11.   In such places the abundant rains produce a tall thick forest beneath which the air is constantly warm and humid.

12.   It still depends on flow-patterns, even when the air is so thin as to be almost negligible.

13.   It was hot and jammed and the air was redolent with the sickly sweet smell of cheap champagne.

14.   Logic suggests that if the air is warmer, more water evaporates.

15.   Nevertheless, as the team assembled in their headquarters, there was an air of quiet confidence.

16.   No more snow had fallen, the sky was still overcast but the air was crisp and a little warmer.

17.   Now the warm air was full of shouts and movement.

18.   Now, though the office air is clean, the butt-crammed ashtray outside testifies that smoking is far from stubbed out.

19.   One day in two, judged by federal standards, the soft California air is not fit to breathe.

20.   Our polluted air is a clear demonstration of the need for tougher environmental laws.