万物简史 第366期:进入对流层(7)

 Air is deceptive¹ stuff. Even at sea level, we tend to think of the air as being ethereal and all but weightless. In fact, it has plenty of bulk, and that bulk often exerts itself. As a marine² scientist named Wyville Thomson wrote more than a century ago: "We sometimes find when we get up in the morning, by a rise of an inch in the barometer³, that nearly half a ton has been quietly piled upon us during the night, but we experience no inconvenience, rather a feeling of exhilaration and buoyancy, since it requires a little less exertion⁴ to move our bodies in the denser⁵ medium." The reason you don't feel crushed under that extra half ton of pressure is the same reason your body would not be crushed deep beneath the sea: it is made mostly of incompressible fluids, which push back, equalizing the pressures within and without.

空气是一种很会骗人的东西。即使在海平面的高度，我们往往会认为空气很轻，几乎没有分量。实际上，空气质量很大，还往往表现出来。海洋科学家怀维尔·汤姆森在一个多世纪以前写道：“早上起床的时候，我们有时候发现气压计升高了2.5厘米，说明夜间有将近半吨的分量一直悄悄地压在我们身上，而我们并没有觉得什么不方便，倒是有一种精力充沛的感觉，因为在密度较大的气体旦我们移动身体只需要较小的力。”你在增加半吨重的压力之下不会产生被压垮的感觉，与你的身体在大海深处不会被压垮的原因是一样的：你的身体主要是由无法压缩的液体组成的；液体会产生推力，使体内和体外的压力保持平衡。

But get air in motion, as with a hurricane or even a stiff breeze, and you will quickly be reminded that it has very considerable mass. Altogether there are about 5,200 million million tons of air around us—25 million tons for every square mile of the planet—a not inconsequential volume. When you get millions of tons of atmosphere rushing past at thirty or forty miles an hour, it's hardly a surprise that limbs snap and roof tiles go flying. As Anthony Smith notes, a typical weather front may consist of 750 million tons of cold air pinned beneath a billion tons of warmer air. Hardly a wonder that the result is at times meteorologically exciting.

但是。要是空气处于流动状态，比如飓风，甚至是一阵强风，你很快会想到空气的质量还真不小。我们身边大约有5200万亿吨空气——本行星的每平方公里上有900多万吨——这是个不小的数量。当几百万吨空气以每小时五六十公里的速度流动的时候，树枝折断，屋顶瓦片飞走这是不足为怪的。正如安东尼·史密斯所说，一次典型的天气前锋，可能由10亿吨热空气加上压在底下的7.5亿吨冷空气组成。难怪气象部门有时候会很兴奋。

1 deceptive   

adj.骗人的，造成假象的，靠不住的

参考例句：

• His appearance was deceptive.他的外表带有欺骗性。
• The storyline is deceptively simple.故事情节看似简单，其实不然。

2 marine   

adj.海的；海生的；航海的；海事的；n.水兵

参考例句：

• Marine creatures are those which live in the sea. 海洋生物是生存在海里的生物。
• When the war broke out,he volunteered for the Marine Corps.战争爆发时，他自愿参加了海军陆战队。

3 barometer   

n.气压表，睛雨表，反应指标

参考例句：

• The barometer marked a continuing fall in atmospheric pressure.气压表表明气压在继续下降。
• The arrow on the barometer was pointing to"stormy".气压计上的箭头指向“有暴风雨”。

4 exertion   

n.尽力，努力

参考例句：

• We were sweating profusely from the exertion of moving the furniture.我们搬动家具大费气力，累得大汗淋漓。
• She was hot and breathless from the exertion of cycling uphill.由于用力骑车爬坡，她浑身发热。

5 denser   

adj. 不易看透的, 密集的, 浓厚的, 愚钝的

参考例句：

• The denser population necessitates closer consolidation both for internal and external action. 住得日益稠密的居民，对内和对外都不得不更紧密地团结起来。 来自英汉非文学 - 家庭、私有制和国家的起源
• As Tito entered the neighbourhood of San Martino, he found the throng rather denser. 蒂托走近圣马丁教堂附近一带时，发现人群相当密集。