[TowerTalk] lightning & trees

[Martin Ewing]

On Fri, 18 Mar 2005 13:13:38 -0500, Gary Schafer
<garyschafer at comcast.net> wrote:
> Streamers usually start at sharp points or tapered points of objects.
> Corners of buildings etc. Charge tends to push towards and accumulate at
> a small area. Same thing happens with corona discharge with very high
> voltage circuits. Charge moves toward the sharp points.

The more familiar way (for me) to say it is that the electric field
(volts/meter) produced by a conductor at a certain voltage relative to
a distant object depends on the "sharpness" of the conductor.  If
you're working with high voltages, you want your terminals to be large
and spherical to minimize the field strength.  The breakdown field
strength (as between infinite flat plates) at sea level is about 75
kV/inch, but a 1-inch spark-gap (needle gap) has a breakdown of less
than 30 kV.
---
martin.ewing at gmail.com
AA6E