Scientists have developed a unique method to measure the energy contained in a lightning bolt.
University of South Florida Professor Matthew Pasek and his colleague Marc Hurst of Independent Geological Sciences have worked out how to accurately measure the energy of lightning strikes from the mark they leave on the ground.
Their research found that the energy produced by a lightning strike peaked at greater than 20 megajoules, equal to 20 cars simultaneously hitting the ground at 60mph.
When lightning strikes sand, soil, rock or clay, the current flows heat the material to above its vaporising level. Rapid cooling produces a cylindrical tube of glass called a fulgurite.
By conducting this lightning strike archaeology, the researchers were able to measure the energy in a bolt of lightning that struck Florida sand thousands of years ago.
Professor Pasek said: “The structure of the fulgurite, created by the energy and heat in a lightning strike, can tell us a lot about the nature of the strike, particularly about the amount of energy in a single bolt of lightning.”
He went on: “Ours is the first attempt at determining lightning energy distribution from fulgurites and is also the first data set to measure lightning’s energy delivery and its potential damage to a solid earth surface.”