© Michael Bruhn
Innere Stadt, Vienna, Austria
Latitude: 48° 12' 23'' N
Longitude: 16° 21' 50'' E
13 October 2014 1227 (Local Time)
Camera direction: towards NW
Image P/S code: P.8.3
Image I.D.: 5875
CL = 6, CM = /, CH = /
In general, Stratus is a grey layer of cloud with a fairly uniform base, which may give drizzle, snow or snow grains. When the Sun (or Moon) is visible through Stratus, its outline is clearly discernible. In this image, the cloud is uniformly grey with no discernible form, which identifies it as the species nebulosus. It is also sufficiently dense and opaque that the Sun is not visible, defining the variety as opacus.
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The synoptic chart for 1200 UTC shows several centres of low pressure over western Europe and the near Atlantic. The location of the photograph (denoted by the red arrow) is within an area dominated by a weak pressure gradient and light winds.
The Vienna, Austria (WMO 11035) sounding from 1200 UTC shows a near-saturated layer between 950 and 900 hPa, capped by a weakening subsidence inversion.
A low Stratus cloud, possibly as sea fog at the sea surface, laps onto the western shores of Lismore Island near Oban in the west of Scotland, UK. Cumulus mediocris can also be seen building in the far distance over the mountains of the Scottish mainland to the north. A little Cirrus is also in the sky.
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Viewed beneath Tai Mo Shan, Hong Kong's highest peak (957 m), is a layer of Stratus. The upper surface of Stratus generally shows undulations (usually of short wavelength) and sometimes displays protuberances. In strong winds the undulations become more pronounced.
At the top of the picture is a layer of Stratocumulus. The extensive nature of the cloud identifies the species as stratiformis. The layer of large rounded masses is sufficiently opaque to mask the Sun (variety opacus); however, some sunlight can be seen penetrating through gaps between elements, suggesting also the variety perlucidus. The dark, bluish streaks and light beams are a form of crepuscular rays.
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