If you could get into the middle of a thunderstorm cloud, you would find that there is a lot going on.
The up and down flow of air inside the cloud is especially pronounced.
In fact, the entire life of the thunderstorm depends on the movement of air up and into the cloud, then that same air falling down and out of the cloud.
The thunderstorm continues as long as this general movement continues.
As the thunderstorm matures, more air begins to fall out of the cloud than is drawn up into it.
The storm will finally die out when air stops rising into it, cutting off most of the energy that keeps it going.