BALL-LIGHTNING AS AN EXAMPLE OF A MAGNETOHYDRODYNAMIC EQUILIBRIUM

Magnetohydrodynamic equilibria appropriate for describing ball lightni ng are discussed in this paper. It is argued that lightning-induced fi reballs should have a magnetic field decaying at infinity. Such equili bria, in fact, have a vanishing magnetic field outside a singly connec ted plasma region and are confined by the atmospheric pressure only. A n equilibrium of this type with a spherical plasma boundary is investi gated, and characteristic quantities are computed. Perturbation of the pressure and current profiles leads to deformation of the spherical p lasma boundary, thus indicating the existence of a large class of equi libria with a nonspherical boundary. Finally, some remarks are made co ncerning the stability of these equilibria.