While not everyone can smell the rain before it begins, there is actually scientific evidence that some people do possess this capability. Those with good olfactory senses are often able to pick up a scent that has, according to Scientific American, a “sweet, pungent zing” that's been likened to chlorine bleach.
Science says yes! There are a few reasons why you might be able to smell incoming rain. One of those reasons is that soil-dwelling bacteria secrete geosmin when producing spores. Geosmin has a distinctive earthy or musty odor.
Now scientists have discovered why people can smell the storms so far away. A sensitive snout is smelling ozone, petrichor and geosmin; in other words, the nose smells oxygen, the debris that raindrops kick up and wet bacteria.
Petrichor is the smell of rain. The word comes from the Greek words 'petra', meaning stone, and 'ichor', which in Greek mythology refers to the golden fluid that flows in the veins of the immortals.
Before it rains, a person might be able to smell the scent of ozone, or O3, which is a naturally present gas in the atmosphere which gets its name from the Greek word 'ozein', or smell. It sometimes indicate that a storm is on the way because pockets of gas are pushed down to ground level by winds.
When these microbes die, they release a musty earth-smelling chemical called geosmin (it's also the cause of the earthy taste in beets.) One out of every 10 people, however, can't smell geosmin, which is the main contributor to petrichor.
The human nose is sensitive to geosmin and is able to detect it at concentrations as low as 0.4 parts per billion. Some scientists believe that humans appreciate the rain scent because ancestors may have relied on rainy weather for survival.
Springtails use the scent to find food
Humans aren't the only ones to appreciate the earthy aroma after an April rain shower. That smell—known as petrichor—stems from microscopic streptomycete bacteria in the soil that produce a compound called geosmin, The Times reports.
Gas leaks, garlic breath, skunks in the neighborhood—ah, the scent of thiols. The human nose is particularly sensitive to these sulfur-containing compounds, which is no surprise given that they are often associated with things to avoid.
When it rains, spores produced by the actinomycetes are pushed up into the air, releasing the geosmin and creating that fresh, distinctive scent, according to Smithsonian.
We humans are not famous for our olfactory prowess, yet we can reportedly detect the signature musk of geosmin in concentrations as low as 100 parts per trillion. To put that in perspective, sharks' famous blood sniffing snouts can only suss out one part per million in seawater.
Scientists say it's a combination of ozone, petrichor and geosmin. Before it rains, a person might say that they can smell the storm coming. Their nostrils might be picking up the scent of ozone, or O3.
Effects. The human olfactory system is extremely sensitive to geosmin and is able to detect it at concentrations as low as anywhere from 0.4 parts per billion to 5 parts per trillion. Geosmin is responsible for the muddy smell in many commercially important freshwater fish such as carp and catfish.
Rain itself has no smell. The scientific term, what we consider the smell of rain is petrichor. And, it's actually caused by plants and bacteria. If we're being specific, it's caused by geosmin- which is a metabolic byproduct of certain bacteria.
Every person has a unique scent. “It's like a fingerprint,” says Johan Lundström, a neuroscientist at the Karolinska Institute in Sweden. “There is a large genetic component to body odor. Even trained sniffer dogs have a hard time distinguishing between identical twins, unless the twins are on different diets.”
Many examples exist in animals but their role in humans remains uncertain since adults have no functioning vomeronasal organ, which processes pheromone signals in animals. Yet pheromones can be detected by the olfactory system although humans under develop and underrate their smelling sense.
On standard tests of smelling ability – including odour detection, discrimination and identification – women consistently score significantly higher than men. One researcher has claimed that the superior olfactory ability of females is evident even in newborn babies.
Every time you sweat, there's a chance you'll produce an unpleasant body odor. Some people are more susceptible to foul body odor than other people. Other factors that can affect body odor are: Exercise.
The scent of rain, petrichor, has two main constituents with actual chemical names and origins – ozone (O3) and geosmin (C12H22O) and humans can sense it at 5 parts per trillion. Trillion!
It's not all in your head, either. That pleasant, earthy smell of rain, known as petrichor, is caused by the release of specific chemicals when the rain reaches the ground. It's as if the earth is rewarding everyone for putting up with terrifying thunderstorms and sudden deluges sans umbrella.
Petrichor, the distinct way that dry earth smells after it rains, comes in part from bacteria in the soil that release a chemical odorant called geosmin. The human nose is quite sensitive to the odor, as is that of the fruit fly, Drosophila melanogaster.
It turns out it's not just gratitude that makes rain smell so appealing after a long period of dry weather. There's actually some chemistry involved too. Bacteria, plants and even lightning can all play a role in the pleasant smell we experience after a thunderstorm; that of clean air and wet earth.
The geosmin and other petrichor compounds that may be present on the ground or dissolved within the raindrop are released in aerosol form and carried by the wind to surrounding areas. If the rainfall is heavy enough, the petrichor scent can travel rapidly downwind and alert people that rain is soon on the way.
The second reaction that creates petrichor occurs when chemicals produced by soil-dwelling bacteria known as actinomycetes are released. These aromatic compounds combine to create the pleasant petrichor scent when rain hits the ground.