When the summer ends, we will start to face the rainy season. The dry soil will become wet and hot temperatures also will become more cooler. When it rains for the first time, we will smell the soil that has been moistened with rainwater. Don’t get me wrong, for most of the people, they’re really liking this smell. This smell is called "petrichor".
This petrichor comes when dry soil meet rainwater which is actually odorless (before that water hits the ground). The smell is formed by the Streptomyces Bacteria and they produce Geosmin molecule where it produces the odor that we perceive as smell of the encounter between rainwater and soil. But, there is another opinion that there are certain plants that secrete an oily substance during the dry season, then they emit their scent into the air. So, when the rain comes, the smell mixes with the water. The word of "petrichor" itself, invented by Joy Bear and Roderisck G. Thomas in 1964.
Then, there is question in my head, why the most of people liking petrichor smell ? I thought that the scent would bring them back to memories or past experiences. This smell comes from suggestion and experience. So, its difficult to explain scientifically. However, when it's connected according to science, Rachel Herz said that the sense of smell has connections with the inner brain and hippocampus then they will record past activities and emotional feelings. So, when it rains, the memory will appear randomly according to how we feel at that time (its either good or bad experience).
But, there is another reason. It is caused by evolution of human development. How and why ? According to Diana Young (Australian Anthropologist), she calls that cause as a cultural synthesis. For the explanation, he thought that humans in ancient times used rain as a sign that there were plenty of animals and plants to eat when the rain comes, so they’re feel happy with that smell.
Whatever of that possibility, we hope the smell of rain carries a positive sign for us as a human and other living beings.
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