"What kind of strange cloud is that to the south?"

Looking up, the boy saw that a strange cloud had come into being in the western sky.

Robert Shaffer first thought the strange white cloud might be fog.

In fact the sky was pretty clear, aside from that strange luminous cloud.

This morning some strange clouds, wispy and very high, had begun to form quite early.

A living, thinking thing rather than just a strange cloud of chemical elements?

Richard looked up over his shoulder and saw the same strange snakelike cloud.

"Nothing except a strange cloud of black smoke about two or three miles astern."

At two thousand feet the strange, white cloud was circling.

And then he saw a strange white cloud moving across the now golden face of the city's cliffs in the sunset.