Petrichor is a consequence of a first rain after drought. The scientists Isabelle Bear (Australia) and Richard Thomas (UK) published an article in the journal Nature describing this phenomenon in 1965. They were the first to use the term «petrichor». Scientists have suggested that during drought some plants release oils, which are then absorbed by the soil. These oils delay seed germination during drought. Risk of death from the lack of moisture is especially big at this time. Delaying germination protects future plants.
During the first rain, the oil from the ground evaporates and no longer interferes with seed germination. The oils aren evaporating together with the secretions of actinobacteria. The result is a characteristic aroma.
Researchers at Massachusetts Institute of Technology have confirmed this theory with high-speed cameras in 2015. They set up 600 experiments on 28 surfaces. Video cameras captured a drop of rain falling to a porous soil surface, and then oil bubbles appearing on it. These bubbles evaporate and carry aroma, bacteria and viruses from the soil. Scientists claim that people like the smell of rain because in ancient times rain was essential for survival.
The famous Italian composer and pianist Ludovico Einaudi has released a musical composition «Petrichor». Here's the link to the concert recording, just listen.
Do you hear how the first raindrops begin to fall on the dry land warmed by the sun?
At first, there are few drops, they mix with the dust and turn into small dark lumps. At first, the earth wins over the rain.
Over time, more and more drops appear. The entire dusty surface of the earth is covered with dark rain spots, a stubborn struggle between earth and sky is going on…
And finally, the long-awaited rain begins, bringing life to the dying of thirst soil.
If you close your eyes, you can see raindrops on the green leaves of grapes, feel how the vineyards greedily absorb life-giving moisture, the gift from heaven.
At this moment, light steam rises above the ground. It carries the unique Petrichor scent. Earth rejoices: rain will give life to everything that grows.