1.   The fog is quite thin in places.

2.   The fog was as dense as ever.

3.   The fog was so bad that we could barely see the road in front of us.

4.   There is heavy fog on all roads tonight so drivers are advised to reduce speed and drive with extra care.

5.   Fog is formed when warm moist air moves over a cold surface.

6.   The fog was thick this morning.

7.   The fog was still thick when they crossed the German Line, but it thinned out on higher ground.

8.   The fog was yellow and acrid and bit at the back of the throat like acid.

9.   And above, where a thick morning fog produced by the Watauga River is commonplace, was a silvery cloud bank running splendidly the length of the valley.

10.   And the fog was as thick as snow.