万物简史 第376期:进入对流层(17)

 　　When you look at a lake, you are looking at a collection of molecules¹ that have been there on average for about a decade. 要是你望一眼湖水，你看到的是一大堆分子，它们在那里平均已达10年之久。

　　In the ocean the residence time is thought to be more like a hundred years. 据认为，水分子在海洋里逗留的时间更可能是100年。

　　Altogether about 60 percent of water molecules in a rainfall are returned to the atmosphere within a day or two. 总的来说，下了一场雨以后，大约有60%的水分子在一两天内又回到了大气层。

　　Once evaporated, they spend no more than a week or so—Drury says twelve days—in the sky before falling again as rain.  一旦蒸发，它们在天空中待 不了一个星期左右——德鲁里说是12天，然后又以雨的形式落了下来。

　　Evaporation² is a swift process, as you can easily gauge³ by the fate of a puddle⁴ on a summer's day.  蒸发是个很快的过程，你很容易根据夏日里一摊水的命运来测定。

　　Even something as large as the Mediterranean⁵ would dry out in a thousand years if it were not continually replenished⁶. 要是不连续补充水的话连地中海这佯的大家伙也会在1000年里干涸。

　　Such an event occurred a little under six million years ago and provoked what is known to science as the Messinian Salinity⁷ Crisis. 这种情况在稍稍不到600万年以前发生过，产生了科学界所谓的“墨西拿盐度危机”，

　　What happened was that continental⁸ movement closed the Strait of Gibraltar. 原因是大陆移动阻塞了直布罗陀海峡。

　　As the Mediterranean dried, its evaporated contents fell as freshwater rain into other seas, 随着地中海干干涸，被蒸发的水汽以淡雨的形式落在别的海里。

　　mildly diluting⁹ their saltiness—indeed, making them just dilute¹⁰ enough to freeze over larger areas than normal. 稍稍降低了那些海的盐度——实际上，怡好稀释到能使更大区域结冰的程度。

　　The enlarged area of ice bounced back more of the Sun's heat and pushed Earth into an ice age. 冰区的扩大把更多的太阳热量反弹回去，从而把地球推进到了冰期。

　　So at least the theory goes. 至少从理论上说是这样的。

　　What is certainly true, as far as we can tell, is that a little change in the Earth's dynamics¹¹ can have repercussions¹² beyond our imagining. 就我们所知，有一点是肯定的，只要地球的动力稍稍发生变化，就可能产生难以想像的后果。

　　Such an event, as we shall see a little further on, may even have created us. 我们过一会儿将会看到，或许，连我们也就在这样的事件中诞生了。

1 molecules   

分子( molecule的名词复数 )

参考例句：

• The structure of molecules can be seen under an electron microscope. 分子的结构可在电子显微镜下观察到。
• Inside the reactor the large molecules are cracked into smaller molecules. 在反应堆里，大分子裂变为小分子。

2 evaporation   

n.蒸发，消失

参考例句：

• Be careful not to lose too much liquid by evaporation.小心不要因蒸发失去太多水分。
• Our bodies can sweat,thereby losing heat by evaporation.我们的身体能出汗，由此可以蒸发散热。

3 gauge   

v.精确计量；估计；n.标准度量；计量器

参考例句：

• Can you gauge what her reaction is likely to be?你能揣测她的反应可能是什么吗？
• It's difficult to gauge one's character.要判断一个人的品格是很困难的。

4 puddle   

n.(雨)水坑，泥潭

参考例句：

• The boy hopped the mud puddle and ran down the walk.这个男孩跳过泥坑，沿着人行道跑了。
• She tripped over and landed in a puddle.她绊了一下，跌在水坑里。

5 Mediterranean   

adj.地中海的；地中海沿岸的

参考例句：

• The houses are Mediterranean in character.这些房子都属地中海风格。
• Gibraltar is the key to the Mediterranean.直布罗陀是地中海的要冲。

6 replenished   

补充( replenish的过去式和过去分词 )； 重新装满

参考例句：

• She replenished her wardrobe. 她添置了衣服。
• She has replenished a leather [fur] coat recently. 她最近添置了一件皮袄。

7 salinity   

n.盐分；咸度；盐浓度；咸性

参考例句：

• In the sea water sampled the salinity is two parts per thousand.在取样的海水中，盐度为千分之二。
• In many sedimentary basins the salinity of the formation water increases with depth or compaction.在许多沉积盆地中，地层水的含盐量随深度或压实作用而增高。

8 continental   

adj.大陆的，大陆性的，欧洲大陆的

参考例句：

• A continental climate is different from an insular one.大陆性气候不同于岛屿气候。
• The most ancient parts of the continental crust are 4000 million years old.大陆地壳最古老的部分有40亿年历史。

9 diluting   

稀释，冲淡( dilute的现在分词 )； 削弱，使降低效果

参考例句：

• A companion would have been a distraction, diluting the pathos of the moment. 要是有一个伴侣在旁就会分散我的注意，冲淡此时此刻的哀婉之情。
• Diluting agent has certain transparency for ink multi-color overprint. 冲淡剂具有必定的透明量，适分油不朱的众色叠印。

10 dilute   

vt.稀释，冲淡；adj.稀释的，冲淡的

参考例句：

• The water will dilute the wine.水能使酒变淡。
• Zinc displaces the hydrogen of dilute acids.锌置换了稀酸中的氢。

11 dynamics   

n.力学，动力学，动力，原动力；动态

参考例句：

• In order to succeed,you must master complicated knowledge of dynamics.要取得胜利，你必须掌握很复杂的动力学知识。
• Dynamics is a discipline that cannot be mastered without extensive practice.动力学是一门不做大量习题就不能掌握的学科。

12 repercussions   

n.后果，反响( repercussion的名词复数 )；余波

参考例句：

• The collapse of the company will have repercussions for the whole industry. 这家公司的垮台将会给整个行业造成间接的负面影响。
• Human acts have repercussions far beyond the frontiers of the human world. 人类行为所产生的影响远远超出人类世界的范围。 来自《简明英汉词典》