Why Does Rain Smell So Fresh After a Storm?

课文

1. That pleasant earthy scent after rain is called petrichor, and it comes from soil-dwelling bacteria.

   雨后那宜人的泥土气息被称为‘潮土油味’，源自土壤中的细菌。

2. During dry periods, certain microbes like Streptomyces release oily compounds into the ground.

   干旱期，链霉菌等微生物会向土壤中释放油脂类化合物。

3. When raindrops hit porous surfaces like soil or rock, they trap tiny air bubbles beneath them.

   雨滴落在土壤或岩石等多孔表面时，会在下方困住微小气泡。

4. These bubbles rise and burst at the surface, releasing aerosols carrying geosmin—the main odor molecule.

   这些气泡上升至表面并破裂，释放携带土臭素的气溶胶——土臭素是主要气味分子。

5. Geosmin has an extremely low detection threshold: humans can smell it at just five parts per trillion.

   土臭素的感知阈值极低：人类仅需每万亿份中含五份即可察觉。

6. Light rain produces more aerosols than heavy downpours because gentle impacts create finer mist.

   小雨比暴雨产生更多气溶胶，因为轻柔撞击能形成更细密的水雾。

7. Plant oils also mix into the scent, adding green, herbal notes to the overall aroma.

   植物油脂也融入气味中，为整体香气增添青绿、草本气息。

8. Desert-dwellers often notice petrichor most strongly, since dry conditions concentrate the compounds longer.

   沙漠居民往往最强烈地感知潮土油味，因干燥环境使相关化合物存留更久。

9. Our brains associate this smell with safety, renewal, and fertility—an evolutionary advantage.

   大脑将这种气味与安全、新生和丰饶联系起来，具有进化优势。

10. Even indoor plants can release similar compounds when watered, mimicking natural petrichor.

    室内植物浇水时也会释放类似化合物，模拟天然潮土油味。