Smell the Rain

Have you ever smelled the aroma that lingers after it rains?

Scientists call it “petrichor,” and since the 1960s, they’ve believed it comes from oils and chemicals that are released when raindrops hit the ground.

Now, for the first time, scientists at MIT have used high-speed cameras to show how that “rain smell” gets into the air, just check out the video for a look at their footage:

For the research, Buie and post-doctoral researcher Youngsoo Joung filmed raindrops as they hit a variety of surfaces, including 16 different soil samples. They also varied the intensity and speed of the “rainfall”–from light to heavy–by dropping the water from different heights.

They found that when a raindrop hits a porous surface, tiny bubbles form inside the droplet. These bubbles grow bigger and float upward–like bubbles in a glass of champagne. When the bubbles reach the surface, they burst and release a “fizz of aerosols” into the air.

They also noticed that light and moderate rain, which falls at a slower rate, tends to produce more aerosols compared to the heavy rain–which explains why petrichor is more common after a light rain.

The research was published on Jan. 14 in the journal Nature Communications.