1. Spot the Differences (14)

2. EQ: How does dew form on the morning ground?
Title: Humidity Notes
EQ: How does dew form on the morning ground?
INB pg. 23

3. States of water *Let’s see what you know….

4. A. Specific Humidity
Def. - Amount of water vapor in air. 1. Warm air can hold more water vapor, because its molecules are further apart have more vacancy.

5. B. Relative Humidity
- how near the air is to its maximum capacity for holding water vapor.
1. Saturated air has a relative humidity of 100%.
Let’s draw this diagram!

6. C. Dew point
dew- water vapor condenses on a surface (ex. Grass, shower, car window)
Dew point= temp. at which saturation occurs and condensation begins.

7. Earth Science Lab
Pg. 24: Humidity & Dew Point Lab

8. Pre-Lab Questions Compare specific humidity vs. relative humidity.
Draw the relative humidity diagram on pg. 392 (blue txt) to help support your answer to question #1.
Define dew point in your own terms.
Read the “Formation of Dew and Frost” on pg. 394 Sketch a diagram on why dew forms on grass & leaves.
The amount of dew decreases during the daytime. Explain why this occurs. (Hint: think about what temperature holds more water and when dew forms.)

9. 15.5
Capacity
Vapor
Temperature (°C) 10
Capacity
Vapor
Over capacity = DEW
4.5
Capacity
Vapor
0 g
4 g
8 g

10. D. Measuring relative humidity= psychrometer (evaporation causes cooling.)

11. The “Dry Bulb” Don’t let it fool you. It is just a thermometer.
It measures the air temperature.
Duh!
20°C

12. The “Wet Bulb” Has a little wet sleeve tied to the bottom.
Gets cool when water evaporates.
12°C
Wet Sleeve

13. A Dry Day… A lot of moisture will evaporate.
The wet bulb will be a lot cooler than the dry bulb.
20°C
20°C
14°C
12°C
8°C
Difference between wet bulb & dry bulb is 12 °C.

14. A Humid Day… A little bit of moisture will evaporate.
The wet bulb will not be much cooler than the dry bulb.
20°C
14°C
Difference between wet bulb & dry bulb is 6 °C.

15. Dry-bulb temperature is your air temperature.
20 °C

16. Subtract (the difference) between the dry bulb and wet bulb

17. 20°C
14°C
20-14=6

18. 18°C
16°C
18-16=2

19. Put it all together
20°C
8°C
20-8=12
Relative Humidity = 11%

20. 14°C
10°C
14-10=4
Relative Humidity = 60%

21. Lab Instructions:
Copy Data Table A & B pg. 519 (black text) into your comp. book.
Draw the procedure for Part A & Part B
Following instructions PRECISELY
Answer 1-3 “Analysis & Conclusion” questions