© Michael Bruhn
Middle Park VIC 3206, Australia
Latitude: 37° 51' 15'' S
Longitude: 144° 57' 41'' E
23 August 2007 1152 (Local Time)
Camera direction: towards WNW
Image P/S code: P.1.14
Image I.D.: 5886
CL = 0, CM = 3, CH = 2
The ragged lower parts and fibrous trails (ice crystal virga) identify these large tufts as the species floccus. The floccus has transformed (water droplets have frozen throughout) from Altocumulus to Cirrus, as evidenced by the fibrous appearance on the left; the fibrous appearance and milky sheen to the left of the centre; and the milky sheen on the right.
The receding sheet of Altocumulus on the horizon is at the same height as the Cirrus floccus; occasionally, Cirrus floccus altocumulomutatus is observed with a lower base than Altocumulus, in the same sky.
A full sky observation will detect one or two Cumulus humilis cells to the right of the Spirit of Tasmania.
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A large high pressure system to the south-east dominates south-eastern Australia.
The sounding is from 22 km to the north-north-west. The cloud represents a discrete layer of moisture not sensed by the Melbourne Airport, Victoria, Australia sonde. There is a subsidence inversion at 814 hPa and high-level moisture above 372 hPa.
This image shows a solitary and dense Cirrus castellanus altocumulogenitus cloud that has developed from Altocumulus castellanus through the glaciation of the whole cloud. Therefore, the common base of the cloud is not quite horizontal, but contains short, virga-like protuberances. Due to the history of the cloud, it can be assumed that the altitude is unusually low for Cirrus. A thin layer of Cirrus fibratus is present closer to the observer. It is generated by the glaciation of the rear edge of the frontal Altocumulus stratiformis translucidus, present at the top of the image and wide in the sky behind and to the side of the observer but not visible in the image. The altitude of middle clouds measured by a ceilometer 30 km north-north-east of the photo location does not match the respective sounding temperatures very well. The Cumulus at levels of 450–800 m, according to the ceilometer, is mostly ragged Cumulus fractus, but some whitish clouds in the background are more compact and look like Cumulus mediocris.
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