Clouds, in wave form. Spotted by Laurine Ayers Briel in Maui, Hawaii.

Another odd shape indeed, with bonus prismatic effect, seen by Danny McNeal of Sacramento, California.

A fish in the sky, spotted by Gavin Tobin of the Blasket Islands in Ireland.

A natural mushroom cloud, spotted by Mick Ohrberg in Kansas City, Missouri.

A cloud in the shape of a UFO, spotted by Ron Biggs in Puerto de la Cruz in Spain.