The Italian diplomat and writer Niccolò Machiavelli (1469–1527) is mainly remembered today for his political treatise Il Principe (The Prince) [ebook/audio], a handbook for unscrupulous politicians (see also the term Machiavellian). Besides being a political scientist, Machiavelli was also a playwright (e.g., Mandragola), a poet (e.g., Decennale primo) and he also wrote extensively on the history of Florence. In Istorie Florentine (1520–1525) (The History of Florence), a work commissioned by Giulio de' Medici (later Pope Clement VII), Machiavelli describes the effects of a tornado that occurred on 24 August 1456. 

In the year 1456, the disturbances occasioned by Jacopo Piccinino having subsided, and human weapons laid aside, the heavens seemed to make war against the earth; dreadful tempestuous winds [tempesta di venti in the original Italian] then occurring, which produced effects unprecedented in Tuscany, and which to posterity will appear marvellous and unaccountable. On the twenty-fourth of August, about an hour before daybreak, there arose from the Adriatic near Ancona, a whirlwind, [turbine in the original Italian] which crossing from east to west, again reached the sea near Pisa, accompanied by thick clouds, and the most intense and impenetrable darkness, covering a breadth of about two miles in the direction of its course. Under some natural or supernatural influence, this vast and overcharged volume of condensed vapor burst; its fragments contended with indescribable fury, and huge bodies sometimes ascending toward heaven, and sometimes precipitated upon the earth, struggled, as it were, in mutual conflict, whirling in circles with intense velocity, and accompanied by winds, impetuous beyond all conception; while flashes of awful brilliancy, and murky, lurid flames incessantly broke forth. From these confused clouds, furious winds, and momentary fires, sounds issued, of which no earthquake or thunder ever heard could afford the least idea; striking such awe into all, that it was thought the end of the world had arrived, that the earth, waters, heavens, and entire universe, mingling together, were being resolved into their ancient chaos. Wherever this awful tempest [turbine in the original Italian] passed, it produced unprecedented and marvellous effects; but these were more especially experienced near the castle of St. Casciano, about eight miles from Florence, upon the hill which separates the valleys of Pisa and Grieve. Between this castle and the Borgo St. Andrea, upon the same hill, the tempest passed without touching the latter, and in the former, only threw down some of the battlements and the chimneys of a few houses; but in the space between them, it leveled many buildings quite to the ground. The roofs of the churches of St. Martin, at Bagnolo, and Santa Maria della Pace, were carried more than a mile, unbroken as when upon their respective edifices. A muleteer and his beasts were driven from the road into the adjoining valley, and found dead. All the large oaks and lofty trees which could not bend beneath its influence, were not only stripped of their branches but borne to a great distance from the places where they grew, and when the tempest had passed over and daylight made the desolation visible, the inhabitants were transfixed with dismay. The country had lost all its habitable character; churches and dwellings were laid in heaps; nothing was heard but the lamentations of those whose possessions had perished, or whose cattle or friends were buried beneath the ruins; and all who witnessed the scene were filled with anguish or compassion. It was doubtless the design of the Omnipotent, rather to threaten Tuscany than to chastise her; for had the hurricane been directed over the city, filled with houses and inhabitants, instead of proceeding among oaks and elms, or small and thinly scattered dwellings, it would have been such a scourge as the mind, with all its ideas of horror, could not have conceived. But the Almighty desired that this slight example should suffice to recall the minds of men to a knowledge of himself and of his power.
— History Of Florence (1532) [1]

Machiavelli did not witnessed the event, since he was born in 1469, but he describes an event that had a strong impact and was keep alive in the memory of Tuscany [2].  It is clear from Machiavelli's description that this event was at least a damaging wind event (tempesta di venti, which can be translated as windstorm). The use of the term turbine (whirlwind), which can be used to describe tornadoes (e.g., Boscovich 1749 [3]) and the description of the phenomena as "ora verso la terra scendendo, insieme si urtavano; e ora in giro con una velocità grandissima si movevano" [4] (translated as sometimes precipitated upon the earth, struggled, as it were, in mutual conflict, whirling in circles with intense velocity or sometimes as furiously towards the Earth, sometimes twisting round like a Cylinder [5]) indicates in my opinion the presence of a tornado or at least of a funnel cloud.  


[1] Machiavelli, N., 1532: History Of Florence And Of The Affairs Of Italy From The Earliest Times To The Death Of Lorenzo The Magnificent. Commentator: Hugo Albert Rennert via

[2] Pedretti, C, 1973: Leonardo: A Study in Chronology and Style. University of California Press, 192 pp.

[3] Boscovich, R. G., 1749: Sopra il turbine che la notte tra gli XI, e XII giugno del MDCCXLIX danneggió una gran parte di Roma (Upon the Whirlwind that on the Night between the 11th and 12th of June 1749 Damaged a Large Part of Rome).Appresso Niccoló, é Marco Pagliarini, 231 pp.

[4] Machiavelli, N, 1532. Istorie Florentine

[5] Machiavelli, N. 1891: The History of Florence From the translation of "The Works of the Famous Nicholas Machiavelli" published in 1675, edited by Sir Henry Morley, LL.D., London, Gerge Routledge and Sons, p. 319–321.

Machiavelli's portrait is by Santi di Tito (1536–1603) via

AuthorBogdan Antonescu

Poster presented at the 8th European Conference on Severe Storm, Wiener Neustadt, Austria, 14–18 September 2015. A PDF version of the poster can be found here

Two weeks ago, I have presented this poster on the early theories on tornado formation at the 8th European Conference on Severe Storms. The poster shows the major contributors, from Aristotle to Peltier, and their theories on the formation of tornadoes. Given the size of the poster, I was not able to include all the contributions. There is one contribution in particular which I think deserves more attention - "On the violence of the tornado, and the storm",  Book 1, Chapter XI from Historiade Gentibus Septentrionalibus (History of the Nordic People) by Olaus Magnus. 

Olaus Magnus (or, Olof Månsson) a Swedish ecclesiastic, historian and geographer, was born at Linköping in 1490. In 1510 he began his ecclesiastic studies in Germany and returned to Sweden in 1517. Like his elder brother, Johannes Magnus, Olaus obtained several ecclesiastical positions, as canon at Uppsala and Linköping, and then as archdeacon of Strängnäs. In 1523, King Gustave I appointed Johannes Magnus as Archbishop of Uppsala.  After Gustav I's breaking with the Catholic Church, Johannes accompanied by Olaus as his secretary went to Rome in 1537. Johannes died in 1544, and Olaus was appointed as his successor in Uppsala. This was nothing more than a title since by this time Sweden was not Catholic anymore. Olaus spend the rest of his life in Italy, for the most part in Rome were he died in 1558.

The cover of the History of the Northern People (Rome, 1555) courtesy of Google Books.

Olaus Magnus is mainly remembered today for his History of the Northern People printed in Rome in 1555. The History, one of the first works about the Sweden and its inhabitants, also depicts the history and folklore of other north European countries. The History is divided into 22 books and 476 chapters illustrated with 353 woodcuts.  

Another work by Olaus Magnus to which many illustrations from the History refer to is the Carta Marina. Drawn by Olaus between 1529–1539, this is a stunningly detailed map and one of the earlies maps of the Nordic countries. The map also contains a very accurate depiction of the oceanic currents between the Iceland and Faroe Islands. Rossby and Miller (2003) argued that whorls drawn in the ocean by Olaus are to deliberate to be purely artistic expression. Instead, they are representations of the Iceland-Faroe front, that "separates the warm waters flowing north between Iceland and Faroes from the cold waters flowing east east and south around the northern coast of Iceland" (Rosbby and Miller, 2003, p. 87).

Let's now return to Chapter 11 (Books 1) "On the violence of the tornado, and the storm" from the History. As the title indicates, this chapter is devoted to the effects of tornadoes and storms in general. The illustration accompanying the chapter shows a tornado (turbo, in the original Latin text) uprooting trees and lifting the roofs of a church and a house.

Woodcut from the chapter "On the violence of tornado, and the storm" from the History of the Nordic People by Olaus Magnus. (source:

 Here is the translation form Latin by Cassia Price of the chapter. 

As all who tell the secrets of nature or who have observed them know, tornadoes, and the storms of Northern places, have awesome and dangerous energy. Especially because of the complex and unfailing cause of their origins, the means for which might be found. Therefore, a tornado (argues Isidore), is the twisting of winds, and this has been said on earth as many times as the wind rouses itself, and the earth is sent into a spin: this tornado brings about even more winds from the struggle with itself (Seneca is a witness of this in his Naturales quaestiones). And these areas are caught up around the earth and brought forth: and for this reason orchards are torn from their roots, and whatever it broods over it strips bare to the ground, and, at the same time, ripping up the trees, and the rooves just lower than the clouds; at any rate nothing is higher. Its shape is round: while the wheeling column spins itself, all the clouds seize it quicker and quicker. And its motion is wandering, dividing, swirling. But then it cannot stay, for it struggles, because it is wandering, inconstant air; at the end however, it moves least of all. And so no storm lasts long. But the commotions of storms, however much more power they might have, the less time they last, having arrived, because when they come to their climax, all the force is diminished, and that excitement is necessary so that it might exert itself to the point of its own ruin. And so no one has seen a tornado for a full day, not even for an hour. Their speed is extraordinary, and how short-lived they are, remarkable. The more forcefully and quickly it turns around the earth, the slacker it becomes, and, on account of this they fall apart. For it is made with the divided air troubled by some clouds, and it turns about, but making a ring around it, so that a part of the cloud is drawn in, as if it is inseparable from it, and it seizes it, moving in circles, its end is not to be found, turning in on itself again. From waves and from the sea it often sweeps up the waters under boats, and knocks sailors high from underneath: from land it scatters snatched up rocks and other animals and small trifles. Not only that by the lead rooves of temples and all sorts of houses, and indeed even those of the strongest materials, are seized by the air, and from elsewhere the air, joining more vigorously, carries it to an area further away. Most wisely, when huge stones have been rolled along from the windmill, sound against the storm, those people who are safe are taken to far off places. Indeed, so huge is the storm that descends that, enveloping the towns, citadels, and villages, rooves far and wide (so it is said) are bourn to the fields, according to Vincent, Book XXV, Speculum Historiae, Chapter LXXXVII, as he bears witness in Book XXVI, Chapter XXVI, making mention of the tornado. Not in the account of Diodorus Siculus, missing from Book VI of his Historia, saying the amazing force of the wind is in the directions of Aquilo. For in summer the Occidental and Septentrional last with such great force and vigour of the winds that it seizes rocks from the earth of such a size that a hand can hold. It builds them into piles that are not small as if they were sand or pebbles, and finally, from men it might snatch weapons and clothing, whereas from a horse it might steal their rider by force, as he mentioned in the next chapter. In fact, as it happens at some point in Vichia Norvegiae, through the air and the great burning sun, the largest fish in rich fishing places, driven from the streams, from their fishing poles like planks of wood in great heaps, were received as a gift given by God. But no one is entitled to demand action, for God reserves judgment to help he needy.
— "On the violence of the tornado, and the storm"

In his explanations of the origin of tornadoes, Olaus relies on two theories. In the first theory, proposed by Isidore of Seville  (c. 560–636), "the last scholar of the ancient world" and the patron saint of the Internet, tornadoes are produced by the "twisting of winds" (I would discuss Isidore's theory in more details in the next blog post). The second theory in which the tornado "brings about even more winds from the struggle with itself" is attributed by Olaus to Seneca (c. 4 BC–AD 65). As far as I am aware this theory was first proposed by Aristotle (384–322 BC), who stated that tornadoes are produced by the winds trapped in the cloud, spinning around trying to get out and producing cone or column shaped clouds (see Theory 2 in the above poster).  After discussing their origin, Olaus describes the characteristics tornadoes. Tornadoes are "round while the wheeling column spins itself", their motions is "wandering, dividing, swirling", they have short life time ("no one has seen a tornado for a full day, not even for an hour") and their "speed is extraordinary".  The chapter ends with descriptions the effects of tornadoes: "huge stones have been rolled along from the windmill" by tornadoes, also "from men it my snatch weapons and clothing, whereas from a horse it might steal their rider by [their] force".  Thus, as in the case of the Carta Marina, Olaus provides in this chapter from the History stunning details of tornadoes and their effects. Not only this, but in Chapter 35 (Book 1) "On the Signification of Thunderstorms for Every Specific Month" Olaus describes the annual cycle of thunderstorms over Sweden.

Woodcut from the chapter "On the Signification of Thunderstorms for Every Specific Month"  from the History of the Nordic People by Olaus Magnus (source:

In this early "infographic", the year is symbolized by the ribbon. On the ribbon the month are represented by letters i) the summer months: - A-Aprilis, M-Maius, I-Iunius, I-Iulius, A-Augustus, and S-September (upper part of the ribbon) and ii) the winter months: O-October, N-November, D-December, I-Ianuaris, F-Februarius and M-Martius (lower part of the ribbon). The summer months are associated with more rain (upper part of the figure) and lightning (the emerging branches from the letters representing the months, with more branches indicating more frequent thunderstorms). The winter months are associated with more snow (lower part of the figure). This annual cycle, shows that thunderstorms occur all year round in Sweden,  with a maximum between May and August. This is consistent with the annual cycle of tornadoes in Sweden, with tornadoes reported in almost every month in Sweden and a maximum between June and August (see Fig. 5 from this paper). 

A beautiful representation of a tornado near Hague (Netherlands) on July 1751 by the Dutch lawyer Jan Francois Dryfhout. This is one of the very few representations of tornadoes from the 18th Century (the majority of the depictions from this period were for waterspouts). The case was not included by Wegener in his collection of tornadoes and waterspouts in Europe (Wegener 1917). 

Fig. 1 - Plate I from Dryfhout (1757) showing the evolution of a tornado near Hague on July 1751 (courtesy of Universiteitsbibliotheek Gent).

The first Plate (Fig. 1) shows the evolution of the tornado from growth to decay (Plate I, Figs. IV). Figure V show the final stage when the tornado was drifting out to sea "having lost its upright posture, [it] was blown upward toward south, in the manner of a fluttering ribbon" (Leighly 1974). 

Fig. 2 - Plate II from Dryfhout (1757) showing the parent cloud of a tornado near Hague on July 1751 (courtesy of Universiteitsbibliotheek Gent).

The second Plate (Fig. 2) shows the parent cloud of the tornado and suggest the presence of mammatus clouds (see Schultz et al. 20056 for a review). Dryfhout describes the parent cloud as "composed of a great number of smaller cloudlets, resembling round balls" (Leighly 1974).  

The complete description of this event can be found here. Unfortunately I can not read Dutch, but I would be very gratefully for any help on obtaining more details about this tornado (and maybe we can write a short article about it).

source: Dryfhout, J. F.:  Nauuwkeurige beschouwinge van een hoos, benevens een ondersoek, 
hoe dezelve geboren worden en werken (A detailed examination of a tornado formation and additional research on how they form and function). Verhandelingen uitgegeven door de Hollandsche Maatschappij der Wetenschappen te Haarlem, 3, 321377. (PDF via Google Books).


Leighly, J., 1974: An Early Drawing and Description of a Tornado, Isis, 65, 474486. (link)

Wegener, A. L., 1917: Wind- und Wasserhosen in Europa. Vieweg, Braunschweig, 301 pp. (link)

Today I have submitted to Monthly Weather Review a manuscript written together with David M. Schultz and Fiona Lomas (University of Manchester) on European tornadoes. The manuscript, a synthesis of the European tornado datasets, is also a short history of tornado observations in Europe and a literature review of the major contributions on tornado research in Europe.  

There are three reasons for which we believe that this research was necessary. First, there is not a widespread recognition or the threat of tornadoes in Europe, and this lead to an underestimate of the importance of tornadoes in the current climate in Europe. Second, to better understand the climatology of tornadoes in Europe we need to understand the evolution of tornado databases for different European countries and to identifying the major influences on the development of these databases. Third,  when considering the possible influence of climate change on severe convective storms, the first step is to consider the
observational data. Without knowing what is occurring now, how many tornadoes occur each
year in Europe, and what is the current spatial distribution of tornadoes, all the analyses
of the influence of climate change on tornadoes are premature.


We hoped that this manuscript of the current knowledge on tornadoes in Europe [in a way, this is a companion paper to Groenemeijer & Kühne (2014)] will encourage further discussions and stimulate the interest of the scientific community, national meteorological services and the public on European tornadoes. We hope that this would result in increased awareness, in the identification of new data sources, or in the initiation of new databases that would allow a extension of the current European tornado database both in time and in space. 

You can read the draft of the paper here.

Recently, browsing through Gallica, the digital library of the Bibliothèque Nationale de France, I have found this book, containing illustrations from the Cosmic Meteorology by Robert Fludd. I was sufficiently intrigued to try to find more about the book, especially because one of the illustrations contained, among other meteorological phenomena, a representation of a tornado.

Robert Fludd (1574 –1637) (image courtesy of Smithsonian Library).

Philosophia Sacra et Vere Christiana seu Meteorologia Cosmica was first published by Théodore de Bry at Frankfurt  in 1623. I was to some extent familiar with the author, Robert Fludd, through the works of Frances Yates (1899 –1981). Robert Fludd (1574 –1637), an English mystic, philosopher, alchemist, scientist and musician, was educated at Oxford and practised medicine in London. In addition to his medical practice, influenced by the doctrines of Paracelsus (1493–1541), he published a large number of books, richly illustrated and covering medical, practical and speculative topics in an attempt to reconcile the mysticism with the science of 17th Century.  In the Cosmic Meteorology, Fludd applies the word meteor not only to meteorological phenomena but also to planets, starts and comets. 

Fig.1 - Frontispiece of Philosophia Sacra et Vere Christiana seu Meteorologia Cosmica  (Frankfurt1623) with engravingsby Matthäus Merian ( 1593 –1650). (image courtesy of Gallica)

 The frontispiece of the book (Fig.1) shows, according to Godwin (1979) the effects of the macrocosmic meteors and in particular of the wind. The wind played a central role in Fludd's medical speculations, since was capable to carry the good (from angels) and the bad (from demons) influences (lower centre). One illustration from the frontispiece shows the beneficial effects of the winds (lower right), the others are showing the detrimental effects: an earthquake, produce by the wind bellow the earth's surface (lower right), a "rain of fire" (upper left), a thunderstorm producing rain, lighting and hail (upper centre) and a thunderstorm at sea (upper right). The left and right middle panels are showing different types of comets (right) and parhelia (sundogs, left).   

The most fascinating illustration by Matthäus Merian (1593 –1650) from Cosmic Meteorology is the Great Meteorological Chart (Fig. 2). In Godwin's (1979) interpretation, God is represented on the top of the chart and the semicircles contains representations of all the meteorological phenomena. Different types of comets are represented first, followed clouds and their associated phenomena: whirlwind and a tornado (turbo and prester as fiery exhalations, left) (Fig. 3),  blood (gutta sanguinia), stone (lapides) and frog (rane) rains and lightning (fulmen) (centre) and hail (grando), rain (pluuia) and shown (nix) (right).  

Below the clouds are represented the twelve winds and at the surface there is an other representation of a whirlwind (turbo) (centre) (Fig. 4).  On the lower left is a list of "meteors sent for man's benefit" (i.e., wind, whirlwinds, cold, ice, rain, lightning) and on the lower right a list of "meteors sent for man's chastisement or punishment" (i.e., fiery whirlwinds, with and without demons; lighting, hail) (Godwind, 1979).    

Fig. 2 - The Great Meteorological Chart from Cosmic Meteorology (1626) by Robert Fludd. (image courtesy of archive.rog) (click here more details).

Fig. 3 - Detail (lower left) from The Great Meteorological Chart showing a whirlwind (turbo) and a tornado (prester, fiery exhalation). (image courtesy of archive.rog)

Fig. 4 - Detail (lower left) from The Great Meteorological Chart showing a whirlwind (turbo). (image courtesy of archive.rog)

The Great Meteorological Chart, despite being a part of a mystical text, is a very interesting summary of the knowledge on meteorological phenomena in the 17th Century.



Godwin, J., 1979: Robert Fludd, Hermetic Philosopher and Surveyor of Two Worlds. Thames and Hudson, p. 96.  

AuthorBogdan Antonescu