Hello everybody,
Just had an email from my niece who's asking what the cause is of that
nice smell you get when it rains after a warm spell. Told her I'd seek advice,
so any suggestions would be welcome. My own guess is that it may well be a
man-made substance, as it is most noticeable over surfaces containing tar but I
can't quite understand why it needs wetting to release it. Being a retired
industrial chemist I do know a bit about this sort of thing, but obviously not
quite enough, and I do need to retain credibility with my niece.

Tudor Hughes, Warlingham, Surrey.

TudorHgh wrote:

Hello everybody,
Just had an email from my niece who's asking what the cause is of that
nice smell you get when it rains after a warm spell. Told her I'd seek advice,
so any suggestions would be welcome. My own guess is that it may well be a
man-made substance, as it is most noticeable over surfaces containing tar but I
can't quite understand why it needs wetting to release it. Being a retired
industrial chemist I do know a bit about this sort of thing, but obviously not
quite enough, and I do need to retain credibility with my niece.

I disagree that it's a "nice" pong - I positively hate it! Could it be
that after it's been dry for a while, there's lots of settled dust on
the ground and the rain causes this to be disturbed?

Jonathan

In message , TudorHgh
writes
Hello everybody,
Just had an email from my niece who's asking what the cause is of that
nice smell you get when it rains after a warm spell. Told her I'd seek advice,
so any suggestions would be welcome. My own guess is that it may well be a
man-made substance, as it is most noticeable over surfaces containing tar but I
can't quite understand why it needs wetting to release it. Being a retired
industrial chemist I do know a bit about this sort of thing, but obviously not
quite enough, and I do need to retain credibility with my niece.

Tudor Hughes, Warlingham, Surrey.


Hi

I'm no scientist but am not sure about it being mean made. We live way
out in the sticks, the nearest tarmac road surface (a lane) is at least
200/300m distant. The smell after rain seems to emanate from the trees,
grass and the ground itself, sort of damp and peaty, yet fresh at the
same time. I'm with your niece, it's really nice whatever it is.


--
Bill

In message , Bill
writes

I'm no scientist but am not sure about it being mean made. We live way



Apology for typo - substitute "mean" made, for man made!!

Finger in gear, brain in neutral; obviously a senior moment, which are
becoming all too frequent these days.

--
Bill

I seem to remember a tale of a french chap who went bust trying to bottle
this "earthscent". He went to his grave a pauper and never did manage it.

I think it may be microbes, fungi, bacteria etc. Dormant during dry spells
but bursting into life during damp periods. Emiting all kinds of gasses
during their respiration, digestion and division. They would love the warm,
damp conditions at the moment. Seeing as there are oil loving organisms too
as you mention tar ( a very natural substance BTW ) and the smell is very
noticable but different in the woods or countryside too.

I think a Copernic search for this french chap is in order. Perhaps it was
Lyall Watson in his book "Supernature" that mentioned it. That seems to ring
a bell.

Les

Hi Tudor,
well as a retired analytical chemist myself I guess I should know as well -
but I don't! I agree about the peaty smell and wonder if it is connected
with humic acids being released.

Dave

"TudorHgh" wrote in message
...
Hello everybody,
Just had an email from my niece who's asking what the cause is of
that
nice smell you get when it rains after a warm spell. Told her I'd seek
advice,
so any suggestions would be welcome. My own guess is that it may well be
a
man-made substance, as it is most noticeable over surfaces containing tar
but I
can't quite understand why it needs wetting to release it. Being a
retired
industrial chemist I do know a bit about this sort of thing, but obviously
not
quite enough, and I do need to retain credibility with my niece.

Tudor Hughes, Warlingham, Surrey.

Tudor,

I always thought it was a build up of various oils or secretions given off
from many plants and trees which accumulate in the top layer of the soil
during dry weather. When it rains there is a combination with iron compounds
in the soil which provide a catalyst to form the familiar rain odour. If you
could bottle it you would earn a fortune. It was dry and warm for several
days of late before the rains of yesterday. However not really having much
confidence with chemistry I may well be on the wrong track.
I was awoken but very loud thunder at 05.50hrs this morning in Coulsdon. The
storms of yesterday were very similar to a heat induced summer situation and
most unlike the normal April scenario as were the storms coming in from the
east last night. However there were some severe night storms over the
Southeast especially Sussex on the 14th April 1981. Some 91mm of rain fell
at Horsham.

Ian Currie -Coulsdon
www.frostedearth.com



Hello everybody,
Just had an email from my niece who's asking what the cause is of
that
nice smell you get when it rains after a warm spell. Told her I'd seek
advice,
so any suggestions would be welcome. My own guess is that it may well
be
a
man-made substance, as it is most noticeable over surfaces containing
tar
but I
can't quite understand why it needs wetting to release it. Being a
retired
industrial chemist I do know a bit about this sort of thing, but
obviously
not
quite enough, and I do need to retain credibility with my niece.

Tudor Hughes, Warlingham, Surrey.

Yn erthygl , sgrifennodd
Les & Claire :
I think it may be microbes, fungi, bacteria etc. Dormant during dry spells
but bursting into life during damp periods.

But it's the so-called "fragrance after the rain" we're talking about, not
the "fragrance when it's wet".

I've been told ozone has something to do with it - though I've no idea
why it would. But that uplifting feeling it gives you would certainly
back that up.

Adrian

--
Adrian Shaw ais@
Adran Cyfrifiadureg, Prifysgol Cymru, aber.
Aberystwyth, Ceredigion, Cymru ac.
http://users.aber.ac.uk/ais uk

I tell my girls its the smell of empty clouds

Or it could be all the banana punch spilled at the Monkeys Weddings )





"TudorHgh" wrote in message
...
Hello everybody,
Just had an email from my niece who's asking what the cause is of
that
nice smell you get when it rains after a warm spell. Told her I'd seek
advice,
so any suggestions would be welcome. My own guess is that it may well be
a
man-made substance, as it is most noticeable over surfaces containing tar
but I
can't quite understand why it needs wetting to release it. Being a
retired
industrial chemist I do know a bit about this sort of thing, but obviously
not
quite enough, and I do need to retain credibility with my niece.

Tudor Hughes, Warlingham, Surrey.

Thanks for all your replies so far. Perhaps I didn't make it clear enough
in the original posting that the smell I was referring to was the one you get
from concrete or tarry surfaces, and not the more rural damp freshness, which
has something to do with rotting vegetation, I think.
Any further ideas welcome before I email my niece late tonight with a
distillation of this wisdom.

Tudor Hughes, Warlingham, Surrey.