Our historians and physicists have come together to discover what appears to be the earliest known account of a rare weather phenomenon called ball lightning in England.
Ball lightning, usually associated with thunderstorms, is unexplained and has been described as a bright spherical object on average 25 centimetres, but sometimes up to several metres, in diameter.
Emeritus physicist Emeritus Professor Brian Tanner and historian Professor Giles Gasper, made the connection to a ball lightning event while exploring a medieval text written some 750 years ago.
The account, by the 12th century Benedictine monk Gervase of Christ Church Cathedral Priory, Canterbury, pre-dates the previous earliest known description of ball lightning recorded in England by nearly 450 years.
In his Chronicle, composed around 1200, Gervase stated that “a marvellous sign descended near London” on 7 June 1195.
He went on to describe a dense and dark cloud, emitting a white substance which grew into a spherical shape under the cloud, from which a fiery globe fell towards the river.
The Durham researchers compared the text in Gervase’s Chronicle with historical and modern reports of ball lightning.
Prior to Gervase’s account, the earliest report of ball lightning from England is during a great thunderstorm in Widecombe, Devon on 21 October 1638.
Professor Tanner said: “Ball lightning is a rare weather event that is still not understood today.
“Gervase’s description of a white substance coming out of the dark cloud, falling as a spinning fiery sphere and then having some horizontal motion is very similar to historic and contemporary descriptions of ball lightning.”
Our researchers also looked at Gervase’s credibility as a writer and a witness, having previously examined his records of eclipses and a description of the splitting of the image of the crescent moon.
Professor Gasper added: “Given that Gervase appears to be a reliable reporter, we believe that his description of the fiery globe on the Thames on 7 June 1195 was the first fully convincing account of ball lightning anywhere.”
Main image: 19th century engraving depicting ball lightning: Public Domain, https://commons.wikimedia.org/w/index.php?curid=58806