选修九 2.5Unit 2 Sailing the oceans .ppt

新课标人教版课件系列 高中英语 选修 模块 9 2 5 sailingtheoceans warmingup 5minutes sailing question howmanyoceansarethereintheworld pacificocean atlanticocean indianocean arcticocean worldmapexploration writedownthewordsyouknow whicharerelatedtonavigationandsea navigation sail sailor voyage latitude longitude equator horizon captain landisland nauticalmiddles explore exploration sea seaman seaweed seafood shore offshore onshore beach beach ball seabed sea bird seagull seashell seaside seawater seasick coast coastline tide wave current pre reading 5minutes compass astrolabe 星盘 sextant 六分仪 sea nauticalchart navigators earlynavigationalinstruments whatisanavigator whatisthedifferencebetweenanavigatorandanexplorer anavigatorexploresnewroutesacrossthesea anavigatorexploresthesea anexplorerdiscoversnewplacesonland zhenghe isheanavigatororanexplorer hemadesevenvoyagesduringhislifetimeandcontributedgreatlytothescienceofnavigationinchina zhenghe marcopolo jamescook howdoyouthinkseamanfoundtheirwaybeforemodernaccuratemethodsofnavigationwereinvented howdidtheynavigatesowell reading readaboutwhatnavigationwaslikebeforemoderninstrumentswereused 25minutes sailingtheoceans fast readingtogetthegeneralidea page1 10minutes usingnature keepingalongsidethecoastlineusingcelestialbodiesusingwildlifeusingtheweatherusingthesea 1minute usingcelestialbodies toplotthepositions toworkoutthelatitude aspecialcloudformationindicatesthereislandcloseby 2minutes usingwildlife ifseaweedwasfreshandsmelledstrongly theshipwasclosetoland seabirdscouldbeusedtoshowthewaytolandwhenitwasnowheretobeseen 1minute usingtheweather fog tohelpidentifythepositionofastreamorriverwhen todirecttheirsailing 1minute usetheinformationtoanalyzethenavigationalskillsandwritetheanswersinyourownwords tofindtheship spositionatseaasailorused asailorknewthatlandwasnearbyifhesaw sailorsused toincreasetheirspeed thenorthstarandthesun seacurrentsortidesand winds usingnature clouds freshseaweed nestingbirdsorfog 5minutes fast readingtogetthegeneralidea thenanswerthequestions page2 10minutes usingnavigationalinstruments 1 findinglongitude 2 findinglatitude thecompass thebearingcircle 方位圆 theastrolabe 星盘 thequadrant 象限仪 四分仪 thesextant 六分仪 2minutes readthepassageandanswerthefollowingquestions whatistheuseofabearingcircle astrolabe quadrantorsextant whatistheuseofacompass a tosetthecourseoftheshipb tomeasurethepositionoftheshipc tomeasurethespeedoftheshipd totellthetime b a usinginstruments 2minutes readagainandfillintheblanks thereweretwomethodstofindlongitude 1 2 measuringtimeandspeed compassandcomplicated mathematicaltables usinginstruments 1minute writedowntheworkingprinciplesofthefollowinginstruments bearingcircle astrolabe quadrant sextant tocomparetheheightofthesunnowwiththepositionofthesunatmidday tocomparethepositionoftheshipinrelationtosomestarsorthesun amorepreciseformoftheastrolabe tomeasurehowhighstarsareabovethehorizon andcomparethatmeasurementwithpreviousmeasurements anupdatedversionofthequadrantandsoitwasmoreaccurate tomeasuretheanglebetweentowfixedpintsoutsidetheship 5minutes horizon sunheight abearingcircle bearingthesun heightandazimuth themarkswereusedtomeasuretheshadowofthesunanditsheightandpositioninthesky 方位 listentothetapeandthenanswerthequestions detailedreading page2 5minutes 1 whyarespeedandtimeimportantinworkingoutthelongitudeofaship becausetheearthmovesfifteendegreeswestwardseveryhour ifyouknowyourdirection speedandtime youcanworkouttheapproximatelongitude 2 whyisthepositionofthesunandvariousstarsusefulforworkingoutlatitude becausetheyarefixedpointsintheskyandtheirmovementsinrelationtotheeartharealreadyknown sotheycanbeusedtomeasureaship sposition 10minutes discussion whatwouldyoudoifyoucameacrossthefollowingproblemsduringyourvoyage waittillthestormisover andthenfindyournewpositionandreturntoyouroriginalcourse useknotstofindyourspeedandworkoutyourapproximatelongitude usethecompassandtheastrolabe quadrantorsextanttofindoutyourposition returntoyourformercourse follownestingbirdstoshore lookforspecialcloudformationsorf