1. What is the most important gas in the atmosphere?
Bell Ringer
What is the most important gas in the atmosphere?

2. Water Vapor and the Atmosphere

3. Water in the Atmosphere
Precipitation is any form of water that falls from a cloud.
When it comes to understanding atmospheric processes, water vapor is the most important gas in the atmosphere

4. Water Changes State
The three states of matter solid, liquid, and gas (plasma is the fourth)

5. Water Changing State Melting Evaporation Condensation Freezing
Solid to Liquid
Latent Heat – does not produce a temperature change.
Evaporation
Liquid to Gas
Condensation
Gas to Liquid
Freezing
Liquid to Solid
Sublimation
Solid to Gas
Deposition
Gas to Solid

6. Think about it…
Have you ever been outside and the air seemed “sticky” or “wet”? Maybe it gave you “frizzy” hair…what causes this?
TURN AND TALK…discuss this with your partner
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7. Humidity
amount of water vapor in air.

8. Saturation
The state when air contains the maximum quantity of water vapor that it can hold at any given temperature and pressure.
The amount of water vapor required for saturation depends on temperature
When saturated, warm air contain more water vapor than cold air.

9. Relative Humidity
Ratio of the air’s actual water-vapor content compared with the amount of water vapor air can hold at that temperature and pressure.
Lowering air temperature causes an increase in relative humidity
Raising air temperature causes a decrease in relative humidity

10. Dew Point reach saturation.
Dew point is the temperature to which a parcel of air would need to be cooled to
reach saturation.

11. Dew on a Spider Web

12. Measuring Humidity Instrument: Hygrometer
Psychrometer : a type of hygrometer consisting of two identical thermometers mounted side by side
Dry bulb: give the present air temperature
Wet bulb: has thin wet wick tied around the end

13. Sling Psychrometer

14. Think about it… THINK…then TURN AND TALK to your neighbor…
What is the difference between moisture and humidity?
Where are the most humid places on Earth?