 The nuclear explosions also release heavier debris ions, which also carry an electrical charge, and which also travel in a spiral along the Earth's magnetic field lines.The Earth's magnetic field lines arc high above the Earth until they reach the magnetic conjugate area in the opposite hemisphere.According to the DOD nuclear weapon effects reference, "Because the beta particles have high velocities, the beta auroras in the remote (southern) hemisphere appeared within a fraction of a second of those in the hemisphere where the burst had occurred.