I have always loved clouds, and today while looking for a particular cloud, I came across the Wikipedia entry, and some glorious cloud photos, like the approaching thunderstorm above.
Cumulonimbus over Mykonos, Greece
Cirrus fibratus radiatus
Noctilucent, thin, cirriform cloud in deep twilight over Estonia.
A “hole punch” over Austria
Saucer cloud over Campbell’s Mesa, Arizona
Nacreous clouds over Antarctica
Mammatus clouds over Squaw Valley, Idaho