How would you describe this picture?

"sea of clouds" is something I've heard before. Tbh, while I've never heard "rug of clouds", that does work fine and gives me a good mental image of what you're talking about. If this is for a creative writing project, you might even try "carpet of clouds/cloudy carpet", for some nice alliteration.

"Blanket of clouds" might be the term you are looking for?  "Blanket" and "rug" have very similar meanings, but I have only heard "blanket" used in this particular metaphor so it sounds more natural to my ear than "rug" does.

I'd describe the view as 'above the clouds'.

A sea of clouds is how many would describe this

Cloudy

It looks great. As for my description, I'd say an upside down dawn.

"Rug of clouds" is surely more poetic than the many default descriptions that come to mind when I look at this image

A sea of clouds

I’d use “sea of clouds” personally. But if you want the floor metaphor, try “carpet of clouds”.

Beneath the sky, on the clouds.

“Little puffy clouds”

That is a cloudscape - like a landscape but for clouds.

I'd also go with a sea of clouds. If it were a picture of low lying fog I would say a blanket of fog.

Mostly cloudy

Honestly, a rug of clouds sounds poetic imo

*Sea of clouds* or *sea of fluffs*

Cloudy, maybe with some meatballs? I just call it “a lot of clouds”

Sky from above

An ocean of clouds

Relaxing and at the same time ipnotic!

A carpet of clouds

Nothing but soft clouds bathing in warm sun rays of incoming day

Soft clouds illuminated by the warm light of sunset or dawn. The view from above makes them look like a sea of air