Lightning branches and flickers because of the way that its electrical discharge propagates through the air. When a lightning bolt strikes, it creates a rapidly expanding channel of hot, ionized air. This channel is called the lightning leader, and it is responsible for the initial path that the lightning takes.

The leader travels through the air in a series of steps, each of which creates a new branch of the lightning bolt. The branches occur because the leader channel is not a perfect conductor, and so the electrical discharge can sometimes take a different path than the original leader. This can happen when the leader channel encounters an obstacle, such as a pocket of cooler air or a change in the electrical field.

The flicker of lightning is caused by the fact that the leader channel is not a continuous path. Instead, it is made up of a series of short, bright bursts of light. This flickering is due to the way that the electrical discharge is generated in the leader channel. The electrical discharge is caused by the collision of electrons with atoms and molecules in the air. When the electrons collide with these particles, they are slowed down and their energy is converted into light. The amount of light that is produced depends on the number of electrons that are colliding with the particles in the air.

The branching and flickering of lightning is a complex process that is not yet fully understood. However, researchers are making progress in understanding how these phenomena occur, and this knowledge could help to improve lightning safety and protection systems.