Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!watmath!clyde!burl!ulysses!mhuxr!mhuxt!houxm!ihnp4!qantel!hplabs!sri-unix!RESS%LLL@LLL-MFE.ARPA From: RESS%LLL@LLL-MFE.ARPA Newsgroups: net.physics Subject: lightning Message-ID: <424@sri-arpa.ARPA> Date: Thu, 18-Jul-85 19:21:00 EDT Article-I.D.: sri-arpa.424 Posted: Thu Jul 18 19:21:00 1985 Date-Received: Sat, 20-Jul-85 12:15:17 EDT Lines: 28 From: David Ress To: physics@SRI-UNIX.ARPA In a recent bulletin, it was noted that lightning at high altitudes seemed to occur in bursts. A mechanism for such a process occurs to me. Suppose that initially we have a large build-up in potential between two clouds. The resulting electric field tends to accelerate the ambient low density of charged particles. The electrons tend to be confined to geomagnetic field lines, while the ions are less restricted. Electric fields that are oriented along the field lines would probably do the most effective acceleration (?). The accelerated particles interact collisionally with the neutrals to create more ionization, and the charged particle density rises. Finally, along some path, the line density of ionization builds up to point where the current becomes substantial, and a cascade of ion- ization leads to a major discharge. Since lightning tends to follow a jagged path, it is apparent that the discharge does not follow magnetic field lines. One explanation might be that the ions, which have relatively large gyral radii, are the majority charge carriers. Another possibility is that the plasma in the lightning discharge distorts the magnetic field to allow the discharge. Whatever the actual mechanism of the initial dis- charge, the huge energy dissipated is sure to accelerate many more charged particles. The new particles proceed to raise the background ionization still further, thus facilitating the formation of additional discharges until the potential energy of the system is exhausted. I am not an astrophysicist, although I do know a bit about plasmas. Is there an astrophysicist out there who has a better picture on lightning? -------