Explanation: What could create a huge
hole in the clouds? Such a hole, likely hundreds of
meters across, was photographed last month from a
driveway near Mobile, Alabama, USA. Very unusual to see,
hole-punch clouds like this are still the topic of
meteorological speculation. A leading hypothesis holds
that the hole-punch cloud is caused by falling
ice-crystals. The ice-crystals could originate in a
higher cloud or be facilitated by a passing airplane
exhaust. If the air has just the right temperature and
moisture content, the falling crystals will absorb water
from the air and grow. For this to happen, the water
must be so cold that all it needs is a surface to freeze
on. The moisture lost from the air increases the
evaporation rate from the cloud water droplets so they
dissipate to form the hole. The now heavier ice crystals
continue to fall and form the more tenuous wispy
cloud-like virga seen inside and just below the hole.
Water and ice from the virga evaporates before they
reach the ground.
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