[Lewis Thomson (OP)]

Ros has sent in this very peculiar question.

"Why does washing hung outside smell so lovely..?"

Why could this be the case? Leave your comments down below...

[alancalverd]

This has been the subject of lots of research, both to identify the nice smell and to understand the mechanism behind it. IIRC the current feeling is that the process involves some ultraviolet photochemistry that produces chemicals which are only stable at low temperatures, so drying indoors or in a hot tumble dryer won't do the trick. My grandmother used to "air" clothes after ironing them, probably to get the same chemistry going.

The other elusive smell is that of wet earth after a rain shower. Huge commercial potential of you could bottle it, but I don't thinkl anyone has done so yet. 

[Bored chemist]

Huge commercial potential of you could bottle it,

It's largely geosmin.
https://en.wikipedia.org/wiki/Geosmin
You can buy it- in bottles. It's rather expensive.

The whole story is a bit more complex than just one chemical.
https://en.wikipedia.org/wiki/Petrichor