时差N小时:闻起来像雨的味道

If you've been outside before a rainfall in the spring,you might have noticed a particularly fresh or sweetsmell that seeps into the air a few minutes beforethe first drops begin to fall. If you're familiar withthis smell, it's a great way to predict when the rainis about to start. What, exactly, makes the air smelllike rain?

如果在春雨降临之前呆在外面，那么你可能会注意到：在第一滴雨落下之前的几分钟里，空气中弥漫着一股特别的清香。如果你对这种味道很熟悉，那么你就能很好地预测什么时候开始下雨。到底是什么让空气充满雨的味道呢?

A lot of stories and folk tales have arisen to explain this odor. Long ago, people used to believethat rain clouds picked up sweet smells from Heaven, and the rain carried these angelic odors toEarth. A more up-to-date–but equally incorrect–version of this folktale is that the smell comesfrom ozone, carried from the upper atmosphere by the falling rain.

许多故事和民间传说纷纷出现，试图解说这种气味的由来。很久以前，人们以为是乌云吸收了天上的甜蜜气味，然后由雨点将这种天使的气味带到人间。还有另一个最新但同样错误的故事版本，说这种气味来自于臭氧，下雨时将臭氧从高空带到地面。

In fact, that fresh smell isn't coming down from the sky at all. It's coming up, from the groundbeneath your feet. As a spring rain approaches, the humidity level at the ground tends toincrease. Moist air is much better than dry air at transmitting smells–this is why you might usewarm, steaming water to carry the smell from dried potpourri into the air of your house.

实际上这种清新的味道根本不是来自于天上。它来自于你脚下的泥土。当春雨来临之际，地面的湿度水平会上升。潮湿的空气比干燥的空气传播气味的效果更好，这就是为什么你会选择用温暖的水蒸气将干燥的花香扩散至整个屋子。

As the humidity rises, the moist air carries the fresh smell of oils, secreted by grass and otherground plants, up to your nose. It also carries the odors of ground dwelling bacteria andfungi. These smells are always in the air immediately above the ground, as you can test foryourself by sticking your nose into your lawn and breathing deeply. When a rainstormapproaches and the humidity climbs, the odor rises up from its earthly embrace and yousay–it smells like rain!

随着湿气加重，潮湿的空气将草或者其它植物分泌的芳香的精油输送入你的鼻子。同时也带给你寄居地表的细菌和真菌的味道。这些气味就停留在地表上方的空气，你可以亲自测试一下：将鼻子紧贴草丛，深深地呼吸。当暴雨来临时湿度增加，气味就挣脱了尘世的拥抱，这时你可以说——这闻起来像雨。