Mammatus Sunrise

March 26, 2008


Provided and copyright by: Peter Krämer
Summary author: Peter Krämer 

The photo above shows a most impressive crimson and gold sunrise over the Ruhr Valley near Bochum, Germany. It was taken at 7:49 a.m. local time on November 19, 2007. What appears to be mammatus clouds are set aglow by the rising Sun. While mammatus are typically associated with cumulonimbus activity, there was no thunderstorm activity in the region at this time but an area of low pressure was positioned over western Europe. The pendulous cloud formations could be "altostratus mamma," formed when an unstable layer of air was forced downward into more stable air. A high-pressure area over eastern Europe resulted in clear skies to the east, thus the rising Sun was able to illuminate the clouds from below, accentuating the cloud structures and making the sky appear like that from another world.