Name ____________________________________________
Lab 6
Atmospheric Pressure and Temperature
Purpose
The purpose of this lab is to have you identify the relationship between atmospheric
temperature and pressure near the surface of the Earth. You will also utilize the technique of
drawing isotherms for the analysis of surface temperature on surface weather maps.
Materials
Colored pencils
Microsoft Excel
ruler
Atmospheric Pressure
Air pressure is determined by the weight of the overlying air. It varies from place to place and
over time. Air moves in response to horizontal differences in air pressure, setting the stage for
much of the weather we experience. Wind (air in motion) tends to blow from where the air
pressure is relatively high to where the air pressure is relatively low. Once air is in motion, its
speed and direction may be influenced by the rotation of the Earth on its axis (Coriolis Effect)
and/or contact with Earth’s surface (friction).
Procedure A
1. Using the data in Table 6-1, create a line graph showing the temperature and barometric
pressure for one 24-hour period. Plot your data for temperature in one color and the data for
barometric pressure in another color. Be sure to label both lines on the graph. The X-axis
should be labeled “Time of Day,” the primary Y-axis should be labeled “Barometric Pressure
(millibars),” and the secondary Y-axis should be labeled “Temperature (°F).”
2. Create a second line graph using the data in Table 6-2 for a different day’s temperature and
barometric pressure. Set up your graph in the same way as your first.
3. Using information from the textbook, the UIUC meteorology website, and from Mr. Mosser, fill
in the characteristics associated with both high- and low-pressure systems at the Earth’s surface
in Table 6-3.
I hereby declare upon my word of honor that I have neither given nor received any unauthorized aid on
this work.
______________________________________________________
Name ____________________________________________
Lab 6
1. Using your graphs from Procedure A1 and A2, describe the general relationship between
temperature and barometric pressure near the Earth’s surface.
2. A decrease in atmospheric pressure would signal what possible change in the current
temperature?
3. A decrease in the present air temperature would signal what type of change in atmospheric
pressure?
4. Using the data from Table 6-1, what was the rate of temperature change between 12:00 a.m.
and 2:00 p.m (rate of change = change in value/change in time)? Show your work.
5. Using the data from Table 6-1, what was the rate of change of the barometric pressure between
12:00 a.m. and 2:00 p.m (rate of change = change in value/change in time)? Show your work.
6. Using the data from Table 6-2, what was the rate of temperature change between 11:00 a.m.
and 9:00 p.m (rate of change = change in value/change in time)? Show your work.
7. Using the data from Table 6-2, what was the rate of change of the barometric pressure between
11:00 a.m. and 9:00 p.m (rate of change = change in value/change in time)? Show your work.
2
Name ____________________________________________
Lab 6
TIME
12:00a
1:00a
2:00a
3:00a
4:00a
5:00a
6:00a
7:00a
8:00a
9:00a
10:00a
11:00a
Table 6-1 Temperature and Barometric Pressure
TEMP (°F)
BAR (mb)
TIME
TEMP (°F)
40.1
1025.6
12:00p
48.6
40.8
1023.4
1:00p
48.9
40.2
1023.2
2:00p
50.2
40.1
1021.2
3:00p
48.3
41.3
1020.3
4:00p
48.2
42.3
1019.2
5:00p
48.8
42.3
1018.0
6:00p
47.7
40.6
1016.9
7:00p
48.2
41.2
1016.3
8:00p
48.2
42.9
1015.7
9:00p
48.5
44.9
1014.3
10:00p
48.9
46.4
1013.4
11:00p
50.1
12:00a
50.1
BAR (mb)
1011.7
1011.1
1011.0
1010.9
1011.2
1010.9
1010.9
1010.9
1010.8
1011.8
1012.2
1012.4
1012.9
TIME
12:00a
1:00a
2:00a
3:00a
4:00a
5:00a
6:00a
7:00a
8:00a
9:00a
10:00a
11:00a
Table 6-2 Temperature and Barometric Pressure
TEMP (°F)
BAR (mb)
TIME
TEMP (°F)
38.9
1001.5
12:00p
37.5
39.6
1000.7
1:00p
35.9
39.2
999.5
2:00p
35.5
39.3
998.2
3:00p
34.7
39.2
997.6
4:00p
32.7
38.2
997.5
5:00p
32.4
36.9
995.7
6:00p
31.9
36.3
995.3
7:00p
31.2
36.5
995.4
8:00p
30.3
36.2
996.0
9:00p
29.4
36.8
995.4
10:00p
29.4
38.3
993.9
11:00p
29.1
12:00a
28.2
BAR (mb)
993.5
994.4
995.6
996.4
998.1
999.9
1001.8
1003.0
1004.6
1006.3
1007.9
1009.1
1010.0
3
Name ____________________________________________
Lab 6
TABLE 6-3 ATMOSPHERIC PRESSURE SYSTEMS
Pressure
LOW
HIGH
Temperature
Wind Rotation
(Northern Hemisphere)
Moisture
Weather Map Symbol
Rising or Sinking Air?
Procedure B
Using the techniques of isotherm analysis introduced to you by Mr. Mosser, draw isotherms at 10degree intervals on the two surface temperature maps in Figures 27-1 and 27-2.
4
Name ____________________________________________
Lab 6
Procedure C
Pressure gradient force, also known as wind, is an important variable in the atmosphere that helps to
define weather on Earth. By analyzing the differences in pressure between two points on the Earth’s
surface, it is often possible to predict local wind direction and speed. Using the surface weather map
(Figure 29-2), calculate the pressure gradient in millibars per mile between the points shown in Table 64. Show your calculations and record your answers in the spaces provided in Table 6-4.
Points on Map
A-B
A-C
A-D
A-E
H-F
H-G
H-I
5
TABLE 6-4 PRESSURE GRADIENT
Change in
Distance
Calculations
Pressure (mb)
(miles)
Pressure Gradient
(change in
pressure/mile)