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
考研
A. Cloud-to-ground lightening occurring in the U. S. B. Types of lightening C. Cause of lightening D. Differences between thunde
A. Cloud-to-ground lightening occurring in the U. S. B. Types of lightening C. Cause of lightening D. Differences between thunde
admin
2012-05-19
70
问题
A. Cloud-to-ground lightening occurring in the U. S.
B. Types of lightening
C. Cause of lightening
D. Differences between thunder and thunderstorm
E. Frequencies of thunderstorms occurring in the world and the U. S.
F. Shock waves as thunder
G. Forming process of lightening
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.
41. ______
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.
42.______
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.
43. ______
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.
44. ______
Thunder is generated by the tremendous heat released in a lightning discharge. Temperatures near the discharge can reach as high as 50,000T within thousandths of a second. This sudden heating acts as an explosion, generating shock waves we hear as thunder.
45. ______
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 1-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.
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.
选项
答案
G
解析
本段简述了当电压足够大时,穿过云层,释放大量的电子,于是就形成了闪电,因此本段的主旨应该是闪电的形成过程。
转载请注明原文地址:https://kaotiyun.com/show/QNp4777K
0
考研英语一
相关试题推荐
Publicityisanypromotionalcommunicationaboutanorganizationoritsproductsthatispresentedbythemediabutisnotpaid
Highoilpriceshavenotyetproducedaneconomicshockamongconsumingcountries,butfurtherrises,especiallysharp(1)_____,
Eachscientificspecialtyhasitsownsetofjournals.PhysicistshavePhysicalReviewLetters,cellbiologistshaveCell,neuro
What’sthepublic’sopinionaboutnuclearindustry?ThemostimportantreasonwilytheBushadministrationsupportmorenewnuc
AccordingtothepassagewhatappearstobechangingrapidlyinBritainandtheUSA?Aslargeaslearningtouseawordprocess
Television—themostpervasiveandpersuasiveofmoderntechnologies,markedbyrapidchangeandgrowth—ismovingintoanewera,
WhichofthefollowingreflectsthechangeofCatholicChurch?Therelationshipbetweenthefirsttwoparagraphscanbedescrib
Bysaying"tobehappyeverydayistobenothappyatall",Popmeans______.Thepurposeoftheauthorinwritingthetextis
Accordingtothefirstparagraph,asmallgroupsucceeded______.Thepurposeoftheauthorinwritingthetextisto______.
Thescreeninthelivingroomhasbeen______inthefamily.Itwasmygrandmother’soriginally.
随机试题
解脲脲原体常用的鉴定试验是
人乳与牛乳比较正确的是
关节盘的分区不包括
患儿,尿频尿急,尿道灼痛,小便短赤,小腹坠胀,恶寒发热,口苦口粘,舌质红,苔黄腻,脉滑数,指纹紫。辨证用方为
总图运输方案比选的内容有()
负有安全生产监督管理职责的部门实施监督管理;除了主动进入生产经营单位进行检查外,建立()也是一种有效的监督方式。
菜市水利工程项目进行招标,招标人在其行政主管部门领导田某的干预下,选择了甲建筑工程公司并与之签订了施工承包合同。在施工过程中,甲建筑单位未按施工图样中的材料数量进行施工。根据场景,回答下列问题:
商业银行给集团客户贷款时,应在贷款合同中约定,借款人若(),银行有权单方决定停止支付借款人尚未使用的贷款,并提前收回部分或全部贷款本息。
根据本量利分析原理,只能提高安全边际量而不会降低保本点销售量的措施是()。
【2015农业银行】季度财务会计报告的保管期限为()年。
最新回复
(
0
)