Outside, dirty clouds had gathered, obscuring the sun and cooling the breeze.

Steam poured up through the vents from the underground system in dirty clouds.

No wonder some high-tech workers are starting to avoid China, because they don't want to live in a dirty cloud.

The sun, which had been a pallid smudge under dirty clouds, now disappeared.

There was nothing but a sea of dirty cloud beneath them.

Several small, dirty gray clouds of flak appeared off the right wing.

Fog, a light drizzle, and various engine exhaust combined to blanket the place in a dirty cloud.

Dimitri couldn't see the tank in front of him, so he drove the General straight into the dirty cloud that was its wake.

The sun was hidden by dirty gray clouds, but the temperature still felt like ninety or better.

The sky was a soup of dirty clouds, but he'd grown accustomed to the climate.