A zigzag lightning, often called forked lightning, refers to a type of cloud-to-ground (CG) lightning where the path of the discharge appears jagged and irregular as it travels towards the ground.
Understanding Zigzag Lightning
This characteristic "zigzag" appearance is due to the way the negatively charged channel, known as a stepped leader, progresses from the cloud towards the ground. According to the provided reference:
In CG lightning, a channel of negative charge, called a stepped leader, will zigzag downward in a 'forked' pattern - hence it is sometimes called forked lightning. This stepped leader is invisible to the human eye and travels to the ground in a millisecond.
Stepped Leader
The stepped leader doesn't travel in a straight line. Instead, it moves in a series of short, rapid bursts, changing direction abruptly as it seeks the path of least resistance through the air.
Key Characteristics of Zigzag Lightning:
- Cloud-to-Ground (CG): It always originates in a cloud and terminates on the ground.
- Stepped Leader: The primary discharge channel is a stepped leader.
- Forked Appearance: This is the most visually distinctive feature, making it appear like a branching, irregular line.
- Speed: The stepped leader travels very quickly.
- Invisibility: The stepped leader itself is invisible to the naked eye.
Why Does It Zigzag?
The zigzag path results from the stepped leader's tendency to follow the path of least electrical resistance. This path is influenced by factors like:
- Air density variations
- Presence of ionized particles
- Temperature gradients
The stepped leader effectively "samples" the air in short bursts, choosing the path that offers the easiest route for the electrical discharge. This process creates the jagged, forked appearance we recognize as zigzag or forked lightning.
