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20 Cards in this Set
- Front
- Back
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Describe a baroclinic zone
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Active area between 2 different air masses where strong pressure and temperature gradients exist
203.1.1 |
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Describe a barotropic zone
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Exists within an air mass where there is little temperature and pressure changes
203.1.1 |
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Describe a front, or a frontal zone
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Transition zone between two different air masses
203.1.2 |
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Describe a cold front
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- cold air advancing and undercutting warm air
- leading edge of cold air is the front 203.1.2 |
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Describe a warm front
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- cold air retreating and being replaced by warm air
- trailing edge of cold air is the front 203.1.2 |
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Describe a stationary front
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- cold air is neither advancing nor retreating
- frequently called quasistationary fronts 203.1.2 |
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Describe a trowal
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- trough of warm air aloft
203.1.2 |
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State the names of the 4 air masses over North America
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- continental Arctic cA
- maritime Arctic mA - maritime Polar mP - maritime Tropic mT 203.1.3 |
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State the names of the 3 fronts in North America
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Named after colder airmass involved:
- Arctic A - Maritime M - Polar P 203.1.3 |
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Explain the 3 dimensional structure of a cold front
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- cold air moving more quickly than warm
- not a straight wall - cold air pushes against warm air, lifts it, creates scraper effect - wedge of cold air progressively thicker - steep slope about 1:50 - weaker the ground friction the steeper the slope - initiates condensation, cloudséprecipitation along its length 203.1.4 |
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Explain the 3 dimensional structure of a warm front
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- warmer air pushes against and over retreating cold air
- slope of frontal surface inverted - shallow slope, 1:200 203.1.4 |
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Explain the 3 dimensional structure of a trowal
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- cold front catches up with warm front and squeezes warm air aloft
- in cold air under trowal, weak front may form, called occluded front - narrow transition zone between two cold air masses - if advancing air is colder than retreating air, called cold front-type occlusion - reverse called warm front-type occlusion 203.1.4 |
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Describe an upper cold front
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- advancing cold air leaves the ground and moves across top of colder air
- leading edge of advancing cold air called upper cold front 203.1.5 |
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Describe an upper warm front
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- advancing warm air rides up over pool or layer of trapped cold air
- air mass change does not occur on the ground 203.1.5 |
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Describe the effect of frontal passage on temperature
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Cold front:
- warm before - sudden drop during - steadily dropping after Warm front: - cool/cold, slow warming before - steady rise during - warmer than steady after 203.2.1 |
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Describe the effect of frontal passage on humidity/dew point
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Cold front:
- high, remains steady before - sharp drop during - lowering after Warm front: - steady rise before - steady during - rise than steady after 203.2.1 |
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Describe the effect of frontal passage on clouds and weather
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Cold front:
- increasing before, with CI, CS, CB, short periods of showers - CB, heavy rains, ocnl hail, thunder, lightning during - CU, showers then clearing after Warm front: - in order CI, CS, AS, NS, ST/fog, ocnl CB, lgt to mdt RA, SN, sleet, DZ, FZRA before - stratiform, DZ or no precip during - clearing with SC ocnl CB, no precip or ocnl RA/SHRA after 203.2.1 |
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Describe the effect of frontal passage on stability
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Cold front:
- stable before - unstable during - unstable after Warm front: - stable before - stable during - unstable after 203.2.1 |
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Describe the effect of frontal passage on pressure
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Cold front:
- falling steadily before - minimum then sharp rise during - rising steadily after Warm front: - usually falling before - levelling off during - slight rise followed by fall after 203.2.1 |
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Describe the effect of frontal passage on wind
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Cold front:
- south-southwest before - gusty, shifting during - west-northwest after Warm front: - south-southeast before - variable during - south-southwest after 203.2.1 |
