isophene
EYE-so-feen
A line connecting all the places experiencing the same biological season at the same time — spring's advancing front, mapped. Neat across a continent; jagged when you zoom in to a single hillside, where south-facing slopes are weeks ahead of north-facing ones.
Etymology
Greek isos (equal) + phainein (to appear, to show). Equal appearances — places where the same seasonal signs appear simultaneously.
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