© Michael Yeung
Jordan, Hong Kong, China
Latitude: 22° 18' 22'' N
Longitude: 114° 10' 10'' E
19 October 2015 1759 (Local Time)
Image P/S code: S.2.8
Image I.D.: 5861
CL = 0, CM = 0, CH = 9
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Cirrocumulus stratiformis undulatus mamma
When the Sun is just above or on the horizon, it can redden the base of clouds. If the base is corrugated, the colour is distributed in alternate lighter (yellowish or reddish tints) and darker (other tints) bands. This alternate colouring (in fact, the bands are illuminated troughs versus ridges in shadow) shows the detail of the corrugations that otherwise tends to go unnoticed.
This photo was taken around sunset with reference to an observer at mean sea level. Satellite imagery and the King's Park (Hong Kong, China) upper-air sounding suggest the cloud base was at about 10 000 m; that is at a height where the Sun is not yet below the horizon.
The cloud is Cirrocumulus stratiformis undulatus mamma, where stratiformis denotes an extensive sheet or layer, undulatus denotes undulations (wave pattern) that are generally transverse to the wind at that level, and mamma describes the hanging protuberances, like udders, on the under surface of the cloud.
The almost parallel angle of the Sun's rays have magnificently highlighted the undulations and mamma on the under surface of the Cirrocumulus.
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© Michael YeungJordan, Hong Kong, ChinaLatitude: 22° 18' 22'' NLongitude: 114° 10' 10'' E19 October 2015 1759 (Local Time)CL = 0, CM = 0, CH = 9Image P/S code: S.2.8Image I.D.: 5861
The weather chart shows strengthening north to north-east winds as severe tropical storm Koppu moved slowly northward.
© The Government of the Hong Kong Special Administrative Region
The 1200 UTC sounding has a very dry layer from 7 600 to 9 600 m with relative humidity of ≤ 3% (mixing ratio of 0.01 g/kg). This dry layer supports the sublimation of ice crystal virga falling from Cirrocumulus and can account for the formation of short-lived mamma in the upper parts of this layer.
There is a significant increase in moisture above 10 000 m. Satellite imagery shows the moisture is associated with an outflow band from severe tropical storm Koppu.
© The Government of the Hong Kong Special Administrative Region
The 0900 UTC Hot Tower colour enhancement suggests that cloud temperatures in the outflow spiral are in the range of –35 °C to –65 °C. This is in agreement with the high-level moisture profile on the King's Park (Hong Kong, China) upper-air sounding at 1200 UTC.
© Japan Meteorological Agency
Cirrocumulus floccus undulatus with virga and mamma
Cirrocumulus usually appears as a patch of cloud as seen here, consisting of very small elements that are also called cloudlets. Both aspects are typical of the genera. The elements have an apparent width of less than 1° and are of the species floccus. The undulations indicate the variety undulatus and beneath the merged floccus are short trails of virga, which are a supplementary feature. Near the top of the image are what appear to be the hanging protuberances of the supplementary feature mamma. It should be noted that mamma at such a height in Cirrocumulus would be very small.
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© Rubén del Campo-HernándezSanta Cruz de Tenerife, Canary Islands, SpainLatitude: 28° 28' 51'' NLongitude: 16° 14' 45'' W05 September 2014 1914 (Local Time)Camera direction: towards NECL = 0, CM = 0, CH = 9Image P/S code: P.2.8Image I.D.: 4800