“Lightning can strike from a clear blue sky”

It is a widely held belief that thunder and lightning are phenomena strictly confined to the immediate vicinity of a visible storm cloud. The common expectation is that if the sky directly above is clear and blue, there is no threat of a lightning strike. This assumption stems from our direct observations of most thunderstorms, where the dark, imposing clouds are clearly visible as the source of electrical discharges.

However, this common understanding overlooks a very real and dangerous type of lightning known as a 'bolt from the blue.' These strikes originate from the very top of a thunderstorm, often from the positively charged anvil cloud that can extend many miles away from the storm's core. Instead of striking downwards into the storm, these powerful bolts can travel horizontally for up to 25 miles before arcing down to the ground. This creates the illusion that the lightning is coming from a clear sky, as the parent thunderstorm might be too far away to be seen or heard clearly from the strike location.

People commonly believe that lightning only strikes from directly overhead storm clouds because the vast majority of lightning events occur within or very close to the visible storm. The unexpected nature of a 'bolt from the blue' makes it seem counterintuitive, leading many to dismiss the possibility. Yet, these long-range strikes are among the most dangerous forms of lightning due to their typically higher electrical charge and the lack of warning they provide to unsuspecting individuals who believe they are safely outside the storm's reach.