Name: _________________

Hours Studied: __________

Geography 123: Weather & Climate

Exam III

April 15, 1999

Part I: Multiple-multiple choice. Circle the letter of every correct choice. Remember that there may be one, two, three, or four correct choices for each question. Two points each.

1. As air rises

a. it warms at the dry adiabatic lapse rate if the RH<100%.

b. it cools at the wet adiabatic lapse rate if the RH<100%.

c. it warms at the wet adiabatic lapse rate if the RH<100%.

d. it cools at the dry adiabatic lapse rate if the RH<100%.

2. When RH=100%

a. the air is saturated.

b. dew point is lower than the ambient air temperature.

c. condensation will occur if condensation nuclei are present.

d. dew point is the same as the ambient air temperature.

3. A cP air mass

a. is a cold front.

b. is characterized by cold air.

c. is generally drier than mP air.

d. has a high RH.

4. A warm front

a. is mT air.

b. occurs where mT air is moving into the territory occupied by cP air.

c. usually occurs west of a wave cyclone (migratory low).

d. is associated with stratus clouds.

5. The mid-latitude jet stream

a. guides migratory lows across North America.

b. flows from east to west.

c. moves faster than the air around it.

d. reinforces the low pressure of wave cyclones.

6. The Rossby waves

a. form at the boundary of polar easterlies and the prevailing westerlies.

b. are associated with deep incursions of cP air into the southern US when the pattern is zonal.

c. are the location along which the jet stream moves.

d. are the location along which wave cyclones migrate.

7. Along a cold front,

a. warm air rises.

b. cold air rises over warm air.

c. stratus clouds usually form.

d. skies are usually clear and temperatures very cold.

8. In a thunderstorm,

a. electrons flow from cloud tops to the ground.

b. updrafts draw moist air upwards where it reaches dew point.

c. downdrafts are characterized by evaporation of raindrops.

d. squall lines can damage property ahead of the storm.

9. In a tornado,

a. most damage is caused by low pressure.

b. wind speeds may exceed 200 mph.

c. a very steep pressure gradient exists.

d. stratus clouds are usually covering the rest of the sky.

10. In the Barneveld tornado,

a. areas of maximum damage were associated with suction vortices.

b. a major cause of damage was puncture by flying debris.

c. roughly one-third of the town people died.

d. over 90% of the town buildings were destroyed.

Part II. Definitions. Place the term or value defined in the space provided. Two points each.

1. _______________________ The value of the dew point adiabatic lapse rate. (Note: Be certain that you indicate whether the rate is an increase or a decrease with elevation.)

2. _______________________ According to the attached tables, the RH of 75°F. air when the dew point is 66°F.

3. _______________________ The air mass that spawns over the North Pacific Ocean.

4. _______________________ A type of front created when a cold front overtakes a warm front, pushing all warm air aloft.

5. _______________________ A form of lightning that might be an optical illusion.

6. _______________________ The Fugita rating for the strongest tornadoes.

7. _______________________ The season of maximum tornado occurrence in WI.

Part III. Short Answer. Two points each.

1. When air descends, it _______ (warms/cools).

2. In a region of low pressure, air _________ (rises/falls).

3. When warm and cold air collide, the _________ (warm/cold) air rises over the (warm/cold) air.

4. Clouds keep afternoon temperatures _________ (higher/lower) than they would be if the clouds were not present.

5. As air rises, its RH _______ (increases/decreases), all else being equal.

6. Winds blow from ________ (high/low) pressure to ________ (high/low) pressure.

7. The Coriolis bends fluids ________________ (clockwise/counterclockwise) around a low in the northern hemisphere.

8. The prevailing westerlies blow from the ________ (east/west) to the _______ (east/west).

9. Condensation begins when RH = _________%.

10. Tornadoes are generally associated with _____________ clouds.

Part IV. Problem

Assume that a parcel of air rises over a mountain. The parcel starts at sea level with an ambient temperature of 80°F. The air rises 4000’, at which point it reaches its dew point of 58°F. The air keeps rising to an elevation of 8000’ which is the top of the mountain. It then descends to sea level on the east side of the mountain. As soon as the parcel begins its descent, the ambient temperature rises above dew point. Using the attached tables (you will have to round your figure for the ambient air temperature for question 7) and a dry adiabatic lapse rate of 4°F, answer the following questions. Please show your work. Questions 1-7 are 1 point each.

1. What was the dew point of the parcel when it began its journey at sea level? _________

2. What was its RH when it began its journey? __________

3. What is the temperature of the parcel at 8000’? ________

4. What is the dew point at 8000’? __________

5. What is the temperature of the parcel at sea level on the east side of the mountain? __________

6. What is its dew point at sea level on the east side of the mountain? ________

7. What is its RH at sea level on the east side of the mountain? ___________

8. Why is it warmer on the east side at sea level than it was on the west side? Where did the heat come from and how did it get to the east side of the mountain? Four points.

Part V. Diagram.

1. On the square below representing a map, show a typical location of a wave cyclone, a cold front, and a warm front, using the proper map symbols. The squiggly line represents the Rocky Mountains, and north is to the top of the map. Two points.

2. Diagram a side view of a cold front, showing and labeling the region of cold air, warm air, the location of the front, and the types of clouds that form along it. With an arrow, show which air mass is advancing. Five points.

3. Diagram a side view of a warm front, showing and labeling the region of cold air, warm air, the location of the front, and the types of clouds that characterize it. With an arrow, show which air mass is advancing. Five points.

4. Diagram a side view of an occluded front, showing and labeling the region of cold air, warm, air, and the types of clouds associated with it. Three points.

Part VI. Forecast. Using the maps and statistics provided, forecast the weather for July 16 at Manitowoc. To the right of your forecast, explain your reasoning. Remember, your reasoning is far more important than the forecast in garnering you points for this exercise. Twenty points total.