Earth & SkyGreek → English
Thermocline
/ˈθɜːrmoʊklaɪn/noun
The layer in a lake or ocean where temperature drops sharply with depth.
The Greek roots
θερμός
thermós
hot, warm
κλίνω
klínō
to slope, lean
Literally: “heat slope”
The story of the word
Limnologists studying Wisconsin lakes in the 1890s needed a name for the thin band where a swimmer's feet meet cold water while the shoulders stay warm. The word says slope of heat, and the slope is steep: several degrees in a metre or two. Submariners learned to sit beneath one, because the density change bends sonar pings away and hides the boat under a false floor.
- How it travelled
- Ancient Greek → scientific coinage → English
- First recorded
- 1897
Same family
thermometerthermosclinicisocline
In a sentence
The thermocline sat at four metres and the lake below it was shockingly cold.
Once the autumn winds mix the thermocline away, the whole lake turns over.