A new theory of ball lightning

Ball lightning (BL) is a fireball occasionally observed during thunderstorms [1], and it was recorded earliest by Aristotle. For centuries, BL had attracted great interests from scientists, including Musschenbrock, Arago, Faraday, Lodge, Tesla, Bohr, Kapitza and Ginzburg etc. About 100 models had been proposed for BL, but no consensus is reached about the nature of BL.

We will first introduce the characteristics and research history of BL, and then present a new BL theory [2]. Near the ground, lightning can produce a relativistic electron bunch, and the bunch excites an intense microwave pulse. This microwave is so strong to evacuate the ambient plasma and form a spherical plasma cavity. This formation process is demonstrated by particle-in-cell simulation. The microwave bubble model can explain many properties of BL, such as the occurrence site, relation to the lightning channels, appearance in aircraft, its shape, size, sound, spark, spectrum, motion, as well as the resulting injuries and damages. In particular, our theory is unique for a successful explanation of BL formation in aircraft.

Did someone ever detect radio signals with the same origin of BL? Yes, they are trans-ionospheric pulse pairs (TIPPs). TIPPs were first detected by a USA satellite in 1993 and are the most powerful natural radio sources on Earth. Using the BL-exciting mechanism, we quantitatively explain almost all the features of TIPPs [3]. Therefore, high-energy electrons from lighting can emit strong electromagnetic radiation, which is a fundamental assumption of our BL theory.

Finally, we point out further questions need to be answered in future and discuss experimental activities. Our work may drive the development of high-power microwave devices at an extreme level.

References:

[1] M. Stenhoff, Ball Lightning: An unsolved problem in atmospheric physics (Kluwer & Plenum, NY, 1999).

[2] H.-C. Wu, Sci. Rep. 6, 28263 (2016).

[3] H.-C. Wu, Geophys. Res. Lett. 44, 2597 (2017).