Re: [californiadisasters] Possible Positive Bolt in Chula Vista Today

Kim, at the time I read your first post on this, sloweather was showing two
of the eight cloud-to-ground strikes in the preceding 30 minutes to be
positive. (Also showing inter-cloud strikes.)

It would have been interesting to be able to play back the time period of
that Chula Vista strike. I'm pretty sure that data is not archived, though.

http://www.sloweather.com/lightning/stormvue.htm

----- Original Message -----
From: "Kim Noyes" <kimnoyes@gmail.com>
To: <californiadisasters@yahoogroups.com>
Sent: Friday, October 01, 2010 2:29 AM
Subject: Re: [californiadisasters] Possible Positive Bolt in Chula Vista
Today

Ken,

Here is more on this from Wikipedia:

"An average bolt of negative lightning carries an electric current of 30,000
amperes ("amps") — 30 "kiloamps" (kA), and transfers five coulombs of
electric charge and 500 million joules — 500 "megajoules" (MJ) of energy.
Large bolts of lightning can carry up to 120 kA and 350 coulombs.[14] The
voltage is proportional to the length of the bolt.

An average bolt of positive lightning carries an electric current of about
300 kA — about 10 times that of negative lightning."

*
*

*"Positive lightning*

Anvil-to-ground *(Bolt from the blue)* lightning strike
See also: High voltage#Lightning

Positive lightning is a type of lightning strike that comes from apparently
clear or only slightly cloudy skies; they are also known as "bolts from the
blue" because of this trait. Unlike the more common negative lightning, the
positive charge is carried by the top of the clouds (generally anvil clouds)
rather than the ground. The leader forms in the sky travelling horizontally
for several miles before veering down to meet the negatively charged
streamer rising from below. Positive lightning makes up less than 5% of all
lightning strikes.[42] Because of the much greater distance they must travel
before discharging, positive lightning strikes typically carry six to ten
times the charge and voltage difference of a negative bolt and last around
ten times longer.[43] During a positive lightning strike, huge quantities of
ELF and VLF radio waves are generated.[44]

As a result of their greater power, as well as lack of warning, positive
lightning strikes are considerably more dangerous. At the present time,
aircraft are not designed to withstand such strikes, since their existence
was unknown at the time standards were set, and the dangers unappreciated
until the destruction of a glider in 1999.[45] The standard in force at the
time of the crash, Advisory Circular AC 20-53A, was replaced by Advisory
Circular AC 20-53B in 2006,[46] however it is unclear whether adequate
protection against positive lighting was incorporated.[47][48]

Positive lightning is also now believed to have been responsible for the
1963 in-flight explosion and subsequent crash of Pan Am Flight 214, a Boeing
707.[49] Due to the dangers of lightning, aircraft operating in U.S.
airspace have been required to have lightning discharge wicks to reduce the
damage by a lightning strike, but these measures may be insufficient for
positive lightning.[50]"
Source: http://en.wikipedia.org/wiki/Lightning

On Fri, Oct 1, 2010 at 12:18 AM, Ken Swain <peavine15@yahoo.com> wrote:

>
>
> I wasn't aware there WAS such a thing...thanks for the info
>
> --- On *Thu, 9/30/10, Kim Noyes <kimnoyes@gmail.com>* wrote:
>
>
> From: Kim Noyes <kimnoyes@gmail.com>
> Subject: [californiadisasters] Possible Positive Bolt in Chula Vista Today
> To: "CaliforniaDisasters" <californiadisasters@yahoogroups.com>
> Date: Thursday, September 30, 2010, 10:23 PM
>
>
>
> This afternoon in Chula Vista in San Diego County a lightening bolt struck
> a water main damaging it and blew out several nearby windows.
>
> I do not know if this bolt struck a hydrant and then followed that down to
> the main or if it directly impacted the ground and traveled down through
the
> soil and contacted the main that way.
>
> Given what typically happens as a result of the much more garden variety
> and significantly weaker negative bolts I'd say this was a positive bolt
> although I cannot confirm that.
>
> Kimmer
>
>
>
>
>

--
Check out http://groups.yahoo.com/group/californiadisasters/
Read our blog at http://eclecticarcania.blogspot.com/
Visit me on Facebook at http://www.facebook.com/derkimster
Visit my Myspace at http://www.myspace.com/kimusinteruptus
We have an Ebay store at http://stores.ebay.com/K-K-Earthwerks

------------------------------------

Be sure to check out our Links Section at http://groups.yahoo.com/group/californiadisasters/links
Please join our Discussion Group at http://groups.yahoo.com/group/californiadisasters_discussion/ for topical but extended discussions started here or for less topical but nonetheless relevant messages.Yahoo! Groups Links

<*> To visit your group on the web, go to:
http://groups.yahoo.com/group/californiadisasters/

<*> Your email settings:
Individual Email | Traditional

<*> To change settings online go to:
http://groups.yahoo.com/group/californiadisasters/join
(Yahoo! ID required)

<*> To change settings via email:
californiadisasters-digest@yahoogroups.com
californiadisasters-fullfeatured@yahoogroups.com

<*> To unsubscribe from this group, send an email to:
californiadisasters-unsubscribe@yahoogroups.com

<*> Your use of Yahoo! Groups is subject to:
http://docs.yahoo.com/info/terms/