The high frequency magnetic field measurements from ~5 kHz–40 MHz near Rustrel (RST) show that the second positive lightning discharge (upper panel) exhibits resonant type oscillations with a period of ~3.8 μs (~260 kHz) lasting for ~9 cycles over ~34.2 μs (lower panel) attributed to a bouncing-wave discharge

<p><strong>Figure 3.</strong> The high frequency magnetic field measurements from ~5 kHz–40 MHz near Rustrel (RST) show that the second positive lightning discharge (upper panel) exhibits resonant type oscillations with a period of ~3.8 μs (~260 kHz) lasting for ~9 cycles over ~34.2 μs (lower panel) attributed to a bouncing-wave discharge.</p> <p><strong>Abstract</strong></p> <p>The acceleration of electrons results in observable electromagnetic waves which can be used for remote sensing. Here, we make use of ~4 Hz–66 MHz radio waves emitted by two consecutive intense positive lightning discharges to investigate their impact on the atmosphere above a thundercloud. It is found that the first positive lightning discharge initiates a sprite where electrons are accelerated during the exponential growth and branching of the sprite streamers. This preconditioned plasma above the thundercloud is subsequently exposed to a second positive lightning discharge associated with a bouncing-wave discharge. This discharge process causes a re-brightening of the existing sprite streamers above the thundercloud and initiates a subsequent relativistic electron beam.</p>