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