有关热气球的英语作文x
更新时间:2022-09-29 02:14:30 阅读： 评论：0
有关热气球的英语作文
Ahotairballoonconsistsofabagcalledtheenvelopethatiscapableofcontainingheatedair.Suspendedbeneathisagondolaorwickerbasket(insomelong-distanceorhigh-altitudeballoons,acapsule),whichcarriespasngersand(usually)asourceofheat,inmostcasanopenflame.Theheatedairinsidetheenvelopemakesitbuoyantsinceithasalowerdensitythantherelativelycoldairoutsidetheenvelope.Aswithallaircraft,hotairballoonscannotflybeyondtheatmosphere.Unlikegasballoons,theenvelopedoesnothavetobealedatthebottomsincetheairnearthebottomoftheenvelopeisatthesamepressureastheairsurrounding.Formodernsportballoons,theenvelopeisgenerallymadefromnylonfabricandtheinletoftheballoon(closttotheburnerflame)ismadefromfireresistantmaterialsuchasNomex.
Beginningduringthemid-1970s,balloonenvelopeshavebeenmadeinallkindsofshapes,suchasrocketshipsandtheshapesofvariouscommercialproducts,thoughthetraditionalshaperemainspopularformostnon-commercial,andmanycommercial,applications.
