Contrail shadow (volumetric shadow), seen from Ebenalp, Switzerland.
<a href="//commons.wikimedia.org/w/index.php?title=User:Altocumuli&amp;action=edit&amp;redlink=1" class="new" title="User:Altocumuli (page does not exist)">Altocumuli</a>
<span class="int-own-work" lang="en">Own work</span>