1. 1._____process that forms clouds (water cycle 2) 2._____ process that adds heat and changes liquid water to water vapor (water cycle) 3._____what powers the water cycle (water cycle) RAP

2. Key Questions 1.What is humidity? 2. What is relative humidity? 3. What dew point? 4. What is a psychrometer?

3. Water in the Air Chapter 16, Section 1 1. Humidity is the amount of water vapor or moisture in the air. As water evaporates the amount of humidity in the air increases. The air’s ability to hold water depends on air temperature. As the temperature increases, so does the air’s ability to hold water.

4. Water in the Air Chapter 16, Section 1  2. Relative Humidity is the amount of moisture the air contains, compared with the maximum amount it can hold at a particular temperature.  Relative humidity is given as a percentage.  When air holds all the humidity it can hold at a given temperature it is said to be saturated.  Saturated air has a relative humidity of 100%.

5. Water in the Air Chapter 16, Section 1  3. A psychrometer is an instrument used to measure relative humidity.  It is used to make two readings of temperature. One is a dry bulb reading and the other is a wet bulb reading.  See chart on page 424 of text to determine actual relative humidity.

6. Water in the Air Chapter 16, Section 1  4. The dew point is the temperature to which air must cool to be completely saturated. And condensation occurs  Air can become saturated when water vapor is added to the air through evaporation or transpiration. (transfer of water from plants to the atmosphere)  Air can also become saturated as in the case of the glass of water, when it cools to its dew point.

7. Quick Lab I will now fill two glasses with water. In one of the glass I will put room temperature water. In the other I will put Ice water What happened to the outside of the glasses? What is the liquid on the ice water glass? Where did it come from?