Scientists are still not entirely sure what causes ball lightning, but there are several theories. One theory is that ball lightning is formed when a lightning bolt strikes the ground and creates a magnetic field. This magnetic field can trap the ionized gas from the lightning bolt and cause it to form a sphere. Another theory is that ball lightning is formed when the electric field between the ground and the clouds becomes strong enough to ionize the air. This ionized air can then form a sphere that is suspended in the air.
Ball lightning is a dangerous phenomenon and has been known to cause fires, injuries, and even death. If you see ball lightning, it is important to stay away from it and seek shelter.