Download Lesson 12

lesson12.notebook
March 31, 2014
Review:
­ layers of the atmosphere
­ major properties of each layer
­ atmospheric gases
­ relationship between altitude, pressure, and temperature
Apr 1­2:41 PM
Weather System
­ the total of all the conditions of temperature, humidity, atmospheric pressure, wind speed, and direction for a relatively large geographic area that moves over the region for a period of several days
­ weather systems can include both low and high pressure systems
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lesson12.notebook
March 31, 2014
(a) Low Pressure (cyclonic) System (pages 547­548)
­ generally associated with cloudy conditions
­ cold air and warm air mass meet but do not mix
­ a boundary forms between them called a front
­ the cold air sinks below the warm air but as the cold air warms it rises which creates a low near the ground
­ this low pulls in more air from the surface which begins to swirl counter clockwise creating winds
­ the warm front rising over the cold also carries moisture and as the cold front passes under it pushes up this moisture and creates precipitation ahead of the warm front
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­ clouds are also formed as the cold front pushes up the warm air
­ eventually the cold front catches the warm front and the low begins to weaken and the precipitation is reduced
* see figure 2 on page 547
Apr 1­2:50 PM
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lesson12.notebook
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(b) High Pressure (Anti­cyclonic) System
­ this system rotates clockwise and tends to bring clear skies
­ caused by colder, denser air moving downward towards earth creating a high as it falls
­ this tends to create a large area of similar pressure ­ because the pressure does not vary much a high tends to bring calm weather
Apr 1­2:53 PM
Fronts:
A front refers to the leading edge of an air mass
(a) Cold Front
­ the leading edge of a cold air mass
­ starts in the polar regions and tends to move to the tropics
(b) Warm Front
­ leading edge of a warm air mass
­ starts in the tropics and tends to move to the poles
Apr 1­3:01 PM
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(c) Occluded Front
­ occurs when a warm front and a cold front meet
­ caused when a cold front catches up to a warm front and cuts off the flow of warm air
­ results in a storm weakening
(d) Stationary Front
­ when a warm front and a cold front meet but remain stationary for hours if not days
Apr 1­3:03 PM
Severe Weather Systems
­ include: hurricanes, typhoons, tropical cyclones, tornados, ice storms, droughts, floods, hail storms, blizzards, extreme heat, extreme cold
See page 580, figure 1
Apr 1­3:07 PM
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Apr 1­3:18 PM
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Readings:
Pages 546 ­ 549
Pages 578 ­ 581
* Go over handout on Air Masses and Technology
Jeopardy Review Game
jeopardy1257776853
Apr 1­3:22 PM
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