A map of lightning flash density (IMAGE) University of Portsmouth Caption A map of lightning flash density per kilometre squared per year using one of the datasets, which shows where the greatest density of lightning events is in the UK. Credit University of Portsmouth Usage Restrictions None License Original content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.