There were enough now to form a dark cloud, as if the outside storm had found a way in.

These gases form a cloud around the core of the star.

It the air, water vapor can form clouds which block light.

A jet of hair shot out and formed a cloud around the pot.

Her breath formed a faint white cloud as she spoke.

They formed a cloud above us and rushed in circles.

These are ways air can cool enough to form clouds:

Wings form clouds above the watch to represent "eternal time".

So if warm air with lots of water inside cools, it can form a cloud.

On a recent day, the mosquitoes were so thick that they seemed to form a vicious cloud.