The anvils in this picture are not heavy steel or iron blocks but rather soft clouds coloured orange by the setting sun. The term is used to describe the upper part of a cumulonimbus or thunderstorm cloud that tends to spread out in an anvil shape as warm air bumps up against the bottom of the stratosphere (the atmospheric layer between 15-50 kilometres height).
Katja Weigel, a researcher at the Institute of Environmental Physics, University of Bremen, Germany took this picture at Mindil Beach in Darwin, Australia, shortly after sunset on 11 November 2005. She travelled there for the SCOUT-O3 (Stratospheric-Climate Interactions with Emphasis on the Upper Troposphere and Lower Stratosphere) campaign.
“The aim of the campaign was to observe and investigate transport into the stratosphere by strong tropical convection. The 11 November 2005 was the day before the research aircraft M55-Geophysika arrived in Darwin. Therefore, we did not take measurements in the clouds shown here but in and around similar clouds during the following weeks,” Weigel said.
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