  Ball lightning is an impressive natural electromagnetic phenomenon occurring
in atmosphere under suitable circumstances. Its origin, composition and
stability issues are a matter of debate, due to presence of many evidences
still unexplained. An attempt to provide a model, in alternative to the ones
already available, is here presented. The aim is to interpret the phenomenon
through a fluid plasma self-trapped in very stable toroid-shaped regions. To
this end, a suitable adaptation of the equations ruling electrodynamics is
taken into account.
