教材文本 unit 2 reading

《教材文本 unit 2 reading》由会员上传分享，免费在线阅读，更多相关内容在教育资源-天天文库。

1、Unit2SailingtheOceansPre-readingLookatthepictures.Thenanswerthequestions.1Howdoyouthinkseamenfoundtheirwaybeforemodernaccuratemethodsofnavigationwereinvented?2Whichdoyouthinkwaseasiertoworkout:latitudeorlongitude?3Canyouidentifytheseearlynavigationalinstrumentsseamenusedandexpl

2、ainhowtheyareused?1______________2______________3______________4______________4Whichonesdoyouthinkarestillusedtoday?Nowreadaboutwhatnavigationwaslikebeforemoderninstrumentswereused.ReadingSAILINGTHEOCEANSWemaywellwonderhowseamenexploredtheoceansbeforelatitudeandlongitudemadeitp

3、ossibletoplotaship’spositiononamap.Thevoyagesoftravellersbeforethe17thcenturyshowthattheywerenotatthemercyoftheseaeventhoughtheydidnothavemodernnavigationalaids.Sohowdidtheynavigatesowell?Readthesepagesfromanencyclopedia.Pagel:UsingnaturetohelpKeepingalongsidethecoastlineThisse

4、emstohavebeenthefirstandmostusefulformofexplorationwhichcarriedtheminimumamountofrisk.Usingcelestialbodies●NorthStarAttheNorthPoletheNorthStarisatitshighestpositioninthesky,butattheequatoritisalongthehorizon.Soaccomplishednavigatorswereabletouseittoplottheirpositions.●SunOnacle

5、ardayespeciallyduringthesummerthesailorscouldusethesunoverheadatmiddaytonavigateby.Theycanusetheheightofthesuntoworkouttheirlatitude.●CloudsSeacaptainsobservedthecloudsoverislands.Thereisaspecialcloudformationwhichindicatesthereislandcloseby.Usingwildlife●SeaweedSailorsoftensaw

6、seaweedintheseaandcouldtellbythecolourandsmellhowlongithadbeenthere.Ifitwasfreshandsmelledstrongly,thentheshipwasclosetoland.●BirdsSeabirdscouldbeusedtoshowthewaytolandwhenitwasnowheretobeseen.Intheeveningnestingbirdsreturntolandandtheirnests.Soseamencouldfollowthebirdstolandev

7、eniftheywereoffshoreandintheopensea.Usingtheweather●FogFoggathersatseaaswellasoverstreamsorrivers.Seamenusedittohelpidentifythepositionofastreamorriverwhentheywereclosetoland.●WindsWiseseamenusedthewindstodirecttheirsailing.Theycouldacceleratethespeed,buttheycouldalsobedangerou

8、s.SotheVikingswouldobservethewindsbeforeandduringtheir