Great brown clouds had floated to the still heights of air before him.

Today, pulmonologists are studying the effects of the brown cloud.

The water was clear and as each beast went into it, the dip washed off in a dark brown cloud.

A small ragged brown cloud drifted into his field of vision.

Already more than half the planet was enshrouded in brown and black clouds.

The sound the brown cloud made had become a little louder, but was still far away and indefinable.

A dark brown cloud rolled in to fill the sky.

The wind dropped and the brown cloud settled to the earth.

But on some days, the mountains are obscured by Denver's brown cloud, drifting north.

Wolf had come back down the tree as fast as he could, with a brown cloud around his head.