地球磁气圈作用如筛子
文章来源:未知 文章作者:enread 发布时间:2012-10-25 05:39 字体: [ ]  进入论坛
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ESA's quartet of satellites studying Earth's magnetosphere(磁气圈), Cluster, has discovered that our protective magnetic bubble lets the solar wind in under a wider range of conditions than previously1 believed. Earth's magnetic field is our planet's first line of defence against the bombardment of the solar wind. This stream of plasma2 is launched by the Sun and travels across the Solar System, carrying its own magnetic field with it.
 
Depending on how the solar wind's interplanetary magnetic field -- IMF -- is aligned3 with Earth's magnetic field, different phenomena4 can arise in Earth's immediate5 environment.
 
One well-known process is magnetic reconnection, where magnetic field lines pointing in opposite directions spontaneously break and reconnect with other nearby field lines. This redirects their plasma load into the magnetosphere, opening the door to the solar wind and allowing it to reach Earth.
 
Under certain circumstances this can drive 'space weather', generating spectacular aurorae6, interrupting GPS signals and affecting terrestrial(陆地的) power systems.
 
In 2006, Cluster made the surprising discovery that huge, 40 000 km swirls7 of plasma along the boundary of the magnetosphere -- the magnetopause -- could allow the solar wind to enter, even when Earth's magnetic field and the IMF are aligned.
 
These swirls were found at low, equatorial latitudes9, where the magnetic fields were most closely aligned.
 
These giant vortices are driven by a process known as the Kelvin-Helmholtz (KH) effect, which can occur anywhere in nature when two adjacent(邻近的) flows slip past each other at different speeds.
 
Examples include waves whipped up by wind sliding across the surface of the ocean, or in atmospheric10 clouds.
 
Analysis of Cluster data has now found that KH waves can also occur at a wider range of magnetopause locations and when the IMF is arranged in a number of other configurations11, providing a mechanism12 for the continuous transport of the solar wind into Earth's magnetosphere.
 
"We found that when the interplanetary magnetic field is westward13 or eastward14, magnetopause boundary layers at higher latitude8 become most subject to KH instabilities, regions quite distant from previous observations of these waves," says Kyoung-Joo Hwang of NASA's Goddard Space Flight Center and lead author of the paper published in the Journal of Geophysical Research.


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1 previously bkzzzC     
adv.以前,先前(地)
参考例句:
  • The bicycle tyre blew out at a previously damaged point.自行车胎在以前损坏过的地方又爆开了。
  • Let me digress for a moment and explain what had happened previously.让我岔开一会儿,解释原先发生了什么。
2 plasma z2xzC     
n.血浆,细胞质,乳清
参考例句:
  • Keep some blood plasma back for the serious cases.留一些血浆给重病号。
  • The plasma is the liquid portion of blood that is free of cells .血浆是血液的液体部分,不包含各种细胞。
3 aligned 165f93b99f87c219277d70d866425da6     
adj.对齐的,均衡的
参考例句:
  • Make sure the shelf is aligned with the top of the cupboard.务必使搁架与橱柜顶端对齐。
4 phenomena 8N9xp     
n.现象
参考例句:
  • Ade couldn't relate the phenomena with any theory he knew.艾德无法用他所知道的任何理论来解释这种现象。
  • The object of these experiments was to find the connection,if any,between the two phenomena.这些实验的目的就是探索这两种现象之间的联系,如果存在着任何联系的话。
5 immediate aapxh     
adj.立即的;直接的,最接近的;紧靠的
参考例句:
  • His immediate neighbours felt it their duty to call.他的近邻认为他们有责任去拜访。
  • We declared ourselves for the immediate convocation of the meeting.我们主张立即召开这个会议。
6 aurorae 91494244af6752255787b15fc40dfa9f     
n.北极光,南极光,黎明;晨曦( aurora的名词复数 );曙光;朝霞;北极光
参考例句:
7 swirls 05339556c814e770ea5e4a39869bdcc2     
n.旋转( swirl的名词复数 );卷状物;漩涡;尘旋v.旋转,打旋( swirl的第三人称单数 )
参考例句:
  • Swirls of smoke rose through the trees. 树林中升起盘旋的青烟。 来自辞典例句
  • On reaching the southeast corner of Himalaya-Tibet, It'swirls cyclonically across the Yunnan Plateau. 在到达喜马拉雅--西藏高原东南角处,它作气旋性转向越过云南高原。 来自辞典例句
8 latitude i23xV     
n.纬度,行动或言论的自由(范围),(pl.)地区
参考例句:
  • The latitude of the island is 20 degrees south.该岛的纬度是南纬20度。
  • The two cities are at approximately the same latitude.这两个城市差不多位于同一纬度上。
9 latitudes 90df39afd31b3508eb257043703bc0f3     
纬度
参考例句:
  • Latitudes are the lines that go from east to west. 纬线是从东到西的线。
  • It was the brief Indian Summer of the high latitudes. 这是高纬度地方的那种短暂的晚秋。
10 atmospheric 6eayR     
adj.大气的,空气的;大气层的;大气所引起的
参考例句:
  • Sea surface temperatures and atmospheric circulation are strongly coupled.海洋表面温度与大气环流是密切相关的。
  • Clouds return radiant energy to the surface primarily via the atmospheric window.云主要通过大气窗区向地表辐射能量。
11 configurations 86f23519571eb918e8812e1979d55409     
n.[化学]结构( configuration的名词复数 );构造;(计算机的)配置;构形(原子在分子中的相对空间位置)
参考例句:
  • Such configurations, obtained theoretically by calculation, are called models of a star. 通过理论计算得到的恒星结构称为恒星模型。 来自辞典例句
  • The other two configurations have overriding advantages for special applications. 其它两种接法对特殊应用具有突出的优点。 来自辞典例句
12 mechanism zCWxr     
n.机械装置;机构,结构
参考例句:
  • The bones and muscles are parts of the mechanism of the body.骨骼和肌肉是人体的组成部件。
  • The mechanism of the machine is very complicated.这台机器的结构是非常复杂的。
13 westward XIvyz     
n.西方,西部;adj.西方的,向西的;adv.向西
参考例句:
  • We live on the westward slope of the hill.我们住在这座山的西山坡。
  • Explore westward or wherever.向西或到什么别的地方去勘探。
14 eastward CrjxP     
adv.向东;adj.向东的;n.东方,东部
参考例句:
  • The river here tends eastward.这条河从这里向东流。
  • The crowd is heading eastward,believing that they can find gold there.人群正在向东移去,他们认为在那里可以找到黄金。
TAG标签: earth solar magnetic
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