Globular lightning, commonly known as rolling thunder, is a lightning ball in a spherical shape. It is an actual physical phenomenon, not an energy cannon from science fiction novels or cartoon series. Shen Kuo (1031-1095), a famous scientist of the Northern Song Dynasty, documented an instance of globular lightning in his book "Dream Brook Essays," describing its movement process. After entering through the sky into the "west room" and then exiting through the window eaves, there was no damage to the house except for the walls and window paper being charred black. That is to say, inside the room, wooden shelves and their contents (including lacquered items) were not destroyed by the electric fire; instead, the silver decorations embedded in the lacquerware were melted by the electric fire, with their liquid flowing onto the ground. A steel sword, which was extremely sturdy, was also melted into liquid. These strange phenomena left Shen Kuo and generations of scientists unable to provide a correct explanation, making it a historical mystery.
From 1838's literature records, scientists have studied this phenomenon for over 160 years, with thousands of reports and more than two thousand scientific papers published. However, we still do not have a reasonable explanation for this phenomenon. The claim that it can penetrate any object is unreliable because silver and steel are conductive while bamboo, wood, leather-made sheaths are not conductive.
Globular lightning typically occurs during thunderstorms, appearing very bright and roughly spherical, with a diameter generally around 20 to 100 cm. Usually, it lasts only a few seconds but has been recorded lasting up to 1-2 minutes. More astonishingly, it can move independently and slowly in the air. Some witnesses reported seeing it bouncing back into the air after hitting the ground. A few claimed it followed metallic objects like telephone wires, though most said its path was unpredictable. Most witnesses stated it moved horizontally. In its short life span, its brightness, shape, and size remain unchanged. It has appeared in open fields, closed rooms, and even inside airplane cabins! There are signs indicating its close relationship with lightning between clouds and the ground (common ordinary lightning). Witnesses report it forming or disappearing after ordinary lightning. Globular lightning can either explode violently or quietly disappear. Its colors vary greatly without consistent descriptions.
Globular lightning possesses destructive power. It can break glass windows and cause the outer layer of walls to peel off. It has caused casualties among people and animals, but due to insufficient data, the exact cause of death remains unknown. There is no evidence showing that globular lightning damages trees, which differs slightly from ordinary lightning. Globular lightning is almost indestructible; someone once shot it with a rifle but had no effect.
Because of its low frequency of occurrence, scientists find it difficult to conduct systematic observations. No one has taken high-quality photographs for scientific research yet. Theoretically, some believe it is a hot air mass or vaporized elements such as carbon, sodium, or copper. Although this theory explains some characteristics of globular lightning, it cannot explain why it forms inside airplane cabins. There are many other theories, such as plasma, ions, charged dust, water with an outer electron shell... but none can perfectly explain this scientific mystery. If you have seen globular lightning or photographed it, be sure to record all the details! It will be invaluable research material.