Wednesday, October 21

You discover why you like the smell of rain so much

It may remind you of your childhood, your favorite landscape or autumn afternoons, but it is very likely that you will love the smell of rain. And like everything, there is a reason behind the phenomenon that we explain below. Do you love the smell of rain, that earthy and pleasant aroma, unmistakable and that is accentuated especially after a storm or an abundant afternoon of rainfall? The odor has a specific name, known as petricor, and is caused by the release of specific chemicals when rain hits the ground. The etymology of the word comes from the ancient Greek: πέτρα pétra ‘stone’ and ἰχώρ icór ‘icor’, blood of the Homeric gods. In Greek mythology it would be the essence that runs through the veins of the gods instead of blood. In Argentina this smell of rain or wet earth is known as Tarabañá, and it is the distinctive aroma that accompanies the first rain after a long period of drought. The soil-dwelling bacteria called Streptomyces secretes a molecule called geosmin, the BBC reports. When rain hits the ground, the raindrops trap air bubbles that contain geosmin. The bubbles move through the raindrop and explode as aerosols, including other tiny airborne particles. Choosing a good headset that suits your wearing habits may not seem like an easy thing, but with this guide you will learn everything you need to know. When geosmin lifts off the ground and rises into the air, we can clearly smell it because the human nose is extremely sensitive to it. According to Smithsonian magazine, some people can smell it even when the concentration is as low as five parts per billion. Another contributing factor to petricor is a combination of vegetable oils. Australian researchers Isabel Joy Bear and RG Thomas, who coined the term petrichor in 1964, discovered that some plants secrete oils in times of drought. When it finally rains, the oils that had been building up are released into the air in the same way that geosmin does. In a later work, Bear and Thomas (1965) showed that aromatic oils retard seed germination and plant growth, in order to protect the seeds, preventing them from germinating in times of drought. That is why after periods of drought in desert areas, the smell is much more perceptible and penetrating. It should be noted that petricor could not be synthesized due to its complex composition, since it has more than fifty substances. And specifically, after electrical storms ozone is largely to blame: lightning can split oxygen and nitrogen, which in turn are capable of recombining to form nitric oxide, one of the compounds necessary to create ozone. That molecule is known for its pungent chlorine odor. The MIT Experiment In 2015, scientists from the Massachusetts Institute of Technology (MIT) recorded how the smell gets into the air using high-speed cameras. In their experiment they filmed raindrops falling on sixteen different surfaces, varying the intensity and height of the fall. When hitting a porous surface, small bubbles are created that grow and bloom upwards, releasing an effervescence of aerosols in the air in charge of transporting the aroma. In short, secretions of lightning and bacteria and the infinite wisdom of the earth crouch behind the secret of the smell of rain and its impenetrable magnetism. This article was published on TICbeat by Andrea Núñez-Torrón Stock.

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