Presentation ~ above theme: "Air Masses and Fronts. Waiting Masses An air mass is an immense body of waiting (1600 km/1000 mi or much more across and several km/2 mi thick) the is characterized."— Presentation transcript:




You are watching: An immense body of air characterized by similar properties

1 waiting Masses and also Fronts

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2 air Masses An air mass is an enormous body of air (1600 km/1000 mi or more across and also several km/2 mi thick) that is defined by comparable temperatures and amounts of humidity at any given altitude.

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3 motion of air Masses due to the fact that of the size, it may take numerous days for an wait mass to move over an area, so the area experiences fairly continuous weather throughout its passage. Remember critical week’s really cool weather? us were in a big cold air mass.

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4 once an wait mass moves the end of the region over which it is formed, it carries its temperature and also moisture conditions with it. As it moves, the characteristics adjust and for this reason does the weather it causes. Just how much warmer was the wait mass when it reached Tampico, Mexico, than when it formed?

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5 Classifying waiting Masses The area over which an waiting mass it s okay its characteristic properties of temperature and also moisture is referred to as its resource region. Polar (P) wait masses type at high latitudes tropic (T) wait masses kind at short latitudes

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6 Moisture classification In addition to their in its entirety temperature, wait masses room classified follow to the surface ar over i beg your pardon they kind and explain the wait mass’ moisture characteristics: continental (c) wait masses type over land and are most likely to be dry naval (m) wait masses type over water and are humid or moist.

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7 Four an easy Types of wait Masses using this classifi- cation, there space 4 an easy types of air masses: (embedded movie)

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8 continental Polar (cP) SOURCES: Canada, Alaska, north US room uniformly cold and dry in winter and also cool and also dry in summer in addition to maritime tropical wait masses, responsible for lot of the weather in phibìc America. Can bring heavy snow to the leeward shores the the good Lakes (downwind native the Lakes)

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10 marine Polar (mP) SOURCES: north Pacific, north Atlantic Cool, humid, unstable maritime air regularly starts together cP air end Siberia but becomes an ext humid and warmer in its long journey over the Pacific s mP air masses in the Atlantic affect weather in the northeastern says when brand-new England is north or northwest the a passing low press center, resulting in winter storms dubbed nor’easters

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11 continental Tropical (cT) SOURCES: Mexico, southwestern united state Hot, dry air masses the usually execute not influence weather outside of your source region (have the least affect on united state weather) In the summer, can reason extremely HOT and also dry conditions in the an excellent Plains region In the fall, when relocating north toward the an excellent Lakes region, reasons warm and mild problems called “Indian summer”

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12 maritime Tropical (mT) SOURCE: Gulf that Mexico, Pacific turn off Mexico warm to hot, an extremely moist, usually unstable in addition to cP waiting masses, pat a dominant role in north American weather Responsible for many of the precipitation that drops in the east two-thirds of the us (east of the Rocky Mountains) In summer, can carry high temperatures and oppressive humidity

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13 Weather Fronts

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14 wait Mass review We learned that air masses are big (1600 km by several kilometres deep) preserve the temperature and moisture qualities of their source regions labeling by their source region So, what happens once air masses meet?

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15 What is a front? A boundary the separates two air masses very narrow—between 15 and also 200 km vast Warmer wait overlies cooler, denser waiting Both air masses have the right to move in ~ the exact same speed and also direction, yet most often, one moves quicker than the other, advancing into the slower mass with some mix of waiting

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16 varieties of fronts share by the temperature the the advancing air mass four kinds:  heat  Cold  Stationary  Occluded

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17 Cold former Cold, thick air moves right into an area populated by warmth air twice as steep as warm front, moves much faster If the warmth air is unstable, violent weather occurs with cumulonimbus clouds, hefty downpours and also gusty winds Behind the front, cumulus or stratocumulus clouds kind where the cold, stable air mass dominates.

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18 heat air moves right into an area formerly covered by cooler waiting Gradual, low slope Cloud sequence: cirrus, cirrostratus, altostratus, ultimately stratus and nimbostratus about 300 km ahead of prior Moves progressively Light-to-moderate precipitation over an extended duration Winds transition from eastern to SOUTHWEST heat Front

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19 Stationary Front occasionally there is a standoff, and neither wait mass move The resulting surface front doesn’t move deserve to have gentle to middle precipitation

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20 Occluded prior An active cold front overtakes a heat front, forcing the warmth air increase so that it is over the surface

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21 Mid-Latitude Cyclones apply your brand-new under- standing of fronts come weather patterns in the contiguous us The main weather producers space mid-latitude cyclones or low press systems that travel from west come east and cause stormy weather this storms usually have a cold front and also a heat front connected with them

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22 The mid-latitude cyclone starts through a frontal boundary, v wind moving in opposite directions. End time, a ‘kink’ or ‘wave’ develops, and also warm air move poleward and also cold air move equatorward. This establishes into a counterclockwise rotation with falling press at the ‘kink.’ as the cold air overtakes the heat air, one occlusion begins, strengthening the storm. Pressure at the facility of the storm proceeds to drop and wind speeds increase.

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23 throughout the winter, this phase of the storm can carry heavy snowfalls and also blizzard-like conditions. During the summer, this phase of the storm can bring severe thunderstorms and also tornadoes.

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24 air flow Aloft Maintains Cyclones Cyclones regularly exist because that a main or longer. Remember the lows are locations of surface ar convergence, so for them to stay as storms this long, there need to be divergence aloft the maintains the surface ar storm. Most of the time air aloft is what fuels a mid-latitude cyclone.

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25 Lastly, wherein does the diverging wait aloft go? wherein does the inflowing surface air come from? an alert that cyclones (lows) and also anticyclones (highs) happen together.

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Prefer cyclones, anticyclones depend on air aloft to preserve their circulation.

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26 Reviewing ideas Answer these concerns on a sheet of paper: 1.What happens once two waiting masses meet? 2.Describe a warm front (clouds, precip., timing, symbol on weather map) 3.What space the attributes of a cold front? 4.What are the step in the development of one occluded front? 5.What is a mid-latitude cyclone? 6.What sustains a mid-latitude cyclone?

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