Follow that link to a page about an artist who creates real clouds indoors, for a moment, and photographs them. It's interesting. And here's an old poem.

CLOUD

We speak of life as an oboe
speaks, in Summer colors
stirring the orchards
playing the windchimes by the door.

You put the telephone down
and your voice hangs
a little cloud of new rain
over the cold and restless sea.
I cannot hope to disconnect.

How can a man admit he loves
so well, so hopelessly
these clouds that only turn
maybe hover
do not descend, never touch.

Now birds are rising in the dial tone
with a motion as still and breathless
as the respirations of a dying seal.

A squadron of great brown pelicans
is lifted from the harbor
to investigate the coming night.

If they will watch the sky for me
maybe I can sleep.