The researchers describe thatthe smell comes from oils secreted by some plants that permeate the soil during dry periods rocky and are absorbed by clay soils. When it rains the oil is released into the airalong with other compounds like geosmin, a substance produced by bacteria and cyanobacteria found in the soil and that is typically perceptible when the soil becomes wet; for example, when it rains;it is also due to ozone if there is an electrical storm. Due to its complex composition (more than 50 substances), petricor could not be synthesized.
The name Petrichor established by the Australian scientists Isabel Joy Bear and R.G Thomas in 1964 is made up of two Greek words: petra, which means stone, and ichor, which means the blood of mythological gods.
According to Agencia Uno, it is not the only factor that affects the smell of rain, but memories can also influence.
Pamela Dalton of the Philadelphia Center for the Senses explained to Smithsonian Magazine that our memories can change how we smell rain.
"What we perceive is based on genetics, nasal anatomy, and past experiences," says Dalton.
According to Wikipedia
Petricor (from ancient Greek ?????? pétros, stone, e ???? ikh? R, ichor1) is a name given to the smell that rain produces when falling on dry soils within the Anglo-Saxon culture.2 It is defined as the distinctive aroma that accompanies the first rain after a long period of drought.
The term petricor, petrichor in English, was created in 1964 by two Australian geologists: Isabel Joy Bear and R. G. Thomas. It first appeared in the journal Nature (993/2).45 In their article, the authors described it as "the odor derived from an oil exuded by certain plants during periods of drought." This oil is absorbed to the surface of the rocks, mainly sedimentary ones such as clayey ones, and when it comes into contact with the rain it is released into the air along with another compound: geosmin.6 Geosmin is a metabolic product of certain actinobacteria. The emission of these compounds is what produces the distinctive aroma,7 to which ozone can be added if there is additionally electrical activity.8
In later work, Bear and Thomas (1965) showed that these aromatic oils retard seed germination and plant growth.6 This could indicate that the plants exude these oils in order to protect the seeds, preventing them from germinating in times of drought. After periods of drought in desert areas, the smell is much more perceptible and penetrating when the rainy season arrives. Due to its complex composition (more than 50 substances), petricor could not be synthesized.
In 2015, MIT scientists used high-speed cameras to show how this scent gets into the air.9 For this they filmed raindrops falling on 16 different surfaces, varying the intensity and height of the fall. They found that hitting a porous surface creates tiny bubbles inside the drop. They increase in size and float upwards. Upon reaching the surface, they break apart and release an "aerosol fizz" into the air, which carries the aroma.10
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