I’ll bet you didn’t think rain has a smell, but I’ve always smelled something delightful with a fresh rain. There is a word, petrichor, derived from the Greek (petra, meaning rock, + ichor, meaning fluid that flows in the veins of gods), for the scent of rain on dry earth. Now two Australian scientists, in an article for the journal Nature, have discovered that the smell comes from an oil exuded by certain plants during dry periods and absorbed by the earth and rocks. During a rain, the oil is released into the air along with a bacterial by-product to produce the distinctive smell. Rain also absorbs ions and thus can smell of ozone in a thunderstorm.
Lots of science for the wonderful fresh odor of rain.