What’s on the surface and in the air—the terpenes and bacteria of a particular area—and how long these compounds have accumulated there, dictates the precise scent and extent of aroma released by the rain, smells which are then carried by the wind. The velocity of the raindrop, along with porousness of the surface on which it falls, influences the aerosol spritz. Interestingly, more aerosol is released in light rain than during a heavy downpour, the researchers found.

— Read more at The artful science behind the scent of bottled rain at Quartz.