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EncyclopedicEntry
stormsurge
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Astormsurgeisariseinsealevelthatoccursduringtropicalcyclones,intensestormsalsoknownastyphoonsor
hurricanes.Thestormsproducestrongwindsthatpushthewaterintoshore,whichcanleadtoflooding.This
makesstormsurgesverydangerousforcoastalregions.
Tropicalcyclonesarecircularstormscharacterizedbyhighwindsandheavyrainfall.Theyformoverwarm,tropical
oceans.Thecenterofacycloneiscalledtheeye.Theeyeissurroundedbyaringofcloudscalledtheeyewall,
wherethewindsarestrongest.Surroundingtheeyewallarecloudsthatspiraloutward,calledspiralingrainbands.
Astormsurgeisprimarilycausedbytherelationshipbetweenthewindsandtheocean’ssurface.Thewaterlevel
riseswherethewindsarestrongest.Inaddition,waterispushedinthedirectionthewindsareblowing.The
rotationoftheEarthcauseswindstomovetowardtherightintheNorthernHemisphereandtowardtheleftinthe
SouthernHemisphere—aphenomenonknownastheCorioliseffect.IfacyclonedevelopsintheNorthern
Hemisphere,thesurgewillbelargestintheright-forwardpartofthestorm.IntheSouthernHemisphere,thesurge
willbelargestintheleft-forwardpartofthecyclone.
Anotherfactorcontributingtostormsurgeisatmosphericpressure.Atmosphericpressureistheforceexertedby
theweightofairintheEarth’satmosphere.Thepressureishigherattheedgesofacyclonethanitisatthecenter.
Thispushesdownthewaterintheouterpartsofthestorm,causingthewatertobulgeattheeyeandeyewall—
wherethewindshavehelpedaddtotheriseinsealevel.
Morefactorscontributetothestrengthofastormsurgeasthedomeofwatercomesashore.Thewaterlevelcan
reachashighas10meters(33feet)ifthestormsurgehappensatthesametimeashightide.Theslopeofthe
landjustoffthecoastalsoplaysapart:Waterwillmoreeasilyfloodashallowcoastthanasteepone.
StormSurgesandCoastalCommunities
Tropicalcyclones,andthestormsurgestheygenerate,areaserioushazardforcoastalareasintropicaland
subtropicalregionsoftheworld.Developinginthelatesummermonths(July-AugustintheNorthernHemisphere,
January-FebruaryintheSouthernHemisphere),whenthewatersarewarmest,tropicalcycloneshitregionsasfar
apartastheGulfCoastoftheUnitedStates,northwesternAustraliaandBangladesh.
Whenacyclonehitsland,theaccompanyingstormsurgewillmostoftenfloodthesurroundingcoastalarea.
Floodingisresponsibleformostdeathsandeconomicdamageassociatedwithtropicalcyclonelandfalls.Whena
hurricanehitGalveston,Texas,in1900,thestormsurgewasresponsibleforapproximately6,000deaths.InEast
Pakistan(nowBangladesh),theBholacyclonekilledasmanyas500,000peoplein1970.Thestormsurgefrom
theBholacyclonewasestimatedtobe10meters(33feet)high.
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Improvementsinforecastingcyclonesandissuingearlywarningstothepublichavebecomeindispensableasboth
coastalpopulationsandtheoccurrenceofextremestormscontinuetorise.
However,evensophisticatedmeteorologyandstormwarningsdonotalwaysprotectagainstdevastatingstorm
surges.HurricaneKatrina’sstormsurgefloodedtheU.S.coastalcommunitiesofLouisianaandMississippi,aswell
astheurbanareasofNewOrleans,Louisiana,andBiloxi,Mississippi,in2005.Thefloodingkilledmorethan1,500
peopleinNewOrleansalone,andcausedmillionsofdollarsindamage.Homes,businesses,schools,and
hospitalsweredestroyed.
Still,improvementsinforecastinggreatlybenefitregionsliketheChesapeakeBay,intheU.S.statesofMaryland
andVirginia.TheChesapeakeBaysufferedseveredamagefromHurricaneIsabelin2003.Emergencymanagers
failedtopredictIsabel’sextremestormsurges,whichcausedwidespreadfloodingintheregion.
Now,meteorologistsandemergencymanagersmonitorthestormsforminginthesoutheastmoreclosely.New
computersimulationsbytheFederalEmergencyManagementAgency(FEMA)examinedtheeffectsofaCategory
4hurricane(131-155mphwinds)landingintheU.S.statesofNorthorSouthCarolina,hundredsofmilessouthof
theChesapeake.Thesimulationshowedthehurricanecouldproducestormsurgesashighas5or6meters(18or
20feet)alongtheChesapeakeshoreline.FEMAusedthelatestversionofitscomputerizedSLOSHmodelto
predictthesurge.Anacronymfor"Sea,Lake,andOverlandSurgesfromHurricanes,''theSLOSHprogramisused
bytheNationalWeatherServiceandtheNationalHurricaneCenter.
TheMarylandEmergencyManagementAgencyisnowworkingwiththeU.S.ArmyCorpsofEngineersandlocal
officialstoturntheSLOSHsimulationdataintoupdatedmapsforemergencyplanning.Thenewmapsshowhow
farinlandfloodingcouldstretchundercertainconditions.Withthisnewforecastingdata,emergencyplannersand
citizenswillbebetterpreparedforstormsurges.
Governmentagenciescanarrangeforresidentstoevacuate.Someresidentsdon’thavecarsandmayrequire
transportationtosaferground.Othersmaynothaveaplacetogoandrequireemergencyshelter.Manyresidents,
suchasthoseinhospitalsandprisons,areespeciallyatrisk.
Advancewarningofastrongstormsurgealsoallowshomesandbusinessestopreparefordamage.Business
ownerscanrelocateexpensivemachineryortoolstosafeareas,andhomeownerscanboardupwindowsto
protectagainststrongfloodsormovefurnitureandothervaluablestoasecondstory.
Wetlands
Coastalresidentscanreducethedamagedonebyastormsurgebyprotectinglocalwetlands.Wetlands,suchas
swamps,estuaries,andmudflats,actasspongesfortropicalcyclones.Asthecyclonemakeslandfall,themarshy
landandplantsabsorbthewaterandtheenergyofthestormsurge.Siltandswampvegetationpreventthemost
intensepartofthestormsurgefromhittinghomesandbusinesses.
EstuariesaresuchanimportantpartofournaturalenvironmentthattheU.S.EnvironmentalProtectionAgency
(EPA)createdtheNationalEstuaryProgramin1987.Thisprogramseekstoimprovethequalityofestuariesto
protectimportantwildlifehabitats,publicwatersupplies,andcoastalregionsaffectedbyseverestorms.
Thedevelopmentofcoastalwetlandsforhousing,industry,oragriculturereducesthenaturalbarrierthatwetlands
provide.Communitiescanprotectthemselvesagainststormsurgesbymaintaininghealthycoastalwetland
ecosystems.
VOCABULARY
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Term
PartofSpeech
Definition
accompany
verb
tojoinwithsomeoneorsomething.
adversely
adverb
negativelyorinabadway.
agriculture
noun
theartandscienceofcultivatingthelandforgrowingcrops(farming)orraising
livestock(ranching).
ArmyCorpsof
Engineers
noun
governmentorganizationconcernedwithconstructionprojects.
atmosphere
noun
layersofgasessurroundingaplanetorothercelestialbody.
atmospheric
pressure
noun
forceperunitareaexertedbythemassoftheatmosphereasgravitypullsitto
Earth.
Bholacyclone
noun
(1970)stormthatcausedwidespreaddamageanddeathinBangladeshand
India.
Carolinas
noun
theU.S.statesofNorthCarolinaandSouthCarolina.
Chesapeake
Bay
noun
large,shallowestuaryoftheSusquehannaandotherriversthatflowthroughthe
U.S.statesofMaryland,Virginia,WestVirginia,Delaware,Pennsylvania,andNew
YorkandthecapitalofWashington,D.C.,beforeemptyingintheAtlanticOcean.
Corioliseffect
noun
theresultofEarth'srotationonweatherpatternsandoceancurrents.TheCoriolis
effectmakesstormsswirlclockwiseintheSouthernhemisphereand
counterclockwiseintheNorthernHemisphere.
cyclone
noun
weathersystemthatrotatesaroundacenteroflowpressureandincludes
thunderstormsandrain.Usually,hurricanesrefertocyclonesthatformoverthe
AtlanticOcean.
data
pluralnoun
(singular:datum)informationcollectedduringascientificstudy.
economic
adjective
havingtodowithmoney.
ecosystem
noun
communityandinteractionsoflivingandnonlivingthingsinanarea.
Environmental
Protection
Agency(EPA)
noun
U.S.governmentorganizationwhosemissionisto"protecthumanhealthandthe
environment."
estuary
noun
mouthofariverwheretheriver'scurrentmeetsthesea'stide.
evacuate
verb
toleaveorremovefromadangerousplace.
exert
verb
toforceorpressure.
expensive
adjective
verycostly.
eye
noun
centerofatropicalcyclone,characterizedbyaroughlycircularareaoflightwinds
andrain-freeskies.
eyewall
noun
ringofthunderstormsthatsurroundsahurricane'seye.
Federal
Emergency
Management
Agency(FEMA)
noun
U.S.HomelandSecurityagencyresponsibleforcoordinatingresponseandaid
distributionafternaturalandmanmadedisasters.
flood
noun
overflowofabodyofwaterontoland.
forecast
verb
topredict,especiallytheweather.
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forecast
verb
topredict,especiallytheweather.
generate
verb
tocreateorbegin.
GulfCoast
noun
landintheUnitedStatessurroundingtheGulfofMexico.
habitat
noun
environmentwhereanorganismlivesthroughouttheyearorforshorterperiodsof
time.
hazard
noun
dangerorrisk.
hightide
noun
waterlevelthathasrisenasaresultofthemoon'sgravitationalpullontheEarth.
hurricane
noun
tropicalstormwithwindspeedsofatleast119kilometers(74miles)perhour.
Hurricanesarethesamethingastyphoons,butusuallylocatedintheAtlantic
Oceanregion.
HurricaneIsabel
noun
(2003)stormthatcauseddamagetotheU.S.statesofSouthCarolina,North
Carolina,andVirginia.
Hurricane
Katrina
noun
2005stormthatwasoneofthedeadliestinU.S.history.
low-pressure
system
noun
weatherpatterncharacterizedbylowairpressure,usuallyasaresultofwarming.
Low-pressuresystemsareoftenassociatedwithstorms.
machinery
noun
mechanicalappliancesortoolsusedinmanufacturing.
map
noun
symbolicrepresentationofselectedcharacteristicsofaplace,usuallydrawnona
flatsurface.
marsh
noun
wetlandareausuallycoveredbyashallowlayerofseawaterorfreshwater.
meteorologist
noun
personwhostudiespatternsandchangesinEarth'satmosphere.
meteorology
noun
studyofweatherandatmosphere.
mudflat
noun
arealeftbarebyrecedinglakeortidalwaters.
Northern
Hemisphere
noun
halfoftheEarthbetweentheNorthPoleandtheEquator.
phenomenon
noun
anunusualactoroccurrence.
precaution
noun
actiontakentoavoidanegativeoutcomeorevent.
sealevel
noun
baselevelformeasuringelevations.Sealevelisdeterminedbymeasurements
takenovera19-yearcycle.
shoreline
noun
beach,orwhereabodyofwatermeetsland.
silt
noun
smallsedimentparticles.
simulation
noun
copyorreenactment.
SLOSH
noun
(Sea,LakeandOverlandSurgesfromHurricanes)modelsimulationprogram
usedtodeterminewhichareasmustbeevacuatedduetoastormsurge.
sophisticated
adjective
knowledgeableorcomplex.
Southern
Hemisphere
noun
halfoftheEarthbetweentheSouthPoleandtheEquator.
storm
noun
severeweatherindicatingadisturbedstateoftheatmosphereresultingfrom
upliftedair.
stormsurge
noun
abnormalriseinsealevelaccompanyingahurricaneorotherintensestorm.Also
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stormsurge
noun
abnormalriseinsealevelaccompanyingahurricaneorotherintensestorm.Also
calledastormtide.
subtropical
adjective
borderingthetropics,justnorthoftheTropicofCancerandsouthoftheTropicof
Capricorn.
swamp
noun
landpermanentlysaturatedwithwaterandsometimescoveredwithit.
temperature
noun
degreeofhotnessorcoldnessmeasuredbyathermometerwithanumerical
scale.
transportation
noun
movementofpeopleorgoodsfromoneplacetoanother.
tropical
adjective
existinginthetropics,thelatitudesbetweentheTropicofCancerinthenorthand
theTropicofCapricorninthesouth.
typhoon
noun
tropicalstormwithwindspeedsofatleast74miles(119kilometers)perhour.
Typhoonsarethesamethingashurricanes,butusuallylocatedinthePacificor
IndianOceanregion.
urbanarea
noun
developed,denselypopulatedareawheremostinhabitantshavenonagricultural
jobs.
vegetation
noun
alltheplantlifeofaspecificplace.
watersupply
noun
amountofavailablefreshwaterfordrinking,hygiene,andindustrialand
agriculturaluse.
weather
noun
stateoftheatmosphere,includingtemperature,atmosphericpressure,wind,
humidity,precipitation,andcloudiness.
wetland
noun
areaoflandcoveredbyshallowwaterorsaturatedbywater.
wind
noun
movementofair(fromahighpressurezonetoalowpressurezone)causedbythe
unevenheatingoftheEarthbythesun.
ForFurtherExploration
Audio&Video
NationalGeographicVideo:StormSurge
NationalGeographicChannel:NakedScience—HurricaneSurge
Websites
NationalHurricaneCenter:StormSurge
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