Science

Medieval monk wrote a spot-on description of mysterious ball lightning

"A marvellous sign..." The report dating back around 800 years appears to be the earliest of ball lightning in England.

NASA used this lightning image to illustrate a discussion of lightning safety from 2011.
NASA

Ball lightning is a mysterious, eye-searing phenomenon connected to thunderstorms. The National Weather Service describes it as a "relatively rare form of lightning consisting of a luminous ball, often reddish in color, which moves rapidly along solid objects or remains floating in mid-air." That meshes with what a monk in England wrote about in a medieval manuscript thought to be the earliest report of the spectacle there. 

A physicist teamed up with a historian from Durham University in the UK to publish a paper this week in the Royal Meteorological Society journal Weather. The study delves into a written account of ball lightning from Benedictine monk Gervase of Christ Church Cathedral Priory, Canterbury from around 1200. 

This extract from the Chronicle of Gervase of Canterbury is where the medieval monk describes the ball lightning phenomenon. 

The Master and Fellows of Trinity College, Cambridge. Reference: Cambridge, Trinity College, MS R.4.11, p.324.

Gervase's chronicle includes a passage about a "marvellous sign descended near London" in June 1195. "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," said physicist Brian Tanner, co-author of the paper.

If the monk was indeed talking about ball lightning, that makes his account one of the earliest known. The next closest account from England dates to 1638 and describes a massive thunderstorm in Devon. 

Gervase had a good track record of describing unusual events, including eclipses, which added to his credibility as an observer. "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," historian Giles Gasper said. 

The rarity and mystery of ball lightning means any account of the phenomenon is notable, whether it's a modern-day sighting or one from long ago. Gervase's narrative is a gem, and it shows that even back then, ball lightning was a strange and notable sight.