Precipitation

This series of images was taken from the 9th level of a multi-storey building near the coastal road "Avenida Beira Mar" at Fortaleza. At first small Cumulus congestus clouds arrived from easterly directions parallel to the coast. They showed a very fast convective development (Rain1.jpg and Rain2.jpg). Then a large cloud complex came up which was partly above the ocean and partly above the land (from Rain3.jpg on). The series shows the formation of blast rotors, hints of a "wall cloud" (Rain7.jpg) and finally the beginning of precipitation at the location of the observer (Rain22.jpg).

The low altitude of the base of the major clouds which almost reached down to the twenty-two storey buildings is remarkable. The temperature of the rain was relatively warm. Therefore it cannot be said for sure that the ice-phase was involved in the rain formation. It could be also a large Cumulus congestus complex or a Cumulonimbus calvus cloud having not formed an iced anvil yet. The observed event lasted for around 20 minutes, however the cloud proceeded in westerly direction.

Rain1.jpg to Rain22.jpg: S. Borrmann, Fortaleza, Ceara, Brazil, 29 February 2004, 6:34 a.m. to 7:58 a.m.

Camera Parameters

Olympus E-1 SLR with 14-54 mm objective. Exposure and ASA selectivity choice (100 ASA) were performed by the program automation of the camera. The images were taken in the sRGB colour range with a resolution of 2560 x 1920 Pixel x 24 colours.