Read Chapter 18, Section 1 (page 506 – 509) to assist you in answering the following:
1. Use the table on page 506 to determine the saturation point for each of the following:
a. Temperature @ -22 degrees F:: Saturation point = .3
b. Temperature @ 14 degrees F:: Saturation point = 2
c. Temperature @ 32 degrees F:: Saturation point = 3.5
d. Temperature @ 50 degrees F:: Saturation point = 7
e. Temperature @ 77 degrees F:: Saturation point = 20
f. Temperature @ 95 degrees F:: Saturation point = 35
2. Create a graph comparing temperature (F) to water vapor saturation (g/kg), using the data from
question 1a – 1f.
T
E
M
P
E (F)
R
A
T
U
R
E
100
75
50
25
0
- 25
5
10
15
20
25
Saturation Point (g/kg)
30
35
40
3. What 2 variables control relative humidity? Water vapor and temperature.
4. How does relative humidity change with cooling air? If the amount of water vapor in the air remains the
same and air temperature decreases, the relative humidity will increase.
5. How does relative humidity change with warming air? If the amount of water vapor in the air remains the
same and air temperature increases, the relative humidity will decrease.
6. Is the dew point a measure of relative humidity or temperature? Explain your answer. Dew point
measures the temperature at which the air becomes saturated and begins to form dew, fog, or clouds.
7. Which dew points are associated with moist air? High dew points = moist air
8. Which dew points are associated with dry air? Low dew points = dry air
9. Explain why dew forms on spider webs and grass. When objects near the ground (such as a spider web)
cool below the dew point, they become coated with water (dew). Plants also transpire and release water
vapor and causes the air near the grass to have a higher dew point than the air above. As a result, dew
forms on the plants.
10. What 2 variables are compared to measure relative humidity? A wet-bulb and a dry-bulb thermometer
are used to compare the 2 temperature readings (known as “depression of the wet bulb”). The Dry Bulb
reading is then correlated with the Depression reading on a Relative Humidity chart to record the percent
of relative humidity in the air.
11. Use the Data Table 2 on page 525 to determine the following relative humidity measurements:
Dry-bulb Temperature
Depression of Wet-bulb
Relative Humidity
(C)
Temperature (C)
(percent)
0
4
28
8
4
51
8
8
6
16
8
29
32
4
73
32
8
51
32
16
14
12. Write a summary statement describing the relationship observed in your data and from analyzing Data
Table 2 on page 525. If dry-bulb temperature remains constant, relative humidity decreases as the
depression of wet-bulb temperature increases.
Read Chapter 18, Section 2 (page 510 – 516) to assist you in answering the
following:
1. How does air compression affect the air temperature?
As air is compressed, the temperature becomes warmer.
2. How does air expansion affect the air temperature?
As air expands, the temperature becomes cooler.
3. Changes in air temperature as a result of pressure changes are referred to as
adiabatic
temperature changes.
4. Explain how adiabatic cooling causes clouds to form.
Rising air continues to cool until it reaches the dew point, when condensation begins to
form clouds.
5. Create illustrations of the 4 processes that can lift air. Add labels and descriptions to
make your illustration easier to understand. (See the illustrations of orographic lifting,
frontal wedging, convergence, and localized convection lifting on pages 512 – 513.)
6. Which of the 4 processes illustrated above are most likely to occur in our region?
Frontal wedging occurs when southerly breezes blow across the inland portions of NC and
the friction causes the air to heat up. As this air mass moves over the cooler air mass
above the ocean, summer time thunderstorms can form.
Localized convective lifting often occur during our summers due to uneven heating along
inland and coastal areas.
7. How does unstable air react in relation to the altitude of the troposphere?
Unstable air continues to rise, expand, and cool until it reaches an altitude where the
surrounding temperature matches.
8. How does stable air react in relation to the troposphere?
Stable air resists vertical movement and tends to remain in position. Stable air temperature
decreases gradually as the altitude increases. When air temperature INCREASES with
altitude increases, a temperature inversion occurs. This is often seen as a result of
radiation cooling of Earth’s surface on clear nights.
9. What type of instrument is used to measure air stability?
Radiosondes are attached to weather balloons and launched to record various changes in
air temperature at different altitudes.
10. How do clouds produced from stable air differ from the clouds produced by unstable
air? Add an illustration to show the differences.
Clouds produced from stable air = widespread clouds and little precipitation.
Clouds produced from unstable air = large, tall clouds that produce thunderstorms,
tornados.
11. Explain how condensation nuclei assist in creating water vapor and precipitation.
Condensation nuclei, such as microscopic particles of salt, dust, pollution, and smoke,
provide a framework for water molecules to attach and form cloud droplets.
DON’T FORGET TO REVIEW YOUR CLOUD TYPES FROM CHAPTER 18, SECTION
3!!