The Scent of Rain

Rain on the prairie

Rain on the prairie (Photo credit: readerwalker)

“Like a welcome summer rain, humor may suddenly cleanse and cool the earth, the air and you.”
Langston Hughes

Unlike last year, we’ve had a lot of rain and flooding here in Northern, Illinois. Needless to say, it has been a wetter than normal spring. Some days one can smell the rain before it reaches and as it hits the dry earth. The distinctive scent of rain as it hits the land is referred to as petrichor.

12123121123123123123123

Petrichor or the scent of rain has been identified by Isabel Joy Bear, R. G. Thomas, and Nancy Gerber as a combination of three fatty acids: palmitic, stearic, and oleic acid and the bicyclic alcohol, geosmin. Interestingly enough, the human nose is able to detect geosmin at very low concentrations. Could this be rain’s pheromone?

Much like the scent of a woman or man, the fragrance of rain can be a very exhilarating experience. Psychologist Pamela Dalton of the Monell Chemical Senses Center has shown that while humans don’t have innate responses to the smell of rain, we have learned to associate them with our experiences. Rain brings relief from the relentless summer heat, providing memories that associate rain with a cleansing and refreshing event says Dalton.

Meanwhile, Anthropologist DianaYoung says the aboriginal people link the smell of rain to the color green, a connection she calls “cultural synesthesia.” When one look at the language of other cultures, the etymology of the word green comes from the Middle English and Old English word grene, and like the German word grün, has the same root as the words grass and grow. Taken literally, rain makes the grass grow green.

While rain does make grass green, rain generally promotes both plant germination and growth. In fact, the three fatty acids identified as the compounds that make up the scent of rain, actually act as growth inhibitors on cress, mustard, and grass. It is believed that after long periods of dryness, these compounds inhibit seed germination unless there is sufficient rainfall to wash away the inhibitory acids.

That being said, there has been sufficient rain to wash away the petrichor in my prairie garden. Once the flooding had subsided, prairie plant volunteers along with invasive weeds have successfully germinated. My prairie garden is full of wonderful shades of green! And much to my relief, many of last spring’s seedling plugs survived the great drought of 2012.

Related articles

Resources

Bear, I.J.; R.G. Thomas (March 1964). “Nature of argillaceous odour”. Nature 201 (4923): 993–995. doi:10.1038/201993a0.

“Storm Scents: It’s True, You Can Smell Oncoming Summer Rain: Researchers have teased out the aromas associated with a rainstorm and deciphered the olfactory messages they convey”Scientific American. Retrieved July 20, 2012.

Bear, I.J.; R.G. Thomas (September 1965). “Petrichor and plant growth”. Nature 207 (5005): 1415–1416. doi:10.1038/2071415a0.

“Scent of Rain.” Chemical and Engineering News. 6 May 2013: 56.

Advertisements
%d bloggers like this: