From Wikipedia.org:
Petrichor (IPA: pět’ɹǐkəɹ) (from Greek petros, "stone" + ichor) is the scent of rain on dry earth; more specifically, it is the name of the yellow organic oil that yields this scent. The term was coined by two Australian researchers in 1964 for an article in the journal Nature. In the article, the smell is shown to derive 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, the researchers showed the oil retards seed germination and early plant growth.
The scent is generally regarded as pleasant and refreshing, and is one of the most frequently cited "favorite smells". In desert regions, the smell is especially strong during the first rain after a long dry spell. 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. It is composed of more than fifty distinct chemical substances.
(I haven’t pressed Post yet, but I presume the IPA characters representing the pronunciation will not translate correctly using this board’s software…)
-Tim
