air masses and fronts quiz

Question 1

what are air masses?

Answer 1

very large body of air whose temperature & humidity are similar horizontally & vertically

Question 2

what are air mass source regions?

Answer 2

area where air mass originates
usually flat and uniform composition with light surface winds

Question 3

how are air masses classified?

Answer 3

based upon temperature and humidity

Question 4

what are the two letters for moisture and what do they mean?

Answer 4

m = maritime (ocean, humid)
c = continental (land, drier)

Question 5

what are the four letters for temperature and what do they mean?

Answer 5

P = polar (cold, Canada)
T = tropical (warm)
A = arctic (coldest, cA)
E = equatorial (warmest, equator, mE)

Question 6

what are cP and cA?

Answer 6

• dry, cold, stable (cA more extreme) (fair weather, little cloud cover)
• usually marked with a cold core (thermal) high pressure
• may form subsidence inversions

Question 7

what are the source regions of cP and cA?

Answer 7

N Canada, Alaska

Question 8

what is mP?

Answer 8

• cool, humid, unstable
• ocean influence makes surface warm, but keeps air aloft cool
• many mP start out as cP but traverse over the oceans picking up moisture
• after traversing mountain ranges, moisture is extracted, air mass becomes cP

Question 9

what is the source region for mP?

Answer 9

N Pacific, N Atlantic

Question 10

what is mT?

Answer 10

• wet, warm, unstable (host moisture, near subtropical)
• sometimes called subtropical air mass
• Pineapple Express: moisture advecting onto SW USA via the Pacific High
• also called Bermuda High

Question 11

what are the source regions for mT?

Answer 11

Gulf of Mexico
Caribbean
SE Pacific
South Atlantic

Question 12

what is cT?

Answer 12

• hot, dry, conditionally unstable (LFC however usually 10,000ft+)
• presence of upper-level high will often increase stability
• summer only

Question 13

what are the source regions for cT?

Answer 13

SW USA, Mexican Plateau

Question 14

what are fronts?

Answer 14

transition zone between two air masses of different densities

Question 15

how can you identify one on a chart?

Answer 15

• sharp temperature change
• sharp change in dew point
• shift in wind direction
• sharp pressure change
• clouds and precipitation

Question 16

what is frontolysis?

Answer 16

weakening, decaying fronts

Question 17

what is frontogenesis?

Answer 17

strengthening, growing fronts

Question 18

what are the commonly seen frontal symbols?

Answer 18

• triangle points in the direction the cold air is moving
• half-circle points where the warm air is moving

Question 19

how are fronts analyzed?

Answer 19

• alternating red and blue line with blue triangles and red semi-circles
• winds parallel but opposite direction
• variable weather

Question 20

what is a cold front?

Answer 20

• cold, dry, stable air replaces warm, moist, and unstable air
• analyzed with blue line with blue triangles
• winds southerly component ahead, westerly component behind
• clouds of vertical development: steep slope, thunderstorms, squall lines

Question 21

what is a ‘back door’ cold front?

Answer 21

• occur along the US east coast when a mP moves towards land
• cold front which moves southwest, opposite of typical cold fronts (‘back door’)
• shallow, cold air is trapped up against Appalachian Mountains (cold air damming)

Question 22

what is a front warm?

Answer 22

• warm, moist, unstable air overrides cold, dry, unstable air (overrunning)
• analyzed with red line with red semi-circles
• horizontal cloud development with steady rain, weak slope
• typically easterly component to winds ahead of front, southerly behind front
• frontal inversion

Question 23

what is an occluded front?

Answer 23

• cold front catches up to and overtakes a warm front
• analyzed with purple line with purple triangles and semi-circles
• cold occlusion: coldest air behind cold front
• warm occlusion: coldest air ahead of warm front
• both cases, warmest air is cut off from the surface
• near the cyclone’s final days