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26 Cards in this Set
- Front
- Back
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Define: Front
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Transition zone between two air masses
108.1.1 |
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Name the frontal systems found over North America in summer and in winter and give their standard identification
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- fronts named after colder air mass involved
- Arctic front between cA and mA air masses, only in winter, labelled A - Maritime front between mA and mP air masses, labelled M - Polar front between mP and mT air masses, labelled P 108.1.2 |
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For a given front, name the two air masses separated by the front
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- Arctic front: cA and mA
- Maritime front: mA and mP - Polar front: mP and mT 108.1.3 |
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Define: Frontal surface
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Transition zone separating warm and cold air aloft
108.1.4 |
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Define: Surface front
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Transition zone separating warm and cold air at the surface
108.1.4 |
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Define: Cold front
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Transition zone between warm air and advancing cold air
108.1.4 |
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Define: Warm front
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Transition zone between warm air and retreating cold air
108.1.4 |
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Define: Stationary front
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Transition zone between two air masses not moving
108.1.4 |
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List the factors used to associate air mass temperature, moisture, and stability with the severity of frontal weather conditions
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- slope of frontal surface
- speed of frontal surface - temp of lifted air mass - moisture content of lifted air mass - stability of lifted air mass 108.2.1 |
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List what changes usually occur to temperature with the passage of a cold front and a warm front
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- increases with warm front passage
- decreases with cold front passage 108.2.2 |
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List what changes usually occur to dew point temperature with the passage of a cold front and a warm front
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- generally increases with warm front passage
- generally decreases with cold front passage 108.2.2 |
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List what changes usually occur to pressure with the passage of a cold front and a warm front
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- generally falls with warm front passage
- usually markedly rises after cold front passage 108.2.2 |
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Describe the effect of frontal slope on weather
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- shallow slope tends to produce wide area of cloud and precipitation
- steep slope tends to produce narrow band of cloud and precipitation - cold front slope 1:50, stationary front slope 1:100, warm front slope 1:200 108.2.3 |
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Describe the causes of cloud and precipitation at a warm front
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- moisture content of overrunning warm air
- stability of overrunning warm air - degree of overrunning 108.2.4 |
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Describe the causes of cloud and precipitation at a cold front
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- moisture content of lifted warm air
- stability of lifted warm air - degree of lift ie. frontal surface slope, front speed 108.2.4 |
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List the cloud types associated with a warm front
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Dry:
- no clouds or CI, AC, SC with no precipitation Moist and stable: - CI, CS, AS, NS, and continuous precipitation causing SF and fog Moist and unstable: - CI, CS, AS, NS, CB, and continuous precipitation with occasional convective showers 108.2.5 |
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List the cloud types associated with a cold front
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Dry and stable:
- no clouds or SC, AC, CU with no precipitation Moist and stable: - wide SC and AC with continuous or intermittent precipitation if advancing slowly - narrower band of SC and AC with continuous/intermittent precipitation if moving quickly Moist and unstable: - SC, SF in showers, CU, TCU, ACC, CB, showery precipitation 108.2.5 |
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Describe the extent and type of precipitation and icing a pilot would experience while flying through a warm front
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- precip gradually increases in intensity and becomes steadier while approaching
- SN, RA, FZRA, PL - icing in precip, especially FZRA aloft - icing may occur in cloud below frontal surface, if below freezing - icing regions can be larger with warm fronts due to extensive cloud cover 108.2.6 |
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Describe the extent and type of precipitation and icing a pilot would experience while flying through a cold front
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- narrow band of showery precip
- heavy icing in CB 108.2.6 |
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Describe the visibility in advance of and behind a warm front
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- reduced well in advance of front
- reduced by continuous precip, frontal fog, low ceilings - usually worst just ahead of front - little change after frontal passage 108.2.7 |
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Describe the visibility in advance of and behind a cold front
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- generally good ahead of front
- reduced in precip and mist close to front - marked improvement after frontal passage 108.2.7 |
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State the wind shift expected when flying through a warm or cold front
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- whatever direction the aircraft flies from, when crossing a frontal surface, the aircraft will have to correct its heading to the right
- wind veers when crossing a front against its direction of movement - wind backs when crossing a front with its direction of movement 108.2.8 |
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State the weather phenomena which could indicate turbulence in a frontal system
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Warm front:
- embedded CB - may be impossible to see Cold front: - from convective cloud - wind shift possible even when few clouds present - wind shear Frontal wind shear: - can be present with either front 108.2.9 |
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Define: Frontal wave
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Wave-shaped distortion on a front usually associated with a trough
108.3.1 |
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Define trough of warm air aloft and describe the symbology used to represent and define a trowal
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- as cold air of cold front overtakes warmer air of warm front, warm air is forced aloft, creating trough of warm air aloft
- represented on weather map by slightly curved line with a barb at the end 108.3.2 |
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State the temperature changes that occur with the passage of a frontal wave
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- as frontal wave approaches, temps gradually increase
- once surface warm front passes, in the warm sector - once cold front passes, temps usually drop as cooler air mass moves over 108.3.4 |
