Deck 11: Air Masses and Fronts

Question 1

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.

Answer 1

B

Question 2

Continental polar (cP)and continental Arctic (cA)air masses

A) both originate over polar oceans.
B) form in summer only.
C) bring strong thunderstorms.
D) are very similar.

Answer 2

D

Question 3

Record breaking low temperatures are associated with which air mass?

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

Answer 3

C

Question 4

Cumuliform cloud development would be most likely in which of the following?

A) cT air mass moving over a mountain range
B) cP air mass moving over warm water
C) mT air mass moving over cold land surface
D) cT air mass moving over cold water

Question 5

Which air mass would show the most dramatic change in both temperature and moisture content as it moves over a large body of very warm water?

A) cT in summer
B) cP in winter
C) mP in winter
D) mT in summer

Question 6

In an exceptionally cold winter during which the Great Lakes were entirely covered by ice,lake effect snows would be expected in extremely high frequency and intensity.

Question 7

Wintertime mP air masses are less common along the Atlantic coast of North America than along the Pacific coast mainly because

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

Question 8

The coldest of all air masses is

A) mT.
B) mP.
C) cT.
D) cF.
E) cA.

Question 9

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

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

Question 10

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 11

The lake effect occurs when ____ air mass moves over a ____ body of water.

A) an mT,cold
B) an mT,warm
C) a cP,cold
D) a cP,warm

Question 12

Clear sunny days with very cold nights would be associated with what type of air mass?

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

Question 13

The greatest contrast in both temperature and moisture will occur along the boundary separating which air masses?

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

Question 14

The designation for a cool,moist air mass is

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

Question 15

Which of the following statements is most plausible?

A) In winter,cP source regions have higher temperatures than mT source regions.
B) In summer,mP source regions have higher temperatures than cT source regions.
C) In winter,cA source regions have lower temperatures than cP source regions.
D) In summer,mT source regions have lower temperatures than mP source regions.
E) They are all equally plausible.

Question 16

A good source region for an air mass would be

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 17

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

A) temperature,pressure
B) pressure,moisture
C) winds,moisture
D) temperature,moisture

Question 18

What type of air mass would be responsible for refreshing cool,dry breezes after a long summer hot spell in the Central Plains?

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

Question 19

What type of air mass would be responsible for persistent cold,damp weather with drizzle along the east coast of North America?

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

Question 20

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 21

Which of the following is not correct concerning a cold front?

A) It marks the position of a trough of low pressure.
B) It marks a zone of shifting winds.
C) It is colored purple on a weather map.
D) It has cold air behind it.

Question 22

Before the passage of a cold front the pressure normally ____,and after the passage of a cold front the pressure normally ____.

A) drops,drops
B) drops,rises
C) rises,rises
D) rises,drops

Question 23

Along the boundary between continental polar and maritime tropical air masses,____ is often found.

A) a large area of calm (extremely light wind)
B) intense heat and drought
C) widespread precipitation and storminess
D) both a and c

Question 24

On a weather map,the transition zone between two air masses with sharply contrasting properties is marked by

A) the letter "H."
B) the words "air mass weather."
C) a front.
D) the letter "L."

Question 25

During the spring,which air mass would most likely bring record-breaking high temperatures to the eastern half of the United States?

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

Question 26

The air mass with the highest actual water vapor content is

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

Question 27

Squall lines most often form ahead of a

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

Question 28

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

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

Question 29

A stationary front does not move because

A) winds on both sides of the front are calm.
B) the winds blow parallel to the front.
C) the front is between high and low pressure.
D) the winds blow against each other and are of equal strength.

Question 30

Alternating lines of blue and red on a surface weather chart indicate

A) a cold front.
B) a warm front.
C) a stationary front.
D) an occluded front.

Question 31

A true cold front on a weather map is always

A) associated with precipitation.
B) associated with a wind shift.
C) followed by drier air.
D) followed by cooler air.

Question 32

The word "frontogenesis" on a weather map would mean that

A) a front is in the process of dissipating.
B) one front is about to overtake another front.
C) a front is regenerating or strengthening.
D) severe thunderstorms will form along a front.

Question 33

A dryline is

A) a stalled cold front.
B) a stalled warm front.
C) a dew point front.
D) a boundary marking a strong horizontal change in atmospheric moisture.
E) both a dew point front and a boundary marking a strong horizontal change in atmospheric moisture.

Question 34

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
E) cA

Question 35

Fronts are associated with

A) low pressure.
B) high pressure.

Question 36

A "back door" cold front describes which of the following situations?

A) a cold front moving into Washington state from the Pacific ocean
B) a cold front moving into the desert southwest from Northern Mexico
C) a cold front that moves into New England from the Atlantic Ocean
D) a cold front that moves in a clockwise direction around a low pressure center

Question 37

When comparing an "average" cold front to an "average" warm front,which of the following is not correct?

A) Generally,cold fronts move faster than warm fronts.
B) Generally,cold fronts have steeper slopes.
C) Generally,precipitation covers a much broader area with a cold front.
D) Especially in winter,cumuliform clouds are more often associated with cold fronts.

Question 38

An mT air mass lying above a cold ground surface represents a(n)____ situation.

A) stable
B) unstable
C) occluded
D) stationary

Question 39

An upper-air front involves downward motion of the

A) tropopause.
B) stratopause.
C) low-level jet.
D) both tropopause and low-level jet

Question 40

The only indication on the station model of past weather conditions is the

A) temperature.
B) dew point.
C) cloud cover.
D) wind direction.
E) pressure tendency.

Question 41

During the winter as you travel toward a warm front,the most likely sequence of weather you would experience is

A) snow,freezing rain,hail,sleet.
B) rain,snow,sleet,freezing rain.
C) freezing rain,snow,sleet,rain.
D) snow,sleet,freezing rain,rain.

Question 42

Explain why the observation of a halo around the moon or sun could forewarn of the arrival of a warm front.

Question 43

In winter,which sequence of clouds would you most likely expect to observe as a warm front with precipitation approaches your location?

A) cirrus,nimbostratus,altostratus,cumulonimbus
B) cirrus,cirrostratus,altostratus,nimbostratus
C) cirrostratus,nimbostratus,altostratus,fog
D) cirrus,cirrostratus,altostratus,cumulonimbus

Question 44

Why is the formation of air masses associated with high pressure systems rather than low pressure systems?

Question 45

What type of clouds,if any,would you expect to see form when a cP air mass moves across warm water? Would conditions be any different when mT air moves across a cold land surface? Which types of clouds would form in this latter case?

Question 46

Occluded fronts may form as

A) a cold front overtakes a warm front.
B) a warm front overtakes a cold front.
C) a cold front overtakes a squall line.
D) overrunning occurs along a warm front.

Question 47

Which below is not correct concerning an occluded front?

A) It is often associated with a broad band of precipitation.
B) It marks a zone of shifting wind.
C) It is colored purple on a surface weather map.
D) At the surface,it is always followed by colder air.

Question 48

List the four basic types of air masses.Give an example of where each type could originate.

Question 49

Draw side views of a typical warm and cold front.Clearly indicate the temperatures of the separate air masses and show their directions of motion.What types of clouds would you expect to find and where? Where would you expect precipitation to occur?

Question 50

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.Winds southwesterly becoming gusty and shifting to northwesterly by tonight."

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

Question 51

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 light easterly today becoming southeasterly tonight and southwesterly tomorrow."

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

Question 52

How would a warm front,a cold front,and a center of low pressure appear on a surface weather map in the Southern Hemisphere?

Question 53

A halo around the sun or moon indicates that rain may be on the way because the halo indicates

A) a cold front may be approaching.
B) a warm front may be approaching.
C) a sharp drop in atmospheric pressure.
D) a sudden rise in surface dew point temperature.

Question 54

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

Question 55

What type of weather front would be responsible for the following weather forecast? "Light rain and cold today with temperatures just above freezing.Southeasterly winds shifting to westerly tonight.Turning colder with rain becoming mixed with snow,then changing to snow."

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

Question 56

At a warm front,the warm air

A) rises and cools.
B) rises and warms.
C) sinks and cools.
D) sinks and warms.

Question 57

Which of the following is not correct concerning a warm front?

A) It is colored red on a weather map.
B) It has warm air ahead (in advance)of it.
C) In winter it is usually associated with stratiform clouds.
D) It normally moves more slowly than a cold front.

Question 58

How would each of the four basic types of air masses affect local weather conditions if they moved into your region?

Question 59

When warm and cold air masses collide,the warm air is forced upward.Why does this occur?

Question 60

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 61

Is it possible for a stationary front to produce precipitation? If so,would you expect to find the precipitation on the warm or the cold air side of the front?

Question 62

Explain how,using no meteorological instruments other than your eyes,you could identify the passage of an occluded front.

Question 63

How do upper-air fronts form?

Question 64

What types of weather changes accompany the passage of a dryline (dew point front)?

Question 65

Without considering changes in temperature,how are the weather conditions accompanying a cold frontal passage different from those associated with the passage of a warm front?