You know that “smell of rain” after the first drops fall? Ever wonder what causes it? It’s called “petrichor.” According to Wikipedia, “the smell derives from an oil exuded by certain plants during dry periods, whereupon it is absorbed by clay-based soils and rocks. During rain, the oil is released into the air along with another compound, geosmin, a metabolic by-product of certain Actinobacteria, which is emitted by wet soil, producing the distinctive scent.”
We experienced it on a private Herb Walk today in Matilija Canyon along with the welcome sight of raindrops in the Upper North fork of Matilija Creek.