The development of a lightning flash, after initiation in a thunderstorm, occurs as a bidirectional, bipolar, zero-net-charge leader and electrodeless discharge. This process takes place in intracloud (IC), cloud-to-ground (CG), aircraft-triggered and so-called `tipsy' rocket-triggered flashes (with a conductive wire isolated from the ground). The long-delayed acceptance of this concept has led to significant changes in our understanding of the essential physical processes in lightning flashes, and of the analytical relationship between the electrical structure of a cloud and lightning parameters. These changes are described in this chapter, with an emphasis on the unifying nature of the bidirectional leader concept in interpreting the various lightning processes.

Chapter Contents:

• 6.1 Introduction
• 6.2 Definitions and attributes of lightning processes
• 6.3 The composition of a lightning flash
• 6.3.1 The nature of 'recoil streamers' and dart leaders
• 6.3.2 Intracloud flashes
• 6.3.3 Cloud-to-ground flashes
• 6.4 Continuing current as an indicator of a developing leader
• 6.5 Spider lightning
• 6.6 The analytical relationship between the electrical structure of a cloud and lightning parameters
• 6.6.1 Physical model of the development of intracloud and cloud-to-ground leaders
• 6.7 Current cut-off in developing lightning flashes
• 6.7.1 Current cut-off and recoil leaders
• 6.8 The remaining puzzle of positive cloud-to-ground flashes
• 6.9 Upward lightning
• 6.10 M-component
• 6.11 The electrostatic model of M-events
• 6.12 Summary
• References

Inspec keywords: storms; lightning; arcs (electric); clouds

Other keywords: cloud electrical structure; bipolar discharge; tipsy rocket triggered flashes; zero net charge leader discharge; bidirectional discharge; intracloud flashes; lightning flash development physics; cloud-ground flashes; aircraft triggered flashes; electrodeless discharge; lightning parameters; lightning flash initiation; thunderstorm

Subjects: Cloud physics; Arcs and sparks; Atmospheric storms; Atmospheric electricity