1. Water in the Atmosphere

2. States of Matter - Water
melting
evaporation
Solid
Liquid
Gas
freezing
condensation

3. Energy Transfer – Phase Changes

4. energy gained = environment cools down
energy released= environment heats up

5. Latent Heat
Energy is required to break the hydrogen bonds that hold water molecules together
Energy is taken from the environment and is stored in the water molecule
This energy is called latent heat
Energy is released during condensation/freezing

6. Humidity Humidity – measure of the amount of water vapor in the air
Warm air holds more water vapor than cold air
Relative Humidity – the percentage of water in the air, relative to how much it can hold
Saturated - when air can’t hold any more water vapor
Condensation occurs
Dew point – temperature at which saturation occurs
Measured with a sling psychrometer

7. Sling Psychrometer

9. Question: If the dry-bulb temperature is 20o C and the wet-bulb temperature is 12o C, what is the dewpoint?

10. Question: If the dry-bulb temperature is 12o C and the wet-bulb temperature is 10o C, what is the dewpoint?

11. Question: Use the sling psychrometer and determine what temperature the air in the room would have to be reduced to for the moisture in the air to condense.

12. Question: If the dry-bulb temperature is 24o C and the dewpoint is 2o C, what is the wet-bulb temperature?
Dry-Bulb -
∆ W-B & D-B
Web-Bulb
24o C -
11o C
13o C