© Jarmo Koistinen

Kamppi, Helsinki, Finland

Latitude: 60° 10' 7'' N

Longitude: 24° 56' 7'' E

30 September 2015 1809 (Local Time)
Camera direction: towards SW

Image P/S code: S.2.14.1

Image I.D.: 5105

C_L = 0, C_M = 0, C_H = 9

• Images & related info Other Images Images of 1987 edition
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  Cirrocumulus stratiformis with irisation

  The main feature of this zoomed-in photograph is the area of irisation with pastel shaded colours. This colouration indicates the presence of small, uniformly sized, supercooled water droplets that can occur in Cirrocumulus cloud. It also helps the fine elements within the Cirrocumulus stratiformis cloud stand out. 

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  © Jarmo Koistinen
  Kamppi, Helsinki, Finland
  Latitude: 60° 10' 7'' N
  Longitude: 24° 56' 7'' E
  30 September 2015 1809 (Local Time)
  
  
  Camera direction: towards SW
  C_L = 0, C_M = 0, C_H = 9
  Image P/S code: S.2.14.1
  Image I.D.: 5105
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  Cirrocumulus lenticularis

  Cirrocumulus species lenticularis, which appears in patches shaped like lenses or almonds. They are often very elongated and usually have well-defined outlines. The patches are mostly smooth and are very white throughout. This image overall shows distinct undulations, making it the variety undulatus. It also shows some small transverse ripples seen at times in Cirrocumulus cloud.

  Links in the image description will highlight features on the image. Mouse over the features for more detail.

  © Pascual
  Serra, Valencia, Spain
  Latitude: 39° 40' 55'' N
  Longitude: 0° 27' 35'' W
  18 March 2015 1506 (Local Time)
  
  
  Camera direction: towards N
  C_L = 0, C_M = 0, C_H = 9
  Image P/S code: P.2.2
  Image I.D.: 4809
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  Irisation/iridescence

  Iridescent colours cover a large part of this cloud layer. This is known as irisation.

  The cloud is identified as a very high Altocumulus, almost bordering on Cirrocumulus. As the layer is relatively extensive, it is of the species stratiformis. It is also thin and translucent (variety translucidus) and there are undulations (variety undulatus).

  Irisation results from the interaction of sunlight with small, uniformly sized cloud particles. Within about 10° from the Sun, diffraction is the main cause of irisation. Beyond about 10°, the interference of light waves is usually the predominant factor.

  The colours green and pink tend to predominate, although other colours are seen, such as blue. They are often delicate, pastel shades, but can be brilliant. 

  Links in the image description will highlight features on the image. Mouse over the features for more detail.

  © Claudia Hinz
  Brannenburg, Germany
  Latitude: 47° 44' 20'' N
  Longitude: 12° 5' 18'' E
  31 December 2005 1439 (Local Time)
  
  
  Camera direction: towards SW
  C_L = 0, C_M = 3, C_H = 0
  Image P/S code: P.13.3
  Image I.D.: 5624