Visualization of the process of lightning initiation in a thundercloud

<p>This movie visualizes the evolution of 3D streamer / hot-channel systems at 6.5 km altitude in a uniform upward directed electric field, whose magnitude is equal to 70 kV/m. Low-conductivity channels of positive and negative polarity are shown in green and gray, respectively. Channel segments with conductivities higher than 1 S/m (assumed to be &ldquo;hot&rdquo;) are shown in red. All three axes are labeled in meters.</p>