MIT scientists went to work to find out the reason why approaching rain smells its singular way. You know, that fresh aroma that is earthy and very distinctive? Well, these eager researchers spent a lot of time and resources to find out why this mysterious scent happens just before water falls from the sky..
Enter a lot of raindrops. Using their high speed cameras, the scientific team were able to see that when the drop of rain strikes, the action “releases clouds of tiny particles when [hitting] surfaces like soil and leaves,” reports Richard Gray for the British publication, Mail Online’s science and tech department.
Gray says that, in their study, these experts indicated that when a raindrop lands on a surface that isn’t even then the bubbles of air “shoot upwards and burst from the top of the water droplet like fizz in a Champagne glass.”
That’s a good visual. So what happens at that point? Apparently, these little bubbles are carrying both oil and dust. Gusts of wind that come before the rain begins to fall often blow these tiny bubbles far from where they are formed. That’s why you are able to smell the rain a lot longer than the actual storm lasted. In fact, even when there is no further precipitation and the land air dries, the smell can still continue for days.
The effect has a name. It’s called Petrichor and it happens most typically during the summer months and particularly during the first rain after no rain has fallen for some time. Because of this, an excess of oil and dust will have accumulated on the ground and on the surrounding plants, too.
Dr Youngsoo Joung, an MIT scientist representing the iconic school’s department of engineering that conducted the raindrop research, has had direct impact on the medical world. Indeed, the discoveries Joung and his team made could start “to explain how some soil-based bacteria can spread disease.”
Joung expounded, “Until now, people didn’t know that aerosols could be generated from raindrops on soil. When moderate or light rain hits sandy or clay soils, you can observe lots of aerosols, because sandy clay has medium wetting properties. Heavy rain [which takes high] impact speed, means there’s not enough time to make bubbles inside the droplet.”
And so, the research continues at MIT as studies look carefully at the activity of raindrops. More information is expected going forward as the team is inspired by the distinctive smell of incoming rain. Stay tuned.
