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地球能有多冷? – 译学馆
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地球能有多冷?

How Cold Can Earth Get?

Thanks to Brilliant for supporting this episode of SciShow.
感谢Brilliant对本期《科学秀》的支持
Go to Brilliant.org/SciShow to learn how
登录Brilliant.org/SciShow学习如何
you can take your STEM skills to the next level.
把你的理工科技能提升到一个新的水平
地球能有多冷?
In July 1983, a weather station in Antarctica
1983年7月 南极洲的一个气象站
recorded the lowest air temperature ever measured on Earth.
测量出了地球史上的最低气温
It was about -89 degrees Celsius…
大约是-89摄氏度
which is colder than the average temperature on Mars.
比火星的平均温度还要低
But 25 years later, scientists analyzing satellite data
但25年后 科学家分析卫星数据时发现
found small pockets high up on the East Antarctic Plateau
在南极洲东部高原之上的小片地区
where temperatures routinely drop about five degrees lower,
其温度会在定期降到-94℃左右
making them the coldest spots we know of on Earth.
成为地球上已知最冷的地方
But these pockets aren’t just for record books:
但这些地区不只创造低温记录
They’re also helping us understand how cold it’s possible to get on the surface of our planet
还有助于我们了解地球表面能有多冷
and what conditions it takes to get that cold.
以及什么条件下会如此寒冷
These record-breaking temperatures happen during long
这些破纪录的温度都是在
polar nights within little hollows in the ice sheet,
极地极夜时
more than three-and-a-half kilometers above sea level.
海拔3.5公里以上的冰原小洞里量出的
On still nights when the sky is clear,
在晴朗无风的夜晚
the air near the surface of the snow cools down
当热量辐射到太空时
as heat radiates into space,
雪面附近的空气会变冷
and it becomes denser than the slightly warmer air surrounding it.
比周围温度略高的空气有更大的密度
As a result, it starts sliding downhill along the ice sheet
于是 它开始沿着冰原向下滑动
and sinks into these hollows.
沉到这些洞里
If the wind is light enough, the super-cold air gets trapped down there,
如果风够小 超级冷空气就会困在那里
and it acts like a kind of ice pack,
就像一个冰袋
which brings down the temperature of the surface even more.
进一步降低了地表的温度
When that happens,
当这种情况发生时
the air temperature drops down to those record low
气温会降至历史最低水平
until weather stirs things up again.
直到受到天气的干扰
But the lack of wind isn’t the only thing you need to get those temperatures.
但少风并非是导致低温的唯一条件
It also has to be extremely dry,
还必须非常干燥
because water vapor can keep heat from escaping.
因为水蒸气可以防止热量流失
See, heat might feel like this abstract thing,
热量一词听起来可能感觉很抽象
but it’s just waves of infrared radiation.
但它只是红外辐射波
So when heat escapes our planet,
所以当热量从地面散发出去时
infrared waves are radiating from the ground and into space.
红外波从地面辐射到太空中
When temperatures drop, there’s less heat coming from the surface,
当温度下降时 来自地表的热量就会减少
so the waves carrying that heat away lose energy and stretch out.
所以携带热量的红外波会失去能量 波长会变长
And those longer waves are more easily absorbed by water vapor in the air.
更长的电磁波更容易被空气中的水蒸气吸收
So if there’s any moisture in the air,
所以如果空气中有水分
a lot of that radiation won’t escape into space;
很多辐射不会进入太空
it will be absorbed by the water
它会被水吸收
and sent back to the ground to warm things up.
然后返还地面 增加地表温度
In fact, to get below about -90 degrees,
事实上 要想温度低于-90度
you need less than a millimeter’s worth of water in the entire atmosphere
从地表到太空的整个大气中
stretching from the ground all the way into space.
降雨量要低于一毫米
In other words, if you wrung out all the water from that air,
换句话说 如果你从空气中拧出所有的水
it wouldn’t even reach the one-millimeter line on a rain gauge.
它甚至连雨量计上的一毫米都达不到
Those are some strict requirements.
这些要求都十分严格
But for the researchers studying this,
但对研究人员来说
the really surprising thing wasn’t just that
真正令人惊讶的事情不仅是
the temperature got so low in these pockets:
这些地方的温度变得很低
It was that, over time,
而是随着时间的推移
it dropped to nearly the same low temperature over and over again.
温度反复下降 但与之前的记录几乎一致
Like, across 14 years and hundreds of kilometers of the Plateau,
比如 历经14年 在数百公里的高原
the lows at the coldest sites hovered right around -94 degrees,
最冷地区的最低温度在-94度左右上下徘徊
just above the all-time low of -98.
略高于历史最低点-98
So scientists wondered if the temperature was hitting some kind of threshold
因此 科学家猜想温度是否达到了某种阈值
if it was reaching the coldest temperature possible on the surface of our planet.
是否达到了地球表面可能达到的最低温度
And that seems to be what’s happening!
这件事情似乎正在发生!
See, even on still, dry nights,
你看 在干燥平静的夜晚
the heat doesn’t radiate away forever.
热量永远也不会散发出去
Instead, a lot of that infrared radiation gets trapped by carbon dioxide
相反 大量的红外辐射会被二氧化碳捕获
because while CO2 always absorbs some heat,
因为二氧化碳总是会吸收一些热量
it’s especially good at absorbing these longer wavelengths.
尤其擅长吸收较长的电磁波
So at that point, the air itself is trapping heat
所以在这一点上 空气本身就在吸收热量
and sending it back toward the surface.
然后把它送回地面
The atmosphere essentially acts like a blanket,
大气就像一张毯子
and heat can only escape from the surface really slowly.
热量只能缓慢地从表面逸出
Eventually, around -98 degrees Celsius,
最终 到-98摄氏度左右
the temperature is dropping less than half a degree a day
温度开始以一天不到半度的温度下降
too slowly to really change
温度降低得太慢 以至于
befor the weather shifts and winds stir things up.
在天气变化和有风干扰之前 还无法降下来
In theory,
理论上
if air could sit still for days or weeks on end,
如果空气可以连续几天或几周保持静止
the temperature could drop lower,
温度可能会下降得更低
but on a planet with so much weather,
但在一个气候多样的星球上
-98 degrees is essentially as cold as it gets.
-98度基本上是能达到的最冷温度
Which, hey, is fine by me.
这对我来说 倒无所谓
It takes some creative thinking
发现和揭开某些事物的神秘面纱
to find and demystify something like
比如地球上最冷的地方
the coldest place on Earth.
需要一些创造性思维
And if you’re interested in learning to think like a scientist
如果你很有兴趣想学会像科学家一样思考
or better understand the science behind discoveries like this
或更好地理解这类发现背后的科学原理
you might be interested in the courses offered by Brilliant.
你可能会对Brilliant提供的课程感兴趣
Brilliant offers dozens of courses in science, engineering, and math.
Brilliant提供数十门科学 工程和数学课程
They’re hands-on,
这些都是需要亲身实践的课程
with interactive quizzes and guided problems, with explanations
有互动式测验 指导问题 并进行解释
all designed by educators at leading universities,
都是由顶尖大学的教育工作者设计的
like MIT, Caltech, and Duke.
比如麻省理工学院 加州理工学院和杜克大学
And you can save 20% on an annual premium subscription
如果你是Brilliant.org/SciShow网站首批注册的前200人之一
if you’re one of the first 200 people to sign up at Brilliant.org/SciShow.
年费会员可以打八折哦

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地球最冷的地方在哪里?最冷记录是多少度?让我们一起来揭开它的神秘面纱吧

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