Speculating About the Weather: The Unusual Dry Fog of 1783

Satellite image (rotated by 90 degrees) from 11 May 2010, Icelands south coast with Eyjafjallajökull is visible on the left and the ash plume is carried towards Europe. (This image is in the public domain, credit: NASA Goddard / MODIS Rapid Response Team.)

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Let’s talk about the weather! In the summer of 1783 individuals in many parts of the northern hemisphere witnessed blood red sunsets and a peculiar, long-lasting dry fog. Speculation in the press was rife as to the cause. Many theories were put forward at the time but it was a century before the fog of ignorance was lifted. But what had caused this unusual weather? 

Editor’s NoteThis is the first post in the “Seeds 2: New Research in Environmental History” series co-sponsored by NiCHE and Edge Effects, publicising the work of early-career environmental historians. This series serves to highlight new work being done in the field of environmental history and connect this research to other fields and contemporary issues.


By Katrin Kleemann

“The summer of the year 1783 was an amazing and portentous one, and full of horrible phænomena; for besides the alarming meteors and tremendous thunder-storms that affrightened and distressed the different countries of this kingdom, the peculiar haze, or smokey fog, that prevailed for many weeks in this island, and in every part of Europe, and even beyond its limits, was a most extraordinary appearance, unlike anything known within the memory of man.”

—Gilbert White.[1]

As illustrated by Gilbert White in his Natural History of Selborne, in the summer of 1783, Europeans had more than enough reasons to be concerned with the weather. A peculiar dry fog with an odd sulfuric smell cloaked Europe and remained for months, with neither wind nor rain managing to disperse it. The fog was not the only oddity these individuals were facing that summer: The sun had a blood red color when it set and rose; an unusual number of thunderstorms seemed to pass through; meteors were visible over western Europe, earthquakes occurred in Italy, and a new island emerged from the sea off the coast of Iceland. Speculation was rife as to the cause of all this.

Hekla, an Icelandic volcano, known in Europe since medieval times as the gate to hell, was thought to be a potential culprit. When referring to historical maps of Iceland, Hekla is usually pictured as erupting. Famously, Benjamin Franklin suggested that Hekla or Nyey, the newly emerging island, might have caused the dry fog. However, what is often forgotten in this context is that in the same paragraph, Franklin suggested “great burning balls” (meteors) might alternatively have caused it.[2]

This map from around 1700 depicts Mount Hekla erupting, Hekla is Iceland’s most famous and third most active volcano. (Schenk, Peter, and Gerard Valk. „Novissima Islandiae tabula.“ The image is in the public domain. Amsterdam 1700. Click here to view source.)


This illustration shows the “Great Meteor“ of 1783, it is a print by Henry Robinson is titled “An accurate representation of the meteor“ as seen at Winthorpe, England, on 18 August 1783. (This image is in the online collection of the British Museum and it is licensed under a CC BY-NC-SA 4.0 license. Click here to view source.)

At the time a very fashionable explanation was electricity: Lightning was believed to fertilize the soil when it hit the ground. The numerous thunderstorms of the summer quickened the spread of the lightning rod, which had not yet had its breakthrough. The lightning rod was believed to withdraw the beneficial electricity from the atmosphere, which—so the theory went—caused the dry fog, as sulfuric odor had previously been consumed by the “electrical fire.”[3]

There was yet another story making its rounds in the newspapers in July 1783: Not just one but two volcanic eruptions were described within the German territories. The Cottaberg near Dresden as well as the Gleichberg mountains near Hildburghausen were said to have roared to life and to be spitting fire.[4] Both mountains are actually of volcanic origin—however, their last eruptions occurred 25 and 15 million years ago, respectively. The reports were retracted a few weeks later.[5]

A recent photo of the Gleichberg mountains in what is today Thuringia. The two peaks on the horizon are the Großer and Kleiner Gleichberg, respectively. (This photo was taken by Elop, CC BY-SA 2.5. Click here to view source.)

The most popular theory of the time suggested that earthquakes in Italy and this dry fog were directly related: peopl believed the earthquakes had opened a crack in the Earth, which released sulfuric odor from the Earth’s interior into the air. The concept of a subterraneous revolution plausibly explained the sulfuric smell, the fog, the earthquakes, and the newly emerging island.[6]

This hand-colored copper engraving by Jacques François Chéreau from 1783 shows the Strait of Messina from the North and depicts ships struggling with whirlpools and shows damage of buildings caused by the earthquakes (for instance the tower on the left). On the right hand side Mount Etna is depicted erupting (it did not actually erupt in 1783, but in 1776, 1780, and 1781 ). (Used by permission, credit: Jan T. Kozak)


„Subterraneus Pyrophylaciorum“: Fire canals connecting all volcanoes on the planet, depicted in Athanasius Kircher’s Mundus Subterraneus, 1668. (The image is in the public domain. Click here to view source.)

Many more theories were put forward at the time. The natural sciences were not yet able to reliably identify the cause of the dry fog and the unusual weather of the summer. So, what had actually caused this lingering gas behemoth?

The Laki fissure (Lakagígar), a 27 kilometer long row of approximately 140 craters and vents, located in Iceland’s remote highlands, erupted over the course of eight months from June 1783 to February 1784 and released the largest volume of lava of any eruption in the last millennium. The gases produced by the eruption were transported from Iceland via the jet stream and dispersed over the northern hemisphere, where the gases became visible (as well as smellable) as a dry and sulfuric haze. At the time it took three months for the news about an Icelandic volcanic eruption to reach mainland Europe, during the summer of 1783, and Europeans were left alone to find an explanation.

This image shows the position of Iceland and the direction in which the dry fog was blown; it also shows the position of the Mid-Atlantic Ridge and the three major volcanoes. The Laki fissure is just southwest of the Vatnajökull ice shield. (This map was created by Katrin Kleemann and is built upon map materials from Gingko Maps, which are licensed under a CC BY 3.0 license.)


This is one of the numerous craters and vents along the Laki fissure. This photo was taken from Mount Laki by the author in 2016. Published by permission of author.

It took another decade before the Icelandic naturalist and physicist Sveinn Pálsson discovered the Laki fissure in 1794, but his manuscript was not published in its entirety until 1945.[8] The discovery of the volcano did not immediately lead to connecting the dots between the eruption and the dry fog. In 1883, one hundred years after the Laki fissure eruption, Krakatau in Indonesia roared to life. This colossal eruption and the invention of telegraphy made it possible to know about the eruption and simultaneously observe blood red sunsets and sunrises in the western world. It was only in retrospect that the dry fog and the other extraordinary phenomena such as the red skies of 1783 were connected to the Laki fissure eruption.[9]

William Ascroft’s watercolors show blood red sunsets seen visible over London in November 1883 in the aftermath of the August 1883 Krakatau eruption. William Ascroft. „Twilight and Afterglow Effects at Chelsea, London. Nov. 26th 1883.“ The Eruption of Krakatoa and Subsequent Phenomena, edited by G. J. Symons et al. London: Trübner, 1888. (Used by permission, credit: Bodleian Libraries, University of Oxford.)

Many scholars are aware that tropical eruptions, such as the infamous 1815 Tambora eruption, can have far-reaching effects on the globe. High-latitude eruptions, however, can also affect the atmosphere and the weather in different parts of the northern hemisphere. In 2010 an Icelandic volcanic eruption brought international air traffic to its knees and the world (and the humanities) became aware that Iceland is volcanically active. Learning about the not always obvious effects of an Icelandic volcanic eruption can prove useful for European and North American environmental historians to be able to spot similar events in their sources from one of Iceland’s frequent (past or future) volcanic eruptions, or from eruptions originating in Alaska or the Cascades.

Click here to see an interactive map with volcanic eruptions, sulfur dioxide emissions, and earthquakes for the last half century. For more information see: Kleemann, Katrin. “Eruptions, Earthquakes, & Emissions: Visualizing the Planet’s Heartbeat.” Ant, Spider, Bee: Exploring the Digital Humanities, 6 February 2017.


[1] White, Gilbert. “Letter LXV.“ The Natural History of Selborne [1788], edited by Richard Mabey, 265. Reading, UK: Penguin Books Ltd, 1977.

[2] Franklin, Benjamin: “Meteorological Imaginations and Conjectures.“ Memoirs of the Literary and Philosophical Society of Manchester 2 (1785):357–361.

[3] Hochadel, Oliver. “’In Nebula Nebulorum’: The Dry Fog of the Summer of 1783 and the Introduction of Lightning Rods in the German Empire.“ Transactions of the American Philosophical Society, New Series, 99, no. 5 (2009):45–80; Münchner Zeitung [Münchner stats-, gelehrte, und vermischte Nachrichten aus Journalen, Zeitungen, und Correspondenzen übersetzt, und gesammelt], Beylage zur Münchner Zeitung, issue 8, 29 August 1783, 60.

[4] Grattan, John P., D. D. Gilbertson, and A. Dill, “‘A Fire Spitting Volcano in Our Dear Germany’: Documentary Evidence for a Low-Intensity Volcanic Eruption of the Gleichberg in 1783?” in The Archaeology of Geological Catastrophes, ed. W. J. McGuire, D. R. Griffiths, P. L. Hancock, and I. S. Stewart, Special Publications 171, 307–315 (London: Geological Society, 2000).

Cottaberg “eruption“: Königlich privilegirte Berlinische Staats- und gelehrte Zeitung, issue 81, 8 July 1783, 670.

Gleichberg “eruption“: Königlich privilegirte Berlinische Staats- und gelehrte Zeitung, issue 87, 22 July 1783, 714.

[5] Münchner Zeitung, issue 117, 28 July 1783, 461.

[6] Staats- und Gelehrte Zeitung des Hamburgischen unpartheyischen Correspondenten, issue 110, 11 July 1783, no pagination; Münchner Zeitung, issue 110, 15 July 1783, p. 433.

[7] Global Volcanism Program, “Etna (211060),” Volcanoes of the World v. 4.6.1, ed. E. Venzke, Smithsonian Institution, 2013, http://dx.doi.org/10.5479/si.GVP.VOTW4-2013.

[8] In Icelandic: Eyþórsson, Jón, Pálmi Hannesson, and Steindór Steindórsson: Ferðabók Sveins Pálssonar, Dagbækur of ritgerdir 17911797. Reykjavík: Snælandsútgáfan, 1945. In English: Pálsson, Sveinn: Draft of a physical, geographical, and historical description of Icelandic ice mountains on the basis of a journey to the most prominent of them in 17921794, with four maps and eight perspective drawings. Edited and translated from Icelandic into English by Richard S. Williams, Jr., and Oddur Sigurðsson. Reykjavík: The Icelandic Literary Society, 2004.

[9] Symons, George, et al.: The Eruption of Krakatoa, and Subsequent Phenomena. London: Trübner, 1888.

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Katrin Kleemann is a doctoral candidate at the Rachel Carson Center / LMU Munich in Germany, she studies environmental history and geology. Her doctoral project investigates the Icelandic Laki fissure eruption of 1783 and its impacts on the northern hemisphere. She holds a master’s degree in early modern history and a bachelor’s degree in history and cultural anthropology. Katrin works at the Environment & Society Portal, where she coordinates the Virtual Exhibitions and serves as the managing editor of the born-digital journal Arcadia. She also is the social media editor for the Climate History Network and HistoricalClimatology.com.

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