What is it we smell when we say we can smell the rain?

Question

there is a definite odor that is distinct just before during and after it rains, what are we smelling? I will know the right answer when I see it.

Answer 1

Actinomycetes

As it turns out, the smells people associate with rainstorms can be caused by a number of things. One of the more pleasant rain smells, the one we often notice in the woods, is actually caused by bacteria! Actinomycetes, a type of filamentous bacteria, grow in soil when conditions are damp and warm. When the soil dries out, the bacteria produces spores in the soil. The wetness and force of rainfall kick these tiny spores up into the air where the moisture after a rain acts as an aerosol (just like an aerosol air freshener). The moist air easily carries the spores to us so we breathe them in. These spores have a distinctive, earthy smell we often associate with rainfall. The bacteria is extremely common and can be found in areas all over the world, which accounts for the universality of this sweet "after-the-rain" smell. Since the bacteria thrives in moist soil but releases the spores once the soil dries out, the smell is most acute after a rain that follows a dry spell, although you'll notice it to some degree after most rainstorms.

Another sort of smell is caused by the acidity of rain. Because of chemicals in the atmosphere, rainwater tends to be somewhat acidic, especially in urban environments. When it comes in contact with organic debris or chemicals on the ground, it can cause some particularly aromatic reactions. It breaks apart soil and releases minerals trapped inside, and it reacts with chemicals, such as gasoline, giving them a stronger smell. These reactions generally produce more unpleasant smells than bacteria spores, which is why the after-the-rain smell isn't always a good one. Like the smell caused by the bacteria spores, the smell of chemical reactions is most noticeable when it rains following a dry spell. This is because once the chemicals on the ground have been diluted by one downpour, they don't have the same reaction with the rainwater.

Another after-the-rain smell comes from volatile oils that plants and trees release. The oil then collects on surfaces such as rocks. The rain reacts with the oil on the rocks and carries it as a gas through the air. This scent is like the bacteria spores in that most people consider it a pleasant, fresh smell. It has even been bottled and sold for its aromatic qualities!

These are a few common rain smells, but there are also all sorts of other scents after it rains. There is lots of aromatic material that the moisture and impact of rain can stir up, and the moist atmosphere following a downpour is particularly good at carrying these particles through the air. So, when you talk about the after-the-rain smell with a friend, you may mean one thing while your friend is thinking of something else. You'll both agree, however, that the air has a much stronger aroma to it after a good rain.

Answer 2

Good question. The crew of Apollo 11 said they could smell a wet ash sort of smell when they'd brought the moon rock into the spacecraft, taken off their helmets and smelt them. When you've got something very dry, like moon dust which has had the water baked out for billions of years, or dry dust that has just been rained on for the first time in weeks, there will be chemicals that react with the H2O to give volatile compounds that you can smell.

Answer 3

Your smelling the odors of the earth that the rain causes to release.

Answer 4

That heady, romantic, healthy, musty smell is due to tiny organisms in the soil called actinomycetes. They release chemicals called geosmins and other compounds. They are carried in dust particles and such smell is particulary poignant after a light rain on a country, dusty road. The smell reminds you of your childhood and that you are mortal, after all, am I right ?

Answer 5

Someone once told me 'it's the ozone falling' which maybe makes sense now according to some answers above- it's not that pleasant a smell. It's *reminiscent* of wet concrete but not that exactly- I bet we only think that's what wet concrete smells like, because we smell the ozone and see wet concrete. Ah what a wonderful world!

Answer 6

I know what you mean. I have got the same problem. But it is salt that has been evaporated WITH the water that which we are smelling. Did you know that when ever the weather changes like from overcast to clear etc. my nose gets stuffed up. If you have the same thing (sometimes depending on the weather and where you are) then you maybe what I like to call a ''weather psychic.

Answer 7

your sinuses sense the changes in humidity. It also takes out all other smells that are present from pollen and such, so you are not really smelling more things, but it is the absence of them. Then after the rain stops you start to smell the plants releasing more of their goods.

Answer 8

WHAT YOU'RE SMELLING IS THE ATMOSPHERIC CHANGE OF AIR PRESSURE.MOST OF THE TIME FROM EITHER A LOW TO HIGH OR VISE VERSA.THIS IS WHAT BRINGS IN THE RAIN AND THAT'S WHY IT'S SMELLED BEFORE AND AFTER THE SHOWERS.

Answer 9

It's evaporation of the rain right before the atmosphere is "moisturized" enough to produce rain that falls to the ground.

Answer 10

wet concrete. moistoir in the air. the smell of vegetation and plants that probably give off somthign or smell when wet. Plus rain is slightly acidic. so maybe that