1. DYK:
**The atmosphere contains only about 0.001% of the total volume of water on the planet (about 1.46 x 109 km3).
**The rate at which water evaporates into Earth’s atmosphere is about 5.1 x 1017 liters per year.

2. Weather is affected by the amount of water in the air.
Don’t forget
transpiration.

3. Humidity the amount of water vapor (moisture) in the air
warm air can hold more moisture

4. Relative Humidity
Relative Humidity (%)=amount of moisture in the air compared to how much moisture the air can hold (100%=saturated)
evaporational cooling
use psychrometer and chart
2 thing affect RH
amount of water vapor
temperature—RH decreases as the temperature rises and RH increases as temperature drops

5. EX: If the dry bulb reads 10°C,
and the difference between the wet
and dry-bulb thermometers is 8°C,
what is the RH? ____%

6. Condensation gas (water vapor) COOLS and becomes a liquid
air must be saturated (RH=100%)
Dew Point (measure as class activity—using jar, water, ice and thermometer)
temperature where condensation occurs
this is the temperature that dew and frost forms and the temperature where fog/clouds form

7. Humid vs. Dry Air Masses Dry Humid Warm Moist Low density
Rising air current
Counter clockwise rotation
Anti-cyclonic
Cool
Dry
High density
Falling air current
Clockwise rotation
Cyclonic