Petrichor is the name of the scent of rain on dry earth. In 1964, two Australian researchers discovered that the smell that can be experienced after rainfall can be attributed to the oil that is exuded by certain plants during dry periods that is then absorbed by the soil and consequently released into the air when it rains, along with another substance called geosmin (literally ‘earth smell’). The reason why these plants exude this oil is because it slows down the process of new plant growth in the soil, which means the plants are able to ‘wait’ for the rainfall.
The word petrichor is a combination of the Greek words petra, meaning ‘stone’, and ichor, referring to the fluid that apparently flowed through the veins of the ancient mythological Greek gods.