Visualization of the process of lightning initiation in a thundercloud via coalescence of multiple simultaneously developing bipolar streamer/leader systems

<p>This movie visualizes the evolution of 3D streamer / hot-channel systems at 6 km altitude in a uniform upward directed electric field, the&nbsp;magnitude of which is equal to 65 kV/m. Positive and negative streamer channels are shown in green and gray, respectively. Red channels indicate hot leader sections with conductivity exceeding 1 S/m. All three axes are labeled in meters.</p>