首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
外语
Volts from the Sky 1 Lightning has caused awe and wonder since old times. Although Benjamin Franklin demonstrated lightning as a
Volts from the Sky 1 Lightning has caused awe and wonder since old times. Although Benjamin Franklin demonstrated lightning as a
admin
2012-07-30
24
问题
Volts from the Sky
1 Lightning has caused awe and wonder since old times. Although Benjamin Franklin demonstrated lightning as an enormous electrical discharge more than 200 years ago, many puzzles still surround this powerful phenomenon.
2 Lightning is generated when electrical charges separate in rain clouds, though processes are still not fully understood. Typically, positive charges build at the cloud top, while the bottom becomes negatively charged. In most instances of cloud-to-ground lightning, the negatively charged lower portion of the cloud repels negatively charged particles on the ground’s surfaces, making it become positively charged. The positive charge on the ground gathers at elevated points.
3 A flow of electrons begins between the cloud and earth. When the voltage charge becomes large enough, it breaks through the insulating barrier of air, and electrons zigzag earthward. We see the discharge as lightning.
4 Lightning can occur within a cloud, between clouds, or between clouds and the ground. The first variety, intra-cloud lightning, is the most frequent but is often hidden from our view. Cloud-to -ground lightning, making up about 20 percent of lightning discharges, is what we usually see Lightning comes in several forms, including sheet, ribbon, and ball, Intra-cloud lightning can illuminate a cloud so it looks like a white sheet, hence its name. When cloud-to-ground lightning occurs during strong winds, they can shift the lightning channel sideways, so it looks like a ribbon. The average lightning strike is more than 3 miles long and can travel at a tenth of the speed of light. Ball lightning, the rarest and most mysterious form, derives its name from the small luminous ball that appears near the impact point, moves horizontally, and lasts for several seconds.
5 Thunder is generated by the tremendous heat released in a lightning discharge second. This sudden heating acts as an explosion, generating shock waves we hear as thunder.
6 About 2, 000 thunderstorms are occurring in the world at any time, generating about 100 lightning strikes every second, or 8 million daily. Within the United States, lightning strikes are estimated at 20 million a year, or about 22, 000 per day. You have a l-in-600, 000 chance of being struck by lightning during your lifetime. Lightning can strike twice or more in the same spot. The Empire State Building in New York is struck by lightning about two dozen times annually.
7 You can measure how far you are from a lightning strike by counting the seconds between viewing the flash and hearing the bang, and then dividing by five. This approximates the mileage.
A Cloud-to-ground lightning occurring in the U. S.
B Types of lightning
C Cause of lightning
D Differences between thunder and thunderstorm
E Frequencies of thunderstorms occurring in the world and the U. S.
F Shock waves as thunder
Paragraph ______
选项
答案
B
解析
第四段介绍了闪电的三种类型:云层内部闪电,云层与云层之间的闪电,云层与地面之间的闪电。此外,还从形状上介绍了闪电可有片状、带状和球状。
转载请注明原文地址:https://kaotiyun.com/show/ydGd777K
本试题收录于:
职称英语综合类C级题库职称英语分类
0
职称英语综合类C级
职称英语
相关试题推荐
Animal’s"SixthSense"AtsunamiwastriggeredbyanearthquakeintheIndianOceaninDecember,2004.Itkilledtensoftho
NewChangesinAmericanLifeOnceitwaspossibletodefinemaleandfemaleroleseasilybythedivisionoflabor.Menworke
RenewableEnergySourcesTodaypetroleum(石油)providesaround40%oftheworld’senergyneeds,mostlyfuellingautomobiles.Co
AtosendgoodstovariouspartsoftheworldBatanytimeduringtheyearChasgreadypromotedtradeDisitpossibletoprod
FreezingtoDeathforBeautyPeopleinBeijingwearalotofclothingduringwintertofendoff(抵御)thecold.IntheUnitedS
SunspotsIt’snotsurprisingthatsunspots(太阳黑子)wereobservedbyancientastronomers(天文学家).Thelargestsunspotsonthes
Nowadaysmanyscientistsdependonradiocarbonfordatingage-oldobjects.Radarisusedtodeterminethecharacteristicsofra
EgyptFelledbyFamineEvenancientEgyptsmightypyramidbuilderswerepowerlessinthefaceofthefaminethathelpedbrin
Ifyoufindandcureeverybodywhohasthedisease,youcancurbtheepidemicinitstracks.
KeepingCutFlowers1Whileeverybodyenjoysfreshcutflowersaroundtheirhouse,fewpeopleknowhowtokeepthemforaslon
随机试题
ShirleyAllenlovedtosingandplaythepiano.Shestudiedmusicincollege.Herdreamwastobecomea【C1】______orsinger.
宫内节育器的避孕原理不包括
A.疖B.痈C.丹毒D.急性蜂窝织炎E.浅部急性淋巴管炎
2001年3月13日下午。陈某因曾揭发他人违法行为,被两名加害人报复砍伤。陈某逃跑过程中,两加害人仍不罢休,持刀追赶陈。途中,陈某多次拦车欲乘,均遭出租车司机拒载。当两加害人即将追上时,适逢一中年妇女丁某骑一摩托车(价值9000元)缓速行使。陈某当即哀求丁
涂刷防水涂料时,第二层涂刷的方向应与第一层()。
某教师在讲授《自己的事情自己干》一课时,设置了如下教学活动。一、自立的含义和表现这些和我们同龄甚至比我们还小的“候鸟学生”,远离父母,独自在外,他们自己提行李、坐火车,自己打水、梳头、洗衣服,独自面对生活和学习过程中的各种问题。你敢晒晒自己的自立经历
•LookatthestatementsbelowandatthefiveextractsfromanarticleaboutWebhostingprovider,itsresellerandoutsourcing.
Idon’tliketodisturbyou,becauseyou’requitetired()workinghardtoday.
A、It’stoohigh.B、It’sacceptable.C、It’scheapindeed.D、Thewomanshouldhavebargainedforit.C[听力原文]W:Ispent$50onthi
A、Therepairmanhadfinishedcleaningtheplugs.B、Therepairmanhadjuststartedworkingonhercar.C、Therepairmanhadlostt
最新回复
(
0
)