Air exerts pressure only in the downward direction.

Use the clues to fill in the words in the puzzle.

Across

1. Layer of air surrounding the earth.
3. The gas that stops harmful rays of the sun from reaching us.
4. Process which gives the purest form of water.
5. The amount of water vapour present in air.
6. Water dissolves several substances. Water is a
7. A gas present in very small quantity in air, which is very important for plants.
8. Done after sedimentation to pour off clear water.

Down

2. The layer of the atmosphere in which clouds are formed.