Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Theory of ball lightning   We present a comprehensive theory on the formation of ball lightning, a
luminous sphere sometimes observed after normal lightning. In a ball lightning
event, a relativistic electron bunch can be produced by the stepped leader of
lightning and coherently emit high-power microwave when striking the ground.
The intense microwave ionizes the local air and evacuates the resulting plasma
by its radiation pressure, thereby forming a spherical plasma cavity that traps
the microwave. The theory can explain observed properties of ball lightning and
should be useful to lightning protection and aviation safety.

20
The categories of this paper are: acc-phys
17
The categories of this paper are: q-fin
21
The categories of this paper are: adap-org
9
The categories of this paper are: nlin
8
The categories of this paper are: hep-ex
1
The categories of this paper are: cs
13
The categories of this paper are: quant-ph
16
The categories of this paper are: stat
12
The categories of this paper are: nucl-th
29
The categories of this paper are: funct-an
10
The categories of this paper are: q-bio
19
The categories of this paper are: eess
25
The categories of this paper are: patt-sol
5
The categories of this paper are: gr-qc
22
The categories of this paper are: chao-dyn
37
The categories of this paper are: supr-con