1. Moisture in the Atmosphere
Chapter 18

2. Water’s Change of State
18.1
Brain Pop:
States of Matter
Brain Pop:
Matter Changing States

3. Water vapor is the most important gas in the atmosphere when it comes to understanding atmospheric processes and weather changes.
Water vapor varies from nearly 0% to 4% of the atmosphere’s composition by volume.
Water exists in the atmosphere in all three states of matter: solid, liquid, & gas.
Water can undergo six different phase changes while interacting between the atmosphere and the surface of the ground.

4. Solid:
snow
hail
ice

5. rain and cloud droplets
Liquid:
rain and cloud droplets

6. Gas:
invisible H2O vapor

7. H2O may change from one state to another:

8. Melting:
from solid ice to liquid H2O

9. Freezing:
liquid H2O to solid ice

10. Evaporation:
from liquid H2O to H2O vapor

11. Condensation: from H2O vapor to liquid H2O
Example: Dew!

12. Sublimation: change from solid ice to H2O vapor
Example: Dry ice

13. Deposition: from H2O vapor to solid ice
Example: Frost!