@self @cstross @dgerard > maybe I live in a particularly dry place, but my brain isn’t rendering “the scent of damp earth” or why it’d sit thick in the air.

It's somewhat similar to petrichor, but not quite. Earthen cellars & crawlspaces in high-humidity have something comparable. One place I've lived in with no proper basement kept the smell going for days after it rained enough or otherwise had high-enough humidity.