Three images, left to right, of the same thundercloud depict a less - than -10-milliseconds-long sequence of events: (left) formation within the cloud of a small channel, or «leader,» of
electrical conductivity (yellow
line) with weak emission of radio signals (ripples), to (middle) a
burst of both dark lightning (pink) and radio waves (larger ripples), to (right) a discharge of bright lightning and more radio waves.