NATS 101 – Section 39



ATMO 336 – Sections 001 & 002 Name__________________________

Exam 1 – Spring 2009

Write all answers on the answer sheets. Mark your answers clearly. If we cannot determine your answer, it will be marked wrong. You will turn in both the exam sheets and the answer sheets. Write your name on both.

Multiple Choice (2.5 points each)

1. The two most abundant gases in the atmosphere of Earth are __________ .

a) nitrogen and oxygen (c) nitrogen and carbon dioxide

b) oxygen and carbon dioxide (d) carbon dioxide and water vapor

2. Tiny liquid or solid particles that are suspended in air are called _________ .

a) carcinogens (c) aerosols

b) greenhouse agents (d) haze

3. Humans can survive without assistance _____________ .

a) in the lower part of the troposphere only

b) throughout the entire troposphere, but not the stratosphere

c) throughout the entire troposphere, and in the lower stratosphere

d) throughout the entire troposphere and the entire stratosphere

4. In the troposphere, a temperature inversion is a layer of air wherein the air temperature _________ with increasing altitude. Temperature inversions just above the ground surface are most common ____________ .

a) decreases ; near sunrise (c) increases ; near sunrise

b) decreases ; in the late afternoon (d) increases ; in the late afternoon

5. Consider two cities both located at sea level. Suppose both cities have a sea level pressure of 1000 mb. However city A has an air temperature of 70° F and city B has an air temperature of 30° F. Which is correct concerning the air number density at the two cities?

a) Both cities will have the same number density

b) City A will have a higher number density

c) City B will have a higher number density

d) Not enough information is given to compare the number densities of the two cities

6. Higher than about 20,000 ft above sea level, people have trouble breathing. The reason is that _______________ .

a) the air pressure and density are too low to get enough oxygen

b) the percentage of oxygen molecules in the air drops below 21%

c) the air temperature is too cold to breathe

d) the ozone levels are too high

7. When the polar jet stream is over the United States, it most typically moves from ______ .

a) north to south (c) east to west

b) south to north (d) west to east

Use the 500 mb map above to answer questions 8 - 14

8. At which marked point (A-D) do you expect temperature to be the most below average?

9. At which marked point (A-D) do you expect temperature to be the most above average?

10. Which is true concerning the 500 mb wind speed at the marked points?

a) Expect stronger winds at points A and C compared with points B and D

b) Expect stronger winds at points B and D compared with points A and C

c) Expect stronger winds at points A and D compared with points B and C

d) Expect stronger winds at points B and C compared with points A and D

11. At which marked point (A-D) is the 500 mb wind closest to being a north wind? You should use the meteorological definition for wind direction.

12. At which marked points do you expect the best chance for precipitation?

a) A and B (b) B and C (c) C and D (d) B and D

13. The climatological average 500 mb height for mid-February in Tucson is 5690 m. Based on this and the map above, what forecast would you make for Tucson?

a) Sunny, above average temperatures (c) Chance for rain, above average temps

b) Sunny, below average temperatures (d) Chance for rain, below average temps

14. The map shown corresponds to what local time in Tucson?

a) 5 PM, Saturday, Feb 21 (c) 7 AM, Sunday, Feb 22

b) 5 AM, Sunday, Feb 22 (d) 7 PM, Sunday, Feb 22

15. Just downstream of 500 mb ridges, there is _______ of air in the upper troposphere which causes ________ vertical air motion in the atmosphere.

a) divergence ; rising (c) divergence ; sinking

b) convergence ; rising (d) convergence ; sinking

16. Which of the following features is NOT associated with rising vertical air motion?

a) Cold front (c) Surface high pressure

b) Warm front (d) Surface low pressure

Salt Lake City, UT is 1320 m (4330 ft) above sea level

Las Vegas, NV is 663 m (2174 ft) above sea level

Which city will have the lowest station air pressure (i.e., measured with a barometer)?

a) Always Las Vegas

b) Always Salt Lake City

c) Sometimes Salt Lake City, Sometimes Las Vegas

Salt Lake City, UT is 1320 m (4330 ft) above sea level

Las Vegas, NV is 663 m (2174 ft) above sea level

Which city will have the lowest sea level pressure (or equivalent sea level pressure)?

a) Always Las Vegas

b) Always Salt Lake City

c) Sometimes Salt Lake City, Sometimes Las Vegas

17. A meteorologist describes the 500 mb pattern over the continental United States as a “zonal pattern.” What type of weather is most likely across the United States?

a) Near average temperatures everywhere, with strong storm systems likely

b) Near average temperatures everywhere, with strong storm systems unlikely

c) Much below average temperatures in the north and much above average temperatures in the south, with strong storm systems likely

d) Much below average temperatures in the north and much above average temperatures in the south, with strong storm systems unlikely

18. Which process requires the most energy?

a) Evaporating one gram of liquid water

b) Raising the temperature of one gram of liquid water from 0( C to 100( C

c) Melting one gram of ice

d) Raising the temperature of one gram of ice from -100( C to 0( C

19. Suppose we are comparing the forecasts from two different weather prediction models. If the 00 hour forecasts (initial conditions) are slightly different, which of the following is most likely?

a) The two models will produce very similar 48 hour (2 day) forecasts, but very different 144 hour (6 day forecasts).

b) The two models will produce very different 48 hour (2 day) forecasts, but very similar 144 hour (6 day forecasts).

20. Based on the course material, even as computing power continues to increase in the future, we should not expect to make very accurate weather forecasts two weeks into the future.

a) True (b) False

21. When taking a hot shower in a closed room, the concentration of water vapor in the air can become high enough that you can see it.

a) True (b) False

|Temperature |Saturation Mixing Ratio (g/kg) |Temperature |Saturation Mixing Ratio (g/kg) |

|(ºF) | |(ºF) | |

|5 |1.21 |55 |9.32 |

|10 |1.52 |60 |11.19 |

|15 |1.89 |65 |13.38 |

|20 |2.34 |70 |15.95 |

|25 |2.88 |75 |18.94 |

|30 |3.54 |80 |22.43 |

|35 |4.33 |85 |26.48 |

|40 |5.28 |90 |31.16 |

|45 |6.40 |95 |36.56 |

|50 |7.74 |100 |42.78 |

Use the table of saturation mixing ratios to answer questions 24 & 25

22. If the air temperature is 70° F and the relative humidity is 58%, approximately what is the dew point temperature?

(a) 40° F (b) 45° F (c) 50° F (d) 55° F

23. What is the relative humidity of air with a temperature of 80° F and a dew point temperature of 40° F?

(a) 6.6% (b) 23.5% (c) 50.0% (d) 56.1%

For questions 26-28, suppose you have an unsaturated parcel of air that contains some water vapor. If the parcel is warmed, what will happen to:

24. The dew point temperature of the air in the parcel?

a) It will decrease in value (b) It will increase in value

(c) Its value will remain the same

25. The relative humidity of the air in the parcel?

a) It will decrease in value (b) It will increase in value

b) Its value will remain the same

26. The saturation mixing ratio of the air in the parcel?

a) It will decrease in value (b) It will increase in value

(c) Its value will remain the same

27. Suppose you take a beer can out of a refrigerator that is at a temperature of 37˚ F. At first, the outside of the can is dry, but then you notice that water condenses on the sides of the can, which of the following is most likely true?

a) The air inside the refrigerator is saturated

b) The air outside the refrigerator is saturated

c) The dew point temperature of the air outside the refrigerator is below 37˚ F

d) The dew point temperature of the air outside the refrigerator is above 37˚ F

ATMO 336 Name ______________________________

Exam 1 – Answer sheet Last 4 Digits of Student ID _____________

1. a b c d 16. a b c d

2. a b c d 17. a b c d

3. a b c d 18. a b c d

4. a b c d 19. a b c d

5. a b c d 20. a b c d

6. a b c d 21. a b c d

7. a b c d 22. a b c d

8. a b c d 23. a b c d

9. a b c d 24. a b c d

10. a b c d 25. a b c d

11. a b c d 26. a b c d

12. a b c d 27. a b c d

13. a b c d 28. a b c d

14. a b c d 29. a b c d

15. a b c d

Instructions for Short Answer Questions – 8 Points Each

The short answer questions are on the back of this page. For each numbered question (1-4), you must select and answer either (a) or (b). Write your answers on the lines provided in the short answer section. Make sure you answer all parts of each question you select. Your answers should be short and to the point. Points will be deducted for incorrect or unnecessary statements in your answer, even if the correct answer is found somewhere.

1. Select (a) or (b)

a. Why does the Earth’s atmosphere remain around the planet? In other words, why doesn’t it float away into the near vacuum of outer space? What causes air pressure in the atmosphere? How does air pressure change as you move upward in the atmosphere? Explain why.

b. Some people say that roughly half of the Earth’s atmosphere is above 500 mb and roughly half of the atmosphere is below 500 mb. In what sense is roughly half the atmosphere above 500 mb and roughly half of the atmosphere below 500 mb? Explain how this is possible given that the 500 mb height is at an altitude of about 5 km, while the entire atmosphere extends up to 500 km altitude. The ratio of the 500 mb height to the total height of the atmosphere is about 5/500 (or 1/100), not 1/2.

2. Select (a) or (b)

a. Suppose a very warm air mass covers the entire Eastern half of the continental United States and a very cold air mass covers the entire western half of the United States. Where would you expect to find the strongest winds at 500 mb … above the middle of the cold air mass, above the middle of the warm air mass or above the boundary between the warm and cold air masses? Explain why. Determine the 500 mb wind direction above the boundary between the two air masses. You should include all the important forces that act on the air in your answer.

b. A hurricane has an area of low sea level pressure at its center. On a surface weather map a large L would mark the center of the hurricane and it would be surrounded by circular isobars. A strong hurricane with wind speeds over 150 mph (miles per hour) will have a central sea level pressure of 920 mb or lower. The average sea level pressure is 1013 mb. Explain why the wind speed generated by a hurricane gets stronger as the sea level pressure at its center becomes lower. Describe the surface wind flow pattern surrounding the center of a hurricane in the Northern Hemisphere. What role does this surface wind pattern play in the development of the heavy rain produced by hurricanes.

3. Select (a) or (b)

a. When rain first begins to fall, it is common for the air temperature in the lower atmosphere to drop. Explain why the onset of rain can cause the air temperature near the ground to drop. (Hint. Once raindrops fall below the cloud, they typically fall through an environment where relative humidity is less than 100%). Suppose the air temperature is 50° F and the dew point temperature is 40° F just as rain starts to fall. After 10 minutes, the air temperature falls to 45° F and remains steady even though rain continues to fall. Explain why the air temperature does not cool down to 40° F, the dew point temperature measured before the rain.

b. Some scientific applications require very dry air (low water vapor content). One way to produce dry air is to “freeze dry” it. A simple system would draw air through a cold, freezer tube (shown at the bottom of the page). Suppose the air is cooled to -40° F as it passes through the tube. When the system is running, a thick layer of ice grows on the inner surface of the tube. Explain how a freeze dry system works to lower the water vapor content of the air that passes through it. What is the relative humidity of the cold air that comes out of the freeze dry chamber? Explain why the relative humidity of the air changed the way it did after passing through the freeze dry chamber? (Hint. You should not need to calculate anything to answer this).

4. Select (a) or (b)

a. Describe the water cycle on Earth with regard to the movement of water into, within, and out of the atmosphere. You should use the terminology presented on the water cycle diagram on the class web page notes. (No you cannot look at the diagram now)! In your description, you should specifically mention where in the cycle energy needs to be added to the water and where energy is released by water.

b. What is a cloud? Explain in as much detail as you can how most clouds form. If it helps, you may use the concept of an air parcel in your answer.

ATMO 336 Name__________________________

Exam 1 – Short Answer Sheet

Question #1. Please select and answer either part (a) or (b).

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Question #2. Please select and answer either part (a) or (b).

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Question #3. Please select and answer either part (a) or (b).

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Question #4. Please select and answer either part (a) or (b).

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