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ATPL - BGS [Mod 1] Meteorology > 17. Air Mass Weather > Flashcards

17. Air Mass Weather Flashcards

1
Q

Air Mass Weather

Sources of air masses are BIG or SMALL regions of HIGH or LOW pressure

A
  1. BIG
  2. HIGH

AIR MASSES

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2
Q

Air Mass Weather

Defintions of air masses;

  1. All air masses start STABLE or UNSTABLE
  2. If a source region for an air mass is over land, or over ice and snow, the air mass will be WET or DRY
  3. Air masses travelling over land are WET or DRY
  4. Air masses travelling over the sea will have an INCREASED or DECREASED relative humidity at lower layers
  5. Air masses moving over warmer surfaces are heated at lower layers. This will make the air MORE or LESS stable
  6. Air masses mover over colder surfaces are cooled in the lower layers. This will make the air mass MORE or LESS stable
A
  1. STABLE
  2. DRY
  3. DRY
  4. INCREASED
  5. LESS STABLE
  6. MORE STABLE

  • Air masses all start stable
  • If travelling over land, ice or snow, the air masses will pick up little to no moisture
  • Therefor emasses travelling over land are dry
  • in comparison, air masses travelling over sea will pick up moisture
  • When air is warmed at lower layers, it will want to rise. If the air around it is colder, then this will make it unstable
  • When air is colled at lower layers, it will want to stay at the surface, making it more stable.

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3
Q

Air Mass Weather

Refer to the following diagram. Complete the air mass classifications based on their track, source region, and temperature

A
  1. mPc
  2. mPw
  3. mTw
  4. mAc
  5. cPc
  6. cTw

COMPLETED

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4
Q

Air Mass Weather

What are the 3 main high pressure source regions that impact Northwest Europe

[ ] Azores Warm High
[ ] Tropical Storm High
[ ] Polar High
[ ] Siberian Cold High
[ ] Polar Front

A

[X] Azores Warm High
[ ] Tropical Storm High
[X] Polar High
[X] Siberian Cold High
[ ] Polar Front

  • As well as the source region of the high pressure, the state of the surface inland needs to be factored in
  • What triggers are present
  • Hills for example give orographiclifting, daytime heating of the land in summer will set off thermal convection etc

NORTHWEST EUROPE AIR MASSES

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5
Q

Air Mass Weather

“air mass starts over the polar cap as cold dry, stable air. It moves south from its source region tracking over the North Atlantic, picking up moisture. The warmer sea heats up the lower levels and the temperature is raised. The air mass becomes less stable and convective currents distribute the moisture to higher levels. When it arrives at NW Europe it arrives as coold, moist and unstable air associated with convective cloud, showers, and good visibility”

This is the definition of which air mass effecting Northwest Europe

A

MARITIME POLAR COLD AIR
(mPc)

mPc

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6
Q

Air Mass Weather

Maritime Polar Cold Air (mPc) has which following traits/characteristics;

  1. Arrives as STABLE or CONDITIONALLY UNSTABLE or UNSTABLE air mass
  2. In winter, the air mass triggered by orographic lifting will produced small to medium As or Cu or Ci or CB cloud that WILL or WILL NOT dissipate throughout the night
  3. In summer, the air mass triggered by orographic lifting will produced medium to large As or Cu or Ci or CB cloud that WILL or WILL NOT dissipate throughout the night
  4. The air normally arrives to Europe from the W / NW or S / SW
  5. The visiibility associated with mPc is GOOD or BAD
  6. In winter, it will be associated with RADIATION or ADVECTIVE fog
A
  1. CONDITIONALLY UNSTABLE
  2. Cu / WILL DISSIPATAE
  3. CB / WILL NOT DISSIPATE
  4. W / NW
  5. GOOD
  6. RADIATION

mPc

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7
Q

Air Mass Weather

“air sourced from the Arctic ice cap. The temperature contrast between very cold air and relatively warm open sea makes the very cold air mass moist and unstable on arrival. Cu and Cb clouds form over sea, sometimes spreading out to be Sc, bringing heavy snowfall to the NE of England”

This is the definition of which air mass effecting Northwest Europe

A

MARITIME ARCTIC COLD
(mAc)

mAc

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8
Q

Air Mass Weather

Maritime Arctic Cold (mAc) has which followin traits/characteristics;

  1. Arrives as a STABLE or CONDITIONALLY UNSTABLE or UNSTABLE air mass
  2. Produces Ci or AS or CU or CB over sea
  3. May bring heavy snowfall to NORTH or EAST or SOUTH or WEST of England
  4. A thermal depression known as a polar HIGH or LOW can bring +1 ft of snow on an airfield in one pass
A
  1. UNSTABLE
  2. CU, CB
  3. NORTH and EAST
  4. LOW

mAc

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9
Q

Air Mass Weather

“the airs source region is the Siberian High, a cold, dry, stable airmass that sits over eastern Europe and the Russian plains in winter. It brings typically dry, cold, stable airmass conditions to central and northern Europe”

This is the definition of which air mass effecting Northwest Europe

A

CONTINENTAL POLAR COLD
(cPc)

cPc

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10
Q

Air Mass Weather

Continential Polar Cold (cPc) has which followin traits/characteristics;

  1. Arrives as a STABLE or CONDITIONALLY UNSTABLE or UNSTABLE air mass
  2. Brings DRY AND COLD or DRY AND WARM or DRY AND WET conditions
  3. The visiibility associated with cPc is GOOD or BAD
  4. Winds will be STRONG or LIGHT below the inversion
  5. Winds will be EASTERLY or WESTERLY above the inversion
A
  1. STABLE
  2. DRY AND COLD
  3. BAD
  4. LIGHT
  5. EASTERLY

  • The temperature inversion associated with the cPc traps industrial contamination in the lower layers, bringing poor visibility

cPc

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11
Q

Air Mass Weather

  1. What is specific about the cPc in terms of Winter and Summer
  2. The cPc air mass will pick up heat and moisture from the sea, warming the lower layers. What sort of precipitation will it bring
A
  1. DOES NOT EXIST IN SUMMER
  2. SLEET or SNOW

cPc

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12
Q

Air Mass Weather

“air mass that comes from North Africa, Turkey, and the Eastern Mediterranean un summer where it is stable and hot. As the air mass moves north it colls, increasing teh stability of the lower levels. Much of the moisture picked up whilst crossing the Mediterranean is lost as the air moves over the mountain barrier of the Alps and Pyrenees”

This is the definition of which air mass effecting Northwest Europe

A

CONTINENTAL TROPICAL WARM
(cTw)

cTw

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13
Q

Air Mass Weather

Continential Tropical Warm (cTw) has which followin traits/characteristics;

  1. As the airmass moves North it WARMS or COOLS WHICH;
  2. Brings INCREASED or DECREASED stability at lower layers
  3. The visiibility associated with cTw is GOOD or BAD
  4. Daytime heating over land may bring As or Cu or Cb or Ci cloud if there is a slack pressure gradient and light winds
  5. It will be associated with RADIATION or ADVECTIVE fog over the North Sea, known as Haar fog in Scotland
A
  1. COOLS
  2. INCREASED STABILITY
  3. CU
  4. ADVECTIVE FOG

  • If the continental tropical air takes the route along the North Sea, it will pick up moisture in the lower layers
  • This will be trapped underneath the inversion layer
  • The cooling over sea will produce a thin layer of advection fog which is blown on to shore
  • Continential tropical warm air is rare over NW Europe

cTw

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14
Q

Air Mass Weather

What is specific about the cTw in terms of Winter and Summer

A

DOES NOT EXIST IN WINTER

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15
Q

Air Mass Weather

“air source region is the warm, moist, stable Azores high. As the air tracks North East to Northwest Europe, the lower levels cool, increasing the relative humidity and making the air mass more stable. Cooling accentuates the inversion at low level. Visibility is moderate to poor”

This is the definition of which air mass effecting Northwest Europe

A

MARITIME TROPICAL WARM
(mTw)

mTw

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16
Q

Air Mass Weather

Maritime Tropical Warm (mTw) has which following traits/characteristics;

  1. Is a STABLE or CONDITIONALLY UNSTABLE or UNSTABLE air mass
  2. As it tracks North East to NW Europe, lower levels WARM or COOL WHICH;
  3. makes the air mass MORE or LESS stable
  4. The visiibility associated with mTw is GOOD or BAD
  5. The precipitation associated with mTw is SNOW or SHOWERS or DRIZZLE or HAIL
  6. At low levels, it will be associated with RADIATION or ADVECTIVE fog
  7. The typical cloud associated with mTw is Cu or Ci or Cb or St or Sc
  8. Winds will be from the SE or SW or NW
A
  1. STABLE
  2. COOL
  3. MORE
  4. BAD
  5. DRIZZLE
  6. ADVECTION
  7. St, Sc
  8. SW

  • Coling from below accentuates the inversion at lower layers, which makes visibility worse
  • It brings low level stratus and advection fog
  • Winds will be light to moderate from the South West

mTw

12/13

17
Q

Air Mass Weather

In mTw air, the risk of caruettor icing is INCREASED or DECREASED

A

INCREASED

  • the air is warm and moist, so contains higher water vapour content
  • As the air rapidly cools in the carburettor, this carries the increased risk of icing

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18
Q

Air Mass Weather

“air mass source region of the Altanic, travelling south first, and then returning to NW Europe latitudes on southwesterly winds.”

This is the definition of which air mass effecting Northwest Europe

A

MARITIME POLAR WARM
(mPw)

aka RETURNING MARITIME POLAR (rMp)

mPw(rMp)

14

19
Q

Air Mass Weather

Maritime Polar Warm (mPw) has which following traits/characteristics;

  1. Is a STABLE or CONDITIONALLY UNSTABLE or UNSTABLE air mass
  2. As the air mass moves south, it becomes MORE or LESS stable at all levels
  3. As the air mass returns north, it becomes MORE or LESS stable at lower levels
  4. As the air mass returns north, it becomes MORE or LESS stable at medium levels
  5. mPw shows the characteristics of MPC or MTW at medium level AND;
  6. mPw shows the characteristics of MPC or MTW at low level
A
  1. CONDITIONALLY STABLE (see notes below)
  2. LESS STABLE
  3. MORE STABLE
  4. LESS STABLE
  5. MPC
  6. MTW

  • As the air tracks south it warms and picks up moisture in the lower levels, which leads to a greater ELR
  • This brings with it less stability at all levels however;
  • as the air tracks north again, the lower level cools, becoming more stable whilst still picking up moisture
  • The air at lower levels becomes more stable, whilst air aloft becomes less stable

mPw(rMp)

14

20
Q

Air Mass Weather

Maritime Polar Warm (mPw) air arriving at Northwest Europe will initially give weather associated with moist stable air;

  1. HIGH or LOW stratus
  2. GOOD or POOR visibility
  3. DRIZZLE or SHOWER precipitation
  4. Possibility of ADVECTION or RADIATION fog
  5. The air at medium level can bring what sort of cloud type
  6. In summer, mPw air will typically bring St or Sc or Cu or Cb cloud on windward coast and convective cloud inland
A
  1. LOW STRATUS
  2. POOR VISIBILITY
  3. DRIZZLE
  4. ADVECTION FOG
  5. AC CASTELLANUS
  6. St, Sc

  • In winter, stable weather conditions persist over much of the NW Europe

mPw(rMp)

15

21
Q

Air Mass Weather

“an air mass that develops at latitudes from 25°N to 10°S. Temperatures are high and the air mass is always maritime. It is laden with moisture as water readily evaporates into the hot air”

This is a definition of what air mass that never impinges on the North West Euorpe

A

EQUITORIAL AIR MASS

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22
Q

Air Mass Weather

What type of weather phenomenon is typical in association with Equatorial Air Masses

A

THUNDERSTORMS

  • warm air has a tendency to rise creating an aera of low pressure
  • Trade winds that blow into this area of low pressure near the equator push warm air into the cooler upper atmosphere
  • The moisture condenses into ice crystals and turns into rain as it falls

16

23
Q

Air Mass Weather

The rains which feed the Amazon rainforest, Congo basin and East Indies are a result of which air mass

A

EQUATORIAL AIR MASS

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ATPL - BGS [Mod 1] Meteorology (27 decks)

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