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
48
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
Paragraphs and ______
选项
答案
C
解析
第二段以云层到地面的闪电为例子解释了闪电的原理。第三段述及闪电发生的过程。
转载请注明原文地址:https://kaotiyun.com/show/fdGd777K
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
Animal’s"SixthSense"AtsunamiwastriggeredbyanearthquakeintheIndianOceaninDecember,2004.Itkilledtensoftho
TransportandTrade1Transportisoneoftheaidstotrade.Bymovinggoodsfromplaceswheretheyareplentifultoplaceswher
Animal’s"SixthSense"AtsunamiwastriggeredbyanearthquakeintheIndianOceaninDecember,2004.Itkilledtensoftho
Reliefworkerswereshockedbywhattheysaw.
MindThoseMannersontheSubwaySo,thereyouare,justsittingthereinthesubwaycar,enjoyingthatbookyoujustbought
TheeyeofahurricanereferstoitsWhichofthefollowingisNOTa"requirement"fortheformationofahurricane?
Accordingtothepassage,Coustean’sinfluenceisgreatbecausehe______.WhichofthefollowingstatementsaboutCousteau’sf
TheIcemanOnaSeptemberdayin1991,twoGermanswereclimbingthemountainsbetweenAustriaandItaly.Highuponamountai
SpellingandWritingThereisapopularbeliefamongparentsthatschoolsarenolongerinterestedinspelling.NoschoolI
随机试题
环境保护法的基本原则不包括【】
A.血尿伴肾绞痛B.血尿伴膀胱刺激症状C.血尿伴水肿、高血压D.血尿伴肾肿块E.血尿伴皮肤黏膜出血肾肿瘤可见
急性脊髓炎
A.乙胺嘧啶B.苄青霉素C.特布他林D.红霉素E.甲硝唑治疗厌氧菌感染的首选药是
工程量清单的每一个细目,不论有无列出数量,都须填入单价或总价。( )
关于职业健康安全和环境管理体系标准的比较,说法正确的是( )。
关于税收执法监督,下列表述正确的是()。
个人贷款与公司贷款比较,()是个人贷款最明显的特征。
阅读下面材料,回答下面问题。××省人民政府文件【2005】×府发6号××省人民政府转发省劳动保障局等部门《关于安宁市完善城镇社会保障体系试点情况报告》的决定各市(区)人民政府、省各有关委办局、
Thereareagreatmanybooks,websites,andtraining【C1】______todaymoreorlessdedicatedtotheideathatbeingboredisama
最新回复
(
0
)