Path: utzoo!mnetor!uunet!lll-winken!lll-lcc!lll-tis!ames!umd5!cvl!elsie!nih-csl!bob
From: bob@nih-csl.UUCP (Bob Dew)
Newsgroups: sci.misc
Subject: Re: Lightning, Up or Down?
Message-ID: <312@nih-csl.UUCP>
Date: 1 Mar 88 20:44:04 GMT
References: <64600001@mic> <1620@bgsuvax.UUCP>
Organization: NIH-CSL, Bethesda, MD
Lines: 9


     Several years ago, I attended a graduate seminar in
electrical engineering devoted to the subject of lightning.
Two types of lightning, positive and negative (or down & up),
were identified that occur in common electrical thunder storms.
The type of atomoshpere-to-ground lightning that strikes depends upon
whether the atmosphere is positively or negatively charged
with respect to the target.  Both positive and negative lightning
can be observed in a typical thunder storm, but positive 
lightning is observed about 100 times more frequently.