petrichor
noun
pe·tri·chor ˈpe-trə-ˌkȯr 
: a distinctive, earthy, usually pleasant odor that is associated with rainfall especially when following a warm, dry period and that arises from a combination of volatile plant oils and geosmin released from the soil into the air and by ozone carried by downdrafts
Australian scientists first documented the process of petrichor formation in 1964 …
Tim Logan
Tim LoganThe intensity of the petrichor smell can vary with the type of soil and how heavily the rain is falling. John Boyer
John Boyer
Word History
Etymology
petr(o)- + ichor
Note: The word was introduced by the Australian mineral chemists Isabel Joy Bear (born 1927) and Richard Grenfell Thomas (†1974) in "Nature of argillaceous odour," Nature, vol. 201, No. 4923 (March 7, 1964), pp. 993-95. According to the authors, "The diverse nature of the host material has led us to propose the name 'petrichor' for this apparently unique odour which can be regarded as an 'ichor' or 'tenuous essence' derived from rock or stone."
First Known Use
1964, in the meaning defined above