Deck 8: Air Masses

Question 1

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

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

Answer 1

C

Question 2

Characteristics of an air mass source region include:

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

Answer 2

D

Question 3

An air mass from the Gulf of Mexico is called:

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

Answer 3

B

Question 4

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 subtropical Pacific.
C) mT air masses from the Northern Pacific
D) mT air masses from Australia

Question 5

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

Question 6

An mP air mass is:

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

Question 7

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

Question 8

An air mass is a body of air with:

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

Question 9

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

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

Question 10

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 11

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

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

Question 12

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

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

Question 13

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

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

Question 14

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

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

Question 15

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

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

Question 16

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

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

Question 17

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

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

Question 18

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

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

Question 19

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

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

Question 20

A nor'easter typically occurs when:

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

Question 21

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

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

Question 22

What is an atmospheric river?

A) A period of extended rainfall in areas that are typically very dry.
B) A zone of saturated air and frequent fog near the Gulf Stream.
C) An atmospheric flow that transports vast amounts of moisture to regions outside of the tropics.
D) A zone of intense rainfall associated with an mP air mass.

Question 23

Air masses passing from the Gulf of Mexico over land in the Southeastern United States in the summertime are modified by the hot surface and become:

A) mTw.
B) mPk.
C) mTk.
D) cTw.

Question 24

The cP air- mass in North America originates in:

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

Question 25

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

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

Question 26

The stability of an air mass can be affected by:

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

Question 27

Air mass source regions tend to be dominated by:

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

Question 28

An air- mass source region:

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

Question 29

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

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

Question 30

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

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

Question 31

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

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

Question 32

An mT air mass moving onto land in the Southeastern United States during the summer time typically becomes:

A) more stable.
B) saturated.
C) conditionally unstable.
D) more unstable.

Question 33

A cT air mass is:

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

Question 34

-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) mA
C) mT
D) cP

Question 35

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

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

Question 36

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

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

Question 37

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

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

Question 38

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) m
B) c
C) k
D) w

Question 39

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

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

Question 40

Lake- effect snowfall is caused by:

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

Question 41

The_____________ area where an air mass originates is called a:

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

Question 42

An ideal source region of air masses should be:

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

Question 43

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

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

Question 44

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

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

Question 45

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

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

Question 46

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

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

Question 47

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

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

Question 48

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

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

Question 49

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

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

Question 50

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

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

Question 51

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

Question 52

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

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

Question 53

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

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

Question 54

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

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

Question 55

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

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

Question 56

Where do cA air- masses originate?

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

Question 57

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

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

Question 58

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

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

Question 59

The usual size of an air mass is:

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

Question 60

Topography and the upward and downward movements of cyclones and anticylones create__________ modifications of air masses.

A) convective
B) orographic
C) thermal
D) mechanical (dynamic)

Question 61

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

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

Question 62

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

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

Question 63

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

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

Question 64

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

Question 65

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

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

Question 66

Which two air masses are bitterly cold and very dry during winter?

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

Question 67

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

Question 68

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) an mP air mass from the north Atlantic enters New England and generates snowfall.
C) an unusually cold air mass enters the Rocky Mountains.
D) a modified air mass originating in Siberia reaches the Pacific Northwest.

Question 69

What do the letters k and w signify when added to an air mass identifier?

Question 70

What weather is associated with cA air masses?

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

Question 71

Name two source regions for Maritime Tropical air masses.

Question 72

Name two processes by which an air mass can be modified and give examples.

Question 73

What air- mass type tends to dominate the weather in the U.S. east of the Rocky Mountains during winter? During summer?

Question 74

What is the air mass type and source region for "nor'easters"?

Question 75

Maritime air masses form over landmasses.

Question 76

Name two source regions of mP air masses.

Question 77

Air masses with cA and cP designations are typically:

A) conditionally unstable.
B) stable.
C) absolutely unstable.

Question 78

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

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

Question 79

The place where an air mass originates is known as the _____.

Question 80

Name the three air mass types most important for the continental U.S.