ATSC 2000 Spring 2001 – 4/10/01

Test 3  (15%)

A. Multiple-choice questions (12%, 0.4% each)

1. If the environmental lapse rate is 5° C per 1000 m and the temperature at the earth's surface is 25° C, then the air temperature at 2000 m above the ground is:

a.  25° C

b.  30° C

c.  20° C

d.  15° C

2. If an air parcel is given a small push upward and it falls back to its original position, the atmosphere is said to be:

a.  stable

b.  unstable

c.  isothermal

d.  neutral

3. At the earth's surface, a rising saturated air parcel would cool most rapidly when its temperature is:

a.  10 °F

b.  32 °F

c.  50 °F

d.  68 °F

e.  80 °F

4. The reason that rising saturated air cools at a lesser rate than rising unsaturated air is:

a.  rising saturated air is heavier

b.  rising saturated air is lighter

c.  unsaturated air expands more rapidly

d.  saturated air has a higher heat capacity

e.  latent heat is released by rising saturated air

5. Thunderstorms do not extend into the stratosphere because the air in the stratosphere is:

a.  unstable

b.  stable

c.  too cold

d.  too thin

e.  too dry

6. Which set of conditions, working together, will make the atmosphere the most stable?

a.  cool the surface and warm the air aloft

b.  cool the surface and cool the air aloft

c.  warm the surface and cool the air aloft

d.  warm the surface and warm the air aloft

7. Which of the following conditions would be described as the most stable?

a.  environmental lapse rate is 13 °C per kilometer

b.  environmental lapse rate is  3 °C per kilometer

c.  isothermal conditions

d.  an inversion

8. In a conditionally unstable atmosphere, the environmental lapse rate will be ____ than the moist adiabatic rate and ____ than the dry adiabatic rate.

a.  greater, less

b.  greater, greater

c.  less, greater

d.  less, less

9. Which condition below could make a stable layer of air less stable?

a.  mix the air in the layer

b.  lift the entire air layer

c.  cool the upper part of the layer

d.  all of the above

10. Which cloud type below would most likely form when the lowest two kilometers of the atmosphere are moist and unstable, but the air aloft stable and dry?

a.  cumulonimbus

b.  stratus

c.  cirrostratus

d.  nimbostratus

e.  cumulus humilis

11. Which of the following set of surface conditions would produce a convective cumulus cloud with the highest base?

a.  air temperature 40 °C, dew point 30 °C

b.  air temperature 25 °C, dew point 10 °C

c.  air temperature 35 °C, dew point 10 °C

d.  air temperature 45 °C, dew point 25 °C

e.  air temperature 25 °C, dew point  5 °C

12. Which of the following is not a way of producing clouds?

a.  lifting air along a topographic barrier

b.  lifting air along a front

c.  warming the surface of the earth

d.  convergence of surface air

e.  air motions caused by subsidence

13. The vertical motion of air caused by spontaneous, buoyant ascent is called:

a.  convection

b.  orographic lifting

c.  subsidence

d.  convergence

14. What would the air temperature inside a conventional jet airliner be, if outside air at an altitude of 32,000 ft (10 km), where the pressure is 250 mb and a temperature -60 °C, is brought inside and compressed to a 1000 mb pressure? (Hint: you may assume that 1000 mb pressure is equivalent to 0 m altitude)

a.  -60 °C

b.  0 °C

c.  40 °C (104 °F)

d.  60 °C

15. The LCL is:

a.  the abbreviation for lowest cloud level

b.  a particular cloud type

c.  the cloud base level of a cloud that is formed by lifting

d.  the cloud level determined by radar

16. Which of the following cloud types would commonly be found downwind of a mountain:

a.  lenticular clouds

b.  anvil clouds

c.  mammatus clouds

d.  contrails

17. The name commonly used to describe the drier region observed on the downwind (leeward) side of a mountain range is:

a.  orographic

b.  inversion region

d.  compression region

18. In a sky filled with scattered cumulus humilis clouds, rising motions are found ________ the clouds and sinking motions are found ________ the clouds.

a.  between; under

b.  under; between

c.  under; under

d.  between; between

19. The merging of liquid cloud droplets by collision is called:

a.  coalescence

b.  riming

c.  accretion

d.       deposition

20. If you observe large raindrops hitting the ground, you could probably say that the cloud overhead was ____ and had ____ updrafts.

a.  thick, weak

b.  thick, strong

c.  thin, weak

d.  thin, strong

21. During the ice crystal process of rain formation:

a.  only ice crystals need be present in a cloud

b.  ice crystals grow larger at the expense of the surrounding liquid cloud droplets

c.  the temperature in the cloud must be -40° C (-40° F) or below

d.  the cloud must be a cumuliform cloud

22. Which of the following statements is not correct?

a.  Generally, the smaller the pure water droplet, the lower the temperature at which it will freeze

b.  Ice nuclei are more plentiful in the atmosphere than condensation nuclei

c.  Much of the rain falling in middle northern latitudes begins as snow

d.  Ice crystals may grow in a cold cloud even though supercooled droplets do not.

23. Particles in the atmosphere on which ice crystals grow are called:

a.  virga

b.  ice nuclei

c.  condensation nuclei

d.  graupel

24. Which below best describes why a fluffy covering of snow is able to protect sensitive plants and their root systems from damaging low temperatures.

a.  snow is a good insulator

b.  melting snow releases latent heat

c.  snow is a good emitter of infrared energy

d.  snow is a good reflector of sunlight

25. In the winter you read in the newpaper that a large section of the Midwest is without power due to downed power lines.  Which form of precipitation would most likely produce this situation?

a.  snow

b.  hail

c.  freezing rain

d.  sleet

e.  rain

26. A raindrop or partially melted snowflake that freezes into a pellet of ice in a deep subfreezing layer of air near the surface is called:

a.  snow

b.  freezing rain

c.  sleet

d.  hail

e.  a snow pellet

27. Which type of precipitation would most likely form when the surface air temperature is slightly below freezing and the air temperature increases as you move upward away from the ground?

a.  freezing rain

b.  hail

c.  rain

d.  snow

28. On average, the water equivalent of 10 inches of fresh snow is about ____ inches of water.

a.  0.5

b.  1

c.  2

d.  2.5

e.  5

29.Which of the following sequences of precipitation types is most likely to occur across an east-west oriented stationary front in the Midwest? The sequence is from south to north.

a.  rain, freezing rain, snow, sleet

b.  rain, sleet, freezing rain, snow

c.  freezing rain, rain, sleet, snow

d.  rain, freezing rain, sleet, snow

a.  Electromagnetic (EM )energy emitted by the precipitation particles

b.  absorption characteristics of falling precipitation

c.  amount of EM energy reflected back to a transmitter

d.  amount of sunlight scattered off the precipitation

B. Short-answer questions (3%, 01% each)

31. Based on atmospheric stability considerations, do you think it would be best to burn agricultural debris in the early morning or the afternoon? Why?

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32. Explain why it is possible for an ice crystal to grow in a cold cloud even though supercooled water droplets surrounding the ice crystal do not.

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33. What is the typical size of a raindrop and a cloud droplet? [hint: make sure you have the units right]

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# ATSC 2000 test 3: Answers

A.                  MC questions (0.4 points each, max score=12.0).

1. d
2. a
3. a
4. e
5. b
6. a
7. d
8. a
9. d
10. e
11. c
12. e
13. a
14. c
15. c
16. a
17. c
18. b
19. a
20. b
21. b
22. b
23. b
24. a
25. c
26. c
27. a
28. b
29. d
30. c

## B.                  Short-answer questions (1.0 points each, 3 points max)

1. afternoon (0.5%) Then it mixes throughout the boundary layer. In the morning it doesn’t lift off the ground and doesn’t disperse well, because of high stability and little wind (0.5%)
2. the saturation vapor pressure adjacent to ice is less than that next to supercooled water
3. rain : 1 mm = 1000 micron, cloud droplet: 0.01 mm or 10 micron.