system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: I saw a video of a volcano erupting & lightning strikes happened in the lava as it was in the air. What is making the lightning happen?
gpt
Lightning is many ways the same as the static electricity you can get from walking on come carpets and then touching something and get a small electric arch. They are just on a larger scale and vertical. 

In a volcanic eruption, you get a plume with ash that rises and collide with each other and at a higher altitude, it can get cool down and you get ice crystals.  It is that collision that you get static electricity at very high levels and it will discharge with lightning. The breaking up of rock can have a significant effect in generating changes too.