As wildfires sweep across the continent and the summer heat begins to ramp up, many may forget that distinct odor that seems to linger while the thunderclous begin to roll in the distance. So often people have become used to certain phonema without any explanation and just accept them as truth. Bu scientists have revealed why so many people are able to identify when a rainstorm is coming based purely on smell.
The main culprits behind the phenomenon are geosmin and petrichor. Two Australian researchers in the 1960s found that the smell people experience when rain hits the ground comes from bacteria.
“When you say you smell damp soil, what you’re actually smelling is a molecule being made by a certain type of bacteria,” said Professor Mark Buttner, head of molecular microbiology at the John Innes Centre. That molecule, geosmin, is produced by Streptomyces. Present in most healthy soils, these bacteria are also used to create commercial antibiotics.
Scientists have also found that people can smell rain before it comes as well. Louisa Emmons, a chemist from the National Center for Atmospheric Research, said that the scent that comes down before a rainstorm occurs when a chemical reaction occurs in the atmosphere. Emmons explained that the scent of ozone heralds stormy weather because a thunderstorm’s downdrafts carry O3 from higher altitudes to nose level.