33 terms

Air Mass + Fronts Quiz

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what is an air mass?
a very large section of the troposphere that has almost the same temperature and humidity throughout
when do air masses form?
when a body of air remains stationary over a large area of land or water for any length of time.
what happens when air mass remains stationary?
it tends to take on the temperature and humidity characteristics of the area.
air masses that form in the tropics are called
tropical (T). have temps higher than normal for north united states and canada
air masses that form in the polar regions are called
polar (P). originate in high latitudes and have temps colder than normal
air masses that form over land is called
a continental air mass (c).
air masses that form over water is called
a maritime air mass (m). moist air
continental air masses are
comparatively dry
maritime air masses are
wet and humid
when air masses begin to move
they carry their weather characteristics with them
warm and cold air masses
like oil and water do not mix very well
when cold and warm air masses meet
they form and invisible boundary between them.
fronts
the boundaries between cold and warm air masses. almost always precip
a change in weather
warm front
when the warm air mass is behind the cold air mass.
1. advancing warm air replaces retreating cold air
2. 1,000 miles - gentle slope
3. air moves horizontal - status
the lighter warm air rides over
the denser cooler air and the cold air "retreats" as its place is taken by the warm air
a warm front approaches
gradually, announcing its arrival with a widespread over of clouds.
before a warm front arrives
a steady rain usually begins to fall. The rain may continue to fall for one or two days after the front passes.
when a cold air mass is is moving behind a warm air mass
it is like a wedge pushing under the warm air, forcing it upward.
cold front
the boundary between the cold and warm air.
1. advancing cold air pushes warm air up
2. steep slope 200-300 miles
3. cold front moves faster than warm front
4. warm air - vertical - cumulus
cold fronts frequently bring
bad weather: heavy rains and gusty winds, sometimes accompanied by thunder and lightning.
as a cold front passes
there is a sudden drop in temperature.
what clouds usually accompany a cold front?
cumulus
stationary front
occasionally a front between air masses stop moving
1. 2 unlike air masses face each other
2. little or no air move
3. similar to warm front weather - warm air rises
4. one air mass begins to move cold front or warm front
cold fronts usually move
more rapidly than warm fronts
occluded front
when a cold front overtakes another slower-moving cold front it forces the warm air mass between them completely off the ground
1. cold front overtakes warm fronts
2. warm air lifted off ground by cold air on both sides
3. warm air cools - large cold air mass
4. occluded front weather:
4a) warm front
4b) cold front
fronts generally move from
west to east and are usually accompanied by rain or snow
how do air masses acquire their original characteristics?
remain stationary for 2 to 3 days
what are the original characteristics of an air mass?
temperature and humidity
air masses are usually extensive and may take a number of days to pass a given locality. during this time the weather determined by the original characteristics of the air mass.
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prevail southwest blow air mass w to east across the u.s
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a line along which warm air has been lifted off the ground by opposing wedges of cold air on both sides
occluded
a boundary between warm air and a mass of retreating cooler air over which the warmer air is forced as it advances
warm
a boundary between cod air and a mass of warmer air under which the colder air pushes as a wedge
cold