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Lung Kwu Tan, Hong Kong, China

Latitude: 22° 23' 25'' N

Longitude: 113° 55' 12'' E

02 June 2015 1832 (Local Time)
Camera direction: towards W

Image P/S code: S.4.8

Image I.D.: 5641

C_L = 2, C_M = 3, C_H = 5

Very high sheet of thin Altocumulus
This thin and very high sheet is of the species stratiformis (the cloud is an extensive sheet) and the varieties translucidus (the greater part is sufficiently thin to reveal the position of the Sun), perlucidus (there are distinct, very small spaces between the elements) and undulatus (there are separate elements arranged in broadly parallel lines).

The regularly arranged elements (those more than 30° above the horizon) are about the width of a little finger at arm's length – borderline between Altocumulus and Cirrocumulus in size. The presence of shading suggests Altocumulus; however, an observer has to determine whether this shading is due to a low Sun angle (it was 6° above the horizon at the time of the photo). Continuous observation can assist with this, as the observer may have seen shading in the elements when the Sun was higher. This was the case in this instance, as observations from Hong Kong Airport, Hong Kong (China) reported Altocumulus translucidus throughout the day.

Cirrus fibratus is distinctly visible in a large gap in the Altocumulus layer. A leading edge of Cirrostratus is low on the horizon and a not-too-brightly coloured parhelion (sun dog) is visible to the north (right) of the setting Sun.

Completing the observation is Cumulus of the species mediocris, humilis and fractus.
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© Winnie Cheung
Lung Kwu Tan, Hong Kong, China
Latitude: 22° 23' 25'' N
Longitude: 113° 55' 12'' E
02 June 2015 1832 (Local Time)

Camera direction: towards W
C_L = 2, C_M = 3, C_H = 5
Image P/S code: S.4.8
Image I.D.: 5641
The subtropical ridge covering the northern part of the South China Sea and the coast of Guangdong, China strengthened gradually on this day.
© The Government of the Hong Kong Special Administrative Region
The sounding was taken less than two hours after the photo and shows a very thin layer of almost saturated air (97 %RH with respect to a flat surface of liquid water) at 468 hPa (6 400 m).

There is sufficient high-level moisture for cirriform cloud from 235 to 207 hPa (11 400 to 12 300 m).
© University of Wyoming
Altocumulus stratiformis translucidus perlucidus undulatus
The relatively small white elements in the upper two thirds of this image are identified as Altocumulus. These elements make up an extensive sheet (species stratiformis). To this identification are added the varieties translucidus (the elements are sufficiently translucent to reveal the position of the Sun), perlucidus (small gaps between the elements reveal blue sky) and undulatus (separate elements are arranged in broadly parallel lines).

The Altocumulus and some higher cirriform cloud were advancing from the west (left in the photo) ahead of a weak warm front. Also visible are traces of Cumulus fractus (light grey in the top right) and a layer of dark grey Stratocumulus stretching towards the horizon (lower part of the image).
Links in the image description will highlight features on the image. Mouse over the features for more detail.
© Frank Le Blancq
Near Guernsey
Latitude: 49° 23' 43'' N
Longitude: 2° 28' 13'' W
02 August 2008 2012 (Local Time)

Camera direction: towards NW
C_L = 8, C_M = 3, C_H = /
Image P/S code: P.4.8
Image I.D.: 5168

Very high sheet of thin Altocumulus

Altocumulus stratiformis translucidus perlucidus undulatus