首页
登录
职称英语
The spectacular auroral light displays that appear in Earth’s atmosphere aro
The spectacular auroral light displays that appear in Earth’s atmosphere aro
游客
2025-04-06
26
管理
问题
The spectacular auroral 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 auroral 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 crated 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 field. 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 solar wind, 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 auroral radiations of visual light.
The colors 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 a crimson light. Excited nitrogen atoms contribute bands of color 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 auroral activity are very intense, auroral 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. [br] What does the passage mainly discuss?
选项
A、The periodic variation in the displays of auroras.
B、The information and appearance of auroras around the Earth’s poles.
C、The factors that cause the variety of colors in auroras.
D、The methods used to observe auroras from outer space.
答案
B
解析
主旨题。本文主要讲述了aurora的成因、影响其色彩的因素以及极光的外观等方面的信息。故答案为B。
转载请注明原文地址:https://tihaiku.com/zcyy/4029457.html
相关试题推荐
Atthreethousandfeet,wideplainsbegintoappear,andthereisneveramomentw
Homeschoolingappearstobeagreatsuccessformiddle-classandwealthyfa
Homeschoolingappearstobeagreatsuccessformiddle-classandwealthyfa
Homeschoolingappearstobeagreatsuccessformiddle-classandwealthyfa
Hehadbeen_____toappearincourtonchargesofincitementoflawbreaking.A、ill
Whilestillcatching-uptomeninsomespheresofmodernlife,womenappear
Whilestillcatching-uptomeninsomespheresofmodernlife,womenappear
ThespectacularaurorallightdisplaysthatappearinEarth’satmospherearo
ThespectacularaurorallightdisplaysthatappearinEarth’satmospherearo
ThespectacularaurorallightdisplaysthatappearinEarth’satmospherearo
随机试题
Hippiesweremembersofayouthmovementofthe1960’sand1970’sthatstart
Bicyclesharinghasbeenahotlydebatedtopicoverthepasttwoyears.Bicycles
Tobesuccessfulinajob【B1】______,youshould【B2】______certainpersonal
Strictlyspeaking,ChristmasisthecelebrationofthebirthofJesusforpeople
十九大报告提出一个新目标,即“在本世纪中叶建成()的社会主义现代化强国。
“机械设置”对话框中下述()项的设置,主要用来设置图元之间交叉、发生遮挡关系时的
国际船舶登记制度中较为成功的是( )国际船舶登记制度。A.日本 B.美国
各种运输方式内外部的各个方面的构成和联系,就是( )。 A.运输系统
建设单位应当将大型的人员密集场所和其他特殊建筑工程的消防设计文件报送公安机关消防
某毛石混凝土条形基础顶面的墙体宽度0.72m,毛石混凝土强度等级C15,基底埋深
最新回复
(
0
)