Hole Cloud Above Elewijt, Belgium

September 01, 2005

P71000552 copy

Provided and copyright by: Gert Van Saet
Summary authors & editors: Gert Van Saet

The photo above showing a large opening in an altocumulus cloud deck above Elewijt, Belgium was taken on July 10, 2005. This "hole punch cloud" most likely results from falling ice-crystals, which originate in a higher cloud. Water droplets composing alto form clouds are typically supercooled. The moisture (water droplets) lost from such a cloud due to the falling crystals increases the local evaporation rate, so that a portion of the cloud dissipates to form a hole. The now heavier ice crystals, which have accumulated supercooled droplets, continue their fall but sublimate before reaching the surface (virga). This can be observed inside and just below the hole. Note also the contrail punctuating the hole.

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