Clouds and Moisture Laboratory Assignment
- Due Nov 28, 2021 by 11:59pm
- Points 15
- Submitting a text entry box or a file upload
Introduction
Weather and climate are of vital interest to people in many of their daily activities. There are a few key elements to weather and climate, one of which is moisture content. In this lab we will examine the changes of state of water, how water vapor content of the air is measured, and the events that lead to cloud formation.
Objectives
Upon completion of this exercise, you should be able to:
- Explain adiabatic heating and cooling and be able to calculate temperature changes associated with changing altitudes
- Describe the change of temperature associated with normal lapse rates and calculate temperature changes associated with normal lapse rates
Water Vapor Capacity and Relative Humidity
Use the table below to answer the following question.
Table 1.
|
Water Vapor capacity of a Kilogram of air (at average sea level pressure |
||
|
Temperature Grams of water vapor (ºC) (ºF) per kg of air (g/kg) |
||
|
-40 |
-40 |
0.1 |
|
-30 |
-22 |
0.3 |
|
-20 |
-4 |
0.75 |
|
-10 |
14 |
2 |
|
0 |
32 |
3.5 |
|
5 |
41 |
5 |
|
10 |
50 |
7 |
|
15 |
59 |
10 |
|
20 |
68 |
14 |
|
25 |
77 |
20 |
|
30 |
86 |
26.5 |
|
35 |
95 |
35 |
|
40 |
104 |
47 |
From Tarbuck, Lutgens, Pinzke
Applications and Investigations in Earth Science.
3rd Edition, Prentice Hall, 2000
1. What is the water vapor capacity for a kilogram of air at each of the following temperatures?
-10ºC: __________ g/kg
35ºC: __________ g/kg
41ºF: __________ g/kg
77ºF: __________ g/kg
2. Raising the temperature of a kilogram of air from 20ºC to 25ºC increases or decreases its water vapor capacity and by how much?
3. Decreasing the temperature of a kilogram of air from 95ºF to 86ºF increases or decreases its water vapor capacity and by how much.
Relative Humidity = Water Vapor Content X 100
Water Vapor Capacity
4. Air Temp. Water Vapor Relative
Content Capacity Humidity
20ºC 2g/kg ________g/kg ________%
20ºC 7g/kg ________g/kg ________%
20ºC 10g/kg ________g/kg ________%
5. Air Temp. Water Vapor Relative
Content Capacity Humidity
15ºC 2g/kg ________g/kg ________%
20ºC 2g/kg ________g/kg ________%
25ºC 2g/kg ________g/kg ________%
6. How does the relative humidity vary if the temperature is constant but the water vapor content increases?
7. How does the relative humidity vary if the water vapor content is constant but the temperature increases?
8. What do you think would happen to the relative humidity if the water vapor content remains the same but the temperature decreases?
9. If you turn on the heat in your house, how does that affect the relative humidity?
10. Refer back to the table, What is the dew point temperature of a kilogram of air that contains 10g of water vapor?
Temp. ____________ºC
11. What is the relative humidity and dew point temperature of a kilogram of air that is 15ºC and contains 2 grams of water vapor?
Relative humidity _______________%
Dew-point temperature _______________ºC
Adiabatic Processes.
12. Adiabatic heating and cooling is a temperature change caused by a change in ___?
13. As air is forced to rise, pressure (increase, decreases) and air temperature (increases, decreases).
The Dry Adiabatic Rate vs. the Saturated or Wet Adiabatic Rate (when do you use one or the other to calculate the change in temperature).
The dry adiabatic rate is about 5.4 °F for 1,000 feet of elevation change.
The wet adiabatic rate is about 2.7°F for 1,000 feet of elevation change.
14. Air is moving across a mountain front in Figure 1. Calculate the temperature of air at the points labeled B, C, D and E in Figure 1. Values are in feet and °F.
Assume that the Dew point is reached at 6,000 feet. Once Point D is reached, the air has become unsaturated. Show your calculations to the right of each answer.
B __________
C __________
D __________
E __________
Figure 1. Cross Section Showing Air(Arrow) Rising over Mountain
15. At what elevation could precipitation begin? What type of precipitation would this be?
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