Why does a lightning strike instantly appear, then slowly fade away instead of instantly disappearing?
In: Physics
When you see a lightning strike, you are actually seeing the lightning’s glow or the ionization of the air. The air around the lightning bolt is super hot, causing it to give off a bright glow that we see. As the bolt fades away, the air is slowly cooled down to its normal temperature.
It’s not exactly instant (see below). The glow you see is not just the air being hot, but *exploding* due to the sudden dumping of massive amount of charge through it. The fade is a combination of the latent heat and the burn-in effect you get in your eyes when you look at a light bulb.
[Lightning in very slow motion.](https://www.youtube.com/watch?v=qQKhIK4pvYo&t=215)
Persistence of vision, same process that makes showing you repeatedly still images slightly changing becomes a motion picture.
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