The smell of rain: what is petrichor?

  1. a pleasant smell that frequently accompanies the first rain after a long period of warm, dry weather.
    “other than the petrichor emanating from the rapidly drying grass, there was not a trace of evidence that it had rained at all”

After the goofy first 40 seconds, this video lists two things that make up the ‘smell of rain’: ozone and petrichor.

Petrichor is the decomposing plant matter that rain causes to erupt from the soil. This same substance is – supposedly – a signal to plants that the soil has been dry and will prevent seeds from sprouting.

But when I went looking for more scholarly information on petrichor I found it…practically non-existent. There were no articles that mentioned it in the 2000s. There was one article that mentioned it in the 1990s. There were a few articles that mentioned referred to a specific article from the 70s. In fact, the were only two original research articles that I could find investigating petrichor as a scientific concept, both by the same two authors: IJ Bear and RG Thomas. These are “Petrichor and Plant Growth” and “Genesis of Petrichor“. As far as I can tell, none of the research was followed up on or replicated though the idea has occasionally been taken up in other contexts.

Petrichor clearly exists as a smell, but it turns out that there is precious little knowledge of what it actually is.

[via Ed Yong]


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