【英语时差8,16】闻起来像雨的时候

 If you've been outside before a rainfall in the spring, you might have noticed a particularly fresh or sweet smell that seeps¹ into the air a few minutes before the first drops begin to fall. If you're familiar with this smell, it's a great way to predict when the rain is about to start. What, exactly, makes the air smell like rain? A lot of stories and folk tales have arisen to explain this odor. Long ago, people used to believe that rain clouds picked up sweet smells from Heaven, and the rain carried these angelic odors to Earth. A more up-to-date–but equally incorrect–version of this folktale is that the smell comes from ozone², carried from the upper atmosphere by the falling rain. In fact, that fresh smell isn't coming down from the sky at all. It's coming up, from the ground beneath your feet. As a spring rain approaches, the humidity level at the ground tends to increase. Moist air is much better than dry air at transmitting smells–this is why you might use warm, steaming water to carry the smell from dried potpourri³ into the air of your house. As the humidity rises, the moist air carries the fresh smell of oils, secreted⁴ by grass and other ground plants, up to your nose. It also carries the odors of ground dwelling⁵ bacteria and fungi⁶. These smells are always in the air immediately above the ground, as you can test for yourself by sticking your nose into your lawn and breathing deeply. When a rainstorm approaches and the humidity climbs, the odor rises up from its earthly embrace and you say–it smells like rain!

1 seeps   

n.（液体）渗( seep的名词复数 )；渗透；渗出；漏出v.（液体）渗( seep的第三人称单数 )；渗透；渗出；漏出

参考例句：

• Water seeps through sand. 水渗入沙中。 来自《现代汉英综合大词典》
• Water seeps out of the wall. 水从墙里沁出。 来自《现代汉英综合大词典》

2 ozone   

n.臭氧，新鲜空气

参考例句：

• The ozone layer is a protective layer around the planet Earth.臭氧层是地球的保护层。
• The capacity of ozone can adjust according of requirement.臭氧的产量可根据需要或调节。

3 potpourri   

n.混合之事物；百花香

参考例句：

• As tobacco cigarette burns,a potpourri of 4000 chemicals is released,including carbon monoxide and hydrocyanic acid.当烟被点燃时，融合了四千种化学品的气体被释放出来，其中包括一氧化碳和氢氰酸。
• Even so,there is a slight odour of potpourri emanating from Longfellow.纵然如此，也还是可以闻到来自朗费罗的一种轻微的杂烩的味道。

4 secreted   

v.（尤指动物或植物器官）分泌( secrete的过去式和过去分词 )；隐匿，隐藏

参考例句：

• Insulin is secreted by the pancreas. 胰岛素是胰腺分泌的。
• He secreted his winnings in a drawer. 他把赢来的钱藏在抽届里。 来自《简明英汉词典》

5 dwelling   

n.住宅，住所，寓所

参考例句：

• Those two men are dwelling with us.那两个人跟我们住在一起。
• He occupies a three-story dwelling place on the Park Street.他在派克街上有一幢3层楼的寓所。

6 fungi   

n.真菌，霉菌

参考例句：

• Students practice to apply the study of genetics to multicellular plants and fungi.学生们练习把基因学应用到多细胞植物和真菌中。
• The lawn was covered with fungi.草地上到处都是蘑菇。