Ultra-high-speed footage of a lightning strike. This clip shows the key features of a classic multi-stroke negative lightning strike. Firstly, stepped leaders descend from the negatively-charged cloud base, leaving a network of glowing paths. The concentration of charge attracts opposite, positive, charges from the ground, causing the formation of an upward positive leader from the top of the tower. This contacts one of the downward leaders, forming an ionised channel through which the main discharge can occur. This is what is seen as the lightning bolt to the naked eye. The initial bright return stroke is followed by five successive strokes down the same channel, some of which exhibit both continuing currents and m-components. Filmed at more than 7200 frames per second in South Dakota, USA, in summer.