Ch 8 & 9

Question 1

Air Mass

Answer 1

large body of air that has relatively uniform temperature and moisture level throughout
around 1000 miles horizontal
types of them are determined by their source region

Question 2

Source Region

Answer 2

region where an air mass is formed

major ones are not found in the middle latitude

Question 3

Source Regions must meet 2 criteria

Answer 3

1) must be an extensive and physically uniform area

2) the region is dominated by stationary or slow-moving anticyclones with their extensive areas of calms or light winds

Question 4

Regions under the influence of cyclones

Answer 4

are not likely to produce air mass because such systems are characterized by converging surface winds

Question 5

Classification of an air mass

Answer 5

depends on the latitude of the source region and the nature of the surface in the area of origin

Question 6

Latitude of source region

Answer 6

indicates the temperature conditions within the air mass

Question 7

P

Answer 7

Polar

Question 8

A

Answer 8

Artic

Question 9

T

Answer 9

Tropical

Question 10

m

Answer 10

maritime

Question 11

c

Answer 11

continential

Question 12

maritime air masses

Answer 12

formed over water

Question 13

continental air masses

Answer 13

formed over land

Question 14

Main characteristics that define air masses

Answer 14

temperature and moisture content

Question 15

k is added after the air mass symbol when

Answer 15

an air mass is colder than the surface over which it is passing

Question 16

w is added when

Answer 16

an air mass is warmer than the underlying surface

Question 17

cA

Answer 17

continental arctic
very cold, very dry
air forms farther north, over the arctic basin and the Greenland ice cap

Question 18

cP

Answer 18

continental polar
cold, dry
originates over the often snow-covered interior regions of Canada and Alaska, poleward of the 50th parallel

Question 19

mP

Answer 19

maritime polar
cool, humid
form over oceans at high latitudes;; two regions important sources for air that influence North America: North Pacific and Northwestern Atlantic

Question 20

mT

Answer 20

maritime tropical
warm, humid
originate over the warm waters of the Gulf of Mexico, the caribbean sea, or the adjacent western atlantic ocean

Question 21

cT

Answer 21

continental tropical
hot, dry
normally remains nearly cloudless because of extremely low humidity;; the prevailing weather is hot with an almost complete lack of rainfall

Question 22

Lake-effect snow

Answer 22

highly localized storms, occurring along the leeward shore of the great lakes

Question 23

Pacific Maritime Polar Air Masses

Answer 23

strong influence on the weather along the western coast; especially in winter

Question 24

North Atlantic mT air

Answer 24

maritime tropical air masses from the Gulf-Caribbean- Atlantic source regions greatly affect the weather of the United States east of the Rocky Mountains

Question 25

Fronts

Answer 25

boundary surfaces that separate air masses of different densities

Question 26

Types of Fronts

Answer 26

1) warm 2) cold 3) stationary 4) occluded 5) drylines

Question 27

Warm Fronts

Answer 27

transition zone where a warm air mass is replacing a cooler air mass;; very gradual slope red line with red semi circles pointing towards the colder air and in the direction of movement

Question 28

Warm fronts produce

Answer 28

light-to-moderate precipitation over wide area for an extended period;; if overriding air mass is relatively dry, there will be minimal cloud development, and no precipitation

Question 29

warm fronts in summer

Answer 29

very moist air;; if unstable air is lifted sufficiently it will freely rise on its own, producing towering cumulonimbus clouds and thunderstorms

Question 30

Cold Fronts

Answer 30

transition zone where a cold air mass is replacing a warmer air mass;; twice as steep as warm fronts;; advance faster than warm fronts blue line and blue triangles pointing towards the warmer air and in direction of movement;; thunderstorms

Question 31

Stationary Front

Answer 31

when a warm or cold front stops moving;; blue and red lines with blue triangles pointing towards warmer air and red semi pointing towards the colder air

Question 32

Occluded Fronts

Answer 32

rapidly moving cold front overtakes a warm front, as the cold air wedges the warm front upward, new front forms between the new advancing cold air and the older cool air mass over which the warm front is gliding;; purple line with alternating triangles and semi pointing the direction the front is moving

Question 33

Occluded Frontss

Answer 33

mature mid-latitude cyclone;; partially mid-latitude cyclone;; mid-latitude cyclone

Question 34

cold-type occluded front

Answer 34

cold air--> warm air--> cool air

Question 35

warm-type occluded front

Answer 35

cool air--> warm air--> cold air

Question 36

Drylines

Answer 36

boundary that separates a moist air mass from a dry air mass

Question 37

___ fronts are shown by a line with triangular points on one side

Answer 37

cold front

Question 38

if cirrus clouds are first appearing, followed later by cirrostratus, and then altostratus a ___ front is approaching

Answer 38

warm front

Question 39

The type of front formed when the leading edge of cold air merges with a warm front known as

Answer 39

occluded front

Question 40

The surface position of the stationary front does not move or moves very slowly because

Answer 40

the winds blow parallel to the front

Question 41

Polar Front

Answer 41

weather front located typically in the mid-latitudes that separates arctic and polar air masses from tropical air masses

Question 42

Mid-latitude cyclone

Answer 42

cyclonic storm that forms primarily in the middle latitudes;; these storms also contain warm, cold, and occluded fronts;; atmospheric pressure in their center can get as low as 970 millibars - -occur most often during the winter season in US b/c of large temp difference between the equator and the north pole - -easily identified by comma appearance

Question 43

Polar Front theory (Norwegian Cyclone Model)

Answer 43

1) Front develops 2) wave develops 3) cyclonic circulation established 4) occlusion begins

Question 44

Front Develops

Answer 44

initially will be a boundary, separating warm air to the south from cold air to the north;; stage set for cyclogenesis (cyclone formation)

Question 45

wave develops

Answer 45

wave will form as an upper level disturbance embedded n the jets stream moves over the front;; the front develops a kink where the wave is developing --precipitation will begin to develop with the heaviest occurrence along the front (dark green)

Question 46

Cyclonic circulation established

Answer 46

as wave intensifies both cold and warm fronts become better organized;; resulting flow is a counterclockwise cyclonic circulation that can be seen clearly on the weather map

Question 47

Occlusion begins

Answer 47

wave becomes a mature low pressure system, while the cold front, moving faster than the warm front "catches up" with the warm front. As the cold front overtakes the warm front, an occluded front forms --as occlusion begins the storm often intensifies;; pressure at the storm's falls, and wind speeds increases. In winter, heavy snowfalls and blizzard-like conditions are possible during this phase

Question 48

Occluded front developed

Answer 48

as the cold front continues advancing on the warm front, the occlusion increases and cold air surround the cyclone at low levels --horizontal temp difference that existed between the two contracting air masses has been eliminated, causing the low pressure system to gradually dissipate

Question 49

Typical movement of mid-latitude cyclone

Answer 49

generally moves eastward across the US; requires 2 to 4 days to pass completely over a region

Question 50

A section of mid-latitude cyclone

Answer 50

high cirrus clouds (before warm front)

Question 51

B section

Answer 51

light precipitation;; as warm front nears, the rate of precipitation increases, temperature rises, winds change from an easterly to a southerly flow

Question 52

C section

Answer 52

maritime tropical air mass (warm)

Question 53

D section

Answer 53

approach of cold front

Question 54

E

Answer 54

once the front passes, the skies clear quickly as cooler air invades the region

Question 55

the lifetime of a mid-latitude cyclone is nearly

Answer 55

a few days to 1 week

Question 56

An approaching mid-latitude cyclone would be indicated by a ___ pressure

Answer 56

rapidly falling

Question 57

The area enclosed between the cold front and warm front in a a mid-latitude cyclone is called the

Answer 57

warm sector

Question 58

Anticyclone

Answer 58

large-scale circulation of winds around a central region of high atmospheric pressure, clockwise in the Northern Hemisphere, counterclockwise in the Southern Hemisphere --divergence at the surface is balanced by convergence aloft and general subsidence of the air column

Question 59

Anticyclone weather

Answer 59

owing to the gradual subsidence within them, anticyclones produce clear skies and calm conditions

Question 60

Blocking high

Answer 60

high pressure area (anticyclone), often aloft, that remains nearly stationary or moves slowly compared to west-to-east motion;; blocks the eastward movement of low pressure areas (cyclones) at its latitude --can be in place for several days causing the areas affected by them to have the same kind of weather for an extended period of time

Question 61

Montpellier

Answer 61

example of blocking highs and flood

Question 62

compared to continental air masses with the same air temp, maritime air masses

Answer 62

have higher water vapor content

Question 63

cT air mass is

Answer 63

warm and dry

Question 64

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

Answer 64

the air becomes more stable

Question 65

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

Answer 65

temperature and moisture content

Question 66

Lake-effect snow is associated with the ___ air mass

Answer 66

cP

Question 67

An area on the north side of the low-pressure center of a a middle-latitude cyclone usually has this type of front for the longest period of time

Answer 67

occluded

Question 68

Cold air --> warm air

Answer 68

cold front

Question 69

The type of weather most frequently associated with the front shown on the diagram above cold air--> warm air

Answer 69

thunderstorms and other severe weather

Question 70

cool air--> warm air--> cold air

Answer 70

warm type occluded front

Question 71

on a weather map, a line with blue triangles on one side and red semicircles on the other represents

Answer 71

stationary front