petrichor

A word that literally means "essence of stone" and describes the smell of rain when it falls on dry ground, popularly known as the smell of wet earth. The term was proposed in 1964 by a pair of Australian geologists, who related that smell to the exudation of an oily substance by certain plants, when subjected to the water stress imposed by drought. That oil is absorbed onto rock surfaces and clay soils, and when it rains it is released into the air, together with other odorous substances such as geosmin, resulting in the characteristic smell of rain.