3Atmospheric Pressure – Do you feel pressure? POPAtmospheric pressure is the forceexerted on you by the weight of theatmosphere.Gravity holds the gasses andpulls them down to earth.You feel the weight.Atmospheric pressure decreasesas altitude increases.99% of the atmosphere is foundin the first 32 km.15 lb/in2(psi)mb(metric unit)
4Measuring Atmospheric Pressure A barometer measures the rise and fall ofatmospheric pressure.Mercurial BarometerAtmospheric pressureforces mercury upwardsinto the graduated glasstube.Aneroid BarometerExpansion or contraction of thevacuum chamber, caused by achange in pressure, forces thepointer to move.
5I to breathe our atmosphere. Discuss with a friend: I>Cto breathe our atmosphere.Discuss with a friend:Define atmospheric pressure and twoways atmospheric pressure is measured.2. How is atmospheric pressure held on theearth?3. Describe what happens to atmosphericpressure as one ascends through theatmosphere.I will get an A on my exams and quizzes.
6Wind - Why does air move? Unbalanced air pressures are caused by unequal heating in theatmosphere.High pressure moves to low pressure.High PressureLow Pressure
7a change of atmospheric pressure measured along a line at right Pressure Gradienta change of atmospheric pressuremeasured along a line at rightangles to the isobarsIsobarsPressure Gradientperpendicular to isobar linesIsobars:lines that connect equal points of pressure
8Local Winds and Convection Loops Daytime – sea breezeI will draw diagramson the white boardexplaining:specific heatproperties ofland and waterhow specific heatproperties relateto high and lowpressure systemsthe creation ofconvection loopsduring the day andnightconvection loopNighttime – land breezeconvection loop
9I to breathe our atmosphere. Discuss with a friend: I>Cto breathe our atmosphere.Discuss with a friend:4. What is wind? How is it formed?5. Define isobars and how pressure istypically measured (atmospheric units).6. Describe specific heat properties of landand water and how these propertiesrelate to offshore and onshore breezes.I will get an A on my exams and quizzes.
10Deflected Cyclones, Anticyclones, The Coriolis Effect You are a passenger riding in a car that is missingthe passenger side door, and you forgot to put yourseatbelt on. The driver is traveling 85 mi/hr andsuddenly turns the car to the left to make it arounda sharp curve. What do you think is going tohappen?The earth is rotating counter-clockwise approximately1000 mi/hr (at the equator) without a “passenger-sidedoor.” What is your prediction about the movementof atmospheric gasses and clouds as the earthrotates?Deflected
11The Coriolis Effect Animation Global winds, ocean currents, airplanes are deflecteddue to the earth’s rotation.Deflection occurs whether the object is moving north,south, east, or west.counter-clockwiseearth rotationITCZclockwiseearth rotation
12Can you locate the intertropical convergence zone (ITCZ)? Where are the winds deflected to the right and left?Doldrums
13High Pressure Low Pressure Wind Convection Currents What causes high and low pressure zones?High PressureCold sinking airLow PressureWarm rising air
15Low Pressure (cyclones) air rises (inward and outward) adiabatic processes causeexpansion of airair cools, condenses, typicallyforming cloudsassociated with cloudy,rainy weather“Good Weather”“Bad Weather”High Pressure (anticyclone)air subsides (downward andoutward)adiabatic processes causecompression of airair warms – no condensationassociated with fair weather
16I to breathe our atmosphere. Discuss with a friend: I>Cto breathe our atmosphere.Discuss with a friend:7. What is the Coriolis Effect?8. How does the Coriolis Effect influencethe movement of winds in the N.H. and S.H.?9. Define and explain how cyclones andanticyclones form.I will get an A on my exams and quizzes.
17Wind Convection Currents – Where is air sinking and rising within the earth’s atmosphere?Global Wind PatternsCold air sinks (HP)Warm air rises (LP)Where is the sun’s radiation most intense?On the equatorWhere is the sun’s radiation the least intense?In the polar areasAngle of insolation, seasonal changes, andthe earth’s albedo cause a differencein the amount of solar radiation the earth receives.
18Earth Wind Pattern Wind Convection Currents convection high pressure This is known as a global___________ wind current.convectionhigh pressurecold air sinksEarth Wind Patternlow pressurehot air rises
19C B A A - Hadley cell lies between equator and 30o latitude Coriolis Effect breaks the convectiveflow of air into convective belts.CA - Hadley celllies between equator and 30o latitudedeflected from the northeast to thesouthwestBAB- Farrel cellless well-defined set of convectivecells between 30o-600air flows toward the north and isdeflected to the rightIntertropicalconvergence zoneC- Polar cellcold frigid air flowing from the polestoward the equator (air rises at the600 parallel)air that moves away from the pole isdeflected to the right
20Draw the northern hemisphere convective cells deflected due to the Coriolis Effect.PolarCellFarrelCellHadleyCell
21Geotrophic Winds (GW) – winds in the upper atmosphere winds originating high in the atmosphere thatmove parallel to a system of parallel isobarsPressure gradient forces wind tomove from high pressure to lowpressure.Coriolis Effect “pulls” or deflectswind to the right (N.H.).Pressure gradient and CoriolisEffect reach equilibrium (balance),and winds follow parallel isobars.GW forms streams of air thatcircumvent the earth.
22Rossby Waves – winds in the upper atmosphere undulated meanders of waves that circumvent the eartharise in zones of cold polar air converging with warm tropicalairresponsible for variable mid-latitude weather patterns wherepools of moist and dry air masses invade mid-latitudeLLHHL
23The Jet Stream – winds in the upper atmosphere narrow zones of high wind speedsoccur in strong atmospheric pressure gradientspolar-front jet (polar jet)generally located between 35o and 65o latitudesfound at altitudes of km (30,000-40,000 ft)typically follows the edges of Rossby wavesmarks the boundary between cold polar andwarm subtropical airwind speeds range from m/s ( mi/hr)JetStreamgreatervelocitydecreasedvelocity
24I to breathe our atmosphere. Discuss with a friend: 10. Explain how convection cells form withinthe earth’s troposphere.11. What are the three major convection cellsfound in the N.H.?12. Identify at least 3 characteristics thatdefine geotrophic, Rossby, and jet streamupper atmosphere winds.I will get an A on my exams and quizzes.