One thing about English is that the number of words it includes has gotten completely out of hand. Although there isn’t any way to figure out what the actual total is (it’s not that easy to decide what counts as a word), there are probably at least 250,000. There are even estimates as high as 600,000. But that’s not entirely a bad thing. That huge total means that English includes whole vocabularies that are amazingly specific.
For one of those, consider that limnologists are familiar with hypolimnion, metalimnion, epiclimnion, and even more terms they use in the context of limnology. And thanks to English, they can do all this while the rest of us are left in the dark about what they might be talking about.
If you happen to be fluent in Greek as well as English, of course, you probably have an excellent idea what they’re up to, because all those words are derived from Greek, where “limne” means a lake. “Limnology” is the study of lakes.
If you’re going to study lakes, probably one of the first things you’d do is wade into one. In the summer, most likely. And you might notice that the water at the very top is warmer than the layer of water underneath. And there you have it; “epi-“ in Greek means above, so the top layer of water, warmed by the sun, is the epilimnion. “Hypo-” comes from the Greek word “hypo,” and as you’ve already guessed, that means beneath. So the “hypolimnion” is the cooler water not too far below the surface.
Of course, water doesn’t stay divided into discrete sections like layers because, well, it’s water. So there’s an area between the epilimnion and the hypolimnion where the temperature changes vertically. That has a name too; the “metalimnion,” for “across”. A real limnologist, though, would be more likely to call it the “thermocline,” at least nowadays.
Since we’re pretending to be limnologists who use English, of course, we can be confident that everything we study applies not only to lakes, but also lagoons, ponds, reservoirs, lochs, meres, tarns, basins, lakelets…basically a whole inland sea of similar terms. Now, it’s a hot day, who’s up for a swim?
