Pleasent Smell from rain

[scientistsahai]

I have a question for which I have'nt been able to find the exact scientific answer. Can anyone here help??

 

When there is rain and also just after it there is a pleasent smell or aroma that comes. It is good to smell and has great aesthetic effects too.

Can someone please help me out the reason for this. Please give some sources if possible.....

[paleolithic]

I tried doing several searches involving rain, but the first thing that popped up in my head after reading your post was acid rain, do you think it could be the smell of the acid content? It seems kind of unlikely to me but still worth a shot. Here's a site I came across about acid rain.

 

http://ga.water.usgs.gov/edu/acidrain.html

[mmalluck]

I know lightning contributes a mixture of nitrogen and ozone compounds to that rain smell. Even without a remarkable amount of lightning that smell still persist, so it may be more than lightning that contributes to it.

[Callipygous]

im betting its the moisture in the air. in my experience it hasnt really been a smell so much as a feeling in the air. i think its just that moist air is more pleasant to breathe, or at least when its cool, not hot and muggy like in humid areas.

[Ophiolite]

Rain will also remove particulates from the air so the pleasant smell may be more a case of the absence of unpleasant smells.

[Mokele]

Well, there's two reasons for anything, proximate and ultimate. The proximate is why is smells good at a chemical level, in terms of how we smell and how this particular smell triggers pleasure. The ultimate is why, in an evolutionary sense, do we have a positive perception of this smell versus, say, rotten meat.

 

In terms of proximate, perhaps the smell is a chemical that's not normally volatile alone, but can be carried into the air by microscopic drops of evaporating water?

 

As for ultimate, it's pretty simple, IMHO: Our ancestors were foragers, and after the rain all sorts of stuff comes out and starts moving around, where we can find it. I know for reptiles and amphibians that after a rainstorm is the best time to go field collecting, and I suspect the same is true for many other species, too. Thus, the smell of rain is associated with a food bonanza.

 

Mokele

[scientistsahai]

Well it's not the acid rain nor is it becoz of the unpleasent odour removed. i GUESS u all shud water the garden or a small field and pour water like in rain (thru sprinklers!!).

After a while a good smell comes from the soil. That is what I want to figure out ?

[Ophiolite]

Have you experienced this smell everywhere you have been in a non-urban setting when it has rained? What is the soil type, climate and underlying rock in your home area?

[scientistsahai]

this happens around the world.

[Ophiolite]

No. It does not happen around the world. I have encountered an unpleasant smell after rain - primarily in equatorial regions (Nigeria, Gabon, Malaysia, Indonesia); I have encountered a freshness in the air, which seems to me to be the absence of odours, in temperate zones (Europe) and desert regions (North Africa); I have not encountered a specific fresh smell emanating from the soil itself. That is why I have asked you the circumstances in which you have observed this. You appear to be generalising from personal experience. I am trying to clarify the evidence.

[lepidoptera]

I don't notice a pleasant smell.

[mmalluck]

Maybe you're smelling the sweet smell of plant decomposition. I know water will cause bateria and fungi to kick it into high-gear.

 

It would depend on the material being broken down and the type of bateria/fungi that's growing.

 

Think of it as the difference between the smell generated by leaf-clutter vs. that of a freshly fertilized field. Which one do you think smells better after rain?

[akcapr]

someting to do with the carbonic acid maybe

[scientistsahai]

No. It does not happen around the world. I have encountered an unpleasant smell after rain - primarily in equatorial regions (Nigeria, Gabon, Malaysia, Indonesia); I have encountered a freshness in the air, which seems to me to be the absence of odours, in temperate zones (Europe) and desert regions (North Africa)

 

 

U know after a lot of research I finally got an answer.(and it just wasn't what u all were thinking)

here's the complete document.......

 

 

Most people notice a distinctive smell in the air after it rains. It's frequently linked with spring, as the smell of fresh cut grass is associated with summer. You'll find it in a lot of poetry and also on many inspirational lists of things to be happy about. But what causes it?

 

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.

 

 

 

U knw i was right that it comes everywhere and it's more than just the gases in air or plant decomposition.........it's actually ACTINOMYCETES!!!

[YT2095]

please cite the source of this document, it`s a legal requirement. Cheers