Being outside, we can look up and see clouds gathering.

"Then what are we doing outside while the clouds gather?"

The clouds gathering over the north looked very black indeed.

Then he looked out of the window and saw clouds gathering.

As she spoke, the clouds had gathered all about us.

First the clouds gather, then the rain comes out from them.

Apparently the clouds were gathering force, which didn't at all seem like a good idea.

He looked up; heavy clouds were gathering from the sea.

The clouds are gathering again and it's for the lack of leadership.

Meanwhile, however, the clouds of war were gathering across Europe once again.