Cumulus Clouds (Cu)

CuMediocris1.jpg and CuMediocris2.jpg: These Cumulus clouds already exceeded the Humilis stage. Since they occur in the lowest level they have to be named as Stratocumulus mediocris. The cloud base is everywhere at the same level, the "lifting condensation level". Therefore these clouds which are characteristic for fair weather derive from ascending bubbles of warm air.

CuMediocris3.jpg and CuMediocris4.jpg show in the foreground Cumulus mediocris clouds. In CuMediocris3.jpg also Cumulus humilis (in the foreground) and Cumulus congestus (in the centre) are pictured as well as Cumulonimbus incus (in the back, below the Cirrus clouds) and Cumulonimbus calvus (left border in the back below the anvil). At the centre and at the back of CuMediocris4.jpg Cumulus congestus occur.

CuMediocris5.jpg and CuMediocris6.jpg: The pictures were taken during the descent of the aircraft at Fortaleza, North-Easterly Brazil. They display side views of Cumulus mediocris clouds.

The painting "In the Moor" by Fritz Overbeck (1869 - 1909) presents Cumulus mediocris clouds and a layer of Altocumulus perlucidus translucidus above. The clouds do not have a distinguished lower level. So they were likely not formed by convection at the pictured location (as the clouds in CuMediocris1.jpg), but were advected from their origin farer away to the focus of the painter. During the transportation the lower level could be altered by turbulences. The occurrence of Altocumulus clouds might indicate that the Cumulus mediocris have been formed sometime before the "shoot". Hence the Ac reduce the short-wave radiation which hits the ground and warms it up. Under these circumstances the convective formation of small clouds becomes less probable. The picture was painted in 1901 and is exhibited in the new Pinacoteque in Munich.

The drawing "View from the Spital St. Paul" by Vincent Van Gogh displays a single Cumulus mediocris cloud. Thereby the painter gives many details of the cloud structure. The artwork was created in 1889. Today it is exhibited in the Rijksmuseum Kroeller-Moeller in Otterloo, Holland.

CuMediocris1.jpg: S. Borrmann, Stockholm, Airport Arlanda, 22 June 2002, 1 p.m.

CuMediocris2-6.jpg: S. Borrmann, flight Varig RG2375 from Fortaleza to Sao Paulo in Brazil, 18 February 2004, around 2:30 p.m.

CuMediocris7.jpg: S. Borrmann, Yellow River, Kakadu National Park, Northern Territory, Australia, 2 December 2005, 1:27 p.m.

Oberbeck.jpg: "In the Moor", Fritz Overbeck (1869- 1909), 1901, New Pinakoteque in Munich

VanGogh.jpg:"View from the St. Paul Hospital", Vincent Van Gogh, Picture with Black Chalk, Pen, Ink, 23 cm x 18.5 cm, 1889, Rijksmuseum Kroeller-Moeller in Otterloo, Netherlands

Camera Parameters

Olympus E-1 SLR with a 14-54 mm objective. Exposure and sensitivity choice (200 ASA) was performed by the program automation of the camera. The images were recorded in the sRGB color range with a resolution of 2560 x 1920 Pixel x 24 colours.

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