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.