11.   Most tropical storms pass through the same stages of development, exhibiting similar cloud formations around their centers.

12.   Most rainfall is recycled, and the forest affects light reflection, cloud formation, regional rainfall and temperature.

13.   Recently during a severe weather watch I spotted my significant other standing at the end of the driveway, peering up at the cloud formations.

14.   Spotters spend hours learning to distinguish the characteristics of severe storms from more benign cloud formations.

15.   The film was shot in Nogales, Ariz., which was chosen because of its cloud formations.

16.   The picture was created by printing two negatives together, one of the ship on the far horizon, the other of the dramatic cloud formation.

17.   The sighting of the fireball came from flashes of reflected light that disrupted cloud formations.

18.   These so-called weather spotters spend hours learning to recognize the important characteristics that distinguish developing severe storms from otherwise harmless cloud formations.

19.   These weather spotters spend hours learning to identify the important characteristics that distinguish developing severe storms from ominous-looking but benign cloud formations.

20.   Those and other instruments will monitor the seasonal appearance of polar ice caps, cloud formations and dust storms.