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
56
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
NewChangesinAmericanLifeOnceitwaspossibletodefinemaleandfemaleroleseasilybythedivisionoflabor.Menworke
Thecuriouslooksfromthestrangersaroundhermadeherfeeluneasy.
MindThoseMannersontheSubwaySo,thereyouare,justsittingthereinthesubwaycar,enjoyingthatbookyoujustbought
TheAnimalsinDesertSomedesertanimalscansurvivetheverystrongsummerheatanddrynessbecausetheyhaveveryunusual
Wearewastingprecioustimesittingaroundhere.
NaturalGas1.Naturalgasisproducedfromreservoirsdeepbeneaththeearth’ssurface.Itisafossilfuel(矿物燃料),meaningtha
AVerySlowRideThesurfaceoftheearthmayseemverystabletoyou.Butyoumightbeamazedifyouknewsomeofthething
Energyequalsmasstimesthespeedoflightsquared.ThisisthefamousequationofAlbertEinstein.It(51)tothecategoryofth
MusicalTrainingCanImproveCommunicationSkillsAmericanscientistssaymusicaltrainingseemstoimprovecommunicationsk
KeepingCutFlowers1Whileeverybodyenjoysfreshcutflowersaroundtheirhouse,fewpeopleknowhowtokeepthemforaslong
随机试题
在Word2010中,可以在________中查看页数、总页数等信息。
阑尾最常发生的肿瘤是
根据我国有关规定,省辖市、自治区首府及人口在()城市的总体规划,由所在省、自治区人民政府审查同意后,报国务院审批。
下列()最符合有机疏散理论的思想。
下列属于地下水的动态特征的是()。
在圆形水池施工中,缠丝时严格控制钢线间距,缠到锚固槽时,用( )锚定。
(a1a4-b1b4)(a2a3-b2b3)方法一由于行列式含零较多,可直接用降阶法处理,即方法二利用行列式的性质,化为准对角行列式计算,即先将第四列依次与第二、三列交换位置,再将第四行依次与第二、三行交换位置,得
VBA"定时"操作中,需要设置窗体的"计时器间隔"(TimerInterval)属性值。其计量单位是()。
TheIdealHusbandSciencenowmightbeabletoexplainwomen’sfascinationwithBradPitt’sfaceandGeorgeClooney’seye
TheTreesHaveEyesAAnelaboratecombinationoftechnologiesisbeingdeployedtotrytocurbtheillegalhuntingofendanger
最新回复
(
0
)