章节大纲

  • 常规

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  • 中间层

    Lesson
    ::经验教训

     

    Close-up view of a textured surface resembling liquid, with reddish tones and bubbles.
     

    Next up: a field trip to the mesosphere!
    ::下一位: 前往中间层的实地考察!

    Not so fast. The mesosphere is the least known layer of the  atmosphere . The mesosphere lies above the highest  altitude  an airplane can go. It lies below the lowest altitude a spacecraft can  orbit . Maybe that's just as well. If you were in the mesosphere without a space suit, your blood would boil! This is because the pressure is so low that liquids would boil at normal body  .
    ::不要太快。 中间层是大气中最不为人知的层。 中间层位于飞机可以飞到的最高高度之上。 中间层位于航天器可以飞到的最低高度之下。 也许这也是同样的情况。 如果您在中间层没有太空服, 血液就会沸腾! 这是因为压力太低, 液体会在正常身体中沸腾 。

    Mesosphere
    ::中间层

    The  mesosphere  is the layer above the  . It rises to about 85 kilometers (53 miles) above the surface. Temperature decreases with altitude in this layer.
    ::中间层是 . 上方的层。 它会升至约85公里(53英里)的表面之上, 温度会随着该层的高度而下降 。

    Temperature in the Mesosphere
    ::中间层中的温度

    There are very few gas molecules in the mesosphere. This means that there is little matter to absorb the Sun’s rays and  heat  the air. Most of the heat that enters the mesosphere comes from the stratosphere below. That’s why the mesosphere is warmest at the bottom.
    ::中间层的气体分子很少。 这意味着吸收太阳射线和热空气的物质很少。 进入中间层的大部分热来自下面的平流层。 这就是为什么中间层在底部最温暖的原因。

    Meteors in the Mesosphere
    ::气象圈中的气象器

    Did you ever see a  meteor shower  ( Figure )?   burn as they fall through the mesosphere. The space   experience friction with the gas molecules. The friction makes the meteors get very hot. Many meteors burn up completely in the mesosphere.
    ::你是否见过流星雨(图)?当流星雨坠落于中间层时会燃烧。空间与气体分子发生摩擦。摩擦使流星变得非常热。许多流星在中间层完全燃烧。

    A view of the Milky Way with meteors streaking through the night sky.
     
    The Perseid meteor shower with the Milky Way.

    Transient Luminous Events
    ::瞬间光辉事件

    Transient Luminous Events are brief flashes of light that can sometimes be seen above   in the upper atmosphere.  There are many types, including sprites, elves, and trolls, which were named after fairy-tale creatures because of their elusive, difficult-to-photograph nature.  Like  lightning , they are electrical discharges, but they are not the same thing as lightning. They more closely resemble the discharges seen in fluorescent tubes. These events occur much higher up in the atmosphere than lightning ( Figure ).
    ::瞬息万变的事件是短短的光亮闪光,有时可以在上层大气中看到。 有许多种类,包括精灵、精灵和巨魔,它们以童话般的生物命名,因为它们是难以捉摸的、难以摄影的。 和闪电一样,它们是放电,但和闪电不一样。 它们更接近荧光管中看到的放电。 这些事件在大气中比闪电( 图示)要高得多。

    Transient Luminous Events: elves, sprites, and blue jets in atmospheric layers.
     
    Red sprites occur in the mesosphere, 50-90 km above the ground. Blue jets are electrical discharges in the stratosphere, while lightning only occurs in the troposphere.

    Polar Mesospheric Clouds
    ::极地中层云

     in the mesosphere are very rare. The ones that exist occur near the poles. The clouds are called  polar mesospheric clouds . At the edge of these clouds are noctilucent clouds ( Figure ). They are forming more often now, perhaps as a result of  climate  change.
    ::中间层中的云层非常罕见。 存在的云层出现在极地附近。 云层被称为极地中间层云层。 在这些云层的边缘是高温云层( 图层 ) 。 它们现在的形成频率更高, 也许是气候变化的结果。

    Polar mesospheric clouds at twilight, featuring a dusky sky and silhouetted trees.
     
    Noctilucent clouds are the highest clouds in the atmosphere.

    Mesopause
    ::中观

    At the top of the mesosphere is the mesopause. Temperatures here are colder than anywhere else in the atmosphere. They are as low as -100° C (-212° F)! Nowhere on Earth’s surface is it that cold.
    ::在中间层的顶端是中间层。 这里的温度比大气中其他地方都冷, 低到 - 100 °C (-212 °F ) 。 地球上没有任何地方是这么冷的。

    Summary
    ::摘要

    • The mesosphere has a very low density of gas molecules.
      ::中间层气体分子密度非常低。
    • Temperature decreases in the mesosphere with altitude. This is because the heat source is the stratosphere.
      ::中间层温度随高度而下降,这是因为热源是平流层。
    • The mesosphere has several types of electrical discharges and rare clouds.
      ::中间层有几种类型的放电和稀有云。
    • The mesosphere is no place for human life!
      ::中间层不是人类生命的地方!

    Review
    ::回顾

    1. How does temperature change with altitude in the mesosphere? Why?
      ::中间层高度的温度如何变化?为什么?
    1. What types of clouds are found in the mesosphere?
      ::在中间层中发现了什么类型的云?
    1. How can meteors burn in the mesosphere when the air density is so low?
      ::当空气密度如此低时,流星怎么会在中间层燃烧呢?

    Explore More
    ::探索更多

    Use the resource below to answer the questions that follow.
    ::利用以下资源回答以下问题。

    1. Where is the mesophere found?
      ::中间线在哪里找到的?
    1. What does it protect us from? What is a shooting star?
      ::它能保护我们免遭什么?
    1. What are noctilucent clouds?
      ::什么是高贵的云?
    1. When can noctilucent clouds be seen? Why?
      ::何时能看见高贵的云?