1. Topic: Water in the Atmosphere PSSA: 3.5.7.C / S8.D.2.1

2. Objective: TLW explain how water moves through the water cycle. TLW explain how water moves through the water cycle. TLW explain how relative humidity is calculated. TLW explain how relative humidity is calculated. TLW describe the relationship between dew point and condensation. TLW describe the relationship between dew point and condensation.

3. MI #1: The Water Cycle

4. MI #2: The Water Cycle (Important Terms) Evaporation Evaporation Condensation Condensation Precipitation Precipitation Percolation Percolation Runoff Runoff

5. MI #3: Humidity Humidity is the amount of water vapor in the air. Humidity is the amount of water vapor in the air. The air’s ability to hold water changes as the air temperature changes. The air’s ability to hold water changes as the air temperature changes. The warmer the air, the more water it can hold, the colder the air, the less water vapor it can hold The warmer the air, the more water it can hold, the colder the air, the less water vapor it can hold

6. MI #4: Relative Humidity Relative humidity is the amount of water vapor in the air compared with the maximum amount of water vapor that the air can hold. Relative humidity is the amount of water vapor in the air compared with the maximum amount of water vapor that the air can hold. When air holds all of the water vapor it can it is said to be saturated. When air holds all of the water vapor it can it is said to be saturated. The amount of water vapor and the air temperature determine relative humidity. The amount of water vapor and the air temperature determine relative humidity.

7. MI #5: Condensation Condensation is the process by which a gas (like water vapor) becomes a liquid. Condensation is the process by which a gas (like water vapor) becomes a liquid. For condensation to occur, the air must saturated. For condensation to occur, the air must saturated. Condensation occurs when saturated air cools. Condensation occurs when saturated air cools.

8. MI #6: Dew Point Air becomes saturated when water vapor is added through evaporation ; it also become saturated when its temperature drops and the air reaches its dew point. Air becomes saturated when water vapor is added through evaporation ; it also become saturated when its temperature drops and the air reaches its dew point. The dew point is the temperature at which a gas becomes a liquid. The dew point is the temperature at which a gas becomes a liquid. As the temperature drops, the amount of water vapor that the air can hold drops too, eventually the air becomes saturated and the water vapor condenses. As the temperature drops, the amount of water vapor that the air can hold drops too, eventually the air becomes saturated and the water vapor condenses.

9. So What…? Real Life Application Understanding the water cycle and humidity is important because it allows us to see how water moves through an environment. Understanding the water cycle and humidity is important because it allows us to see how water moves through an environment.