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《北极光》

(2008-03-31 14:40:38)
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it

 

The Northern Lights

 

     The Sun is stormy and has its own kind of weather. It is so hot and active that even the Sun's gravity cannot hold its atmosphere in check1! Energy flows away from the Sun toward the Earth in a stream of electrified particles that move at speeds around a million miles per hour2. These particles are called plasma, and the stream of plasma3 coming from the Sun is called the solar wind. The more active the Sun, the stronger the solar wind.

     The solar wind constantly streams toward the Earth, but don't worry because a protective magnetic field surrounds our planet. The same magnetic field that makes your compass point north also steers the particles from the Sun to the north and south poles. The charged particles become trapped in magnetic belts around the Earth. When a large blast of solar wind crashes into the Earth's magnetic field, the magnetic field first gets squeezed and then the magnetic field lines break and reconnect.4

     The breaking and reconnecting of the magnetic field lines can cause atomic particles called electrons trapped in the belts to fall into the Earth's atmosphere at the poles. As the electrons fall to the Earth, they collide with gas molecules in the atmosphere, creating flashes of light in the sky. Each atmospheric gas glows a different color. Oxygen and nitrogen glows red and green and nitrogen glows violet-purple. As these various colors glow and dance in the night sky, they create the Northern Lights and the Southern Lights.

     Watching auroras is fun and exciting, but normally you can only see them in places far north like Alaska and Canada. The movement of the aurora across the sky is usually slow enough to easily follow with your eyes but they can also pulsate, flicker, or even move like waves. During solar maximum,5 auroras are seen as far south as Florida, even Mexico!6

      Auroras often seem to be very close to the ground, but the lowest aurora is still about 100 kilometers above the ground, a distance much higher than clouds are formed or airplanes can fly. A typical aurora band can be thousands of kilometers long, a few hundred kilometers high, but only a few hundred meters thick.

      We hope you are able to travel to far-north places like the Arctic Circle and see the Northern Lights at least once during your lifetime. We know you will never forget it!

 

词汇:

electrify v.使带电

plasma n.等离子体

steer v.驾驶;导向,引向

electron n.电子

collide v.碰撞

molecule n.分子

aurora n.极光

pulsate v.跳动

flicker v.闪烁

Arctic adj. 北极的

 

注释:

1.The sun cannot hold its atmosphere in check:太阳无法控制它自己的大气层。hold…in check是“控制,支配”,例如:

He wants to hold the company in check through the manager's secretary.

他想通过经理的秘书控制公司。

2.move at speeds around a million miles per hour:以约100万英里的时速运动。Around=about。

3.the stream of plasma:等离子流

4.…the magnetic field first gets squeezed and then the magnetic field lines break and reconnect:首先,磁场受到挤压,接着磁场磁力线断开又闭合。

5.During solar maximum:在太阳风暴达到最高峰的期间

6.auroras are seen as far south as Florida,even Mexico!:位于极南面的佛罗里达州,乃至于墨西哥都能看到极光。far south意为“极南面”。

 

 

 太阳是狂暴的,有它自己独特的气候。太阳太热,其活动又太剧烈,以至于无法控制它自己的大气层。热量以电粒子流的形式逃离太阳,流向地球,时速高达100万英里。这些粒子叫等离子体,来自太阳的等离子流叫太阳风。太阳活动越剧烈,太阳风越强烈。

    太阳风不断地流向地球,但是不必担心,因为有一个保护性的磁场包围着我们的地球。使指南针指向北方的相同的磁场也把来自太阳的粒子导向地球的南北两极。这些受控的粒子被吸附在地球周围的磁场。当强大的太阳风侵入地球磁场时,首先磁场受到挤压,接着磁场磁力线断开又闭合。

    磁场磁力线的断开和闭合产生叫做电子的原子粒子,被截留在磁场,落人地球两极的大气层。等离子流的电子进人地球,与大气层的气体分子发生碰撞,在天空中产生光芒。每一种大气层的气体产生不同颜色的光。氧和氮发红绿光,氮气发蓝紫光。当这些不同的颜色在夜空中闪烁跳跃时,就形成了北极光和南极光。

    看极光是很有意思也很令人振奋的。然而通常只有在极北面,像阿拉斯加州和加拿大等地方才能看到。横过天空的极光移动速度通常很慢,用肉眼就能很轻易地观测到。而他们还能跳动闪烁甚至像波一样流动。在太阳风暴达到最高峰的期间,明亮的北极光甚至在位于极南面的佛罗里达州乃至墨西哥都能看到。

    极光似乎很接近地面,但是最靠近地面的极光离地面也有100公里,比云层都高,飞机也无法到达。一条典型的极光带有数千公里长,几百公里高,但是只有几百米厚。

    希望你在有生之年至少去极北面像北极圈等地区旅游一次,看看北极光。此次经历必将使你终生难忘。

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