Altocumulus clouds form above 18,000 feet (5500 meters). The mackerel sky appearance reveals the rising and falling of many air parcels across a small distance.
Altocumulus clouds (DI01777)
2003-08-08
Carlye Calvin
University Corporation for Atmospheric Research (UCAR)
image
Clouds
NCAR/UCAR Image and Multimedia Gallery
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DI01777
http://n2t.net/ark:/85065/d7r49nw8