Rapid motion of filaments in solar active regions

Static magnetic field distribution above the photosphere surface is given, as a rule, by the solution of the potential theory problem called Neuman problem. In the case when magnetic field varies with time, an induced electrical field arises in the semispace z>0, its distribution being obtained by the solution of the Laplace vector equation. For the region above the plane z=0, the solutions of both problems are expressed with the help of quadratures. Corresponding values are obtained for both fields and for the drift velocity vector and Pointing vector as well. The results are applied to the filament ''activating'' phenomenon of November 2, 1980. It is shown that filament motion can be described by the drift, and that there exists correspondence between the observed distribution of the flare brightness and the isolines of the Pointing vector z-component. It is pointed out that relatively small velocity ∼30 km/s and correspondingly long characteristic time of the variation of the spot field τ>103 s are the essential restriction. For the description of the processes whose velocity is greater than several km per second, the account of the filaments's own curent is necessary