Why is there a sweeter smell in the air just before it rains??

Question

I love the smell in the air just before it starts raining... but I wonder why the sweetness in it?? Where does it come from??

Answer 1

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.

Answer 2

I'm not quite sure, but I suppose the smell comes from the ground. Before it rains, the humidity is very high, almost 100%. Probably, this humidity passes in the ground, taking some soil smelling ingredients with it and by the slightest breeze we can smell it.

Answer 3

Storms often have outflow which is a gust of air flowing outward from under the storm. This will reach places before the storm does and carry very humid and cooler air which always smells nice.

Answer 4

i think its something to do with air preasure droping and the smell of the earth comming up.

Answer 5

Yea, I think Amanda has this one.