AS352 Test III 3/27/’97 8 points

 

There are 24 MC questions. One and only one answer is correct.

Please fill out your answers on a scantron. Don't forget your name on the scantron.

 

1. Supercell storms do not occur ...

a: when the lower troposphere is extremely unstable;

b: when the ambient wind blows uniformly at all levels;

c: when the winds at low and upper levels blow in opposite directions, relative to the thunderstorm;

d: over a body of water.

 

2. Airmass thunderstorms are characterized by:

a: multiple aligned cells, developing sequentially;

b: a large, long-lived anvil;

c: a short life cycle;

d: the occurrence of hail.

 

3. A mesoscale convective complex is identified and characterized by:

a: the strength of the wind;

b: the occurrence of a tornado;

c: the presence of hail;

d: its anvil.

 

4. Which type of deep convection lives longest ?

a: an airmass thunderstorm;

b: a mesoscale convective complex;

c: a multicell thunderstorm;

d: a supercell thunderstorm.

5. Which type of organized convection is the largest ?

a: an airmass thunderstorm;

b: a supercell thunderstorm;

c: a multicell thunderstorm;

d: a squall line.

 

6. An estimated 80% of all tornadoes are cyclonic. You, as a pilot, are approaching a runway oriented 240 to 60 for landing. Suddenly you see a tornado between you and the runway. You are running low on fuel so you cannot abort the landing procedure. How do you best deal with the situation ?

a: fly to the right (south) of the tornado;

b: fly to the left (north) of the tornado;

c: fly right through the eye of the tornado (and enter the Guiness Book of Records);

d: make a nosedive.

 

7. The leading edge of a cool thunderstorm outflow is called a ...

a: cold front;

b: mesoscale convective complex;

c: gust front;

d: squall line.

8. A wall cloud is a ...

a: a continuous cloud line, from horizon to horizon, at the leading edge of a cold front;

b: a solid cloud whose base is below that of the parent supercell storm;

c: an arc cloud above a gust front;

d: a shelf cloud.

 

9. Severe tornadoes are most likely in ...

a: airmass thunderstorms;

b: mesoscale convective complexes;

c: multicell thunderstorms;

d: supercell storms.

 

10. Squall lines are often accompanied by a region of stratiform precipitation. Where is this stratiform region usually, relative to the line of convection ?

a: ahead;

b: behind;

c: embedded;

d: to the right.

 

11. A bounded weak echo region (WER) is :

a: the azimuth angles where a radar can’t see storms in the distance, due to nearby beam blockage or ground clutter;

b: a cloud-free vault between a squall line and a stratiform region;

c: the hollow shaft of a tornado;

d: the region of strongest updrafts in a supercell storm.

 

12. Organized deep-convective storms, such as supercells or squall lines, are most common :

a: at or ahead of a warm front;

b: in the warm sector;

c: behind a surface cold front;

d: along the coast, where sea breezes trigger them.

 

13. Thunderstorms sometimes cluster into a massive system. What does such mesoscale organization look like ?

a: there is a squall line and a stratiform region, which is symmetrically trailing the squall line;

b: there is a squall line and a stratiform region, which is located only behind part of the squall line;

c: there is a stratiform region, within which thunderstorm cells are embedded;

d: any of the above.

14. Many, but not all, supercells, squall lines and MCCs feature :

a: mid-tropospheric cyclonic spin;

b: cyclonic spin near the surface;

c: mid-tropospheric anticyclonic spin;

d: upper-tropospheric cyclonic spin.

15. The ratio of the typical diameters of MCCs, bow echo squall lines, and supercells, respectively, is:

a: 1:10:100;

b: 50:10:1;

c: 1:1:1;

d: 3:2:1.

16. The ratio of the typical depths (or cloud top heights) of MCCs, squall lines, and supercells, respectively, is:

a: 1:10:100;

b: 100:10:1;

c: 1:1:1;

d: 3:2:1.

17. Some squall lines are trailed by a region of stratiform precipitation, and the relation between the two components of such a system appears to be symbiotic, hence this configuration is often long-lived. The critical factor of this symbiotic relation is the presence of:

a: strong, deep wind shear in the environment;

b: a dry, subsiding rear inflow jet;

c: a cold front;

d: hail.

18. Which one of the following phenomena occurs in every thunderstorm ?

a: mammata;

b: an anvil;

c: hail;

d: lightning.

19. Some squall lines are bow-shaped, with a 'book-end vortex' at one or both ends of the bow. These bow echoes are an indication of ...

a: strong updrafts and strong mid-to upper level winds;

b: strong updrafts and weak mid-to upper level winds;

c: strong downdrafts and strong mid-to upper level winds;

d: strong downdrafts and weak mid-to upper level winds.

 

20. Numerical weather prediction using dynamic simulations of the atmospheric circulation is the main resource for weather forecasts up to ...

a: 2 days;

b: 4 days;

c: 10 days;

d: a month.

 

21. Nowcasting is a technique to predict the weather in the very near future (the next 6 hours or so). Which forecasting technique is used for nowcasting ?

a: the climatology method;

b: the trend (steady-state) method;

c: the persistence method;

d: the statistical method.

 

22. Which weather element is predicted least accurately in short- to medium range forecasts ?

a: the jet stream;

b: the sea level pressure pattern;

c: the temperature;

d: clouds and precipitation.

 

23. Baroclinic instability refers to ...

a: the interaction of low- and upper-level processes that explains the formation and intensification of a frontal disturbance;

b: the development of thunderstorms;

c: the growth of hurricanes, from easterly waves;

d: cyclogenesis.

 

24. When a weak upper level shortwave trof approaches a weak surface low (which contains a deep, warm, and moist boundary layer ) from the west, what will happen to the surface low ?

a: it will dissipate;

b: it will intensify and eventually, when it is strongest, it will move under the upper level trof;

c: it will intensify and always stay to the east of the upper level trof;

d: it will remain unchanged, and the upper level trof will simply pass by.

 

 

 

 

 

 a long Rossby wave;

c: the equatorward branch of a short Rossby wave;

d: the equatorward branch of a long Rossby wave.

27. If a north-south oriented cold front is about to pass Prescott from the west, and winds are calm at the surface, then the wind at 500hPa must blow from the :

a: east;

b: west;

c: north;

d: south.

28. In a low on a surface weather chart, the frictional force is responsible for:

a: tornadoes;

b: net convergence;

c: surface warming;

d: subsidence.

 

B. Short Answer Questions

 

Please write the answer on the back side of the scantron.

 

66. There is sometimes a popping sensation in the ears when taking off in an unpressurized aircraft, due to a pressure difference across the semi-impervious membrane in the eardrum. The sensation can be relieved by yawning. Over what elevation gain this happens appears to vary from person to person, and for any individual person, on age and health condition. For some people, popping happens when one has risen 1000ft, for others it is 3000ft. If the popping sensation happens each 1600ft, what difference of pressure is involved?

 

67. At a freshman bragging party at the Daytona Beach Embry-Riddle campus, one student boasts that he can suck up a soft drink through a three-foot straw, held vertically. At least what pressure reduction does the student need to achieve in his lungs, in order to be successful ?

 

68. (regarding the previous question) Would this stunt be easier for him if he had enrolled at Prescott ?

 

69. At what temperature are Celsius and Fahrenheit values the same?

 

70. What is the standard mean sea level pressure ? Please give the value both in inches of mercury and in mb.

 

71. We know that highs on a sea level pressure chart correspond with highs on a height contour chart of the 1000 mb topography. Yet pressure decreases with increasing height. Explain this apparent paradox.

 

Answers

 

1. d

2. c

3. c

4. d

5. a

6. b

7. c

8. d

9. a

10. c

11. d

12. d

13. a

14. a

15. d

16. a

17. b

18. c

19. c

20. c

21. d

22. a

23. a

24. b

25. d

26. a

27. d

28. b

66: 50mb

67: at least 90mb below the air pressure, i.e. at most 923mb. This pressure reduction is better than the performance of some commercial vacuum cleaners.

68: No, the same performance is required at Prescott.

69: -40

70: 29.92'' or 1013mb

71: because a place with a low height on a 850 hPa map must have a relatively low air pressure compared to other places at the same altitude; or else: because a location with low MSLP must have the 1000hPa surface low, possibly below sea level;

 

 

 

 ude;