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I read in a book that apparently a 'sea salt' or sailor could smell the rain and then predict oncoming weather. Is this true, can people smell rain?

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    What (type of) book is it? – Martin Scharrer May 12 '11 at 11:44
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    I was thinking that this could be answered by referencing research done on Petrichor, but I doubt that the same effect occurs at sea. Is your question specifically about sailors at sea, or sailors in general (not necessarily at sea)? – Jason Plank May 12 '11 at 13:13
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    @Jason Plank, that is a "post-rain" smell, which presumably isn't useful for predicting rain faster than seeing it coming. My guess is that humidity increases, barometric pressure changes and the presence of clouds and wind is being interpreted as smell, and that the only link to sailors is that they, as a profession, tend to be alert to changing weather conditions. (No proof, so not an answer.) – Oddthinking May 12 '11 at 14:00
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    @Oddthinking agree, many people can "predict" approaching rainstorms when there is a drop in pressure and there are dark clouds in the sky :) – John Lyon May 12 '11 at 22:47
  • I have heard that the "smell of rain" is due to the oils released into the air from trees after rain falls. – Sheathey Apr 8 '13 at 2:43
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Yes, you can:

Before the rain begins, one of the first odors you may notice as winds pick up and clouds roll in is a sweet, pungent zing in your nostrils. That's the sharp, fresh aroma of ozone—a form of oxygen whose name comes from the Greek word ozein (to smell). Tropospheric chemist Louisa Emmons at the National Center for Atmospheric Research explains that ozone emanates from fertilizers and pollutants as well as natural sources. An electrical charge—from lightning or a man-made source such as an electrical generator—splits atmospheric nitrogen and oxygen molecules into separate atoms. Some of these recombine into nitric oxide, and this in turn reacts with other atmospheric chemicals, occasionally producing a molecule made up of three oxygen atoms—ozone, or O3. (Most atmospheric oxygen is made up of two atoms—O2.) The scent of ozone heralds stormy weather because a thunderstorm's downdrafts carry O3 from higher altitudes to nose level.

source: "Storm Scents: It's True, You Can Smell Oncoming Summer Rain" in Scientific American.

Of course you at that point you won't be "predicting" the rain on the smell alone. A that point most likely you'll see other indications that the storm is coming: big dark cumulonimbus, gusty winds, drop in pressure.

Note in picture below (storm supercell) warm updraft passes through the storm cell and comes down well in front of it. Also the cold downdraft precedes the rain.

enter image description here

Source of the graphic: Meteorology 302 course, Department of Geosciences, SFSU

  • I saw that article and considered using it, but I have to admit I didn't find the science very convincing... – Oddthinking Apr 8 '13 at 9:37
  • @Oddthinking: But ozone creation via static electricity discharge is undisputed fact. See last paragraph of en.wikipedia.org/wiki/Ozone#Laboratory_production – vartec Apr 8 '13 at 9:45
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    I wasn't convinced that they had demonstrated that the ozone (and pollen and other post-rain smells) travel in sufficient quantities much faster than the rain, so you can smell then 30 minutes before the storm. (And the cultural synaethesia stuff was out there.) – Oddthinking Apr 8 '13 at 9:52
  • @Oddthinking: there isn't "30 minutes" claim though. As I understand above, it's more like you can smell the storm coming, about at same as you can see (dark cumulonimbus) and feel (gusty wind) it coming. And the way cumulonimbus system works, is that air rises below cloud, goes up, outwards, down and then at ground level blows toward the center of storm again. That gust comes good few minutes before the rain hits. – vartec Apr 8 '13 at 10:05
  • Whoa, did I just make up the 30 minute part? I could have sworn I read it here. So sorry! If the claim is just you can smell an existing storm when it is only a few km away, I am satisfied that is plausible and withdraw my objection. Is that what the OP meant? – Oddthinking Apr 8 '13 at 10:10

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