A mechanism for the nonlinear excitation of the ionospheric Alfven resonator by elves- or/and sprites-produced lightning discharge is proposed. The source of the time-varying nonlinear current, located at altitudes below 95 km, is due to the large impulse electron heating and breakdown of the atmosphere by a strong tropospheric discharge. The discussed mechanism may be responsible for anomalously large ULF events observed onboard the satellites above atmospheric weather systems. ¿ 1997 American Geophysical Union