Isocrymes

Part of speech: noun

Definitions

1. Lines drawn on a map that connect places sharing the same average winter temperature
2. Contour-like lines showing regions where the mean temperature of the coldest season is identical
3. Curves on a climate chart linking locations that have matching average temperatures in winter

Etymology: "Isocrymes" is the plural of "isocryme," a term that James D. Dana coined in 1854 for an imaginary line on a map. Dana was a geologist and naturalist who had sailed on the United States Exploring Expedition, and in his work on the geographical distribution of crustaceans he needed a way to name lines joining places with the same winter temperature, much as isotherms join places with the same average temperature. The word combines the Greek prefix "iso-" meaning "equal" with "krumos," a Greek noun meaning "cold" or "chilliness." Dana glossed that Greek root as "extreme cold," so the term literally marks places sharing the same extent of severe cold. The Greek root is related to "krüos," meaning frost, which gives the word its pinch of icy atmosphere.