1.   A small dapper gentleman two seats away knocked back a shot of something and exhaled an invisible sweet cloud.

2.   Music and laughter wafted out like an invisible cloud.

3.   Because they are usually so far away, their light travels through and illuminates otherwise invisible clouds of intervening hydrogen gas.

4.   Carpeting is a major hangout, and each time a rug is stepped on, an invisible cloud of allergenic dust rises.

5.   Distant, frigid Uranus derives its vivid coloration from methane, the same gas that sometimes hovers in an invisible cloud over marshes on Earth.

6.   Zagat departs, trailing invisible clouds of thanks and reverence from the beatified staff of Chez Jean-Pierre.