Instances of ball lightning—glowing, electric orbs in the sky—have captivated and mystified us for centuries. The bizarre phenomenon, also known as globe lightning, usually appears during thunderstorms as a floating sphere that can range in color from blue to orange to yellow, disappearing within a few seconds. It's sometimes accompanied by a hissing sound and an acrid odor.
Lightning in general is an electrical discharge caused by positive and negative imbalances within clouds themselves, or between storm clouds and the ground. A lightning flash can heat the air around it to temperatures five times hotter than the sun’s surface. The heat causes surrounding air to rapidly expand and vibrate, which creates thunder.
Is ball lightning real?
One of the first recorded sightings of ball lightning occurred in 1638, when a "great ball of fire" came through the window of an English church. That and other early accounts suggest that ball lightning can be deadly.
At least one study has theorized that about half of all ball lightning sightings are hallucinations caused by the magnetic fields during storms. That said, scientists seem to agree ball lightning is real, even if they don't yet fully understand what causes it.
Researchers from Lanzhou, China's Northwest Normal University inadvertently recorded a ball lightning event while studying a 2012 thunderstorm using video cameras and spectrometers. The ball appeared just after a lightning strike and traveled horizontally for about 10 meters (33 feet). The spectrometer detected silicon, iron, and calcium in the ball, all of which were also present in the local soil.
What causes ball lightning?
The Lanzhou researchers' paper supports the theory that ball lightning results from a ground strike that creates a reaction between oxygen and vaporized elements from the soil. This ionized air, or plasma, is the same condition that enables St. Elmo's Fire, the stationary glow that is sometimes confused with ball lightning.
The presence of glass may generate ball lightning, according to another theory published in 2012. Atmospheric ions could pile up at the surface of a window, producing enough of an electrical field on the other side to generate a discharge. Another study, published in 2016, suggests that microwave radiation produced when lightning strikes the ground could become encapsulated in a plasma bubble, resulting in ball lightning.
Ball lightning has also been associated with earthquakes. The rare flashes of light sometimes seen around earthquakes can take many forms: bluish flames that appear to come out of the ground at ankle height; quick flashes of bright light that resemble regular lightning strikes, except they originate from the ground instead of the sky; and the floating orbs known as ball lightning. In a 2014 study of earthquake lights, researchers concluded that certain rocks tend to release electrical charges when a seismic wave hits, sparking colorful displays of light.
Aiming to understand how ball lightning happens, scientists have tried to recreate it. In 2006 researchers at Israel’s University of Tel Aviv created a laboratory version of ball lightning using a microwave beam. In 2018 quantum physicists demonstrated a synthetic, knotted magnetic field that mirrors and possibly helps explain ball lightning.
But despite all these investigations and lab experiments, ball lightning still refuses to be pinned down. Scientists say they have much to learn about the mysterious phenomenon.