Name:
Introduction to Weather and Climate and Vertical Structure of the Atmosphere Lab Activity (90 points)
Introduction
This lab activity introduces the concept of atmospheric pressure. We will construct and interpret a number of graphs to measure how pressure, density, and temperature change with height above the Earth’s surface. We will focus on how these relationships are expressed in the troposphere, which is where the majority of the weather occurs.
The atmosphere is a compressible fluid, made up of gases whose molecules are pulled to the Earth’s surface by gravity. As a result, the molecules that make up the atmosphere are most compressed close to Earth’s surface, and atmospheric density decreases most rapidly with height there (Figure 1-1).
Figure 1-1
Although the boundary between Earth’s surface and the atmosphere is obvious, there is no clear “top” to the atmosphere. It thins out with increasing height, but never actually ends. However, since very few gas molecules within Earth’s gravitational field exist beyond 100 kilometers (km), we can consider this height to be an a
itrary “top” to the atmosphere.
We may use a simple rule to describe the rate at which density decreases with height: For every 5.6 km you ascend, there is half the atmospheric mass above you as when you started.
1. Using the above rule, indicate the percentage of the atmosphere above and below each height in Table 1-1. Complete table from the bottom and work up the column! Insert values directly into the table. Sea-level has been completed for you. (12 pts)
TABLE 1-1
Height (km)
% of Atmosphere Above
% of Atmosphere Below
33.6
1.56
98.4
28.0
3.125
96.9
22.4
6.25
93.8
16.8
12.5
75
11.2
50
50
5.6
50
0
Sea level
100%
0%
2. Use the data in the first two columns of Table 1-1 to construct a line graph using the grid below. Connect the points with a curved line. The vertical axis is divided into 17 equally spaced intervals (every vertical lines is 2 km). Label this axis “Height Above Sea Level (km)” and label the intervals. Label the horizontal axis “Percentage of the Atmosphere Above” and label its intervals (0-100%). Give your graph an informative title. Hint: when your graph is complete, it should look very similar to the graph in Figure 1.18 on page XXXXXXXXXXpts)
*Insert graph in the space below (copy and paste from Excel or save as an image)*
You will use the graph to answer questions 3-7.
3. Jet airplanes travel at about 11.2 km above sea level (≈37,000 ft). Approximately what fraction of the atmosphere is above these jets? (1 pt)
_____75____%
4. What fraction is below the summit of Mt. McKinley in Alaska (6.19 km, 20,320 ft)? (1 pt)
____ 56____%
5. Approximately what fraction is above Pike’s Peak in Colorado (4.34 km, 14,110 ft)? (1 pt)
____61.3____%
Layers of the Atmosphere - Changes in Temperature with Height
We define four layers of the atmosphere (the troposphere, stratosphere, mesosphere, and thermosphere) according to their average lapse rate—the rate at which temperature changes with height (Figure 1-2). Although the lapse rate at any given time or place will differ from this average, the figure provides a starting point for understanding the temperature profile of the atmosphere. The tropopause, stratopause, and mesopause mark the top (end) of each layer.
6. Ozone is a good abso
er of ultraviolet radiation from the sun. How does its highest concentration at 20-30 km influence the stratospheric lapse rate? (2 pts)
Ozone influences the stratospheric lapse rate due to Ozone being able to abso
UV radiation and is converted into heat. The higher you go the warmer it gets.
Figure 1-2
7. Which two layers of the atmosphere exhibit a decreasing temperature trend with height? (2 pts)
Insert answer here
8. Which two layers of the atmosphere exhibit an increasing temperature trend with height? (2 pts)
Insert answer here
9. What is the approximately temperature at 85 km? Which “pause” is located closest to this height? (2 pts)
Insert answer here
10. Which two layers shown in Figure 1-2 are defined based on chemical properties? (2 pts)
Insert answer here
Tropospheric Lapse Rate
Let us examine in more detail the environmental lapse rate in the troposphere—the layer in which most weather phenomena occur. When averaged over all seasons, air temperature is 15°C at the Earth’s surface and decreases by 6.5°C per kilometer in the lowest 11 km. Consequently, this decrease is often refe
ed to as the average lapse rate—the average for all locations and seasons. Of course, the measured atmospheric lapse rate for a specific time and place will likely differ from the average.
11. Table 1-2 lists atmospheric temperatures measured at various heights above Key West, Florida and Fai
anks, Alaska on December 8, 1996, 12:00 GMT. Plot the data in the graph below the table and connect with straight lines. The height (m) is on the vertical axis while the temperature (°C) is on the horizontal axis. Label the axis with the variable names and units. As a reference, plot the average tropospheric lapse rate (6.5°C/km) on the same graph. Give your graph an informative title. Hint: when your graph is complete, it should look very similar to the graph in Figure 1.22 on page XXXXXXXXXXpts)
TABLE 1-2
Key West, Florida
Height (m)
Surface
800
3300
5300
7500
12000
16000
17000
20500
28000
Temperature (°C)
24
18
7
-6
-21
-57
-74
-74
-62
-56
Fai
anks, Alaska
Height (m)
Surface
800
3300
5300
7500
12000
16000
17000
20500
28000
Temperature (°C)
-26
-11
-7
-22
-30
-60
-51
-48
-47
-42
*Insert graph in the space below (copy and paste from Excel or save as an image)*
12. Which station has the higher surface temperature? (1 pt)
Station Name
13. Which station has the higher temperature at 10 km? (1 pt)
Station Name
14. Which station has the higher temperature at 16 km? (1 pt)
Station Name
15. How does the temperature profile in the lowest 1 km differ between the two stations? (2 pts)
Insert answer here
16. The tropopause marks the top of the troposphere and is defined as the height of coolest tropospheric temperature. Record the tropopause height at Key West and Fai
anks and their respective temperatures in Table 1-3 below. Type your answers into the table. (4 pts)
TABLE 1-3 TROPOPAUSE HEIGHT AND TEMPERATURE
Station
Height (km)
Temperature (°C)
Key West
16,000 km
-75.6 C
Fai
anks
10,000 km
-52.7 C
Review Questions (use textbook reading and PowerPoint to help with your answers)
17. In your own words, describe how air pressure, density, and temperature vary with height in the troposphere. (3 pts)
Insert answer here
18. The thickness of the troposphere varies from place to place and from day to day. What influences this thickness? Hint: Look at the graph above. (3 pts)
Insert answer here
19. Do you think air pressure changes faster as you move horizontally or vertically within the atmosphere? Explain your reasoning. Hint: Think of the definition of atmospheric pressure. (As a reference, an average hu
icane has a horizontal radius of approximately 600 km and a central pressure of 950 mb.) (5 pts)
Insert answer here
For each of the following situations, decide whether it is an example of weather or climate. Put “W” for weather or “C” for climate on the line next to each scenario. (15 pts; 1 pt each)
20. _____ A violent tornado touches down in Kansas and kills 45 people.
21. _____ The tundra climate (ET) has short, mild summers and long, cold winters.
22. _____ A three-day heat wave with temperatures above 100°F.
23. _____ The normal maximum temperature in Boston, MA on Fe
uary 1 is 31°F.
24. _____ An Alberta Clipper deposits two inches of snow across northern New England.
25. _____ An El Niño causes significant floods in Indonesia and a drought in India.
26. _____ Maritime polar air masses routinely
ing cool, moist oceanic air to the regions that experience Marine West Coast (Cfb) climate patterns.
27. _____ A thunderstorm topples 25 acres of forest with wind speeds over 100 mph.
28. _____ An ice storm causes cancellations, delays and disruptions to air travel.
29. _____ Tropical rainforests receive 175 to 200 centimeters of precipitation annually.
30. _____ A sunny day with calm winds and temperatures in the 50s.
31. _____ The typical temperatures in a steppe region (dry grassland) range from -5°C in the winter to 20°C in the summer.
32. _____ Lighting, thunder and microbursts within a summertime thunderstorm.
33. _____ The Thermohaline Circulation (an oceanic circulation of heat and salinity) a
uptly slows down causes a rapid decrease in normal temperatures leading to 100 years of below average temperatures. (This actually happened and lead to the “Little Ice Age” in Europe from approximately 1650 to 1750).
34. _____ A warm and humid air mass from the Gulf of Mexico moves toward New England.
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Temperature Calculations and Analysis Lab Activity (125 points)
Section 1: Daily Temperature Calculations
1. John’s home weather station reports that the minimum temperature was 18.5°F and the maximum temperature was 50.2°F.
a. What was the daily mean temperature? Show your work. You can insert a picture if you want. Include units. (3 pts)
Answer:
. What was the daily temperature range? Show your work. You can insert a picture if you want. Include units. (3 pts)
Answer:
2. The automated weather observation system (ASOS) records hourly temperatures of 2.4°F, 3.2°F, 4.5°F, 6.0°F, 8.4°F, 10.7°F, 12.3°F, 15.0°F, 17.1°F, 20.3°F, 24.9°F, 22.0°F, 19.3°F, 16.5°F, 14.2°F, 9.8°F and 6.2°F.
a. Calculate the daily mean temperature using both methods discussed in the lecture. Show work. You can insert a picture if you want. (6 pts)
Answer:
. Are the values you calculated the