Raymarine LIGHTHOUSE 4 - Page 246

T
ermDefinition
away.Allshrubs,trees,andsignsblowndown.Completedestructionofmobilehomes.Severeandextensivewindowanddoor
damage.Lowlyingescaperoutesarecutbyrisingwater3–5hoursbeforearrivalofthecentreofthehurricane.Majordamageto
lowerfloorsofallstructureslocatedlessthan15ftabovesealevelandwithin500yardsoftheshoreline.Massiveevacuationof
residentialareasonlowgroundwithin5–10miles(8–16km)oftheshorelinemayberequired.
IsobarAlineonaweathermaplinkingareaswithequalairpressure
.
Lightning
Dischargeofstaticelectricityintheatmosphere
,usuallybetweenthegroundandastormcloud.
L
ow
Alsocalleda'depression'thisregionoflowpressurecanmeanwetweather.
L owPressure
AmassofairthatpressesdownonlyweaklyonthesurfaceoftheEarth’ssurfaceasitiswarmedanditthereforelessdense.
MillibarAunitusedtomeasureatmosphericpressure .
OccludedFrontAnareawherewarmairispushedupwardsasacoldfrontovertak esawarmfrontandpushesunderneathit.
Precipitation
Moisturethatisreleasedfromtheatmosphereasrain,drizzle ,hail,sleetorsnow,aswellasdewandfog.
PressureCentreAregionofhighorlowpressure .
SqualllineAnon-frontalband,orline ,ofthunderstorms.
Supertyphoon
Atyphoonthatreachesmaximumsustained1minutesurfacewindsofatleast65m/s(130kt,150mph).Thisistheequivalentofa
strongcategory4or5hurricaneintheA
tlanticbasinoracategory5severetropicalcycloneintheAustralianbasin.
T ornado
Afunnelshapedwhirlwindwhichextendstothegroundfromstormclouds.
T ropicalcyclone
Alowpressuresystemthatgenerallyformsinthetropics.Thecycloneisaccompaniedbythunderstormsand,intheNorthern
Hemisphere,acounterclockwisecirculationofwindsneartheearth'ssurface.
T ropicaldepression
Anorganizedsystemofcloudsandthunderstormswithadefinedsurfacecirculationandmaximumsustainedwindsof38mph
(33kt)orless.
T ropicalstorm
Anorganizedsystemofstrongthunderstormswithadefinedsurfacecirculationandmaximumsustainedwindsof39–73mph
(34–63kt).
T ropics
AnareaontheEarth'ssurfacethatliesbetween30ºnorthand30ºsouthoftheequator.
T rough
Anelongatedareaofrelativelylowatmosphericpressure,usuallyextendingfromthecentreofalowpressureregion.
T yphoon
ThenameforatropicalstormoriginatinginthePacificOcean,usuallytheChinaSea.Theyarebasicallythesameasthehurricanes
oftheAtlanticOceanandthecyclonesoftheBayofBengal.
W avecyclone
Astormorlowpressurecentrethatmovesalongafront.
W aveperiodTheperiodisthetimegapbetweensuccessivewavesandthelongertheperiodtheslowerthewavestravel.
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