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
75
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.
Auroras may be seen in the southern regions of the United States when______.
选项
A、magnetic storms do not affect Earth
B、solar flares are very intense
C、the speed of the solar wind is reduced
D、the excitation of atoms is low
答案
B
解析
本题细节定位于倒数第二段最后一句话“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”。由此可知,当太阳耀斑和极光活动非常强烈时,在远至美国的南部地区可能会出现极光。因此选择B。
转载请注明原文地址:https://kaotiyun.com/show/MbTO777K
0
考博英语
相关试题推荐
Duringrecentyearswehaveheardmuchabout"race":howthisracedoescertainthingsandthatracebelievescertainthingsand
JusthowmuchdoestheConstitutionprotectyourdigitaldata?TheSupremeCourtwillnowconsiderwhetherpolicecansearchthe
【T1】Whenyouareinthebusinessofsendingspacecrafttootherplanets,itisprobablywisetodoeverythingyoucantokeepyo
Thepatient’sprogresswasveryencouragingashecould______getoutofbedwithouthelp.
Mr.Smithbecamevery______whenitwassuggestedthathehadmadeamistake.
Ateacherissomeonewhocommunicatesinformationorskillsothatsomeoneelsemaylearn.Parentsarethe【C1】______teachers.Ju
Therearefourbasictypesofcompetitioninbusinessthatformacontinuumfrompurecompetitionthroughmonopolisticcompetiti
Usingextremelydifferentdecoratingschemesinadjoiningroomsmayresultin______andlackofunityinstyle.
Anewstudysuggeststhatcontrarytomostsurveys,peopleareactuallymorestressedathomethanatwork.Researchersmeasured
IndustrialproductionmanagerscoordinatetheresourcesandactivitiesrequiredtoproducemillionsofgoodseveryyearintheU
随机试题
简述美国独立管制机构的特点。
在国际上,根据各种保险业务的性质和经营规则,将整个保险业务划分为()
非金融类不良资产是指非金融机构所有。但不能为其带来经济利益.或带来的经济利益低于账面价值,已经发生价值贬损的资产,以及各类金融机构作为中间人委托管理其他法人或自然人财产形成的不良资产等其他经监管部门认为的不良资产。()
你的助理小王工作时常常先激情满怀,加班加点地干,过两天热情就迅速消退,常把单位的活动搞得虎头蛇尾。你应该()。
企业难以将某项变更区分为会计政策变更还是会计估计变更的,应将其作为会计政策变更处理。()
按市场工具划分,资本市场不包括哪一项?()
若f(x)在[a,b]上具有连续的导数,且f(a)=f(b)=0,又,则=[].
经济文化相对落后的国家建设社会主义具有长期性,这是因为
将内存变量定义为全局变量的VisualFoxPro命令是
A、He’sindependent.B、He’sambitious.C、He’srighteous.D、He’suntrustworthy.D语义理解题。男士说如果他们拒绝Peter的报价,他们可能就找不到别的合作者了;女士说她也是这么想的
最新回复
(
0
)