Clouds in the Sky
by Sieghelm Lockayer 686 Contributions
If you see a post with clouds, tag it and also whenever you see a post with high emphasis on clouds or emphasis in the sky with none or very little of the ground showing consider tagging cloudscape too.
sky -cloud
Name Tags to Add Tags to Remove
Cloud cloud
Cloudscape cloudscape

e621 | Wiki Definitions:

Cloud: A cloud is a visible mass of water droplets or frozen ice crystals suspended in the atmosphere above the surface of the Earth or another planetary body.

Cloudscape: A scenery tag, used when a post has a particular emphasis on the sky. Usually this will mean highly detailed fluffy clouds, but the tag can technically be used for any type of sky, even ones without clouds.

If there's more than a sliver of ground visible, just tag sky instead of cloudscape.