WRITE ON YOUR OWN
PAPER
Vertical Structure of the Atmosphere
1. Think about it: Answer the following questions, based on your current level of understanding. Remember,” I don’t know”
is NOT an answer.
 What holds air close to Earth?
 Why do jet fighter pilots where air masks?
 Why are commercial airplane cockpits pressurized?
2A. Copy figure 1 below onto your own paper. You must use a pencil and ruler.
Figure 1 The Effect of Percent of the Atmosphere Above on Height above Surface
Height (km)
33.6
28
22.4
16.8
11.2
5.6
0 (sea level)
% of Atmosphere
Above
% of Atmosphere
Below
Pressure Above
Pressure Below
100%
0%
1000mb
0mb
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 mostly compressed close to the earth’s surface. We may use a simple
rule to describe the rate at which density decreased with height.
No matter where you begin in the atmosphere, if you move up in the atmosphere 5.6 kilometers (km), you will cut in half
the atmospheric mass above.
2B. Using the above rule, indicate on your table the percent of the atmosphere above and below each height in Figure 1.
3. Use the data in figure 1 to construct a graph. You must take up the whole page, use a ruler, and a pencil.
The vertical (Y) axis should be divided into 17 equally spaced intervals. Label this axis “Height above the Surface (km)” and
label the intervals. Label the horizontal (X) axis “Percent of the Atmosphere Above” and label its intervals (0-100%).
Give the graph a title. Use the graph to answer the analysis questions.
Answer the following questions in complete sentences with NO pronouns.
4. A jet airplane travels about 11.2 km above sea level. A. Label this point on your graph.
B. Approximately what fraction of the atmosphere is ABOVE these jets?
5. Mt McKinley (Denali) in Alaska is 6.19 km above sea level. A. Label this point on your graph.
B. Approximately what fraction of the atmosphere is BELOW this mountain?
6. Pike’s Peak Alaska is 4.34 km above sea level. A. Label this point on your graph.
B. Approximately what fraction of the atmosphere is ABOVE this mountain?
7. The ozone layer is located at 20 km above sea level. A. Label this point on your graph.
B. Approximately what fraction of the atmosphere is ABOVE the ozone layer?
Since barometric pressure reflects the weight of the atmosphere above a point, there is a close relationship between height and
atmospheric pressure. We can assume that 100% of the atmosphere mass lies above sea level (0 km) and exerts a pressure of
approximately 1000mb (millibars).
Since atmospheric mass at 5.6 km is 50% for its sea level values, the pressure at this height is half at sea level too.
8. Using this relationship, add pressure data to the table. Add pressure to the X axis of the graph and label it “Pressure (mb)”. Use a new
color for the pressure portion of the graph. Make a key.
9. Using the new scale. Estimate the pressure above for the following
A. Height of jet airplanes _____mb
B. The top of Mt. McKinley _____mb
C. Top of Pikes Peak _____mb
D. The ozone layer _____mb
10. Based on the fact that barometric pressure is the weight of air, hypothesize where most of the air in the atmosphere is located.
11. Use the textbook or Ipad to determine the major gases that make up the atmosphere.