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
The spectacular aurora light displays that appear in Earth’s atmosphere around the north and south magnetic poles were once myst
The spectacular aurora light displays that appear in Earth’s atmosphere around the north and south magnetic poles were once myst
admin
2019-08-27
59
问题
The spectacular aurora light displays that appear in Earth’s atmosphere around the north and south magnetic poles were once mysterious phenomena. Now, scientists have data from satellites and ground-based observations from which we know that the aurora brilliance is an immense electrical discharge similar to that occurring in a neon sign.
To understand the cause of auroras, first picture the Earth enclosed by its magnetosphere, a huge region created by the Earth’s magnetic field. Outside the magnetosphere, blasting toward the earth is the solar wind, a swiftly moving plasma of ionized gases with its own magnetic filed. Charged particles in this solar wind speed earthward along the solar wind’s magnetic lines of force with a spiraling motion. The Earth’s magnetosphere is a barrier to the solar winds, and forces the charged particles of the solar wind to flow around the magnetosphere itself. But in the polar regions, the magnetic lines of force of the Earth and of the solar wind bunch together. Here many of the solar wind’s charged particles break through the magnetosphere and enter Earth’s magnetic field. They then spiral back and forth between the Earth’s magnetic poles very rapidly. In the polar regions, electrons from the solar wind ionize and excite the atoms and molecules of the upper atmosphere, causing them to emit aurora radiations of visible light.
The colours of an aurora depend on the atoms emitting them. The dominant greenish white light comes from low energy excitation of oxygen atoms. During huge magnetic storms oxygen atoms also undergo high energy excitation and emit crimson light. Excited nitrogen atoms contribute bands of colour varying from blue to violet. Viewed from outer space, auroras can be seen as dimly glowing belts wrapped around each of the Earth’s magnetic poles. Each aurora hangs like a curtain of light stretching over the polar regions and into the higher latitudes. When the solar flares that result in magnetic storms and aurora activity are very intense, aurora displays may extend as far as the southern regions of the United States.
Studies of auroras have given physicists new information about the behavior of plasmas, which has helped to explain the nature of outer space and is being applied in attempts to harness energy from the fusion of atoms.
The passage describes the magnetosphere as a barrier (Line 9) because______.
选项
A、its position makes it difficult to be observed from Earth
B、it prevents particles from the solar wind from easily entering Earth’s atmosphere
C、it increases the speed of particles from the solar wind
D、it is strongest in the polar regions
答案
B
解析
本题细节定位于第二段第三、四句话“Charged particles in this solar wind speed earthward along the solar wind’s magnetic lines of force with a spiraling motion.The Earth’s magnetosphere is a barrier to the solar winds,and forces the charged particles of the solar wind to flow around the magnetosphere itself”。由此可知,太阳风中的带电粒子快速地向地球移动,地球的磁层是一道阻隔太阳风的屏障,并迫使太阳风中的带电粒子绕地球的磁层流动。据此可知,地球的磁层可以阻隔太阳风中的粒子轻易地穿过大气层,因此选择B。
转载请注明原文地址:https://kaotiyun.com/show/0bTO777K
0
考博英语
相关试题推荐
Thereisnodenyingthatstudentsshouldlearnsomethingabouthowcomputerswork,justasweexpectthematleasttounderstand
I’d______hisreputationwithotherfarmersandbusinesspeopleinthecommunity,andthenmakeadecisionaboutwhetherornott
Duringrecentyearswehaveheardmuchabout"race":howthisracedoescertainthingsandthatracebelievescertainthingsand
SomeAfricanAmericanshavehadaprofoundimpactonAmericansociety,changingmanypeople’sviewsonrace,historyandpolitic
Forme,scientificknowledgeisdividedintomathematicalsciences,naturalsciencesorsciencesdealingwiththenaturalworld(
【T1】Whenyouareinthebusinessofsendingspacecrafttootherplanets,itisprobablywisetodoeverythingyoucantokeepyo
Sincetheearlynineties,thetrendinmostbusinesshadbeentowardon-demand,always-availableproductsandservicesthatsuit
Mr.Smithbecamevery______whenitwassuggestedthathehadmadeamistake.
Ateacherissomeonewhocommunicatesinformationorskillsothatsomeoneelsemaylearn.Parentsarethe【C1】______teachers.Ju
Oursondoesn’tknowwhatto______attheuniversity;hecan’tmakeuphismindabouthisfuture.
随机试题
--Willyoucometothepartythisweekend?--______.
患者男,72岁。因进食时误吞鸭骨后吞咽困难和吞咽疼痛6小时,在当地医院就诊,经照X线片发现食管中段有不透光的阴影,由于当地医院条件有限,仅给予抗感染、对症和支持治疗两天,症状无明显缓解,且出现背部及胸骨后疼痛,多次呕吐,呕吐物为唾液样物,其中两次带有少许鲜
A、0B、∞C、5/4D、3/5C由—般结论
大气环境评价中的监测点的布设应尽量()反映评价范围内的环境空气质量。
Nowletuslookathowweread.Whenwereadaprintedtext,oureyesmoveacrossapageinashort,jerkymovement.Werecognizewo
大足宝顶山石刻在造像上不局限于佛像的宗教题材,而且用大画面、广角度、全方位反映于当时的社会生活、伦理道德、民间疾苦,是不可多得的世俗风情画,最突出表现有()。
在知识经济勃兴的今天,阅读已不仅仅关乎个人的修身养性,更攸关一个国家的国民素质和竞争力。因为,阅读习惯和阅读能力的欠缺将极大地损害人们的想象力和创造力,而想象力和创造力是一个国家一个民族永葆活力的源泉。有一个严峻的事实我们不得不面对:当代世界的知识创新、科
人类历史上,技术革命往往和社会发展的__________相互作用,互为因果。今天,以微博为代表的互联网技术应用正__________着它推进社会生活各个领域发生变化的巨大潜能。依次填入划横线部分最恰当的一项是()。
TheAmericansandEnglishmenbothspeakEnglish.AmericansandEnglishmenhavedifficultiesinunderstandingeachother.
Thewoman’snameisMaryJoanShute.Youmaycallher______.
最新回复
(
0
)