Storms can be scary. High winds, lots of rain, lightning, thunder, hail. In Greek mythology, Zeus is a storm god hurling thunderbolts at hapless mortals who have offended him. Early Greek philosophers wanted to explain storms and other scary events as natural phenomena to be explained by natural forces. They typically accounted for winds, lightning, and the like, as air or fire trapped in clouds that would sometimes burst out.
Aristotle offers the most systematic account we have from any ancient philosopher, in his treatise Meteorologica, which is about meteorology (and also some geology, oceanography, and chemistry). He believes that there are two kinds of “exhalation” (anathumiasis, a word he probably invented) that clash in a storm front. One of these is moist, roughly our idea of water vapor, which can condense into droplets and produce rain. The other is a dry, smoky gas that is the cause of winds and fiery phenomena (book 1, chapter 4).
In English translations we read that violent storm events are caused by a “hurricane,” eknephias (a word Aristotle did not invent, but which was barely used before Aristotle made a big deal about it). There is a problem with the translation ‘hurricane.’ In the first place, the English word was taken from the Carib language, spoken by the natives of the Caribbean Sea area, borrowed into the Spanish language and transmitted into English, describing specifically the massive superstorms that occur in the south Atlantic Ocean. Hurricanes are what is known in modern science as tropical cyclones, created by sucking up huge amounts of warm water from the tropics. But the Mediterranean Sea, the only large body of water Aristotle knew, is not in the tropics, so there are no hurricanes that Aristotle could have experienced.
There are, however, hurricane-like storms in the Mediterranean known as “Medicanes” (short for Mediterranean hurricanes), which, though less violent and shorter-lived than hurricanes, do offer a similar experience. This observation, however, doesn’t help much, because Aristotle describes his eknephias as a small-scale event. Indeed, he introduces the term in the phrase eknephias anemos (book 3, chapter 1), which means, taken fairly literally, wind (anemos) from a cloud (ek nephous). So he is not talking about a superstorm at all, but a column of air being ejected from a cloud.
He uses this notion of a column of air moving downward from a stormcloud, to account for three kinds of storm events: the thunderbolt (keraunos), the whirlwind (tuphōn), and the firewind (prēstēr). Today, we usually consider ‘thunderbolt’ to be just a dramatic name for a discharge of lightning. But Aristotle and some of his near contemporaries seem to view lightning as a different phenomenon from the thunderbolt. Lightning, according to Aristotle, is less intense and more diffuse than the thunderbolt. Furthermore, he takes lightning to stay in the sky, traveling from cloud to cloud, whereas a thunderbolt moves downward to strike the earth or the sea.
In a thunderbolt, according to Aristotle, the dry exhalation shoots downward from a cloud, bringing hot, dry gas that can (but does not always) ignite fires in the objects it strikes.
The whirlwind also travels downward from a cloud, but it fails to break free of the cloud. It drags the mist from the cloud down with it, creating a funnel-shaped tube to the earth, where it can cause great destruction. With this description, we can give a more precise name to the whirlwind: it is a tornado.
Finally, there is the “firewind” (prēstēr). The English term is dramatic, but vague. What exactly are we talking about when we call something a firewind? Different scholars have identified this with waterspouts, thunderbolts, sheet lightning, and lightning storms. But Aristotle himself describes it as like a whirlwind that that ignites and colors the surrounding air—in other words, like a burning tornado (book 3, chapter 1, page 371a15-17). The only storm event that fits this description is what modern meteorologists call a fire whirl, or in popular parlance, a fire tornado. This is not technically a tornado, since it starts from the ground as an updraft from a massive fire, rather than from a stormcloud. But fire whirls can reach the speed and power of tornadoes.
So what is an eknephias? There is a newly-recognized storm event that fits Aristotle’s description of a column of air pushing downward from a cloud: a downburst. A column of air pushes slowly downward from a cumulonimbus stormcloud; when it hits the ground, it fans out in all directions, producing a violent windshear that can reach hurricane speeds, producing either a “microburst” or a “macroburst,” depending on the extent of the wind. These bursts can uproot trees and cause airplanes to crash. (See information from the U.S. National Weather Service, https://www.weather.gov/lmk/downburst# )
Aristotle would not, of course, have access to modern technology that has established the existence of downbursts, including Doppler radar. But there is a sense in which you can “see” a downburst by its effects. See pictures and videos on Twitter, #downburst, #microburst ( https://twitter.com/search?q=%23downburst&src=typed_query&f=top ; https://twitter.com/search?q=%23microburst&src=typed_query&f=top ).
(This post is based on an article I wrote with two former students, Zachary Herzog and Michael Williams, recently published as “Earth, Wind, and Fire: Aristotle on Violent Storm Events, with Reconsideration of the Terms eknephias, tuphōn, keraunos, and prēstēr.” Apeiron 55.3: 2022: 417-422. See https://www.degruyter.com/document/doi/10.1515/apeiron-2020-0067/html )