Petrichor

"Like sheep which, having been driven to a pasture, can now spread out at their leisure, the clouds began to drift. Afternoon sunlight sliced through into the still waters. The boomerang hung in the sky, and the boy thought he would have to find a new word for the way the colors glowed. In the meantime, he looked down at the water and tried out the word he'd been taught by his grandfather, who'd been taught it by his grandfather, and which had been kept for thousands of years for when it would be needed. It meant the smell after rain. It had, he thought, been well worth waiting for."
-- Terry Pratchett, The Last Continent

Image from The Doctor's Wife, episode of Doctor Who owned by BBC