Raymarine e7 - 13.10 Glossary of weather terms

13.10Glossaryofweatherterms
TermDenition
ColdfrontTheboundarybetweentwodifferentairmasseswherecoldairpusheswarmairoutofthewayandbringscolderweather.
CycloneAlargeareaoflowatmosphericpressure,characterizedbyinwardspirallingwinds.A“low”alsocalleda“depression”.Alsothename
usedforahurricaneintheIndianOceanandWesternPacic.
Depression
Anareaoflowpressure.Alsocalledacyclone.
Dryline
Aregionwherethereisastronggradientindewpointtemperatures.Itisoftenfoundinaregionwherestrongthunderstormsdevelop.
Forecast
Somethingthattellsuswhattheweatherisprobablygoingtobelike.
Front
Theboundarybetweentwomassesofairwithdifferenttemperatures(i.e.amassofcoldairandamassofwarmair).
High
Alsoknownasan’anticyclone’anareaofhighatmosphericpressurewithasystemofwindsrotatingoutwards.Thisusuallymeansdry
weather.Itistheoppositeofa’low’.
HighPressure
AmassofairthatpressesdownstronglyonthesurfaceoftheEarthbecauseitisbeingcooledandisthereforemoredense.
Hurricane
Aviolent,spirallingstormthatformsovertheAtlanticOcean,withwindsover120kph.Suchstormsusuallyhavealifespanofseveraldays.
Alsoknownasatyphoonortropicalcyclone.Thereare5levelsofhurricane:
•Category1—Winds7495mph(6482ktor119153km/hr).Stormsurgegenerally45ftabovenormal.Norealdamagetobuilding
structures.Damageprimarilytounanchoredmobilehomes,shrubbery,andtrees.Somedamagetopoorlyconstructedsigns.Also,
somecoastalroadoodingandminorpierdamage.
•Category2—Winds96110mph(8395ktor154177km/hr).Stormsurgegenerally68feetabovenormal.Someroongmaterial,door,
andwindowdamageofbuildings.Considerabledamagetoshrubberyandtreeswithsometreesblowndown.Considerabledamageto
mobilehomes,poorlyconstructedsigns,andpiers.Coastalandlowlyingescaperoutesood24hoursbeforearrivalofthehurricane
centreSmallcraftinunprotectedanchoragesbreakmoorings.
•Category3—Winds111130mph(96113ktor178209km/hr).Stormsurgegenerally912ftabovenormal.Somestructuraldamageto
smallresidencesandutilitybuildingswithaminoramountofcurtainwallfailures.Damagetoshrubberyandtreeswithfoliageblownoff
treesandlargetreesblowndown.Mobilehomesandpoorlyconstructedsignsaredestroyed.Lowlyingescaperoutesarecutbyrising
water35hoursbeforearrivalofthecentreofthehurricane.Floodingnearthecoastdestroyssmallerstructureswithlargerstructures
damagedbybatteringfromoatingdebris.Terraincontinuouslylowerthan5ftabovemeansealevelmaybeoodedinland8miles(13
km)ormore.Evacuationoflowlyingresidenceswithseveralblocksoftheshorelinemayberequired.
Usingtheweatherapplication(NorthAmericaonly)
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