain was observed in the area early morning of 13 October.

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  © Michael C. Hanna
  Wayland, New York, United States of America
  Latitude: 42° 34' 4'' N
  Longitude: 77° 35' 24'' W
  12 October 2015 1733 (Local Time)
  
  
  Camera direction: towards SE
  C_L = 0, C_M = 0, C_H = 1
  Image P/S code: P.1.2
  Image I.D.: 5996
• 

  The sounding from 100 km west-north-west shows high moisture content in two layers: from 487 to 465 hPa (5 800 to 6 200 m) and from 407 to 385 hPa (7 200 to 7 600 m). The cirriform cloud appears to be above 6 000 m and the temperature range in the higher layer supports heterogeneous nucleation.

  © University of Wyoming
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  Cirrus uncinus and Cirrus fibratus

  Cirrus with hooks identifying it as species uncinus. Species fibratus is also present. An aircraft condensation trail can also be seen.  The cloud was in advance of Atlantic fronts moving towards the British Isles.

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  © Stephen Burt
  Stratfield Mortimer, near Reading, United Kingdom of Great Britain and Northern Ireland
  Latitude: 51° 22' 12'' N
  Longitude: 1° 2' 24'' W
  18 September 2010 0904 (Local Time)
  
  
  Camera direction: towards N
  C_L = 0, C_M = 0, C_H = 1
  Image P/S code: S.1.2 3
  Image I.D.: 4321
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  Cirrus uncinus

  This is an unusual example of Cirrus of the species uncinus as it is viewed from almost directly below, rather than the more usual side-on or oblique view. 

  The cloud is white, is shaped like a comma and terminates at the top in the form of a hook or in a tuft, the upper part of which is not in the form of a rounded protuberance. If it did terminate at the top in the form of a rounded protuberance, it would be identified as Cirrus floccus.

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  © Alfons Puertas
  Vallvidrera - el Tibidabo i les Planes, Barcelona, Barcelona, Spain
  Latitude: 41° 25' 6'' N
  Longitude: 2° 7' 27'' E
  06 October 2015 1206 (Local Time)
  
  
  Camera direction: towards W
  C_L = 0, C_M = 0, C_H = 1
  Image P/S code: S.1.2 5
  Image I.D.: 4801
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  Circumzenithal arc in Cirrus uncinus

  The halo phenomenon here is a circumzenithal arc. This formed by the refraction of sunlight through ice crystals in the Cirrus uncinus. There is thin Cirrocumulus at the top of the picture. The thicker patch of Cirrus, near the bottom left, is suggestive of the species spissatus.

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  © Paulius Beinaravicius
  Radikiai, Lithuania
  Latitude: 54° 57' 45'' N
  Longitude: 23° 56' 56'' E
  05 May 2015 2006 (Local Time)
  
  
  Camera direction: towards W
  C_L = 0, C_M = 0, C_H = 1
  Image P/S code: S.13.1.5.1
  Image I.D.: 4804
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  Cirrus uncinus

  The cloud is white and without shading but has delicate filaments and patches identifying it as Cirrus. Some of the long ice crystal streamers end in tufts, typical of the species uncinus at 1 and 2. The Cirrus was associated with a weak frontolyzing cold front over Cornwall, UK.  

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  © Frank Le Blancq
  St. Brelade, Jersey
  Latitude: 49° 10' 18'' N
  Longitude: 2° 10' 9'' W
  24 June 2010 1626 (Local Time)
  
  
  Camera direction: towards SW
  C_L = 0, C_M = 0, C_H = 1
  Image P/S code: S.1.2
  Image I.D.: 4840
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  Cirrus uncinus and fibratus

  The image shows examples of the species uncinus, which is white and ends in the shape of a hook, and fibratus, which has distinct elements that do not end in a hook or comma shape.

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  © Alfons Puertas
  Vallvidrera, Barcelona, Spain
  Latitude: 41° 25' 6'' N
  Longitude: 2° 7' 27'' E
  18 September 2015 1052 (Local Time)
  
  
  Camera direction: towards S
  C_L = 0, C_M = 0, C_H = 1
  Image P/S code: S.1.2
  Image I.D.: 4849
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  Cirrus uncinus, Cirrus floccus and Cirrocumulus floccus

  This is an outstanding example of Cirrus with a milky sheen. Cirrus of the species floccus and uncinus are present and there is evidence of the species spissatus developing where the uncinus is merging. The much smaller cloud elements behind and above the rooftops on the left-hand side are small enough to be Cirrocumulus floccus; they also have the characteristic ragged base of Cirrocumulus floccus. Cirrus uncinus dominates the sky, hence the coding of C_H = 1.

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  © Matthew Clark
  Exe Street (NW-bound), Exeter, United Kingdom of Great Britain and Northern Ireland
  Latitude: 50° 43' 26'' N
  Longitude: 3° 32' 6'' W
  09 August 2013 2040 (Local Time)
  
  
  Camera direction: towards S
  C_L = 0, C_M = 0, C_H = 1
  Image P/S code: S.1.2 4
  Image I.D.: 5516
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  Cirrus uncinus with Cirrostratus

  (NB. Hour of day estimated)

  Tufts of Cirrus, above 1, are moving rapidly from lower right to upper left in a strong NW current aloft. Some tufts have hooks, and all have long trails below. As is often the case, the Cirrus in the distance above the setting sun appears to merge into Cirrostratus and has thickened and lowered to Altostratus opacus near the horizon. The increasing Cirrus heralded the approach of a fast-moving warm front to a depression 1500 km to the west.

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  © R.K. Pilsbury
  S Cambridgeshire, United Kingdom of Great Britain and Northern Ireland
  Latitude: 52° 8' 56'' N
  Longitude: 0° 2' 53'' E
  03 November 1978 1800 (Local Time)
  
  
  C_L = 0, C_M = 2, C_H = 4
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  Cirrus uncinus

  The characteristic appearance of uncinus is clearly visible. Some elements have the shape of a hook at (1, 2); others are surmounted by a fairly dense tuft, elongated obliquely into a more or less tenuous fibrous trail at (3, 4). On the whole, all trails are fairly parallel, but at some places isolated trails are superposed in a more or less tangled network. Disturbances had been passing the station from the west along the northern border of the Bermuda anticyclone. The warm front of a new approaching depression was at a distance of 500 km.

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  © J.H. Conover
  Milton, Massachusetts, United States of America
  Latitude: 42° 14' 58'' N
  Longitude: 71° 3' 58'' W
  24 July 1948 1850 (Local Time)
  
  
  Camera direction: towards SW
  C_L = 0, C_M = 0, C_H = 4
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  Cirrus uncinus and Cirrostratus

  The clouds are at two levels. The Cirrus, at the higher level, has a very thin filament structure at (1, 2) with hooks at (3, 4), so that the species is uncinus rather than fibratus. The cloud element at4&& verges on the variety intortus. The lower level is represented by patches of Cirrostratus at (&&5, 6), The cloud system was invading the sky progressively. The station was at the border of a depression, the active part of which was to the north-west over the Antarctic Ocean.

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  © A.H. Boujon and R. Pommier
  Port Martin, Adélie Land, Antarctica
  Latitude: 82° 51' 46'' S
  Longitude: 135° 0' 0'' E
  25 December 1950 0830 (Local Time)
  
  
  Camera direction: towards NW
  C_L = 0, C_M = 0, C_H = 5