Try some air pressure experiments!

Teaching Earth and Atmospheric Sciencewith the Kids’ Crossing Web Site

A Guide for Educators

National Center for Atmospheric ResearchBoulder, Colorado

www.eo.ucar.edu/kidswww.eo.ucar.edu/kids/air2.htm

Classroomin the

Classroomin the National Center for Atmospheric Research

Boulder, Colorado

www.eo.ucar.edu/kids

Introduction

It is our hope that Kids’ Crossing conveys atmospheric and Earth science content and activities in a way that is useful for upper elementary and middle school audiences. The purpose of this guide is to facilitate their use within and beyond the classroom.

About Us

The Kids’ Crossing Web site was produced by the UCAR Office of Education and Outreach to ex-plain the science of the National Center for Atmospheric Research (NCAR).

NCAR’s parent organization, University Corporation for Atmospheric Research (UCAR), is a non-profit organization dedicated to basic research in the atmospheric and Earth sciences. UCAR is a group of 75 universities throughout North America that each grant doctoral degrees in the atmo-spheric and related sciences, plus an increasing number of academic and international affiliates and corporate partners.

NCAR is a research organization, established in Boulder, Colorado in 1960, to better understand our atmosphere and how weather and climate affect the Earth. Over 300 Ph.D. researchers and visiting scientists conduct interdisciplinary studies with state of the art technology. They have dis-covered much about the Earth system including how the Sun influences the Earth, how past and future climate can change, and how we can better forecast the weather. NCAR researchers also study how weather and climate affect people and environments around the globe. NCAR is oper-ated by UCAR under a cooperative agreement with the National Science Foundation (NSF), our primary sponsor.

Development of the Kids’ Crossing Web site and this Educators’ Guide was funded by NCAR’s Education and Outreach Strategic Initiative.

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Classroomin the National Center for Atmospheric Research

Boulder, Colorado

www.eo.ucar.edu/kids

Using the Kids’ Crossing Web Site with StudentsNavigating the Sitehttp://www.eo.ucar.edu/kids

Kids’ Crossing covers a range of Earth and atmospheric science content including the following major topics:

Science Content Kids’ Crossing SectionThe Water Cycle Water, Water EverywhereWeather Look Out for Dangerous WeatherWeather Safety/Decision-Making Skills Look Out for Dangerous WeatherClimate and Global Change Living in the GreenhouseCycles of the Earth System Living in the GreenhouseAtmosphere Stuff in the SkyCareers in Science (coming soon!) Making Science Happen

Additionally, Kids’ Crossing contains:Links to UCAR/NCAR educational resources and other recommended online resourcesAn Earth Gallery providing links to useful Earth science imagesActivities written for students to try on their own

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After a section of the site is ac-cessed from the main page (www.eo.ucar.edu/kids), navigate through the section using the graphic navi-gation bar at the top of the page. The example at the right shows the Groundwater content from the Water, Water Everywhere section. Links to individual groundwater pages are in the blue bar below the graphic.

Use the bar (shown at left) at the bottom of each Kids’ Crossing page to navigate to other Kids’ Crossing sections.

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Students observe that air takes up space and that the absence of air can result in crushing behavior. NOTE: This activity requires adult assistance and supervision.

Related Web Pages for Students •http://eo.ucar.edu/kids/sky/index.htm •http://eo.ucar.edu/webweather/basic.html •http://www.ucar.edu/learn

Directions 1.Haveobserversstandorsitapproximatelyfivefeetfromthedemonstration.2.Fillanempty12-ouncesodacanwithapproximatelyoneortwotablespoonsofwater.3.Placethesodacandirectlyonahotplateorelectricburner,andwaitforthewaterinsidethecantobegintoboilandevaporate.4.Next,haveanadultquicklybutsafelyliftthesodacanofftheburnerwithasturdypairoftongs.(Besuretowearsafetyglasses.)Immediatelyimmersethesodacanupsidedownintoalargebowloficewater.5.Whathappenstothesodacan?Why?

Ask yourself the following questions:1.Whathappenstotheairinsidethesodacanwhenitisheated?2.Whathappenstothewaterinsidethecanduringtheactivity?3.Howdoesthecontentsinsidethecanchangeduringtheactivity?4.Whydidthecanimplode?Whathappenstowatervaporwhenitiscooled?Whattooktheplaceofthewatervaporinthecanafteritcondensedbackintoaliquid?5.Howmuchforcewasexerttocrushthecan?Forcefromwhat?

Background InformationAlthoughairisinvisible,itstilltakesupspaceandhasweight.Inthisexperiment,whentheairinthesodacanisheated,theairinsidethecanwillriseandsomewillescape.Whenthewaterinthecanisheated,itbeginstoevaporatebecomingwatervapor,agas.Itfillsmuchofthenewlycreatedspaceleftbytheescapingair.Whenthecanisplacedinthetuboficewater,thewatervaporinstantlycon-densesbackintoliquidwater.

Whattakestheplaceofthewatervaporandsteam?Nothing!Forabriefsecond,thecanisfilledwithonlyalittlewaterandair,andalotofemptyspace!14.7poundsofairpressurepersquareinchonaverageatsealevel(1kgpersquarecm)ispressingontheoutsideofthecan,butverylittleairispushingbackinalldirectionsfromtheinside.Conse-quently,thecaniscrushedinaninstantbythegreaterairpressurepushingonitfromtheoutside.That’sNOTyourusualpop!

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Student Learning Objectives• Studentslearnthatairtakesupspaceandexertspressure

Time•10minutes,activity;•10minutes,discussion

MaterialsPeradultdemonstrator:•One12-oncesodacan•Water•Onebowloficewaterapproximately6”deeporgreater•Onepairoftongs•Onehotplateorelectricburner

Terms to Know and Use•AirPressure•Condensation•Density•Evaporation•Implode•Vacuum•WaterVapor

National Standards•A:ScienceasInquiry•D:EarthScience

Not Your Usual Pop!

Students observe that air exerts pressure.

Related Web Pages for Students •http://eo.ucar.edu/kids/sky/index.htm •http://eo.ucar.edu/webweather/ •http://www.ucar.edu/learn

Directions 1.Puttheplungerstogether,withconcavesidesfacingoneanother.2.Noticethattheytouchbutdonotholdtogether.3.Puttheplungersfirmlytogether,withconcavesidesfacingoneanotheragain,putthistimepushtheairoutthatisheldandsharedbetweenthem.Noticewhathappens.4.Holdtheplungersbytheiroutsideendsandtrytopullthemapart.Donottwistorpeelthem,justpull.Areyouabletopullthemapart?

Ask yourself the following questions:1.Issuctionaforce?Ifnot,whatcausesit?2.Howmuchweightisexertedontheplungersfromairpressure?Howwouldyougoaboutdeterminingthisquantity?

Background InformationAlthoughairisinvisible,itstilltakesupspaceandhasweight.Infact,itmaysurpriseyoutoknowthatairweighs14.7poundspercolumninchatsealevel,orputanotherway,over2,100poundspercolumncubicfoot!Wow!Thereasonwedon’tfeelitsweightisbecauseair,likeallfluids,doesn’tjustpushdown.Instead,itpushesinalldirections.Waterhasweighttoo,butyouaren’tcrushedwhenyouswimtothebot-tomofadeeppoolbecausewater,likeair,alsopushesinalldirections.Butjusttrytoliftallthatwateryou’reswimmingunder.Itweightsover62poundspercubicfoot!

In1654,OttovonGuerickperformedademonstrationsimilartothisactivitywiththeplungers.Heusedtwometalhemispheresthatwere22inchesindiameterandplacedthemtogetherintheshapeofasinglesphere.Hehadinventedtheworld’sfirstvacuumpumpshortlybefore1654,whichpumpedairoutofhissphereinsteadofintoit.Whenhedidso,thetwohemispheresheldtogethertightly.NohumancouldpullOtto’ssphereapart,soinfrontofEmperorFerdinandIIIofPrussianSaxony(nowGermany)andmanyothers,heattachedtwoeight-horseteamstoeachendofhissphere.Despiteagreateffort,thehorsescouldnotpullhissphereapart.Afterall,theyweretryingtopullapartnearly3tons!

Whenairisinsidethesphere,itexertsthesameamountofforceastheairontheoutsideofthesphere.Whenyouremovetheairinsideofthesphere,however,theairontheoutsidepressesthetwohalvesofthespheretogether.Ifyoupeeltheplungersapartslightlyandletairbackinside,thesphere’stwosideswillnolongersticktogether!Theforceontheinsideandoutsidewillonceagainbethesame.4.

Student Learning Objectives•Studentslearnthatairexertspressureat14.7poundspercolumninchatsealevelonaverage(1kgpersq.cm.)•Studentslearnthatavacuumisanareaofemptyspace.

Time10minutes,activity;•10minutes,discussion

MaterialsForeachpairofstudents:•Onesetofsuctioncupsorplungers,anysize.Woodenhandlesarebesttoremove.


PlungerPull

Otto von Guerick’s sphere isknown around the world as the Madgeburg Sphere because it was built in Guerick’s home-town of Madgeburg in what today is Germany.

Students observe that air takes up space. It’s only when air in the bottle escapes, that more air is easily added.

Related Web Pages for Students •http://eo.ucar.edu/kids/sky/index.htm •http://eo.ucar.edu/webweather/basic.html •http://www.ucar.edu/learn

Directions 1.Pushaballooninsideaplasticbottleandstretchtheballoonopening.overthebottle’stop.2.Attempttoblowuptheballooninsidethebottle.Whathappens?3.Next,placeanewballoonintotheplasticbottlewitha1”diameterholeinitssidethathasbeenpluggedwithastopper.Stretchtheballoonopeningoverthelipofthebottlelikebefore.4.Withthestopperpluggingthehole,canyoublowuptheballoon?5.Unplugthestopperintheplasticbottleandattempttoblowuptheballoonyetagain.Whathappens?Why?6.Withtheballooninflatedinsidethebottle,plugthebottle’sholewiththestopper.Whathappenstotheairinsidetheballoonthistime?7.Filltheinflatedballoonwithwaterwhileitisinsidethebottle.Stepoutsideorplacethebottleoversomethingthatcancatchliquid.Nowunplugthestopperandwatchthewaterworks. Ask yourself the following questions:1.Whathappenstotheballooninsidethebottlewhenyoutrytoinflateitwiththeholepluggedandunplugged?Whatmakesthedifference?2.Aftertheballoonisinflatedandtheholeinthebottleplugged,whatpreventstheairfromescapingfrominsidetheballoon?3.Whenwaterisplacedintheinflatedballooninsidethebottle,whatcausesittogushoutwhenthebottle’sunplugged?

Background InformationAlthoughairisinvisible,itstilltakesupspaceandhasweight.Thisisevidentwhentheballoonisplacedinsidethebottleandyoutrytoinflateit.It’snearlyimpossibletoaddanyamountofair!Whenthebottlewiththeholeisused,however,inflatingtheballoonisnearlyeffortless.Theairinsidethebottleisabletoescape,freeingupspacefortheballoontonowinflate.Ifyouthenplugtheholeontheoutsideofthebottle,thebal-loonwillremaininflated.Howdoesthishappen?Whatkeepsthisairinplace?Thisisaconsequenceoftheairpressurebeingloweredinsidethebottlewhenitsholeisplugged.Thehighpressureairinsidetheballoonispulledtowardthelowpressureareainsidethebottle.Whenyouaddwaterinsidetheballoonthenunplugthebottle,watchout!Unpluggingthebottlewillreleaselowpressure’sholdonthehigherpressureairinsidetheballoonandallowoutsideairtoenterthebottleonceagain.Notonlywilltheballooncollapse,thewaterinsideofitwillbepropelledbytheforceoftheair. 5.

Student Learning Objectives• Studentslearnthatairtakesupspaceandexertspressure

Time•10minutes,activity;10minutes,discussion

MaterialsPerstudent:•1-literplasticbottle•Another1-literplasticbottlewitha1”diameterholepluggedwithastopper•2balloonsperperson•1cupwaterperstudent

Terms to Know and Use•HighPressure•LowPressure•Inflate


Balloon in a Bottle

Students observe how air temperature is altered by changesin air pressure, and study conditions needed for clouds to form.


Directions 1.Turnthebottlesothetemperaturestrip(hangingfromtheFizzKeeperinsidethebottle)facesyouandiseasytoread.Handlethebottleaslittleaspossibletoavoidincreasingitstemperaturefromthewarmthofyourhands.2.Recordtheinitialtemperatureinthebottle.3.PumptheFizzKeeper20times.Recordthetemperature.4.PumptheFizzKeeper20moretimesforatotalof40pumps.Recordthetemperature.5.Repeatthissteptwicemoreuntilyouhavethetemperaturerecordedat60and80pumps.Donotexceed80pumpsbecauseyourbottlemightpop!6.UnscrewtheFizzKeeperandrecordthetemperatureofthebottle.7.Inthesamebottle,placeapproximately1-2inchesofwater.8.Next,lightamatch,blowitout,andpromptlydropthesmokingmatchintothebottle.9.QuicklyscrewtheFizzKeeperonthebottle.Repeatsteps1-5above.

Ask yourself the following questions:1.WhathappenedtotheairtemperatureinsidethebottlewhenyoupumpedtheFizzKeeper?2.WhathappenedtotheairtemperatureinthebottlewhenyouunscrewedtheFizzKeeperanddecompressedtheairinsidethebottle?3.Whenyouaddedthewaterandmatchtothebottleandrepeatedtheactivity,didacloudappear?Ifso,whydoyouthinkthishappened?

Background InformationAlthoughairisinvisible,itstilltakesupspaceandhasweight.Undernormalatmosphericconditions,thereisalotof“empty”spacebetweenairmolecules.Whenyoupumpedmoreairintothebottle,youcom-pressedmoreairintoafinitespaceandincreasedtheairpressureinthebottle.Whenairiscompressed,itwarms,whichinhibitscondensa-tion(andtheformationofacloudinthebottle).Whenairdecompress-es,itspressureisloweredanditcools.Thisencourageswatervaportocondense,formingacloudinthebottle.Threeelementsmustbepresentinorderforcloudstoform:moisture,coolingtemperature,andcondensationnuclei,whicharetinyparticlesintheairsuchasdust,dirt,andpollutants.Theyprovideasurfaceonwhichwatermoleculescancondenseandgatherintowaterdroplets.6..

Student Learning Objectives• Studentslearntherelationshipamongairpressure,temperature,andvolume.

•Studentslearnthatmoisture,coolingtemperature,andcondensationnucleiareneededforcloudstoform.


MaterialsForeachpairofstudents:•1clean,clear2Lplasticbeveragebottlewithcap•1FizzKeeper(availableinmostlargesupermarkets)•1temperaturestrip(attachedtoFizzKeeper)•Matchesorsprayairfreshener•Water


Cloud in a Bottle

The purpose of this experiment is to observe how moisture, cooling temperature, and condensation nuclei play a role in cloud formation.

Related Kids’ Crossing Web Pages for StudentsWater, Water Everywhere: Atmosphere http://www.ncar.ucar.edu/eo//kids/wwe/air1.htmStuff in the Sky http://www.eo.ucar.edu/kids/stuffsky/index.htm Student Version of Activity: NCAR’s Web Weather for Kids http://www.ucar.edu/educ_outreach/webweather/cloudact2.html

Directions

Discuss the composition of clouds. Brainstorm what is needed for clouds to form. Tell students that in this experiment they will ex-plore some of their ideas.Instruct students to pour the cold water into the jar, add food color-ing, and swirl for one minute to allow some water to evaporate.Stretch the open end of a rubber glove over the mouth of the jar with the glove fingers hanging down into the jar. Affix a rubber band to the mouth to secure the glove (or a partner can hold it in place). Turn on the lamp so it shines through the jar. After 2 minutes, instruct students to insert a hand into the glove and pull quickly outward without disturbing the jar’s seal.Instruct students to record what they observe inside the jar, push the glove back down into the jar, and record observations again.Tell students about particles in the atmosphere. Would more or fewer clouds form with particles in the jar? Develop hypothesis. Instruct students to remove the glove from the jar, while you drop a lit match into the jar. Students should quickly seal the jar with the rubber glove as before (containing the smoke particles within the jar) then repeat procedure to test the hypothesis made in Step 6.Discuss the process of evaporation. Does the temperature of the water make a difference? Develop hypothesis. Pass out hot tap water and have groups repeat the procedure using hot water to test the hypothesis developed in Step 8 above.Discussion: What helps a cloud form? (Cooling air, condensation nuclei, and evaporation)

Background InformationEvaporation: There must be water vapor in the air to build a cloud. Vapor is created as water evaporates either by heating under the lamp, swirling the water, or using hot water. Cooling air: As air temperature decreases, vapor condenses. When you pull the glove out of the jar, the air pressure lowers inside the jar. The jar contains the same number of air molecules, but they occupy more space and slow down, causing the air temperature to drop.Condensation nuclei: Tiny particles, such as dust, dirt, and pollutants, provide surfaces for water molecules to gather upon and condense into water droplets. The smoke provides tiny nuclei on which water con-denses when the air temperature cools. 7.

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Student Learning Objectives

Students experiment, observe, and articulate results.Students learn the conditions necessary for cloud formation.

Time30 minutes

MaterialsFor each group of 4:

Gallon jarCold water (100 ml)Hot water (100 ml)Rubber gloveFood color (optional)MatchesRuberbandLamp (gooseneck or similar style)Paper and pencil to record observationsInternet access or printed copies of the student directions (at URL above) for each student group

National StandardsA: Science as InquiryB: Physical ScienceD: Earth Science

SourceThis activity has been adapted from NCAR’s Web Weather for Kids.

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Resources for Educators from theNational Center for Atmospheric Research

www.eo.ucar.edu

Create a Portable Cloud!

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In this activity students learn how warm and cool fluids create convection currents.

Related Kids’ Crossing Web Pages for StudentsHow Do Thunderstorms Form? http://www.ncar.ucar.edu/eo//kids/dangerwx/tstorm4.htmStudent Version of Activity from Web Weather for Kids http://www.ucar.edu/educ_outreach/webweather/tornact2.html

Directions

Divide students into groups of four. Have groups read the article How Do Thunderstorms Form? and the Student Version of this activity (URLs listed above). Discuss the reading as a class including discussion of what thun-derstorms need to form and the role of convection. Explain that in this activity students will observe how convection works using water. Air masses move in the same ways.Provide each group with a plastic container 2/3 full of room temper-ature water. Instruct students not to move the container or the table so that the water becomes completely still.Provide each student group with a blue ice cube to put at one end of their container. (Alternatively, use a drop of blue coloring on ice.) Put two drops of red food coloring at the other end of each contain-er. (For dramatic effect, heat the red coloring bottle in warm water.)Have students observe the long sides of the container to see where the blue and red food coloring travel. Ask each student to draw a picture that describes his/her observations and hang it on the wall. Ask students to look at the pictures of other groups. Class discussion: Did similar things happen to the food coloring for each group? (Hopefully, yes.) What happened to the blue? (It sunk.) And the red? (It stayed above the blue.) What was the difference between the blue and red water? (Temperature) That’s convection! How is convection needed to form a thunderstorm?

Background InformationConvection is the transfer of heat by the movement or flow of a sub-stance from one position to another. A thunderstorm is caused when a body of warm air is forced to rise by an approaching cold front. This rising air is called an updraft. The warm air is typically moist and when it rises, meeting cold air above, the water in it condenses, becoming a cumulus cloud. The condensation releases latent heat which helps fuel the thunderstorm.

ExtensionsRead and discuss: A Close Encounter with Lightning (http://www.eo.ucar.edu/kids/dangerwx/tstorm9.htm) and Thunderstorm Safety (http://www.eo.ucar.edu/kids/dangerwx/tstorm7.htm).

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Student Learning Objectives

Students experiment, records observations, and draw conclusions.Students learn how convection currents form and apply this knowledge to understand how thunderstorms form.

Time30 minutes

MaterialsA clear plastic shoebox-sized container for each groupRed food coloringIce cubes made with blue food coloring and water Colored pencils (red and blue)Index cards or paperInternet access or printed copies of the student version (URL above)

National StandardsA: Science as InquiryD: Earth Science

SourceThis activity is from Web Weather for Kids, another great educational project of NCAR/UCAR!

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Resources for Educators from theNational Center for Atmospheric Research

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Make Convection Currents!

Students observe that wind is the result of horizontal differences in air pres-sure, and that air flows from areas of higher pressure to lower areas of pres-sure.


Directions 1.Holdthebottleapproximatelyahand’sdistancefromyourmouthwiththebottleflatonitssideandtheopeningpointingdirectlyatyourmouth.2.Placethesmallroundpaperwadontheedgeoftheinsidelipofthebottleopening.3.Standasstillaspossibleandblowintothebottle.(Donotmoveyourheadorthebottleduringthisprocess.)4.Observewhathappenstothepaperwad.

Note:Your objective is NOT to get the paper into the bottle, but to observe what happens naturally in the process of this investigation to the paper.

Ask yourself the following questions: • Whydoesn’tthepapergointothebottle?•IfIblowsoftly,willthepapergointhen,andifnot,whynot?•Whereistheairpressurehighest?Whereisitlowest?•Whatwouldhappeniftherewasaholeattheoppositeendofthebottle?

Background InformationAlthoughairisinvisible,itstilltakesupspaceandhasweight.Undernormalatmosphericconditions,thereisalotof“empty”spacebetweenairmolecules.Underhighpressureconditions,theairismoredense,andwhenlowpressureconditionsexist,theairislessdense.Whenairmovesatgreatspeeds,thisalsomakestheairlessdenseandresultsinlowerairpressure.Agoodanal-ogyarecarsonafreeway.Thefasterthecarsgo,themorespacethatexistsbetweenthem.Butwhentheirspeedsslow,theycrowdtogether.

Whenyoublowintoabottle,airiscompressedintoafinitespaceandtheairpressureinthebottleincreases.Thinkaboutaballoon.Whenyoublowitup,youtrapairinsideofitaswell.Ifyouletgooftheballoonbeforetyingit,theairrapidlyexistsit.Thisisbecauseairmovesfromareasofhighpressuretowardareasoflowpressure.Thegreaterthedifferenceinthepressure,thefastertheairwillmove.Theairblownintoabottleisalotlikeairblownintoaballoon.Ifit’snottrapped,itwillrushoutofthebottletowardlowerpressure.Consequently,thepaperispushedoutofthebottleinsteadofintoit.

Inthelargeratmosphere,airmovestowardlowpressurebutit’smotionisinfluencedalsobythespinoftheEarth.ThisiscalledtheCoriolisEffectandcausesairtomovecounterclockwisearoundlowpressureintheNorthernHemisphereandclockwiseintheSouthernHemisphere.Consequently,hur-ricanes,whichareareasofextremelowpressure,travelinthesedirectionsinbothHemispheresalso.

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Student Learning Objectives•Studentslearnthatairmovestowardlowpressure.•Studentslearntherelationshipbetweenairpressureandwind.

Time5minutes•

MaterialsForeachpairofstudents:•1clean,clear12ounceplasticbeveragebottlewithcapoff•Onepaperwadapproximately1cmindiameter


AirontheGo:WatchItBlow

Air Pressure Records

United States:Highest:31.85”inNorthway,AlaskainJanuary1989Lowest:26.05”overtheGulfofMexicoduringHurricaneWilma,Oct.2005;Tornadiclow:25.10”onJune24,2003duringanF4tornadoinManchester,SouthDakato.

Global:Highest:32.06”inTonsontsengal,MongoliaonDec.19,2001Lowest:25.69”(870mb)duringaTypoonTiponOct.12,1979inthePhilippineSeainthesouthwesternPacificOcean.

Students observe how a single breath of air can fill a large trash bag due to the Bernoulli Effect.


Directions1.Havestudentsguesshowmanybreathsittakestoblowupalargeplastictrashbag.Determinetheamountbyhavingastudentblowintothebagusingthetraditionalmethodofofblowingintoasmallopeningatthebag’sopenedend.Basedonthesample,havethestudentsapproximatehowmanymorebreathswouldbeneededtofillthebagentirely.2.Askthestudentsiftheythinkitmightbepossibleforsomeonetoblowthebagupusingjustonebreath.3.Havestudentsdemonstratethatitisindeedpossiblebyhavingeachofthemholdthetrashbagopenapproximatelyata1to3-footdistancefromhis/hermouth.4.Usingonlyonebreath,askthestudentstoblowashardastheycantofillitup,thenquicklysqueezethebag’sendclosedwiththeirhands.5.Youcanalsohavetwogroupsracetofillabag,oneusingthetraditionalapproach,andoneblowingintoalargeopeningofthebagfromapproximatelyatwo-tothree-footdistance.Thisapproachcanprovidehumorifthegroupusingthetraditionalmethodisunawareoftheotherteam’stactic.

Ask yourself the following questions:1.Howcanasinglebreathofairfillthebag?2.Willitworkwithasmallerorlargerbag?(UsetheWindbag™tofindout.)3.Willitworkwithasmalland/orslowbreathofairalso?

Background InformationIntheearly1700s,aSwissmathematicianandscientistbythenameofDanielBernoullidiscoveredthatthefasterairtravels,thelowerthepressureitexerts.

Inourexample,thestreamofmovingaircreatesanareaoflowerpres-sure,whichattractshighpressureairadjacenttothestreamofairfromyourlungs.Asaresult,itisnotjustasinglebreathofairthatfillsthetrashbag,butratherairfromthesurroundingareaalso.

Ouratmosphereisalwaystryingtomaintainsteadyairpressure.Asaconsequence,anareaofhighpressurewillmovetowardanareaoflowairpressureinanattempttorestorebalance.PressurewillneverbesteadyaroundtheEarth,however,nomatterhowhardtheatmospheretriestobalanceitself.ThisisduetotheSun’sunevenheatingoftheEarth’ssurface,whichcreateseverchangingareasofhighpressureandlowpressure. 10.

Student Learning Objectives•Studentslearnthatafastmovingstreamofairresultsinanareaoflowpressurethatpullssurroundingairofhigherpressuretoit.ThiscommonlyreferredtoastheBernoulliEffectafterscientistDanielBernoulli.

Time•10minutes,demo;15minutes,discussion

MaterialsForeachstudent:•Two10-gallonorlargerplastictrashbags•Windbag™(optional)(availablethroughSteveSpanglerScienceatwww.stevspanglerscience.com)


Bernoulli’sBagBreath

Students observe the Bernoulli Principle in action: as the velocity of a fluid increases, the pressure exerted by that fluid decreases.


Directions 1.Turnthehairdryeronandpointitandthestreamofairupwardata90degreeangletotheground.2.Placethepingpongballinthestreamofairandletgoofit.3.Placethetubedirectlyontopofthefloatingpingpongballwithoneofitsopenedendsfacingtheball.Donotletgoofthetube.

Repeat the activity using tubes of various lengths. Tubes of variouswidths can also be explored.

Ask yourself the following questions:1.Whydoesthepingpongballfloatinthestreamofairfromthehairdryer?2.Whydoesthepingpongballtravelupandoutofthetube?3.Whydoestheheightreachedbythepingpongballvarydependingonthelengthofthetube?4.Whydoesthepingpongballtravelfartherwithgreaterairspeed?5.Whathappenstothepingpongballifyoucoverthetopofthetubewhenitisplacedontopoftheball?Why?

Background InformationThisactivityisbasedonBernoulli’sPrinciple,namedaftertheSwissmathematicianandscientistDanielBernoulli(1700-1782)morethan250yearsago.Itstatesthatasafluid’svelocityincreases,thepressureexertedbythatfluiddecreases.

Inthisexample,thepingpongballinitiallyfloatsintheairstreambecauseairacceleratesasitisforcedintoanarrowtube,andtheairpressuredropsasaconsequence.Itstayssuspendedintheairstreambecausethespeedofmovingairisincreasedoveritscurvedsurface.Thisresultsinacorespondingdecreaseinairpressurearoundtheball’ssurfaceandproduceslift.Thehighpressureairimmediatelyoutsidetheairstreamhugsthelowpressuresystemandsnugglestheball,keepingitinplace.

Thewindtunnelsortubescausetheairstreamtoaccelerateasitisfunneledintoasmallerarea.Thisincreaseinvelocitylowerstheairpres-sureinthetube.Highpressureairmovestowardlowpressure,sothislowerpessureairliterallysuckstheballupintothetube.

Agoodruleofthumbwhenitcomestoair:High pressure to low, that is where the air tries to go! 11.

Student Learning Objectives•Studentslearnthatasafluid’sspeedincreases,thepressureitexertsdecreases.•Studentslearnthatairmovestowardlowpressure.


MaterialsForeachpairofstudents:•Cardboardorclearplastictubesofvariouslengthswithanopeningateachendlargerthanapingpongball.Mailingtubesworkwell.•1ormorepingpongballs•Hairdryer


The Coriolis Effect,namedafterthe19thCenturyFrenchengineer-mathematicianGustaveGaspardCoriolisin1835,showsthattheCoriolisforceinouratmosphereisanapparentdeflectionofthepathofanobjectthatmoveswithinarotatingsphere.Theobjectdoesnotactuallydeviatefromitspath,butitappearstodosobecauseofthemotionoftheEarth.

UpandAway-Bernoulli’sWay

Related Web Pages for Students • www.eo.ucar.edu/webweather • www.wunderground.com • www.windows.ucar.edu • www.nws.noaa.gov • www.rap.ucar.edu/weather/ • www.weather.com

Directions1. Print out a variety of weather maps covering a particular country or region for a specific day and hour such as a visible satellite map, an infrared satellite map, a weather frontal map, temperature contour map, radar/precipitation map, wind-speed map, etc. (use the weather Web sites above as a resource). Give one map to each small group of students.2. Using the internet as a resource, ask each group to identify what their specific map shows, how the information is gathered, and why it is important and/or useful to weather forecasters and meteorologists (see Summary of Maps provided). Students should also think about the history of weather observations and technology. 3. After the students have researched their particular weather map, have each group of students teach the class about the value of their particular map in terms of forecasting weather; the technology that makes it possible; how long society has used such maps; and how we might have gained and/or conveyed this information in the past, if it was possible at all. Inquiry questions:1. Why is it helpful to use different types of weather maps?2. Do you think some are more important than others? Why?3. Do you know of any other types of maps often used during weather forecasts (e.g. UV index, heat index, pollen counts)? What is their importance?4. What is the history of some of these maps? How long have they been in use? What technology is needed to make them possible?5. How do you think your map was compiled? Are computers necessary?6. Can you think of another map pertaining to weather that could be helpful? 7. Do we know everything we need to know in order to make accurate weather predictions? What advancements or information might still be sought to improve our forecasting capabilities?8. If you wanted to be a weather forecaster, what skills and knowledge might be helpful to you? Where might you work?

Background InformationModern forecasting involves collecting information about the current state of the atmosphere; analyzing this information, usually with a computer, to extend the ob-servations to locations where no observations are available (for example, in remote ocean areas); and then using weather models that move the current state of the atmosphere ahead in time – via mathematical formulas that capture our under-standing of the physics and fluid dynamics that govern the atmosphere – to make a forecast. In the past, the human forecaster used to be responsible for generating the entire weather forecast from the observations. Today, we not only have com-puters and models that have greatly advanced our forecasting capabilities, but we also have numerous advancements in observations tools –– weather balloons, satellites, doppler radar, wind profilers, automated weather stations, and more –– that have revolutionized what we are able to observe and learn about Earth’s weather. Today’s forecasts usually extend to no more than 10 days, with reliability diminishing with time. This is because differences in the initial conditions of the atmosphere can lead to big differences in the weather just a few days later, and these differences can be too small to detect. Today’s forecasts rely upon observa-tions and models, combined with expert human judgment and decision making. 12.

Student Learning Objectives• Students will be able to read and understand weather maps and forecasts. • Students will learn to access current weather maps and forecasts online.• Students will use the internet to find credible and accurate information on various types of weather maps.

Time• Preparation: 1 hour for choosing and printing maps • One to two 45-min. class periods

MaterialsFor each group of 3-5 students:• One specific type of weather map from a reputable online weather site (e.g. temperature, wind, precipitation, radar, satellite, fronts, jet stream, surface weather maps) • Computers and internet access National Standards• A: Science as Inquiry• D: Earth Science• F: Science in Personal and Social Perspectives

ExtensionHave students use current observa-tions of local weather to make a three day forecast. Prediction sitesinclude:• storm.uml.edu/~metweb/game.html• www.edheads.org/activities/weather/• www.theweatherprediction.com• www.alphapure.net/wxcontest/

Weather Map Know-How

Weather Map SummariesThe weather is constantly being measured all over the world. This data goes into weather maps that you can find on the Internet. Analyzing maps with the current weather conditions is an essential part of the entire forecast process. Basically, if we do not know what is currently occurring, it is nearly impossible to predict what will happen in the future. Below is a summary of various weather maps and what we can learn from them.

Air Mass/Front Maps: These maps illustrate where fronts and high and low pressure systems are located. Sollid black contour lines, calaled isobars, are drawn on such maps, which connect areas of similar pressure. The closer the isobars are to each other, the stronger the pressure gradient and the stronger the wind. Blue fronts are cold fronts, red fronts are warm fronts, alternating red and blue fronts are stationary fronts, and purple fronts are occluded fronts. These maps are particularly helpful since specific weather conditions result from high and low pressure systems.

Dew Point Maps: The dew point temperature is the temperature the air would have to be to become saturated, or in other words to reach a relative humidity of 100%. Dew points provide insight into the amount of moisture in the air. The higher the dew point temperature, the higher the moisture content is for air at a given temperature. When the dew point temperature and air temperature are equal, the air is said to be saturated. Dew point temperature is NEVER GREATER than the air temperature. Therefore, if the air cools, moisture must be removed from the air, and this is accomplished through condensation. This process results in the formation of tiny water droplets that can lead to the development of fog, frost, clouds, or even precipitation. Relative humidity can be inferred from dew point values. When the air and dew point temperatures are very close, this indicates that the air has a high relative humidity. The opposite is true when there is a large difference between air and dew point temperatures, which indicates low relative humidity.

Radar Maps: The most effective tool to detect precipitation is radar. Radar, which stands for Radio Detection And Ranging, has been utilized to detect precipitation, and especially thunderstorms, since the 1940s. Radar enhancements have enabled forecasters to examine storms with more precision. Doppler radar is what is most commonly used today. It can detect motions toward or away from the radar, as well as the location of precipitation areas. This ability to detect motion has greatly improved the meteorologist’s ability to peer inside thunderstorms and determine if there is rotation in the cloud, often a precursor to the development of tornadoes.

Precipitation Maps: These maps are developed using doppler radar and show the reflectivity of particles in the atmosphere such as rain, snow or hail. The color of the precipitation corresponds to the rate at which it is falling. Precipitation maps are a type of radar map that are usually viewed at local or regional scales, although large scale precipitation maps are also available.

Satellite Map: Satellite images of Earth have been with us nearly 50 years now -- since the launch of the world’s first successful weather satellite, TIROS 1, in 1960. After much advancement through the years, satellite images now provide us with cloud and weather observations from high in the upper atmosphere. They also allow us to obtain measurements of radiation from both the Earth and atmosphere. There are many different types of satellite weather maps, for example, visible, infrared, and water vapor.

Visible Satellite Map: Visible satellite images provide information about cloud cover from photographs of the Earth. Areas of white indicate clouds while shades of gray indicate largely clear skies. However, it is difficult to distinguish among low, middle, and high level clouds in a visible satellite image because they capture the amount of light reflected or scattered by clouds, which can be similar at different levels in the atmosphere.

Infrared Satellite Map: Infrared satellite images measure temperature of clouds. In these photographs, warmer objects appear darker than colder objects, which appear brighter. Since high level clouds are colder than low level clouds, they appear brighter. Color enhancements use colors ranging from purple to red to make certain features stand out that would otherwise be a shade of gray.

Satellite Water Vapor Maps: In satellite images showing water vapor, dark colors indicate drier air, and brighter shades of white signify areas with greater moisture. This information on both moist and dry air helps forecasters identify swirling wind patterns in the mid-troposphere and jet stream.

Time on Weather MapsSince local time varies around the world, meteorologists everywhere need a common point in time if their observations are to be meaningful to others in different time zones. Universal Time Coordinate (UTC) is what all forecasters use, which is also referred to as Zulu time (Z). You will notice all weather maps, radar, and satellite images have their time expressed in UTC. Doing so allows the many different elements that create our weather (e.g. the high and low pressure systems, fronts, and precipitation areas) to be viewed together at the same point in time. UTC uses a 24-hour system of time notation. “1:00 a.m.” in UTC is expressed as 0100, pronounced “zero one hundred.” Fifteen minutes after 0100 is expressed as 0115. Try to convert your local time to UTC. Learn more and check your answer at www.timeanddate.com/worldclock/.

Relative Humidity Map: This color-filled contour map shows the current relative humidity. Relative humidity is the ratio of water vapor contained in the air to the maximum amount of water vapor that can be contained in the air at the current temperature. The map’s key shows the corresponding relative humidity for each color.

Surface Map: Weather plots are shown on surface maps andrepresent weather information for a given place in time. These plots help meteorologists convey a lot of information about the weather in a given locale without using a lot of words. When all stations are plotted on a map, a “picture” of where the high and low pressure areas are located, as well as the location of fronts, can be obtained. At right is a typical example of one of many weather plots you might find on a surface map and the information it conveys.

Temperature Map: This surface meteorological chart shows the temperature pattern over the area in the map. Surface temperature reported at each station in the U.S. are contoured every five degrees Fahrenheit. (Celsius is used in many other countries.) Areas of warm and hot temperatures are depicted by orange and red colors, and cold temperatures (below freezing) are shadedblue and purple. Areas of sharp temperature gradients (several contours close to each other) tend to be associated with the position of surface fronts. Fronts separate air masses of different temperature and moisture (and therefore density) characteristics. The key below the image shows the corresponding temperature value for each color.

Upper Air Winds/Jet Stream Map: The upper air/jet stream weather maps show current wind speeds and directions for the atmosphere at certain altitudes –– usually 8,000 -10,000 meters above ground for the jet stream and at various other altitudes (specified in millibars that correspond to the air’s pressure at a particular height). Sometimes these maps also include a color-filled contour map with the wind vector arrows displayed to show the wind direction. The key shows the corresponding wind speed for each color. Wind maps can be created for Earth’s surface as well as for the jetstream and/or upper atmosphere. Upper atmosphere wind maps are vital to accurate general weather forecasts and severe storm predictions. These maps also provide information that is especially important to the airline industry.

When trying to determine whether to add a 9 or 10, use the number that will give you a value closest to 1000 mb.

Pressure in millibars. You have to add a 9 or a 10 before the number.

Temperature in F. or C.

Dewpointin F. or C. Weather

symbol forlight fog ormist.

Cloud Cover

Wind Speedand Direction

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Images: Surface map, visible satellite map, and a map displaying fronts and pressure gradients.

Students learn techniques to determine locations of high and low pressure systems by analyzing US pressure maps and drawing corresponding iso-bars.

Related Web Pages for Students •http://eo.ucar.edu/kids/sky •http://eo.ucar.edu/webweather/basic.html •Currentpressure&isobarmapsthroughAMSDataStreme:http://www.ametsoc.org/amsedu/dstreme/index.html

Facts to KnowIsobarsarelinesdrawnonaweathermapconnectingpointsofequalpres-sure.Drawingthemisabitlikeconnectingthedots.Althoughthatsoundseasy,drawingisobarcontourlinesisaskillthattakespractice.Isobarsareusuallydrawnat4millibarintervals:992mb,996mb,1000mb,1004mb,1008mb,1012mb,1016mbandsoon.Whenthereisnoothercorrespond-ingmillibarmeasurementofequalvaluetoconnectto,oneshouldfindpairsofadjacentstationswithreadingsclosetothemillibarmeasurementsbe-ingdrawn.Forexample,ifyou’reconnectingisobarcontourlinesfor1024mb,youwoulddrawyourisobarlineof1024mbbetweentwonumbersthatstraddleandarecloseto1024mb,perhaps1021mband1028mb.Anisobarcontinuestobedrawnuntilitreachestheendoftheplotteddataorclosesoffaloopasitencirclesdata.Itisimportanttonotethatanisobarlinenevercrossesoveranother.Also,pressureslowerthantheisobarvaluearealwaysononesideoftheisobarandhigherpressuresareconsistentlyontheotherside.Lastly,neighboringisobarswilltendtotakesimilarpaths.

Directions1.Asaclass,reviewanddiscussvariousisobarmaps,thenattempttocreateyourownindividuallyorwithapartner.2.Chooseonemillibarreadingbetween992mband1036mbtobegin(992,996,1000,1004,1008,andsoonat4mbintervals).3.Useaparticularcoloredpenciltoplaceadotonthemapwherethatmillibarreadingisfound.4.Useadifferentcoloredpencilforeachmillibarintervalandcontinuetoplacedotsonthemapthatcorrespondtothatspecificinterval.5.Afteryouhavefoundallyourcorrespondingnumbers,youcanbegintoconnectthedotsofthesamecoloronthemap.Interpolateloca-tionswheretheisobarshouldbedrawnwhenthereadingsdonotdirectlycorrespondtothepressureinmillibarsbeingconnected. Ask yourself the following questions:1.Haveanyofmyisobarscrossed?2.Whereareareasoflowpressureandhighpressureonthemap.Placeared“L”andablue“H”intheseareas.3.Sinceairmovesclockwisearoundhighpressureandcounter-clockwisearoundlowpressureintheNorthernHemisphere,whichwayarewindsblowinginvariousplacesonyourmap?Placearrowstorepre-sentwinddirectionaroundyourmap’shighsandlows.4.Wheredoyouthinktheareaofgreatestwindsmightbelocatedonyourmapifthestrongestwindsarefoundinareaswithcloselydrawnisobarsrepresentingchangesinpressureovershortdistances? 16.

Student Learning Objectives• Studentslearntoanalyzeweathermapsusingpres-sureasavariable.• Studentslearndifferenttypesofweatherassociatedwithpressureobservations.

Time•30minutes

Materials•coloredpencils•unplottedpressuremaps

Terms to Know and Use•Isobars•Isotherms•Pressuregradient


Isobars: Lines drawn on a weather map connecting points of equal pressure.

Isotherms: Lines drawn on a weather map connecting points of equal temperature.

Mapping Air Pressure

eastburn

Typewritten Text

Note: These maps have been created to show only air pressure. Often, additional station weather information is shown.

eastburn

Typewritten Text

In this activity students figure out how far they are from a storm by watching lightning and listening for thunder. You’ll need a stormy day, a video of a thunderstorm, or a simulated storm.

Related Web Pages for StudentsKids’ Crossing Web Pages for Students:Watch Out for Dangerous Weather! http://www.eo.ucar.edu/kids/dangerwx/index.htmStudent Version of Activity http://www.eo.ucar.edu/kids/dangerwx/tstorm6.htm Directions1. Divide students into small groups. Have each read the student version of this activity (URL listed above) for instructions. 2. Discuss the reading as a class including how light and sound travel at different speeds. Review the activity in detail.3. Assign each group stopwatches, paper and pencil and a safe space near a window from which to witness lightning if a thunderstorm happens to be occurring. If not, which is likely, make an imaginary storm with a flashlight or switch-controlledlight to represent lightning and clashing cymbols to represent thunder.4. Instruct students to time the number of seconds between the flash of lighting and the rumble of thunder, and to write down the number. Ask them to also write down the actual time. If the weather allows, have groups take several measurements over 15 minutes or more, noting the time of each measurement. (This will allow students to assess whether the storm is moving towards their location or away.) Simulate the movement of the storm by consistently increasing or consistently decreasing the time between lightning and thunder over a given time period of various lightning strikes.5. Have student groups calculate the distance of the storm from the measurements using these instructions: Every 5 seconds counted equates to a distance of one mile. Divide the number of seconds you count by 5 to get the number of miles. If student groups made several measurements, have them perform the calculation for each measurement to try to answer the following: Was the storm moving towards school, away from school, or not moving either direction?

Assessment: Have student groups create a poster from a sheet of craft paper that displays their data both in a table and visually (with a graph or map) to present their analysis to the class. Hang posters around the room and discuss all results.

Background InformationA bolt of lightning heats the air along its path causing it to expand rapidly. Thunder is the sound caused by the rapidly expanding atmo-sphere. The light and sound actually happen at the same time, but the light of the lightning flash travels faster than the grumbling sound of the thunder. The time between the flash of light and thunder will tell you how far you are from where the lightning struck.

ExtensionsRead and discuss: A Close Encounter with Lightning and discuss safety(http://www.eo.ucar.edu/kids/dangerwx/tstorm9.htm).

Student Learning Objectives• Students collect, analyze data and present results.• Students learn that lightning and thunder happen at the same time but light is seen first because light travels faster tha sound.

Time50 minutes (or 10 minutes with-out data analysis)

Materials• A nearby thunderstorm (or simulate one!) • Stopwatches (or the ability to count “one-Mississippi, two- Mississippi...)• Paper and pencil for data recording• Craft paper and markers• Internet access or printed copies of the student version printed from Kids’ Crossing (URL above)

National StandardsA: Science as InquiryB: Physical ScienceD: Earth Science

SourceThis classic activity is from Web Weather for Kids

How Far is That Storm?

11. © University Corporation for Atmospheric Research 2010

Try some air pressure experiments!

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