Raymarine e7 - Page 246

TermDenition
•Category4—Winds131155mph(114135ktor210249km/hr).Stormsurgegenerally1318ftabovenormal.Moreextensivecurtainwall
failureswithsomecompleteroofstructurefailuresonsmallresidences.Shrubs,trees,andallsignsareblowndown.Completedestruction
ofmobilehomes.Extensivedamagetodoorsandwindows.Lowlyingescaperoutesmaybecutbyrisingwater35hoursbeforearrivalof
thecentreofthehurricane.Majordamagetoloweroorsofstructuresneartheshore.Terrainlowerthan10ftabovesealevelmaybe
oodedrequiringmassiveevacuationofresidentialareasasfarinlandas6miles(10km).
•Category5—Windsgreaterthan155mph(135ktor249km/hr).Stormsurgegenerallygreaterthan18ftabovenormal.Completeroof
failureonmanyresidencesandindustrialbuildings.Somecompletebuildingfailureswithsmallutilitybuildingsblownoveroraway.All
shrubs,trees,andsignsblowndown.Completedestructionofmobilehomes.Severeandextensivewindowanddoordamage.Low
lyingescaperoutesarecutbyrisingwater35hoursbeforearrivalofthecentreofthehurricane.Majordamagetoloweroorsofall
structureslocatedlessthan15ftabovesealevelandwithin500yardsoftheshoreline.Massiveevacuationofresidentialareasonlow
groundwithin510miles(816km)oftheshorelinemayberequired.
IsobarAlineonaweathermaplinkingareaswithequalairpressure.
Lightning
Dischargeofstaticelectricityintheatmosphere,usuallybetweenthegroundandastormcloud.
Low
Alsocalleda’depression’thisregionoflowpressurecanmeanwetweather.
LowPressure
AmassofairthatpressesdownonlyweaklyonthesurfaceoftheEarth’ssurfaceasitiswarmedanditthereforelessdense.
MillibarAunitusedtomeasureatmosphericpressure.
OccludedFrontAnareawherewarmairispushedupwardsasacoldfrontovertakesawarmfrontandpushesunderneathit.
Precipitation
Moisturethatisreleasedfromtheatmosphereasrain,drizzle,hail,sleetorsnow,aswellasdewandfog.
PressureCentreAregionofhighorlowpressure.
SqualllineAnon-frontalband,orline,ofthunderstorms.
SupertyphoonAtyphoonthatreachesmaximumsustained1minutesurfacewindsofatleast65m/s(130kt,150mph).Thisistheequivalentofastrong
category4or5hurricaneintheAtlanticbasinoracategory5severetropicalcycloneintheAustralianbasin.
Tornado
Afunnelshapedwhirlwindwhichextendstothegroundfromstormclouds.
Tropicalcyclone
Alowpressuresystemthatgenerallyformsinthetropics.Thecycloneisaccompaniedbythunderstormsand,intheNorthernHemisphere,a
counterclockwisecirculationofwindsneartheearth’ssurface.
246e7/e7D—Userreference