Deck 8: Air Masses, Fronts, and Middle Latitude Cyclones

Question 1

An air mass is characterized by similar properties of ____ and ____ in any horizontal direction at a given altitude.

A) temperature; pressure
B) pressure; winds
C) pressure; humidity
D) temperature; humidity

Answer 1

D

Question 2

The forward progress of a warm front may be inhibited at night as a result of ____.

A) warming of air behind the front
B) radiational cooling
C) overrunning
D) a dryline

Answer 2

B

Question 3

What is the origin of the cP and cA air masses that enter the United States?

A) Northern Siberia
B) the northern Atlantic Ocean
C) Antarctica
D) Northern Canada and Alaska

Answer 3

D

Question 4

Generally, the greatest lake-effect snowfall in the Great Lakes region occurs on the ____ shores.

A) northern
B) southern
C) eastern
D) western

Question 5

What type of weather front would be responsible for the following weather forecast? "Increasing cloudiness and warm today with the possibility of showers by this evening. Turning much colder tonight with southwesterly winds becoming gusty and shifting to the northwest."

A) cold front
B) warm front
C) warm-type occluded front
D) stationary front

Question 6

What type of air mass would be responsible for hot, muggy summer weather in the eastern half of the United States?

A) mP
B) mT
C) cP
D) cT

Question 7

What is the best source region for an air mass?

A) mountains with deep valleys and strong surface winds
B) generally flat areas of uniform composition with light surface winds
C) hilly with deep valleys and light winds
D) generally flat area of uniform composition with strong surface winds

Question 8

One would expect a cP air mass to be ____.

A) cold and dry
B) cold and moist
C) warm and dry
D) warm and moist

Question 9

What type of weather front would be responsible for the following weather forecast? "Increasing high cloudiness and cold this morning. Clouds increasing and lowering this afternoon with a chance of snow or rain tonight. Precipitation ending tomorrow morning. Turning much warmer. Winds from the south and becoming southwesterly tomorrow."

A) cold front
B) warm front
C) stationary front
D) cold-type occluded front

Question 10

Which air mass forms over North America only in summer?

A) mT
B) mP
C) cT
D) cP

Question 11

The coldest of all air masses is ____.

A) cA
B) mP
C) cT
D) cP

Question 12

During the winter, an air mass that moves into coastal sections of Oregon and Washington from the northwest would most likely be ____.

A) mP
B) mT
C) cP
D) cT

Question 13

Record breaking low temperatures are associated with which air mass?

A) mT
B) mP
C) cP
D) cT

Question 14

What type of air mass would be responsible for hot, dry summer weather in southern Arizona?

A) mP
B) mT
C) cP
D) cT

Question 15

The air pressure normally ____ before a cold front passes and ____ after the front passes.

A) drops; drops
B) drops; rises
C) rises; rises
D) rises; drops

Question 16

When two air masses collide at a front, one air mass may be pushed upward by the other. This is because ____.

A) one air mass is moving faster than the other
B) one air mass is denser than the other
C) pressure is falling in one air mass and rising in the other
D) one of the air masses encounters topographical features on the ground

Question 17

Wintertime Atlantic mP air masses are less likely to move into the United States than those along the Pacific coast primarily because the ____.

A) water is colder along the Pacific coast
B) prevailing winds aloft are westerly
C) source region for mP air on the Atlantic coast is western Europe
D) water is warmer along the Atlantic coast

Question 18

Lake-effect snows are best developed around the Great Lakes during ____.

A) early spring when moist, tropical air moves over the frozen lakes
B) late fall and early winter when cold, dry polar air moves over the relatively warm water
C) late fall and early winter when moist, polar air sweeps in from the east
D) middle winter when the unseasonably warm air mass moves over the cold water

Question 19

What type of air mass would be responsible for daily afternoon thunderstorms along the Gulf Coast of the United States?

A) mP
B) mT
C) cP
D) cT

Question 20

Compared to an mP air mass, mT air is ____.

A) warmer and drier
B) warmer and moister
C) colder and drier
D) colder and moister

Question 21

When upper-level divergence of air above a surface low exceeds the surface convergence of air, the surface air pressure will ____ and the storm itself will ____.

A) increase; intensify
B) increase; dissipate
C) decrease; intensify
D) decrease; dissipate

Question 22

If lows and highs aloft are directly above lows and high at the surface, ____.

A) the surface system would dissipate
B) the surface system would intensify
C) cyclogenesis will occur
D) anticyclones will form

Question 23

The stages of a developing wave cyclone (in order of occurrence) are ____.

A) stationary front, open wave, frontal wave, mature, and advanced occlusion
B) stationary front, frontal wave, open wave, mature, and advanced occlusion
C) stationary front, open wave, frontal wave, advanced occlusion, and mature
D) stationary front, frontal wave, open wave, advanced occlusion, and mature

Question 24

During a cold occlusion, the cold front forces the warm front to ____.

A) become stationary
B) rise off the ground
C) move to the side
D) dissipate

Question 25

Atmospheric shortwaves tend to ____ when they approach a longwave trough and ____ when they approach a ridge.

A) deepen; deepen
B) deepen; weaken
C) weaken; deepen
D) weaken; weaken

Question 26

Mid-latitude cyclonic storms are better developed in the United States during the coldest months because the polar jet stream ____.

A) is weakest in the winter
B) moves farther north in the winter
C) is shut down in the winter
D) moves farther south in the winter

Question 27

Squall lines most often form ahead of a(n) ____.

A) cold front
B) warm front
C) stationary front
D) occluded front

Question 28

When a cold front passes, the lowest pressure reading at a station will occur ____.

A) just before the front passes
B) just after the front passes
C) just as the front passes
D) three hours after the front passes

Question 29

In the polar front theory of a developing wave cyclone, the area of most intense weather is normally found to the ____ of the storm's center.

A) northeast
B) southwest
C) southeast
D) northwest

Question 30

Cyclogenesis occurs frequently on the eastern slopes of the Rockies as a result of ____.

A) occlusions
B) compressional heating
C) drylines
D) convergence

Question 31

For a surface storm system to intensify, the upper trough of low pressure must be located to the ____ of the surface low.

A) north
B) south
C) east
D) west

Question 32

Generally, the average speed of a warm front ____ the average speed of a cold front.

A) is about the same as
B) is slower than
C) is faster than
D) varies compared to

Question 33

For a surface low to develop into a major storm system, the upper-level divergence of air must be ____ surface convergence of air.

A) greater than
B) less than
C) equal to
D) the same as

Question 34

Drylines typically occur in the ____ United States.

A) Pacific Northwest of the
B) southern Great Plains of the
C) northeastern
D) southeastern

Question 35

According to the model of the life cycle of a wave cyclone, the storm system is normally most intense as a(n) ____.

A) frontal wave
B) open wave
C) stationary wave
D) mature cyclone

Question 36

The region of air between the cold and warm fronts of an open wave is known as the ____.

A) warm sector
B) frontal wave
C) occlusion
D) convergence

Question 37

A stationary front does not move because winds on both sides of the front ____.

A) are calm
B) blow parallel to the front and in opposite directions
C) blow away from the front and are of equal strength
D) blow against each other and are of equal strength

Question 38

The typical path of a winter mid-latitude cyclone is ____.

A) westward or northwestward
B) eastward or northeastward
C) southward or southeastward
D) southward or southwestward

Question 39

Cold fronts that move into the U.S. from the east, or northeast, are called ____.

A) eastern fronts
B) back door fronts
C) stationary fronts
D) warm-type occluded fronts

Question 40

Developing low pressure areas generally have ____ air near the surface and ____ air aloft.

A) converging; diverging
B) diverging; converging
C) converging; converging
D) diverging; diverging

Question 41

Surface winds tend to blow parallel to a(n) ____________________ front.

Question 42

Because it is located at middle latitudes, the United States is only rarely affected by polar and tropical air masses.

Question 43

Air masses are large bodies of air whose properties of ____________________ and ____________________ are fairly similar in any horizontal direction at any given altitude.

Question 44

Instructions: Choose one answer from each pair of selections. Lake-effect snows result when an air mass moves across a large body of FROZEN | UNFROZEN water.

Question 45

Instructions: Choose one answer from each pair of selections. The process of FILLING | DEEPENING describes a weakening storm system with increasing surface pressure.

Question 46

Instructions: Choose one answer from each pair of selections. Would you expect a city to the EAST or WEST of the Appalachian Mountains to experience colder temperatures after a continental polar air mass has passed?

Question 47

You might expect to find a lee-side low developing near a(n) ____________________.

Question 48

Unstable air results from warm air above cooler air.

Question 49

Instructions: Choose one answer from each pair of selections. Ideal air mass source regions are usually dominated by surface HIGH | LOW pressure.

Question 50

For a surface cyclonic storm to intensify, there must be an upper-level ____________________ of low pressure.

Question 51

Instructions: Choose one answer from each pair of selections. Mixing on both sides of a warm front during the day may INCREASE | DECREASE its speed.

Question 52

Instructions: Choose one answer from each pair of selections. Speed CONVERGENCE | DIVERGENCE occurs when the wind slows down as it moves along.

Question 53

Instructions: Choose one answer from each pair of selections. A warm front tends to have a STEEPER | MORE GENTLE slope than a cold front.

Question 54

Instructions: Choose one answer from each pair of selections. Because wintertime Atlantic maritime polar air masses travel only a short distance over water, they usually are much WARMER | COLDER than their Pacific counterparts.

Question 55

A line of showers or thunderstorms that develops parallel to and often ahead of an advancing cold front is called a(n) ____________________.

Question 56

Some mid-latitude cyclones may have calm winds at their center, similar to a hurricane's "eye".

Question 57

During a cold winter in which the Great Lakes are entirely covered by ice, lake-effect snows would be expected in extremely high frequency and intensity.

Question 58

Stable atmospheric conditions usually result in good visibility.

Question 59

Instructions: Choose one answer from each pair of selections. The term "nor'easter" refers to the strong northeasterly winds that can develop around a strong HIGH | LOW pressure center along the eastern coast of the United States.

Question 60

Instructions: Choose one answer from each pair of selections. In a cold occlusion, the upper-level warm front PRECEDES | FOLLOWS the surface occluded front.

Question 61

Is it possible for a stationary front to produce precipitation? If so, explain the conditions in which precipitation is favorable.

Question 62

Describe or illustrate the various phases in the life cycle of a mid-latitude cyclonic storm in the Northern Hemisphere according to the polar front theory.

Question 63

Describe some of the changes in weather conditions (winds, temperature, clouds, precipitation, pressure changes) you would expect to observe as a cold front approaches and passes through your location.

Question 64

Using the weather map in the accompanying figure, provide the following information: (1) Identify the type of front between points A and B. Describe the weather surrounding the front. (2) Identify the type of front between points B and C. Describe the weather surrounding the front. (3) Show on the weather map where a "warm sector" would be located.

Question 65

Explain the progress of the maritime polar air mass in the accompanying figure as it moves from west to east across several mountain ranges. Describe the air at each point (A-F).