Everybody has seen maps that use contour lines to show, for example, areas of barometric pressure, temperature, or elevation. That type of illustration is called an “isogram,” from the Greek words “isos” (equal) and “gram” (something written). By the way, the “gram” that’s a weight is from the Latin word “gramma” (a small weight).
There’s a specific word for the isogram used by meteorologists to show barometric pressure: an “isobar” chart. “Aha”, you’re probably saying, “there must be a couple of other specific sorts of isograms, and given the context here, maybe they have their own terms as well.” You’d be right about the “other isograms” part, and about the unique words to describe them. But you’d be a little off about the “couple of them” part. If you peruse the dictionary — well, to be more specific, you’ll have to look in several dictionaries, some of them pretty specific — you’ll find sixty different words for individual types of isograms.
Isograms are widely used for visualization of data, which is something scientists are especially interested in, so many of the isograms are about measurements and ratios that most people don’t encounter regularly. For example, there’s the “isovol,” which depicts areas of equivalent ratios of fixed carbon to volatile carbon in deposits of coal (I don’t have any idea what that means either). And the isobar is only the beginning of weather- and climate-related isograms; you might like the “isothermobath” (areas of equal temperature at a given depth of the ocean), as well as several other temperature-related isograms:
isotac – areas where the ice melts at the same time of year
isothere – areas where the temperature is equal in the summer
isocryme – areas where the temperature is equal in the winter
isobatyytherm – areas where the temperature AND ocean depth are the same
isocheim – the same average winter temperature
Other isograms interesting to meteorologists include the isonephelic – areas of equivalent cloud cover, isopleth – equality of any aspect of climate, and isohyet – areas of equal rainfall.
You might even create an isogram of all the similarities among these isograms. What you’d have there would be an isochar — a chart showing connected regions of similar characteristics.
But really, why couldn’t there be any sort of isochar you wanted to generate? For instance, an “isoirritant” would be a map showing areas where equally irritating people can be found. If you wanted to avoid the most diet-friendly restaurants, an “isocaloric” chart could be useful. In the winter, an “isoslip” map would be invaluable if you didn’t want to skid on the ice (or maybe that one would be an “isoice” or even better, an “isoicesoyoudontslip!” An “isopizza” chart would illustrate regional equivalencies in pizza consumption, and pet lovers could consult an “isowoof” or “isomeow” to see where to find fellow dog- or cat-lovers. And of course most importantly, an “isocatachresis” would show you geographic areas you’d definitely want to avoid because it would illustrate where people tend to misuse words the most (the reciprocal of that isogram would be an “isoorthologigram)! It would be much better to use an “isologophile” to find out where everybody likes words the most.
