Deck 8: Air Masses

Question 1

An ideal source region of air masses should be:

A)roughly half land,half water.
B)located at or near the equator.
C)physically uniform.
D)small.
E)located at or near a pole.

Answer 1

C

Question 2

An air mass is a body of air with:

A)very low humidity in its lower layers.
B)very high pressure everywhere.
C)similar values of temperature and moisture in the horizontal.
D)at least two frontal zones.
E)equal density throughout.

Answer 2

C

Question 3

Air-mass source regions are least likely to exist in:

A)subtropical regions.
B)middle-latitude regions.
C)equatorial regions.
D)polar regions.

Answer 3

B

Question 4

The two most important properties that should be relatively homogeneous at the same altitude in an air mass are:

A)temperature and carbon dioxide concentration.
B)vapor pressure and latitude.
C)moisture content and temperature.
D)relative humidity and radiation.

Question 5

An air-mass source region:

A)is characterized by a general stagnation of atmospheric circulation.
B)is best typified by the central United States.
C)is generally an area characterized by a cyclonic circulation pattern.
D)may consist of both land and water.

Question 6

Which of the following is not a good source region for air masses?

A)the Gulf of Mexico
B)central Canada
C)the North Pacific
D)the central United States

Question 7

The usual size of an air mass is:

A)at most a few kilometers across.
B)between 100 and 200 km across.
C)around 1000 km across.
D)at least 1600 km across.

Question 8

Which of the following criteria is NOT a characteristic of a good source region?

A)It must be very large.
B)It must have uniform physical features.
C)The air must able to stagnate over the area for long periods of time.
D)The area must frequently experience cyclones.

Question 9

Which air mass code letter is paired with the wrong word?

A)c = continental
B)t = temperate
C)m = maritime
D)a = arctic

Question 10

An air mass from the Gulf of Mexico is called:

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

Question 11

Compared to continental air masses with the same air temperature,maritime air masses:

A)have lower water vapor content.
B)have about the same water vapor content.
C)have higher water vapor content.

Question 12

When an area is experiencing several consecutive days of rather constant weather,it is experiencing:

A)warm-front weather.
B)air-mass weather.
C)occluded front weather.
D)cold-front weather.

Question 13

A cT air mass is:

A)warm and humid.
B)cold and dry.
C)warm and dry.
D)cold and humid.

Question 14

The area where an air mass originates is called a:

A)source region.
B)site region.
C)local region.
D)large region.

Question 15

Air mass source regions tend to be dominated by:

A)converging winds.
B)dry air.
C)fast wind speeds.
D)cyclones.
E)slow moving anticyclones.

Question 16

The cP air-mass in North America originates in:

A)the North Atlantic.
B)the Arctic basin.
C)Siberia.
D)interior Alaska and Canada.
E)Greenland.

Question 17

Characteristics of an air mass source region include:

A)uniformity of temperature and moisture.
B)sharp temperature contrasts.
C)jet stream winds aloft.
D)high elevation.

Question 18

Air masses are identified by a pair of letters,one lowercase and one uppercase.The uppercase letter (P,A,or T)refers to:

A)average air pressure within the air mass.
B)the approximate latitude of the air mass source region.
C)the humidity levels within the air mass.
D)the elevation of the air mass source region.

Question 19

The typical amount of time it takes for an air mass to pass over a given area is on the order of a few:

A)minutes.
B)weeks.
C)hours.
D)months.
E)days.

Question 20

The situation where a region under the influence of an air mass has generally constant weather conditions is called:

A)boundary layer weather.
B)regional weather.
C)air-mass weather.

Question 21

What weather is associated with cA air masses?

A)occasional periods of clear,cool weather in the summer
B)cold waves in winter
C)hot humid conditions leading to cumulus cloud development and showers or thunderstorms
D)nor'easters

Question 22

An air mass is often modified as it moves over the earth's surface.This modification is largely due to:

A)lifting along fronts.
B)contact with the new surface below.
C)clouds.
D)jet streams above.
E)strong pressure gradients.

Question 23

An air mass moves out of its source region.Two days later,the lower layers of the air mass are found to be warmer than they were originally.What letter should be added to the end of the air mass's classification code?

A)k
B)w
C)m
D)c

Question 24

Why is Maritime Arctic left out of the air-mass classifications?

A)They do not occur.
B)They only rarely occur.
C)They occur every ten years.

Question 25

Which of the following is not an air mass that influences North America?

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

Question 26

When an air mass is warmer than the surface over which it is moving:

A)the letter k is added after the air mass symbol.
B)visibility within the air mass is usually very good.
C)the air becomes more stable.
D)the lapse rate in the air mass is increased.

Question 27

A warm,moist air mass from the Gulf of Mexico that moves over the land in the southeastern U.S.during the summer is likely to be classified as:

A)mTk
B)mTw
C)mEk
D)mWk

Question 28

The stability of an air mass can be affected by:

A)cyclones.
B)mountain ranges.
C)anticyclones.
D)mountain ranges,cyclones,and anticyclones.

Question 29

An mP air mass is:

A)humid and cold.
B)humid and warm.
C)dry and warm.
D)dry and cold.

Question 30

If the lowercase letter k appears at the end of an air mass identification code,what can be said about the changes likely to happen within that air mass?

A)The air mass is likely to become more unstable.
B)The air mass is likely to become more stable.
C)The air mass will not undergo any air mass modifications.
D)The expected air mass modifications are impossible to predict.

Question 31

Which of the following air masses probably has the lowest water vapor content?

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

Question 32

An air mass from the Gulf of Mexico that moves northward over the U.S.in winter would be labeled:

A)cTw.
B)mTk.
C)mPw.
D)cTk.
E)mTw.

Question 33

Which of these is NOT a process by which air masses are modified?

A)calm winds
B)lifting over mountains
C)evaporation of water
D)cooling from below
E)heating from below

Question 34

Air mass modifications produced by cyclones or topography rather than surface temperatures are called:

A)mechanical modifications.
B)thermal modifications.
C)synoptic modifications.
D)microscale modifications.

Question 35

Which two air masses are bitterly cold and very dry?

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

Question 36

The pronounced cooling that occurs on continents at high latitudes during winter leads to the formation of ________ air masses.

A)mA
B)cM
C)mP
D)cP
E)cT

Question 37

Where do cA air-masses originate?

A)Arctic basin and Greenland ice cap
B)Interior Canada and Alaska
C)Northwestern Atlantic
D)Patagonia

Question 38

What does the lowercase letter w indicate about an air mass?

A)The air mass is drier than the surface over which it is passing.
B)The air mass is colder than the surface over which it is passing.
C)The air mass is warmer than the surface over which it is passing.
D)The air mass is wetter than the surface over which it is passing.

Question 39

The air masses that have the greatest influence on weather conditions in the Midwestern United States are:

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

Question 40

The coldest and driest winter air-mass in North America is the:

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

Question 41

Most mP air masses that influence the U.S.originate over:

A)the north Atlantic.
B)the Gulf of Mexico.
C)the north Pacific.
D)the Arctic Ocean.

Question 42

Siberian Express is the term used when:

A)an outbreak of bitterly cold air from Canada intrudes over a large part of the United States.
B)a modified air mass originating in Siberia reaches the Pacific Northwest.
C)an unusually cold air mass enters the Rocky Mountains.
D)an mP air mass from the north Atlantic enters New England and generates snowfall.

Question 43

Why are maritime air masses from the north Atlantic of only limited concern for weather in the U.S.?

A)Temperatures are usually mild over this region.
B)Question is incorrect;these air masses are very important.
C)Prevailing winds move them away from the U.S.
D)They never cause severe storms.
E)Polar fronts block these air masses from the U.S.

Question 44

Which of the following statements is TRUE of lake-effect snowfall?

A)Lake-effect snowfall accounts for only a small portion of seasonal snowfall along the eastern edges of the Great Lakes.
B)Along the Great Lakes,lake-effect snowfall usually only occurs within 80 km of the leeward lake shores.
C)Lake-effect events are not capable of generating more than a centimeter or two of snow.
D)Lake-effect events are produced through the modification of mP air masses.

Question 45

In North America the ________ air mass forms only in the summer.

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

Question 46

A nor'easter typically occurs when:

A)NE winds associated with a low-pressure system draw mP air into the northeastern United States.
B)the polar jet stream weakens and allows mP air to invade New England.
C)the NE tradewinds strengthen in the Pacific during a La Niña event.
D)a cP air mass from the northeast moves into Texas.

Question 47

Where would you expect to find the greatest amount of lake-effect snowfall?

A)on the leeward shores of the Great Lakes
B)on the western coasts of the Great Lakes
C)on the windward side of the Great Lakes
D)directly north of the Great Lakes

Question 48

What term would a meteorologist give to the weather event represented on the map above?

A)The Polar Express
B)The Pineapple Express
C)mP Express
D)The Siberian Express

Question 49

Which one of the following conditions would enhance the development of a lake effect storm?

A)moisture advection associated with an mP air mass
B)aA cPw air mass
C)a large temperature gradient between the lake surface temperature the lower atmosphere
D)strong southerly flow

Question 50

All of the following accompany a classic New England nor'easter EXCEPT:

A)heavy snowfall
B)a strong storm forming in Canada and moving into New England from the North
C)widespread power outages and transportation interruptions
D)mP air pulled in from the Atlantic Ocean

Question 51

The ________ air mass often originates as a different air mass in Siberia and is subsequently altered.

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

Question 52

Consider the map above.What air mass is the most likely to be found in Florida,just ahead of the cold front?

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

Question 53

In the United States,lake-effect snows occur over which area?

A)the eastern side of the Cascade Mountains
B)the windward side of the Mississippi River
C)the leeward shores of the Great Lakes
D)Lake Champlain

Question 54

While on vacation in Florida,you experience several days of weather with maximum temperatures of 90°F and dew points above 65°F.What educated guess could you make about the weather?

A)It is caused by an mP air mass.
B)It is caused by a cT air mass.
C)It is caused by an mT air mass.
D)It is not air mass weather.

Question 55

Which air mass does not usually influence weather in the United States during the summer?

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

Question 56

Lake-effect snowfall is caused by:

A)air mass modification related to the differential heating of land and water.
B)ice crystals falling from a cP air mass on the windward side of a lake.
C)an mP air mass passing over a cold body of water.
D)warm air masses passing over a cold lake in the autumn.

Question 57

Which region of origin for mT air masses has the most impact on North American weather?

A)mT air masses from the Gulf of Mexico
B)mT air masses from the Northern Pacific
C)mT air masses from the subtropical Pacific.
D)mT air masses from Australia

Question 58

"Lake-effect" snow is associated with the ________ air mass.

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

Question 59

The ________ air mass may produce an occasional "nor'easter" in the winter.

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

Question 60

Which air mass is unstable in the winter but stable in the summer?

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

Question 61

The majority of the continental U.S.is not an air mass source region.

Question 62

Most of the precipitation for the region east of the Rocky Mountains comes from:

A)evaporation from soils and vegetation.
B)mA air masses.
C)modified mP air masses.
D)mT air masses.

Question 63

The ________ air mass provides much of the moisture for precipitation in the central and eastern United States.

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

Question 64

When an air mass is warmer than the surface over which it is moving,its lower layers are chilled.

Question 65

What air-mass contributes to the formation of thunderstorms in the central U.S.?

A)mT
B)mP
C)cA
D)stormy ones

Question 66

Maritime Arctic air masses do not form very often.

Question 67

A region dominated by cyclones is more likely to produce an air mass than a region dominated by anticyclones.

Question 68

To qualify as an air mass,a large body of air must have the same temperature at the same altitude,even if the body of air is 1,000 kilometers wide.

Question 69

The moisture content of an air mass is unrelated to its temperature.

Question 70

The ________ is characterized by a strong jet stream pulling mT air from Hawaii towards California.

A)Tropical Jet
B)Pineapple Express
C)Southeaster
D)Santa Ana Wind

Question 71

The physical properties of an air mass are independent of its place of origin.

Question 72

Maritime air masses form over landmasses.

Question 73

Why are cT air masses of minor importance for the U.S.?

A)No large source region is near the U.S.
B)Prevailing winds steer them away.
C)Mountains block their approach.
D)Upper level subsidence limits their formation.

Question 74

Lines connecting places having equal rainfall on a map are called:

A)isotopes.
B)isohyets.
C)isolines.
D)isobars.

Question 75

An air mass is an immense body of air characterized by homogeneous temperature and moisture content.

Question 76

The boundary of an air mass is a region of especially active weather.

Question 77

Which air mass causes occasional drought to the southern Great Plains of the United States?

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

Question 78

Maritime air masses have a higher water vapor content than continental air masses.

Question 79

Air masses are identified by two-letter codes.

Question 80

In the middle latitudes,atmospheric disturbances occur at the boundary zones separating air masses.