Petrichor

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"Smell of rain" redirects here. For the Mortiis album, see The Smell of Rain.

Petrichor (pronounced /ˈpɛtrɨkɚ/) (from Greek petros, "stone" + ichor) is the name of the familiar scent of rain on dry earth.

The term was coined in 1964 by two Australian researchers, Bear and Thomas, for an article in the journal Nature. In the article, the authors describe how the smell derives from an oil exuded by certain plants during dry periods, whereupon it is adsorbed by clay-based soils and rocks. During rain, the oil is released into the air along with another compound, geosmin, producing the distinctive scent. In a follow-up paper, Bear and Thomas (1965) showed that the oil retards seed germination and early plant growth.

The scent is generally regarded as pleasant and refreshing,^{[citation needed]} and is one of the most frequently cited "favorite smells".^{[citation needed]} In desert regions, the smell is especially strong during the first rain after a long dry spell.^{[citation needed]} The oil yielding the scent can be collected from rocks and concentrated to produce perfume. However, it has yet to be synthesized, perhaps due to its complexity.^{[citation needed]} It is composed of more than fifty distinct chemical substances.^{[citation needed]}