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
From Dr. R. S. Scorer of Britain’s Imperial College of Science comes the latest theory about the cause of lightening flashes. Dr
From Dr. R. S. Scorer of Britain’s Imperial College of Science comes the latest theory about the cause of lightening flashes. Dr
admin
2009-02-10
52
问题
From Dr. R. S. Scorer of Britain’s Imperial College of Science comes the latest theory about the cause of lightening flashes. Dr. Scorer believes the cause is hail falling through super - cooled clouds, lee particles bouncing off the falling hail acquire a positive charge and rise to the top of the cloud while the hail carries a negative charge to the bottom of the cloud.
According to Dr. Scorer, Benjamin Franklin first proved thunderclouds are charged with electricity. Later investigation showed that the tops of the clouds have a great positive charge and the bottoms a great negative charge.
When the charges become great enough to break down the insulating properties of the air, lightening flashes carry the electricity within the cloud, or from cloud to cloud, or from cloud to earth. But the question remained: how do the charges develop within the cloud?
To seek the cause, Dr. Scorer and his colleagues at the college first duplicated thundercloud currents in a liquid tank. They doubt that mixture takes place only in the tops of the clouds.
Next a study of thunderclouds over the North Atlantic showed that lightening occurs only when the air temperature around the cloud is below freezing. Particles at the top of the cloud begin to freeze, but those in the remainder of the cloud stay unfrozen although below freezing temperature.
To measure moisture, the scientists sent planes equipped with external refrigerated rods into the clouds. The idea was that moisture would freeze on the rods and could later be measured. The men found, however, that some of the moisture particles bounced off the rods. This accidental discovery set the scientists on a new course of action.
In the laboratory, S. E. Reynolds whirled a refrigerated rod through ice particles and found that the particles bounced off the rod acquired a positive charge. This was the missing link. Without hail and super-cooled clouds, he concluded there could be no lightening.
A study of thunderclouds over the North Atlantic showed that lightening occurred only when the air temperature ______.
选项
A、around the cloud was below freezing
B、above the cloud was lower than the temperature below the cloud
C、around the cloud was above freezing
D、of the cloud was above freezing
答案
A
解析
见原文第五段,“Next a study of thunder clouds over the North Atlantic showed that lightening occurs only when the air temperature around the cloud is below freezing”,因此A为正确选项。
转载请注明原文地址:https://kaotiyun.com/show/qH6K777K
0
专业英语四级
相关试题推荐
TheMessagesinDistanceI.Peoplefromdifferentcultures【T1】______differently【T1】______A.NorthAmericansstandabouttwof
A、Becausetheyimperfectlylearnthespeechoftheirparents.B、Becausetheyprefertolearnthelanguageoftheirfriendsatsc
Time,asweknowit,isaveryrecentinvention.Themoderntime-senseishardlyolderthantheUnitedStates.Itisaby-produ
Collegeeducationornot,thisisadilemmaforthegraduatesofhighschool.Intermsofthisissue,peopleholddifferentopin
(1)Khalida’sfathersaysshe’s9—ormaybe10.AsmuchasSayedShahloveshis10children,thefunctionallyilliterateAfghanfa
Atsometimeinyourlifeyoumayhaveastrongdesiretodosomethingstrangeorterrible.However,chancesarethatyoudon
CurrentChallengesConfrontingU.S.HigherEducationThefirstchallenge:forceofthemarketplace•Currentsituation:—pr
Aftertravelinginthedesertformanydays,theyfoundatinyoasis,wheretherewasawelland______greengrass.
随机试题
面颊部开放性损伤,受伤后12h来就诊,局部处理应
开发设计阶段的质量管理的主要环节有()。
新月公司是一家由国家授权投资的机构单独投资设立的国有独资公司,关于新月公司的定位以及经营管理的一些问题,公司内部的看法不太一致,因此,该公司特向律师进行咨询。请根据上述情况和下列各问中设定的条件回答下列问题:关于新月公司的性质问题,下列说法正确的是:
代理记账机构可以接受委托、代表委托人填制原始凭证。()
某射手每次射击击中目标的概率是,且各次射击的结果互不影响.假设这名射手射击5次,求恰有2次击中目标的概率;
乌申斯基说:“如果你厌恶学生,那么,教育工作刚刚开始时就已经结束了。”这强调教师应具备()。
教师应引导幼儿在生活情境和阅读活动中自然地产生对文字的兴趣。()
教师职业道德建设包括()
まだ3月のはじめなのに、まるで夏の________暑い。
A、Sheforgottogivethemandirections.B、She’llgivethemannewdirections.C、Shedoesn’tknowwherethemanis.D、She’llrep
最新回复
(
0
)