CHAPTER 5
Air Pressure
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MULTIPLE CHOICE QUESTIONS
1. The magnitude of pressure exerted by the gas molecules composing air depends on
a. the mass of the air molecules.
b. the pull of gravity.
c. the kinetic energy of air molecules.
d. All of the above are correct.
e. None of the above is correct.
2. The average air pressure at sea level is
a. 14.7 lb per square inch.
b. 1013.25 mb.
c. 101,325 Pascals.
d. All of these are correct.
e. None of these is correct.
3. The usual world-wide range in sea-level air pressure is ______mb.
a. less than 20
b. less than 2
c. less than 100
d. more than 100
e. more than 1000
4. The type of barometer that is used to measure altitude:
a. mercury
b. aneroid
c. thermal
d. radiosonde
e. psychrometer
5. A barometer can be used to predict the weather by
a. reading the legends on the face of the barometer.
b. keeping track of the air pressure tendency.
c. using the instrument as an altimeter.
d. None of the above is correct.
6. An air-pressure altimeter is actually a(n) ______barometer.
a. mercury
b. aneroid
7. The top of the atmosphere is at an average altitude of
a. 80 km.
b. 100 km.
c. 5 km.
d. 10 km.
e. None of these is correct.
8. The pressure of the atmosphere is greatest
a. at the tropopause.
b. at the Earth's surface.
c. at sea level.
d. at the mesopause.
e. at the stratopause.
9. Between the tropopause and stratopause, the air pressure ______with increasing altitude.
a. increases
b. decreases
c. does not change
10. What fraction of the atmosphere's mass is below an aircraft flying at the 400 mb level?
a. 0.6
b. 0.4
c. 0.2
d. 0.3
e. 0.1
11. What fraction of the atmosphere is below the 500 mb level?
a. 0.6
b. 0.8
c. 0.5
d. 0.3
e. 0.2.
12. Within the thermosphere, the temperature is ______and heat energy is ______.
a. low...... low
b. high...... high
c. low...... high
d. high...... low
13. When air pressure readings at Denver (the "mile-high city") are adjusted to sea level, air pressure readings are
a. increased.
b. decreased.
c. not changed.
14. Adjusting barometer readings to sea-level removes the influence of ______on air pressure.
a. air temperature
b. wind speed
c. station elevation
d. humidity
e. divergence
15. An air mass is a huge volume of air that is relatively uniform horizontally in
a. temperature.
b. humidity.
c. Both of these are correct.
d. None of these is correct.
16. At the same pressure, warm, dry air is ______cold, dry air.
a. denser than
b. less dense than
c. about as dense as
17. At the same pressure, warm and humid air is ______equally warm and dry air.
a. denser than
b. less dense than
c. about as dense as
18. At the same temperature and pressure, humid air is ______dry air.
a. denser than
b. less dense than
c. about as dense as
19. With the same volumes, a cold and dry air mass exerts ______surface air pressure than a warm and humid air mass.
a. higher
b. lower
20. With the same volumes, a warm and dry air mass exerts ______surface air pressure than an equally warm but humid air mass.
a. higher
b. lower
21. When a warm and humid air mass replaces a cold and humid air mass at a particular locality, the air pressure at Earth’s surface usually
a. rises.
b. falls.
c. does not change.
22. Relatively high surface air pressure is usually accompanied by ______weather whereas relatively low surface air pressure is usually accompanied by ______weather.
a. fair...... stormy
b. stormy...... fair
23. The decline of air pressure with altitude is most rapid in ______air masses.
a. warm and humid
b. cold and humid
c. warm and dry
d. cold and dry
24. The troposphere is denser in ______than in ______
a. winter...... summer
b. summer...... winter
25. The tropopause is lower in ______than in ______.
a. winter...... summer
b. summer...... winter
26. If the surface air pressure is the same everywhere, but a mass of cold air is situated next to a mass of warm air, the pressure at high altitudes is
a. greater in the warm air.
b. greater in the cold air.
c. greater between the warm air and cold air.
d. the same in the warm air and the cold air.
27. Changes in air pressure with time at a particular locality may be explained by
a. local radiational heating or cooling.
b. air mass advection.
c. divergence or convergence of surface winds.
d. All of the above are correct.
28. With cold air advection in winter, the air pressure tendency is usually
a. upward
b. downward
c. unchanged
29. With warm air advection in winter, the air pressure tendency is usually _____.
a. upward
b. downward
c. unchanged
30. A variable of state in the atmosphere:
a. temperature
b. pressure
c. density
d. All of these are correct.
e. None of these is correct.
31. Within the atmosphere,
a. air temperature always decreases with altitude.
b. air density always increases with altitude.
c. air pressure always decreases with altitude.
d. All of these are correct.
e. None of these is correct.
32. According to the gas law, air pressure is directly proportional to
a. air density.
b. air temperature.
c. Both of these are correct.
d. None of these is correct.
33. As a mass of arctic air invades our locality, air temperature ______and air density ______.
a. falls...... increases
b. rises...... increases
c. falls...... decreases
d. rises...... decreases
34. As a mass of warmer and more humid air invades our locality, air temperature _____ and air density _____.
a. falls...... increases
b. rises...... increases
c. falls...... decreases
d. rises...... decreases
35. Usually, the air pressure inside a building is _____ the air pressure outside the building.
a. greater than
b. about the same as
c. less than
36. In order that barometer readings are accurate and representative,
a. the instrument must always be mounted outdoors and in a special instrument shelter.
b. the instrument must always be mounted outdoors but not in a special instrument shelter.
c. the instrument must always face the sun during daylight hours.
d. the instrument may be mounted indoors.
e. None of the above is correct.
37. The standard atmosphere
a. is a model of the real atmosphere.
b. features a mean sea-level air pressure of 1013.25 mb.
c. may be useful in reducing barometer readings to sea level.
d. All of the above are correct.
e. None of the above is correct.
38. The elevation of the 500-mb surface
a. depends on the average temperature of the air between Earth's surface and the 500-mb level.
b. varies with latitude and time.
c. can be determined by a radiosonde.
d. All of the above are correct.
e. None of the above is correct.
39. Air pressure decreases ______with increasing altitude.
a. uniform
b. nonuniformly
40. The concentration of oxygen (O2) in parts per million ______with increasing altitude within the troposphere.
a. decreases
b. increases
c. does not change
41. Differences in the altitude of the 500-mb surface from one place to another can be explained primarily by differences in ______of the air below the 500-mb surface.
a. humidity
b. temperature
c. wind speed
d. None of the above is correct
42. Two weather stations (A and B) at sea level report the same surface air pressures. Warm air is above Station A while relatively cold air is above Station B. At an altitude of 25,000 feet, one would expect the pressure above Station A to be
a. higher than that above Station B.
b. lower than that above Station B.
c. the same as that above Station B.
43. Highs and Lows are identified on surface weather maps by areas enclosed within isobars. Which one of the following statements about Highs is true?
a. The highest pressure in a High must always be higher than the lowest pressure in a Low on the same weather map.
b. Air pressure increases outward from the center of a High.
c. All Highs must have central pressures with values greater than 1013.25 mb.
d. There must be one and only one High for each Low on the same weather map.
44. Lows and Highs are identified on surface weather maps by areas enclosed within isobars. Which one of the following statements about Lows is true?
a. The lowest pressure in a Low must always be lower than the highest pressure in a High on the same weather map.
b. Air pressure decreases outward from the center of a Low.
c. All Lows must have central pressures with values less than 1013.25 mb.
d. There must be one and only one Low for each High on the same weather map.
45. Normal atmospheric pressure may be expressed in all of the following ways except
a. 30 inches of mercury
b. 76 cm of mercury
c. 1013 millibars
d. 62.4 lbs per square foot.
46. A typical sea-level pressure could be
a. 760 cm of mercury.
b. 1100 mb.
c. 30 inches of mercury.
d. Any of the above is correct.
47. Compared to horizontal pressure gradients, vertical pressure gradients are
a. much greater.
b. about the same.
c. much smaller.
48. Changes of air pressure in the horizontal are
a. much larger than they are in the vertical.
b. about the same as they are in the vertical.
c. much smaller than they are in the vertical.
49. Half of the Earth's atmosphere (by weight) is located within approximately
a. 3.5 miles of sea level.
b. 29.92 miles of sea level
c. 100 miles of sea level.
d. one mile of sea level.
50. At an altitude of about 3.5 miles above sea level, the air pressure is approximately
a. 1000 mb.
b. 750 mb.
c. 500 mb.
d. 250 mb.