What does MIT say about ionization and lightning??
JAXAshby
Phil Morris
They're all fools here. Some want to insulate their boat but the ionization
potential renders insulation useless, let alone the effects of induced
currents; they want to inject ions in the vicinity of their boats, yet to
create enough potential to neutralize lightning it would, in fact, generate
enough potential to cause lightning from their own boats; because they don't
understand lightning, electricity, or atmospheric electrodynamics, they
claim that lightning is magic - defies all physical laws; they want to
ground their boats to make it part of the lightning discharge
circuit -increasing the chances of getting struck!; the science teacher
claims some special, hidden knowledge of electricity, but yet is not
practiced in the art, he should stick to poetry. Ah yes the fools suffer,
some even buy wonder products from the black magicians. God bless Iron Joe
of the rusty Faraday cage! What doesn't get him in a thunder clap will
slowly rot out his hulk by electrolysis.
There's a simple method to reduce the chances of being struck by many orders
of magnitude by towing a lightning distraction bouy. It's proven many times
over.
Phil
"JAXAshby" <jaxa...@aol.com> wrote in message
news:20040822194747...@mb-m21.aol.com...
> take a guess.
Scout
Why do you make so many assumptions? Do you do this often? It's a dangerous
habit and will only cause you embarrassment and heartache. Are you Jaxie in
drag? Do you agree with a man who says electricity has nothing to do with
mathematics and in the same post uses math to describe the potential of
lightning?
You claim that "they're all fools here" - it seems to me that every post has
pointed out the futility in such systems. Did I miss the post you refer to?
The fact is that the science teacher claims no 'hidden' knowledge of
electricity, and said only that it follows strict rules of behavior. Would
you care to argue that point?
The science teacher never claimed to buy into lightning protection on a
boat, and therefore, has no such system, are you assuming otherwise? Do you
see any post in which he defends these systems, or are his questions merely
conversational in nature? Are you afraid of friendly discussion?
I'll discuss poetry OR electricity with you. You can begin, I'll respond.
Better yet, stick to posting your boring version of the truth in politics.
At least then you're easier to ignore.
Scout
"Phil Morris" <pmorr...@eureka.net> wrote in message
news:gMbWc.10352$3O3....@newsread2.news.pas.earthlink.net...
JAXAshby
subject?
Do you know what MIT is?
do you know what lightning is?
do you know anything?
Scout
I have a question for you now tough guy, even though you wisely chose to
ignore my last challenge: you wanna tell me what MY opinion is regarding
lightning protection on boats? I've read what MIT has to say, what the U.S.
Navy has to say, what the NLSI has to say. I also wanted to know what
sailors had to say.
I can't figure out what your role is here. Village idiot I suppose.
Scout
"JAXAshby" <jaxa...@aol.com> wrote in message
news:20040822221600...@mb-m15.aol.com...
JAXAshby
>a
>taller mast than your own. It's just a theory, of course, but it has always
>worked for me!
>
>BB
actually, owning a St Christopher medal is no less effective.
Scout
the sky; anchor near him; it'll be Jaxie.
Scout
<BinaryBillTheSailor@Sea++.com> wrote in message
news:0skii0991ed2mgsud...@4ax.com...
> The only method that "might" have some benefit is to anchor near someone
with a
> taller mast than your own. It's just a theory, of course, but it has
always
> worked for me!
>
> BB
>
> >
JAXAshby
JAXAshby
>the sky; anchor near him; it'll be Jaxie.
>Scout
look for the village idiot along side the cardboard box, with his shoes off,
mubbling at his shoe laces. it's be scwount.
Scout
By the way, this last paragraph suggests that you believe lightning
protection IS available. So which is it? Are you schizophrenic? John Kerry,
is this really you?
Scout
"Phil Morris" <pmorr...@eureka.net> wrote
Scout
Scout
"JAXAshby" <jaxa...@aol.com> wrote in message
news:20040822222831...@mb-m15.aol.com...
Scout
says, "will anser fisics qwestons for fude"
That'll be Jaxie ~ have a heart and toss him a dime.
Scout
"JAXAshby" <jaxa...@aol.com> wrote in message
news:20040822223115...@mb-m15.aol.com...
Capt. Mooron
off,
| mubbling at his shoe laces. it's be scwount.
????.... Wooooooooooo that's like... just so ..... lamer than a three
legged mule!!
Bwahahahahahahahahahahaaaa....
Really jaxxies.... is that the limit of your abilities?
CM
Capt. Mooron
having a pulse.
All my findings indicate their is no lower threshold...
CM
"Scout" <scout...@hotmail.com> wrote in message
news:LGcWc.237186$OB3....@bgtnsc05-news.ops.worldnet.att.net...
Capt. Mooron
committing the crime twice and a slanderous slur that I actually top-post.
All of which are obvious lies....
"Capt. Mooron" <moo...@overproof.ca> wrote in message
| All my findings indicate their is no lower threshold...
To the Grammar Gestapo:
" All my findings indicate there is no lower threshold"
There... now take a friggin' pill!
CM
Scout
the giver of life, the great reanimator, his mama. For without it, he would
still be the lifeless lump of hopeless clay, strapped to the cold laboratory
bench, week old parts stitched together with love in the name of science,
helpless against the curious, roaming fingers of Igor, vaguely aware of the
passing electrical storm, and waiting, waiting, waiting for 100 million
volts of mamma's milk to spark his obscene, unnatural existence! Ohhhh
Jaxie! You're alive, YOU'RE ALIVE, you abnormal, dysfunctional, ignorant
bastard!
"Capt. Mooron" <moo...@overproof.ca> wrote in message
news:WUcWc.53509$vO1.2...@nnrp1.uunet.ca...
Scout
down or bottom post up?
Scout
"Capt. Mooron" <moo...@overproof.ca> wrote in message
news:n1dWc.53512$vO1.2...@nnrp1.uunet.ca...
Capt. Mooron
it's forced to follow the path of least resistance... and effort! ;-)
CM
"Scout" <scout...@hotmail.com> wrote in message
news:t6dWc.499395$Gx4.2...@bgtnsc04-news.ops.worldnet.att.net...
Scout
Universe. Why, I wonder, must some people do everything the hard way?.
Scout
"Capt. Mooron" <moo...@overproof.ca> wrote in message
news:MddWc.53514$vO1.2...@nnrp1.uunet.ca...
katysails
<BinaryBillTheSailor@Sea++.com> wrote in message
news:0skii0991ed2mgsud...@4ax.com...
> On Mon, 23 Aug 2004 02:05:41 GMT, "Scout" <scout...@hotmail.com> wrote:
>
> The only method that "might" have some benefit is to anchor near someone
with a
> taller mast than your own. It's just a theory, of course, but it has
always
> worked for me!
>
> BB
>
> >
Capt. Mooron
a sow's ear into a silk purse with the knowledge that .... at least it
removes the possibility of cloning.
;-)
CM
"Scout" <scout...@hotmail.com> wrote in message
news:84dWc.237259$OB3....@bgtnsc05-news.ops.worldnet.att.net...
Scout
doubt we are relatives. I've known this for some time, but didn't want to
scare or burden you with the shocking news!
Scout
"katysails" <katy...@worldnet.att.net> wrote in message
news:YldWc.499475$Gx4.3...@bgtnsc04-news.ops.worldnet.att.net...
Scout
Scout
"Capt. Mooron" <moo...@overproof.ca> wrote in message
news:kodWc.53518$vO1.2...@nnrp1.uunet.ca...
katysails
Scout
Scout
"katysails" <katy...@worldnet.att.net> wrote in message
news:ewdWc.499526$Gx4.2...@bgtnsc04-news.ops.worldnet.att.net...
Capt. Mooron
as I slay them..... posters and puppets alike!
CM
"Scout" <scout...@hotmail.com> wrote in message
Scout
opponent.
Scout
"Capt. Mooron" <moo...@overproof.ca> wrote in message
news:9DdWc.53525$vO1.2...@nnrp1.uunet.ca...
DSK
> My guess is that Jaxie is defensive due to a fond recollection of lightning,
> the giver of life, the great reanimator, his mama. For without it, he would
> still be the lifeless lump of hopeless clay, strapped to the cold laboratory
> bench, week old parts stitched together with love in the name of science,
> helpless against the curious, roaming fingers of Igor, vaguely aware of the
> passing electrical storm, and waiting, waiting, waiting for 100 million
> volts of mamma's milk to spark his obscene, unnatural existence! Ohhhh
> Jaxie! You're alive, YOU'RE ALIVE, you abnormal, dysfunctional, ignorant
> bastard!
Why Scout, that's really poetry.
I think you must be acquainted with some of the contractors I'm forced
to work with...
DSK
Flying Tadpole
"Capt. Mooron" wrote:
>
> Write it off to R&D on the level of idiocy jaxxies can achieve while still
> having a pulse.
Jax has a pulse? Now _that's_ an unwarranted assumption.
--
Flying Tadpole
-------------------------
Henpecked? Harrassed? Harangued? Join the chorus:
http://music.download.com/internetopera
http://www.internetopera.netfirms.com
Scout
Scout
"DSK" <d...@dontbotherme.com> wrote in message
news:G6kWc.7686$0o5....@bignews1.bellsouth.net...
Scout
warranty.
He figures thusly: "Extended warranty, I can't lose!"
Scout
"Flying Tadpole" <flying...@hotmail.com> wrote
Joe
God bless Iron Joe
> of the rusty Faraday cage!
First you will find no rust on my fine steel vessel. It is made of
the finest english steel that money can buy. Ever see a 1000 year old
set of English armor? King Aurthurs sword? Same steel, cept I keep
mine painted.
And your plastic crap is developing osmosis blisters as I type!
What doesn't get him in a thunder clap will
> slowly rot out his hulk by electrolysis.
Yeah right, ever here of anoids? Zincs? isolation transformers?
And if your ever struck by lightning the least path of resistance
will be thru all your wiring and electronics melting everything around
them.
>
> There's a simple method to reduce the chances of being struck by many orders
> of magnitude by towing a lightning distraction bouy. It's proven many times
> over.
>
Why don't you tow a 500 foot tower? That should work.
How many Navy ships tow a lightning distraction bouy?
Bwahahahahah what a fool.
Joe
Flying Tadpole
OoozeOne wrote:
>
> On Mon, 23 Aug 2004 21:20:08 +0930, Flying Tadpole
> <flying...@hotmail.com> scribbled thusly:
>
> >
> >
> >"Capt. Mooron" wrote:
> >>
> >> Write it off to R&D on the level of idiocy jaxxies can achieve while still
> >> having a pulse.
> >
> >Jax has a pulse? Now _that's_ an unwarranted assumption.
>
> SWitch mode power supply.
>
...or legumes in the garden.
Phil Morris
electricity but I have six questions for you:
1. Why doesn't lightning travel in a helical path since it does traverse a
magnetic field?
2. Since lightning is a plasma discharge why is it that magnetohydrodynamic
pinching doesn't occur?
3. Does lightning have a magnetic field even though it doesn't travel in a
close loop? Why?
4. Can a conductor manifest Biot-Savart forces upon itself? If so why does
lightning hit the ground?
5. What condition must exist between the E and H fields of charge in ball
lightning or electron clusters to maintain the high charge density?
Remember, like charges repel.
6. What is your favorite colour?
Phil
"Scout" <scout...@hotmail.com> wrote in message
news:VhcWc.237113$OB3.1...@bgtnsc05-news.ops.worldnet.att.net...
> "Phil Morris" <pmorr...@eureka.net> wrote in message
> news:gMbWc.10352$3O3....@newsread2.news.pas.earthlink.net...
> > Jax,
> >
> > They're all fools here. Some want to insulate their boat but the
> ionization
> > potential renders insulation useless, let alone the effects of induced
> > currents; they want to inject ions in the vicinity of their boats, yet
to
> > create enough potential to neutralize lightning it would, in fact,
> generate
> > enough potential to cause lightning from their own boats; because they
> don't
> > understand lightning, electricity, or atmospheric electrodynamics, they
> > claim that lightning is magic - defies all physical laws; they want to
> > ground their boats to make it part of the lightning discharge
> > circuit -increasing the chances of getting struck!; the science teacher
> > claims some special, hidden knowledge of electricity, but yet is not
> > practiced in the art, he should stick to poetry. Ah yes the fools
suffer,
> > some even buy wonder products from the black magicians. God bless Iron
Joe
> > of the rusty Faraday cage! What doesn't get him in a thunder clap will
> > slowly rot out his hulk by electrolysis.
> >
> > There's a simple method to reduce the chances of being struck by many
> orders
> > of magnitude by towing a lightning distraction bouy. It's proven many
> times
> > over.
> >
Parallax
From a fizics view, lightning pertection is possible but depends on
what you mean by "is". I can imagine that a towed buoy with a very
tall pointy conductor (taller'n yer mast) would help but not
practical. I have considered towing my dinghy with its bottom covered
with copper foil attached to big boat with very large stranded cable
with no sharp turns (maybe attached to backstay about 15' up). Better
would be to run the cable direct tot eh mast without any sharp turns.
Having my dink sunk by lightning wouldnt be so bad ( hate my dink) cuz
it'd make a great story.
Phil Morris
> Why don't you tow a 500 foot tower? That should work.
> How many Navy ships tow a lightning distraction bouy?
>
> Bwahahahahah what a fool.
>
> Joe
No Joe, you're the fool:
ROCKET-TRIGGERED LIGHTNING EXPERIMENTS
AT CAMP BLANDING, FLORIDA
Vladimir A. Rakov
University of Florida, Gainesville, USA
1. Introduction
Many aspects of the interaction of lightning with power systems are not yet
well understood and are in need of research that requires the termination of
the lightning channel on or in the immediate vicinity of the power system.
The probability for a natural lightning to strike a given point of interest
on the Earth's surface is very low, even in areas of relatively high
lightning activity. The simulation of lightning in a high-voltage
laboratory has limited application in that it does not allow the proper
testing of large distributed systems such as power lines since the
laboratory current path is different from that of lightning and since the
laboratory discharge does not produce lightning-like electric and magnetic
fields. The most promising tool for studying both the direct and the induced
effects of lightning on power systems is artificially initiated (triggered)
lightning that is stimulated to occur between an overhead thundercloud and a
designated point on the power system or on nearby ground The lightning
triggering techniques and various lightning discharge processes involved are
outlined in Section 2. A relatively new facility for triggered-lightning
experiments is the International Center for Lightning Research and Testing
at Camp Blanding, Florida, located about 40 km north-east of Gainesville and
described in Section 3. The facility was constructed in 1993 by Power
Technologies, Inc. (PTI) under the funding and direction of the Electric
Power Research Institute (EPRI), and has been operated by the University of
Florida (UF) since Fall 1994. In Section 4 we give some examples of the
results of the studies conducted there. Additional information on the
triggered-lightning studies at Camp Blanding can be found in Uman et al.
(1994a,b, 1996a,b, 1997), Rakov et al. (1995a,b, 1996a,b, 1998), Ben Rhouma
et al. (1995), Barker et al. (1996), Fernandez (1997), Fernandez et al.
(1998a,b,c,d), Wang et al. (1999a,b,c,d), Crawford (1998), and Crawford et
al. (1999).
2. Lightning triggering techniques
The most effective technique for triggering lightning involves launching a
small rocket trailing a thin grounded wire toward a charged cloud overhead.
This triggering method is sometimes called "classical" triggering and is
illustrated in Fig. 1. The cloud charge is indirectly sensed by measuring
the electric field at ground, with values of 4 to 10 kV/m generally being
good indicators of favorable conditions for lightning initiation. When the
rocket, ascending at about 200 m/s, is about 200 to 300 m high, the field
enhancement near the rocket tip launches a positively charged (for the
common summer thunderstorm having predominantly negative charge at 5 to 7 km
altitude) leader that propagates upward toward the cloud. This leader
vaporizes the trailing wire and initiates a so-called "initial continuous
current" of the order of several hundred amperes that effectively transports
negative charge from the cloud charge source via the wire trace to the
instrumented triggering facility. There often follows, after the cessation
of the initial continuous current, several downward dart leader/upward
return stroke sequences traversing the same path to the triggering facility.
The dart leaders and following return strokes in triggered lightning are
similar if not identical to dart leader/return stroke sequences in natural
lightning, although the initial processes in natural and classical triggered
lightning are distinctly different. The reproduction of the initial
processes in natural lightning can be accomplished using a triggering wire
not attached to the ground. This ungrounded-wire technique is called
"altitude" triggering and is illustrated in Fig. 2 which shows that a
bi-directional (positive charge up and negative charge down) leader process
is involved in the initiation of the first return stroke. Properties of
altitude triggered lightning are discussed by Laroche et al. (1991), Lalande
et al. (1996, 1998), Uman et al. (1996a), and Rakov et al. (1996b, 1998).
3. The Camp Blanding lightning triggering facility
The Camp Blanding lightning triggering site (see Fig. 3), called the
International Center for Lightning Research and Testing (ICLRT), occupies a
flat, open field with dimension of approximately 1 km by 1 km and since Fall
1994 has been operated under an agreement between the University of Florida
and the Camp Blanding Florida Army National Guard Base. The site includes a
0.8 km test underground power cable, a 0.7 km test overhead power line, four
instrumentation stations, IS1, IS2, IS3, and IS4, located along the
underground cable and containing padmount transformers, a simulated house
fed by one of the transformers, a test runway with operational lighting
system, a number of other test structures, including a lightning protected
shelter, two launch control complexes, a number of rocket launchers, an
office building, and storage facilities. The existing elements of the power
system (overhead line and underground cable), presently unenergized,
can be connected in a variety of configurations. The facility allows the
measurement of the total lightning current injected into the power system's
conductors or to nearby ground and the monitoring of voltages and currents
at various points of the system. Electric and magnetic field measurements,
video recording, and still and high-speed photography are also performed,
making the Center a unique facility for studying simultaneously and
synergistically various aspects of atmospheric electricity, lightning, and
lightning protection. Examples of still photographs of lightning flashes
triggered at Camp Blanding, Florida, are shown in Fig. 4. During summers
1995 through 1998 over 30 scientists and engineers (excluding UF faculty,
students, and staff) from 13 countries representing 4 continents performed
experiments at the Center.
4. Results
The results of triggered-lightning studies provide new insights into the
physics of the lightning discharge and the mechanisms of lightning
interaction with various objects and systems. Some examples are presented
in Sections 4.1 through 4.3.
4.1. Close lightning electric fields
Characterization of the close lightning electromagnetic environment is
needed for the evaluation of lightning induced effects and for the
validation of various models of the lightning discharges.
4.1.1. Electric field waveshapes. Leader/return stroke vertical electric
field waveforms appear as asymmetrical V-shaped pulses, the bottom of the V
being associated with the transition from the leader (the leading edge of
the pulse) to the return stroke (the trailing edge of the pulse), as
described, from earlier Kennedy Space Center (KSC) measurements, by
Rubinstein et al. (1995). Examples of leader/return stroke electric fields
simultaneously measured at 30, 50, and 110 m from the 1993 Camp Blanding
experiment are shown in Figs. 5 and 6. From the 1993 experiment the
geometric mean width of the V at half of peak value is 3.2 ?s at 30 m, 7.3
?s at 50 m, and 13 ?s at 110 m, a distance dependence close to linear. This
waveshape characteristic can be viewed as a measure of the closeness of the
leader electric field rate of change to that of the following return stroke.
As seen in Fig. 5, at 30 m the rate of change of leader electric field near
the bottom of the V can be comparable to that of the return stroke field,
while at 110 m the two rates differ considerably, with the leader rate of
change being appreciably less. This observation, in conjunction with the
fact that within some hundreds of meters the leader and return stroke
electric field changes are about the same in magnitude (Uman et al. 1994a,
Rakov et al. 1998) (see also Figs. 5 and 6), suggests that induced voltages
and currents on power and other systems from very close (a few tens of
meters or less) lightning subsequent strokes can contain an appreciable
component due to the leader.
4.1.2. Leader electric field versus distance. From measurements at 30, 50,
and 110 m at Camp Blanding in 1993 (Uman et al. 1994a, Rakov et al. 1998)
the variation of the leader electric field change with distance was observed
to be somewhat slower than the inverse proportionality theoretically
predicted by using a uniformly-charged leader model by Rubinstein et al.
(1995). The uniformly charged leader model, although clearly a crude
approximation, is supported by experimental data, as explained next.
Thottappillil et al. (1997) showed that the modified transmission line
return stroke model with linear current decay with height (MTLL), developed
using the assumption that there exists a uniform distribution of leader
charge along the channel, predicts a ratio (R) of leader to return stroke
electric field between +0.81 and +0.97 at distances between 20 and 50 km,
assuming a total channel length of 7.5 km (see their Table 2). These values
of R are consistent with the mean value of R = +0.8 determined
experimentally (97 measurements) for this distance range by Beasley et al.
(1982, Fig. 23d). On the other hand, the return stroke model that is
derived assuming that there exists a distribution of leader charge
exponentially decreasing with height (MTLE) predicts values of R between
+2.6 and +3.0 (see Thottappillil et al. 1997, Table 2), while the lightning
model that is derived assuming that there exists a vertically symmetrical
bidirectional leader process (positively charged part propagating upward and
negatively charged downward) predicts values of R approximately between +0.2
and +0.3 (see Mazur and Ruhnke 1993, Fig. 25), in both cases inconsistent
with the experimental data of Beasley et al. (1982). From the 1993 Camp
Blanding experiment, individual leader electric field changes for six
strokes, simultaneously recorded at the three distances, are given in Table
1. Arithmetic mean values of the leader electric field changes for the six
events in Table 1 are 25, 21, and 16 kV/m at 30, 50, and 110 m,
respectively. Using the 50-m value, 21 kV/m, as a reference and assuming an
inverse distance dependence, we estimate values of 35 (versus 25) and 10
(versus 16) kV/m at 30 and 110 m, respectively. A relative insensitivity of
the leader electric field change to distance was also observed from
measurements at 10 and 20 m at Fort McClellan, Alabama (Fisher et al. 1994).
An electric field versus distance dependence that is slower than an inverse
proportionality, observed within 110 m of the channel, is consistent with a
decrease of line charge density with decreasing height near the bottom of
the channel. Such a leader charge distribution near ground might be due to
the incomplete development there of the radially formed corona sheath that
surrounds the channel core and presumably contains most of the leader
charge. Some support for this speculation comes from the observation that
the propagation speeds of radial corona streamers from conductors subjected
to negative high voltage in the laboratory are about 105 m/s (0.1 m/?s)
(Cooray 1993), so some microseconds are required for the development of a
corona sheath with a radius of the order of meters. Since for dart leaders
the downward propagation speeds (107 m/s) are about 2 orders of magnitude
higher than the radial-streamer speeds, the delay in corona-sheath formation
may be appreciable. On the other hand, Depasse (1994) observed, from
triggered-lightning experiments in France, that seven simultaneously
measured vertical electric fields due to return strokes at 50 and 77 m,
expected to be approximately equal in magnitude to the fields due to the
corresponding leaders (Uman et al. 1994a, Rakov et al. 1998) (see also Figs.
5 and 6), exhibited an inverse distance dependence, consistent with a
uniform distribution of charge density along the channel. Further, electric
field measurements at six distances ranging from 10 to 500 m at Camp
Blanding in 1997 suggest that leader field change varies approximately
inversely proportional to distance (Crawford et al. 1999). Additional
multiple-station data and modeling are needed to interpret the observed
variations of leader field change with distance. It is worth noting that,
as shown by Rubinstein et al. (1995) based on a uniformly charged leader
model, the presence of a triggering structure of about 5 m has a very small
effect on the leader field at distances of 30 m and greater. They computed
an error of about 1% at 30 m, with fields at greater distances being even
less sensitive to the presence of the triggering structure.
4.2. Lightning channel termination on ground
In examining the lightning current flowing from the bottom of the channel
into the ground, it is convenient to approximate lightning by a Norton
equivalent circuit (Carlson 1996), i.e., by a current source equal to the
lightning current that would be injected into the ground if that ground were
perfectly conducting (the short-circuit current) in parallel with a
lightning-channel equivalent impedance Zch assumed to be constant. The
lightning grounding impedance Zgr is a load connected in parallel with the
lightning Norton equivalent. Thus the "short-circuit" lightning current Isc
effectively splits between Zgr and Zch so the current measured at the
lightning-channel base is found as Imeas = IscZch/(Zch + Zgr). Both source
characteristics, Isc and Zch, vary from stroke to stroke, and Zch is a
function of channel current, the latter nonlinearity being in violation of
the linearity requirement necessary for obtaining the Norton equivalent
circuit. Nevertheless, if we are concerned only with the peak value of
current and assume that for a large number of strokes the average peak value
of Isc and the average value of Zch at current peak are more or less
constant, the Norton equivalent becomes a useful tool for studying the
relation between lightning current peak and the corresponding values of Zch
and Zgr. For instance, if the measured channel-base current peak statistics
are similar under a variety of grounding conditions, then Zgr must always be
much lower than Zch at the time of the current peak.
Camp Blanding measurements of lightning currents that entered sandy soil
with a relatively poor conductivity of 2.5 x 10-4 S/m without any grounding
electrode resulted in a value of the geometric mean return-stroke peak
current, 13 kA, that is similar to the geometric mean value, 14 kA, from
measurements at KSC made using a launcher of the same geometry which was
much better grounded into salt water with a conductivity of 3-6 S/m via
underwater braided metallic cables. Additionally, a fairly similar
geometric mean value, about 10 kA, of return stroke current peak was found
from KSC measurements using a well-grounded ground-based launcher of
significantly greater height, and fairly similar geometric mean values were
found from the Fort McClellan measurements using a relatively small-height,
poorly grounded launcher (10 kA) and the same launcher well grounded (11
kA). Additionally, Ben Rhouma et al. (1995) give arithmetic mean values of
return stroke current peaks in the range from 15 to 16 kA for the
triggered-lightning experiments at Camp Blanding in 1993 and at KSC in 1987,
1989, and 1991. The geometric mean values of peak current indicated above
along with other pertinent information on the measurements are summarized in
Table 2. The values of grounding resistance (probably the dominant
component of Zgr) given in Table 2 should be understood as the initial
values encountered by lightning before the onset of any breakdown processes
in the soil or along the ground surface. Note from Table 2 that the
grounding resistance varies from 0.1 ? to 64 k?, while Zch was estimated
from the analysis of the current waves traveling along the 540-m high tower
to be in the range from hundreds of ohms to several kiloohms (Gorin et al.
1977; Gorin and Shkilev 1984). The observation that the average return
stroke current is not much influenced by the level of man-made grounding,
ranging from excellent to none, implies that lightning is capable of
lowering its grounding impedance to a value that is always much lower than
the equivalent impedance of the main channel. On the basis of the evidence
of the formation of plasma channels (fulgurites) in the sandy soil at Camp
Blanding (Uman et al. 1994b, 1997) and on optical records showing arcing
along the ground at Camp Blanding and at Fort McClellan, Alabama (see Fig.
7), we infer that surface and underground plasma channels are the principal
means of lowering the lightning grounding impedance, at least for the types
of soil at the lightning triggering sites in Florida and Alabama. Injection
of laboratory currents up to 20 kA into loamy sand in the presence of water
sprays imitating rain resulted in surface arcing that significantly reduced
the grounding resistance at the current peak (M. Darveniza, personal
communication, 1995). The fulgurites found at Camp Blanding usually show
that the in-soil plasma channels develop toward the better conducting layers
of soil or toward buried metallic objects that, when contacted, serve to
further lower the grounding resistance. The percentages of return strokes
producing optically detectable surface arcing versus return stroke peak
current, from the 1993 and 1995 experiments at Fort McClellan, Alabama, are
shown in Fig. 8. The surface arcing appears to be random in direction and
often leaves little if any evidence on the ground. Even within the same
flash, individual strokes can produce arcs developing in different
directions. In one case it was possible to estimate the current carried by
one arc branch which contacted the instrumentation: approximately 1 kA or 5%
of the total current peak in that stroke (Fisher et al. 1994). The observed
horizontal extent of surface arcs was up to 20 m, which was the limit of
photographic coverage during the 1993 Fort McClellan experiment. No
fulgurites were found in the soil (red clay) at Fort McClellan, only
concentrated current exit points at several spots along the 0.3- or 1.3-m
steel earthing rod (see Table 2). It is likely that uniform ionization of
soil, usually postulated in studies of the behavior of grounding electrodes
subjected to lightning surges, is not a valid assumption, at least in the
southeastern United States, where distinct plasma channels in the soil and
on the ground surface appear to be the principal means of lowering the
grounding resistance.
4.3. Testing of MOV arresters
One of the projects at Camp Blanding in 1996 was concerned with the
performance of 10 kV MOV arresters. Given below are selected results, taken
from Fernandez et al. (1998b), for one negative lightning stroke in Flash
9632 whose current was directed to the phase conductor of the overhead line
between Poles 9 and 10 (see Fig. 3) which were separated by about 50 m. The
test power distribution system was configured so that the underground cable
was connected to the overhead line at pole 9, as shown in Fig. 3. The
transformer in IS1 was connected to the cable, and the simulated house
service entrance was attached to the secondary of the transformer. MOV
arresters were installed at the transformer primary (Cooper elbow arrester)
and at Poles 9 and 10 (GE Tranquell arresters). Additionally, there were
MOV surge protective devices (SPDs) installed at the service entrance of the
simulated house. The neutral conductors were grounded at each arrester, at
the terminal poles, at the service entrance, and at IS4.
The waveform of the arrester voltage at Pole 9 for Flash 9632 is shown in
Fig. 9 along with the total lightning current (recorded in the channel
having +/- 7.5 kA measurement range in order to resolve the structure of
relatively low level current after the initial peak). The lightning current
peak was about 12 kA, typical of subsequent strokes in natural lightning.
First strokes in natural lightning have current peaks two to three times
larger. The waveforms in Fig. 9 are displayed on a 10-ms time scale. The
discharge current of the arrester is not shown because it has insufficient
amplitude resolution after some hundreds of microseconds.
After the initial spike (probably associated with both the arrester lead
inductance and magnetic coupling to the voltage measuring circuit), the
voltage waveform in Fig. 9b is clamped near 20 kV for about 4 ms, then
begins to return to zero. The falling trend of the waveform is interrupted,
and the voltage exhibits a hump with amplitude of about 3 kV. (A similar
feature is also seen in the waveform of the total lightning current in Fig.
9a). After the hump, the voltage further decreases, crosses zero, and
produces an opposite polarity overshoot lasting several milliseconds. The
overshoot has peak value of about 8 kV.
At 200 ?s, the arrester discharge current is about one-half of the total
lightning current. Thus, if we assume that the same fraction (one-half) of
the lightning current in Fig. 9a is flowing through the arrester at Pole 9
after 200 ?s and is causing the voltage response in Fig. 9b, we can estimate
the energy absorption by the arrester at Pole 9 as a function of time, shown
in Fig. 10. As seen in Fig. 10, the energy absorbed during the initial 200
?s is about 8 kJ or about one-third of the total energy of 25 kJ absorbed
during the voltage-clamping stage of the arrester operation lasting 4 ms or
so.
For GE Tranquell MOV arresters, the maximum energy capability is 4.0 kJ/kV
of rating (Greenwood, 1991) or 40 kJ for this case. Therefore, during the
first 4 ms of the event considered here, the arrester was subjected to about
60% of its maximum energy capability. Video and photographic records, along
with visual inspection, indicate that physical damage was not sustained to
any of the MOV arresters as a result of this test. Barker et al. (1993),
who measured voltages across and currents through 10 kV MOV arresters
installed in actual four-wire multi-grounded power distribution systems,
estimated the dissipated energy for one negative lightning event to be in
excess of 80 kJ. Although this energy value exceeded the maximum energy
capability of the arrester, the arrester did not fail. The measured
lightning current through the arrester exhibited a slow tail lasting for
about 2 ms at an average level of about 2 kA, and the bulk of the dissipated
energy was associated with this tail.
5. Summary
1. Rocket-triggered lightning appears to be in many respects a controlled
analog of natural lightning. The results of triggered-lightning studies
provide new insights into both the physics of the lightning discharge and
lightning interaction with various objects and systems.
2. At very close ranges (a few tens of meters or less) the time rate of
change of the final portion of the dart leader electric field can be
comparable to that of the return stroke. This observation, coupled with the
fact that within some hundreds of meters the leader and return stroke
electric fields are about equal in magnitude, suggests that very close dart
leaders can make a significant contribution to induced voltages and currents
in power and other systems.
3. The variation of the close dart leader electric field change with
distance can be somewhat slower than the inverse proportionality predicted
by the uniformly charged leader model, perhaps due to a decrease of leader
charge density with decreasing height associated with an incomplete
development of the corona sheath at the bottom of the channel. However, the
bulk of the presently available data on leader electric field changes within
500 m suggests a more or less uniform distribution of charge along the
leader channel. More data and modeling are needed to interpret the observed
variations of leader field change with distance.
4. Judging from the similar average current peak values in dissimilar
grounding situations, lightning appears to be able to reduce the grounding
impedance which it initially encounters at the strike point so that at the
time of channel-base current peak the reduced grounding impedance is always
(regardless of the initial grounding impedance) much lower than the
equivalent impedance of the channel (hundreds of ohms to several kiloohms).
Breakdown processes forming distinct plasma channels in the soil and on the
ground surface are probably the principal means of lowering the grounding
impedance, at least in the case of poorly conducting (of the order of 10-3 -
10-4 S/m) sandy and clay soils.
Acknowledgments. The experiments at Camp Blanding, Florida, reviewed here
were made possible through the efforts of many individuals including M. A.
Uman, K. J. Rambo, M. V. Stapleton, T. W. Vaught, J. A. Versaggi, J. A.
Bach, Y. Su, M. I. Fernandez, D. E. Crawford, C.T. Mata, G. H. Schnetzer,
and R.J. Fisher (UF); A. Eybert-Berard, J. P. Berlandis, L. Barret, and B.
Bador (CENG); P. P. Barker, S. P. Hnat, J. P. Oravsky, T. A. Short, and C.
A. Warren (PTI); R. Bernstein (EPRI), and J. L. Koepfinger (Duquesne Light
Co.).
References
Barker, P.P., Mancao, R.T., Kvaltine, D.J., and Parrish, D.E. 1993.
Characteristics of lightning surges measured at metal oxide distribution
arresters. IEEE Trans. Pow. Del. 8: 301-10.
Barker, P.P., Short, T.A., Eybert-Berard, A.R., and Berlandis, J.P. 1996.
Induced voltage measurements on an experimental distribution line during
nearby rocket triggered lightning flashes. IEEE
Trans. Pow. Del. 11: 980-95.
Beasley, W.H., Uman, M.A., and Rustan, P.L. 1982. Electric fields preceding
cloud-to-ground lightning flashes. J. Geophys. Res. 87: 4883-902.
Ben Rhouma, A., Auriol, P., Eybert-Berard, A., Berlandis, J.-P., and Bador,
B. 1995. Nearby lightning electromagnetic fields. In Proc. of the 11th Int.
Symp. on EMC, March 7-9, Zurich, Switzerland,
paper 80M3, pp. 423-428.
Carlson, A.B. 1996. Circuits. 838 pp., New York: John Wiley & Sons.
Cooray, V. 1993. A model for subsequent return strokes. J. Electrostat. 30:
343-54.
Crawford, D.E. 1998. Multiple-station measuredments of triggered lightning
electric and magnetic fields. MS Thesis, Univ. of Florida, Gainesville.
Crawford, D.E., Rakov, V.A., Uman, M.A., Schnetzer, G.H., Rambo, K.J., and
Stapleton, M.V. 1999. Multiple-station measurements of triggered-lightning
electric and magnetic fields. In Proc. of the
11th Int. Conf. on Atmospheric Electricity, Guntersville, Alabama, June
7-11, 1999, 4 p.
Depasse, P. 1994. Statistics on artificially triggered lightning, J.
Geophys. Res. 99: 18,515-22.
Eybert-Berard, A., Barret, L., and Berlandis, J.P. 1986. Campagne foudre aux
ETATS-UNIS Kennedy Space Center (Florida, Programme RTLP 85* (in French).
STTASP/ASP 86-01, Cent. D'Etud.
Nucl. de Grenoble, Grenoble, France.
Eybert-Berard, A., Barret, L., and Berlandis, J.P. 1988. Campagne
d'experimentations foudre RTLP 87, NASA Kennedy Space Center Florida, USA
(in French). STT/LASP 88-21/AEB/JPB-pD, Cent.
D'Etud. Nucl. de Grenoble, Grenoble, France.
Fernandez, M.I. 1997. Responses of an unenergized test power distribution
system to direct and nearby lightning. MS Thesis, Univ. of Florida,
Gainesville.
Fernandez, M.I., Rakov, V.A., and Uman, M.A. 1998c. Transient currents and
voltages in a power distribution system due to natural lightning. In Proc.
of the 24th Int. Conf. on Lightning
Protection, September 14-18, 1998, Birmingham, United Kingdom, pp.
622-629.
Fernandez, M.I., Rambo, K.J., Rakov, V.A., and Uman, M.A. 1998a. Performance
of MOV arresters during very close, direct lightning strikes to a power
distribution system. IEEE PES Trans., in
press.
Fernandez, M.I., Rambo, K.J., Stapleton, M.V., Rakov, V.A., and Uman, M.A.
1998b. Review of triggered lightning experiments performed on a power
distribution system at Camp Blanding,
Florida, during 1996 and 1997. In Proc. of the 24th Int. Conf. on
Lightning Protection,
September 14-18, 1998, Birmingham, United Kingdom, pp. 29-35.
Greenwood, A. 1991. Electrical transients in power systems. 2nd Ed. New
York: John Wiley & Sons.
Fisher, R.J., Schnetzer, G.H., and Morris, M.E. 1994. Measured fields and
earth potentials at 10 and 20 meters from the base of triggered lightning
channels. In Proc. of the 22nd Int. Conf. on Lightning
Protection, Technical Univ. of Budapest, Budapest, Hungary, paper R1c-10.
Fisher, R.J., Schnetzer, G.H., Thottappillil, R., Rakov, V.A., Uman, M.A.,
and Goldberg, J.D. 1993. Parameters of triggered-lightning flashes in
Florida and Alabama, J. Geophys. Res. 98: 22,887-
902.
Gorin, B.N., Levitov, V.I., and Shkilev, A.V. 1977. Lightning strikes to the
Ostankino tower (in Russian). Elektr. 8: 19-23.
Gorin, B.N., and Shkilev, A.V. 1984. Measurements of lightning currents at
the Ostankino tower (in Russian). Elektr. 8: 64-5.
Hamelin, J., Leteinturier, C., Weidman, C., Eybert-Berard, A., and Barret,
L. 1986. Current and current- derivative in triggered lightning
flashes-Florida 1985. In Proc. of the Int. Conf. on Lightning and
Static Electricity, NASA, Dayton, Ohio.
Lalande, P., Bondiou-Clergerie, A., Laroche, P., Eybert-Berard, A.,
Berlandis, J.P., Bador, B., Bonamy,
A., Uman, M.A., and Rakov, V.A. 1996. Connection to ground of an
artificially triggered
negative downward stepped leader. In Proc. of the 10th Int. Conf. on
Atmospheric Electricity,
1996, Osaka, Japan, pp. 668-671.
Lalande, P., Bondiou-Clergerie, A., Laroche, P., Eybert-Berard, A.,
Berlandis, J.-P., Bador, B., Bonamy, A., Uman, M.A., and Rakov, V.A. 1998.
Leader Properties determined with triggered lightning
techniques. J. Geophys. Res. 103: 14,109-15.
Laroche, P., Idone, V., Eybert-Berard, A., and Barret, L. 1991. Observations
of bi-directional leader development in a triggered lightning flash. In
Proc. of the 1991 Int. Conf. on Lightning and
Static Electricity, Cocoa Beach, Florida, pp. 57/1-10.
Leteinturier, C., Hamelin, J.H., and Eybert-Berard, A. 1991. Submicrosecond
characteristics of lightning return-stroke currents. IEEE Trans.
Electromagn. Compat. 33: 351-7.
Leteinturier, C., Weidman, C., and Hamelin, J. 1990. Current and electric
field derivatives in triggered lightning return strokes. J. Geophys. Res.
95: 811-28.
Mazur, V., and Ruhnke, L.H. 1993. Common physical processes in natural and
artificially triggered lightning. J. Geophys. Res. 98: 12,913-30.
Rakov, V.A., Thottappillil, R., Uman, M.A., and Barker, P.P. 1995a.
Mechanism of the lightning M component, J. Geophys. Res. 100: 25,701-10.
Rakov, V.A., Uman, M.A., and Thottappillil, R. 1995b. Review of recent
lightning research at the University of Florida. Elektrotechnik und
Informationstechnik (Austria), 112: 262-5.
Rakov, V.A., Uman, Thottappillil, R., Eybert-Berard, A., Berlandis, J.P.,
Lalande, P., Bonamy, A., Laroche, P., Bondiou-Clergerie, A., Fisher, R.J.,
and Schnetzer, G.H. 1996a. New insights into
lightning processes gained from triggered-lightning experiments in Florida
and Alabama. In
Proc. of the 10th Int. Conf. on Electricity, Osaka, Japan, pp. 672-675.
Rakov, V.A., Uman, M.A., Fernandez, M.I., Thottappillil, R., Eybert-Berard,
A., Berlandis, J.P., Rachidi, F., Rubinstein, M., Guerrieri, S., and Nucci,
C.A. 1996b. Observed electromagnetic
environment close to the lightning channel. In Proc. of the 23rd Int.
Conf. on Lightning
Protection, Florence, Italy, pp. 30-35.
Rakov, V.A., Uman, M.A., Rambo, K.J., Fernandez, M.I., Fisher, R.J.
Schnetzer, G.H., Thottappillil, R., Eybert-Berard, A., Berlandis, J.P.,
Lalande, P., Bonamy, A., Laroche, P., and Bondiou-Clergerie,
A. 1998. New insights into lightning processes gained from
triggered-lightning experiments in
Florida and Alabama. J. Geophys. Res. 103: 14,117-30.
Rubinstein, M., Rachidi, F., Uman, M.A., Thottappillil, R., Rakov, V.A., and
Nucci, C.A. 1995. Characterization of vertical electric fields 500 m and 30
m from triggered lightning. J. Geophys.
Res. 100: 8863-72.
Thottappillil, R., Rakov, V.A., and Uman, M.A. 1997. Distribution of charge
along the lightning channel: Relation to remote electric and magnetic
fields and to return-stroke models. J. Geophys.
Res. 102: 6987-7006.
Uman, M.A., Cordier, D.J., Chandler, R.M., Rakov, V.A., Bernstein, R., and
Barker, P.P. 1994b. Fulgurites produced by triggered lightning (abstract).
EOS Trans. AGU 75 (44), Fall Meet.
Suppl., 99.
Uman, M.A., Rakov, V.A., Rambo, K.J., Vaught, T.W., Fernandez, M.I., Bach,
J.A., Su, Y., Eybert- Berard, A., Berlandis, J.-P., Bador, B., Lalande, P.,
Bonamy, A., Audran, F., Morillon, F.,
Laroche, P., Bondiou-Clergerie, A., Chauzy, S., Soula, S., Weidman, C.D.,
Rachidi, F.,
Rubinstein, M., Nucci, C.A., Guerrieri, S., Hoidalen, H.K., and Cooray, V.
1996a. 1995 triggered
lightning experiment in Florida. In Proc. of the 10th Int. Conf. on
Atmospheric Electricity,
Osaka, Japan, pp. 644-647.
Uman, M.A., Rakov, V.A., Rambo, K.J., Vaught, T.W., Fernandez, M.I.,
Bernstein, R., and Golden, C. 1996b. Triggered-lightning facility for
studying lightning effects on power systems. In Proc. of
the 23rd Int. Conf. on Lightning Protection, Florence, Italy, pp. 73-78.
Uman, M.A., Rakov, V.A., Rambo, K.J., Vaught, T.W., Fernandez, M.I.,
Cordier, D.J., Chandler, R.M., Bernstein, R., and Golden, C. 1997.
Triggered-lightning experiments at Camp Blanding, Florida
(1993-1995). Trans. IEE Japan 117-B: 446-52.
Uman, M.A., Rakov, V.A., Versaggi, J.A., Thottappillil, R., Eybert-Berard,
A., Barret, L., Berlandis, J.-P., Bador, B., Barker, P.P., Hnat, S.P.,
Oravsky, J.P., Short, T.A., Warren, C.A., and
Bernstein, R. 1994. Electric fields close to triggered lightning. In Proc.
of the Int. Symp. on
Electromagnetic Compatibility (EMC'94 ROMA), Rome, Italy, pp. 33-37.
Wang, D., Ito, T., Takagi, N., Watanabe, T., Rakov, V.A., and Uman, M.A.
1999d. Propagation characteristics of return strokes and M-components in
Florida rocket-triggered lightning. In Proc.
of the 11th Int. Conf. on Atmospheric Electricity, Guntersville, Alabama,
June 7-11, 1999, 4 p.
Wang, D., Rakov, V.A., Uman, M.A., Fernandez, M.I., Rambo, K.J., Schnetzer,
G.H., and Fisher, R.J. 1999b. Characterization of the initial stage of
negative rocket-triggered lightning. J. Geophys.
Res. 104: 4213-22.
Wang, D., Rakov, V.A., Uman, M.A., Takagi, N., Watanabe, T., Crawford, D.,
Rambo, K.J., Schnetzer, G.H., Fisher, R.J., and Kawasaki, Z.I. 1999a.
Attachment process in rocket-triggered lightning
strokes. J. Geophys. Res. 104: 2141-50.
Wang, D., Takagi, N., Watanabe, T., Rakov, V.A., and Uman, M.A. 1999c.
Observed leader and return- stroke propagation characteristics in the bottom
400 m of the rocket triggered lightning channel.
J. Geophys. Res. in press.
katysails
"Phil Morris" <stre...@diarrhea.com> wrote in message
news:2qwWc.31773$9Y6....@newsread1.news.pas.earthlink.net...
> I'm simply Jax's warmup act here. I know absolutely nothing about
> electricity but I have six questions for you:
>
> 1. Why doesn't lightning travel in a helical path since it does traverse a
> magnetic field?
Because
>
> 2. Since lightning is a plasma discharge why is it that
magnetohydrodynamic
> pinching doesn't occur?
Because
>
> 3. Does lightning have a magnetic field even though it doesn't travel in a
> close loop? Why?
Because
>
> 4. Can a conductor manifest Biot-Savart forces upon itself? If so why does
> lightning hit the ground?
Because
>
> 5. What condition must exist between the E and H fields of charge in ball
> lightning or electron clusters to maintain the high charge density?
> Remember, like charges repel.
Because
>
> 6. What is your favorite colour?
Blue....
katysails
picture of my great-grandmother Davitt and her sister leaning on the rail of
whatever steamer it was that brought them here...they were wearing all the
clothes they owned, one on top of the other....
http://www.museumsofmayo.com/davitt.htm
Scout
Scout
"katysails" <katy...@worldnet.att.net> wrote in message
news:rxyWc.240906$OB3.2...@bgtnsc05-news.ops.worldnet.att.net...
Scout
your electrical knowledge, you should go back to page you copied these
questions from and click on "Introduction"
I don't have a favorite color.
Scout
"Phil Morris" <stre...@diarrhea.com> wrote in message
news:2qwWc.31773$9Y6....@newsread1.news.pas.earthlink.net...
Scout
Scout
"Phil Morris" <stre...@diarrhea.com> wrote in message
news:C2yWc.31870$9Y6....@newsread1.news.pas.earthlink.net...
Scout
trees.
Scout
"Phil Morris" <stre...@diarrhea.com> wrote in message
news:2qwWc.31773$9Y6....@newsread1.news.pas.earthlink.net...
Scout
being Jax, and since others here in the past have filled me in on your
background, I will toggle over to my normal, self-confident and generally
gregarious persona, one who can overlook your willingness to attack me and
my credentials without provocation to you, and I will discuss these
questions with you on an individual basis, provided you are civil in return.
My goal here has never been to set traps for others, as is seen so often in
this NG, but to encourage the fair exchange of ideas with reasonable people
with reasonable egos. As in real life, I treat aggressive insults with a
quick foot to the ass, but as in real life, I try to not apply any force
beyond the intensity required to meet the worthiest of goals.
Why don't we start with question #1?
> 1. Why doesn't lightning travel in a helical path since it does traverse a
magnetic field?
Lighning does occassionally travel in a helical path, but that path is
typically caused by the object being struck. , (i.e., pine trees and other
soft and hard woods have exhibit this phenomenon. Other causes of helical
lightning spiralling could may include wind eddies, but this has not been
proven to the best of my knowledge. With the tree model, however, it is
believed that the grain pattern diverts the current flow to its new, helical
path.
If you would like to comment please do so. Otherwise, I'll move to #3, in
which I would like to defend the notion that, in the big picture, including
space and time, lightning does flow in a closed loop.
Scout
"Phil Morris" <stre...@diarrhea.com> wrote in message
news:2qwWc.31773$9Y6....@newsread1.news.pas.earthlink.net...
katysails
else....are you going to opt for the aluminum cap, the pills, or the bottle?
Scout stated: My goal here has never been to set traps for others, as is
Scout
Scout
spite of what everyone else says. ; )
Scout
<OoozeOne> wrote in message
news:r28mi0lncecct4h7u...@4ax.com...
> On Tue, 24 Aug 2004 10:58:37 GMT, "katysails"
> <katy...@worldnet.att.net> scribbled thusly:
>
> > reasonable people
> >with reasonable egos.
> >
>
> Hey, that's me you're talking about :-)
>
>
> Oz1...of the 3 twins.
>
> I welcome you to crackerbox palace,We've been expecting you.
Scout
does
> > lightning hit the ground?
If with Q#4, you are asking why doesn't lightning produce a counter-emf,
choking flow to the ground, I would 'guess' that the linear configuration of
a strike, (versus a coiled conductor and therefore its position relative to
its own magnetic flux), and the fact that lightning is DC versus AC
(exhibiting only one full cycle of expanding/collapsing magnetic flux) would
both be contributing factors to a lack of, or at best, infinitesimally small
counter-force. Even in AC inductive circuits, counter-emf can be
designed/used as a positive attribute, limiting flow but not halting it
completely (e.g., start up current of a motor is much higher (LRA rating)
than the FLA rating, which includes the devices self limiting features.
Scout
"Scout" <scout...@hotmail.com> wrote in message
news:fbDWc.507336$Gx4.1...@bgtnsc04-news.ops.worldnet.att.net...
Scout
give her general anesthesia, and the relief will be worth the trouble.
Scout
<OoozeOne> wrote in message
news:n89mi0hoo9vul5e3o...@4ax.com...
> On Tue, 24 Aug 2004 11:07:14 GMT, "Scout" <scout...@hotmail.com>
> scribbled thusly:
>
> >that's true Oz, I've always thought you to be rational and reasonable, in
> >spite of what everyone else says. ; )
> >Scout
>
> You been talking with my mum again? :-)
>
>
>
> She's off into hospital tomorrow to have her throat expanded?
> Seems the grisly rings that surround her throat have grown and
> narrowed her throat enough that food can get caught when she swallows
>
> Poor darlin is 76 and not looking forward to it.
Scout
> close loop? Why?
Lightning is no exception.
A counter question for you relating to the "closed loop" claim: If you took
a charge capacitor out of its circuit and discharged it, would you say the
circuit is open?
Scout
"Phil Morris" <stre...@diarrhea.com> wrote in message
news:2qwWc.31773$9Y6....@newsread1.news.pas.earthlink.net...
Roy G. Biv
I wonder what industrial maintenance and plant operations has to say
about dissipation technology?
about the 50th link up from the bottom
http://www.impomag.com/scripts/CompOtherProducts.asp?ACCT=0000100
heres a short cut --takes a few seconds to fwd once at msl site
http://makeashorterlink.com/?E10C25F19
jax sells dissipators with the use of adverse advertising, his
arguments against dissipation technology are outrageously unfounded !
Scout
> lightning or electron clusters to maintain the high charge density?
> Remember, like charges repel.
Recent research suggests otherwise:
"Bearden has proposed a theoretical mechanism that generates the flow of
time and its substructure, and shown some evidence of it. In principle the
theory is engineerable, in which case a region of "reversed time" can be
formed, and persist temporarily. Such a time-reversal zone may be involved
in both cold fusion (where TRZs are theorized by Bearden to form temporarily
under certain circumstances, thereby reversing the law of attraction and
repulsion of charges. In such a TRZ -- assuming such forms -- like charges
attract in even numbers, accounting for a variety of cluster formation (as
in Shoulders' patents and experiments) and yielding formation of new nuclei
in the cold fusion experiments. The phenomenon of TRZs may also occur at
intervals in nature, and may therefore explain the temporary persistence of
ball lighting WHERE THE MOVING CHARGES OF LIKE SIGN ARE ATTRACTED TO EACH
OTHER due to time reversal in zone. Such TRZs do decay fairly quickly, and
as they decay the attracted like-sign charges become more and more repulsive
and less attractive, resulting in sudden rupture of the boundary between
decreasing attraction and increasing repulsion. The result would be a
resounding explosion of the kind often seen with ball lightning."
Scout
"Phil Morris" <stre...@diarrhea.com> wrote in message
news:2qwWc.31773$9Y6....@newsread1.news.pas.earthlink.net...
DSK
>
> She's off into hospital tomorrow to have her throat expanded?
> Seems the grisly rings that surround her throat have grown and
> narrowed her throat enough that food can get caught when she swallows
>
> Poor darlin is 76 and not looking forward to it.
Good luck to her. It's not a difficult operation, nor particularly
dangerous, but it's still a bummer to go to the hospital. I hope she
gets relief and feels better.
Regards
Doug King
Parallax
> electricity but I have six questions for you:
>
> 1. Why doesn't lightning travel in a helical path since it does traverse a
> magnetic field?
The only mag field it traverses is the field it produces. The mean
free path of the electrons is too low to allow any significant
helicity.
>
> 2. Since lightning is a plasma discharge why is it that magnetohydrodynamic
> pinching doesn't occur?
Such pinching occurs when a plasma is trapped in a mag field. This is
not true with lightning as the mag field it produces loops around the
lightning path. There is some question of whether lightning is a
"plasma discharge (a discharge within a plasma)"
>
> 3. Does lightning have a magnetic field even though it doesn't travel in a
> close loop? Why?
Of course it does. Moving charges (current) produce mag fields from
Int (b dot dl) = uI. This field is circumfrential to the current
path.
>
> 4. Can a conductor manifest Biot-Savart forces upon itself? If so why does
> lightning hit the ground?
Yes it can, however the mean free path of the electrons as in most
conductors is such that these forces do not "add up" to significant
distortion of the path over the effect of the electric field.
>
> 5. What condition must exist between the E and H fields of charge in ball
> lightning or electron clusters to maintain the high charge density?
> Remember, like charges repel.
>
The mechanism responsible for ball lightning is not really known.
Some theories exist but they do not explain its stability for tens of
seconds and/or its obvious power density. Ball lightning should not
be stable according to known plasma physics. However, even in a
plasma (assuming the ball is a plasma unlike the regular lightning
streamer), maxwells equations must apply.
> 6. What is your favorite colour?
Is this a QM question?
Joe
> > Why don't you tow a 500 foot tower? That should work.
> > How many Navy ships tow a lightning distraction bouy?
> >
> > Bwahahahahah what a fool.
> >
> > Joe
>
> No Joe, you're the fool:
Oh so your saying it is a good thing to tow a lighting distraction
bouy.
How often are you going to re-load these rockets that fire out of the
bouys to induce lighting?
Get real
Joe
Scout
Scout
"Parallax" <dbo...@mindspring.com> wrote
Scout
Nav
Cheers
katysails
"Scout" <scout...@hotmail.com> wrote in message
news:CjFWc.241983$OB3....@bgtnsc05-news.ops.worldnet.att.net...
katysails
way to treat it...and the stuff they use to thicken liquids if you fail a
swallow test is nasty nasty nasty...we require our aids to drink a glass of
juice with it so they have the experience of what they're giving to
patients.
<OoozeOne> wrote in message
news:ghbmi015q6kbbjtc5...@4ax.com...
> Thanks for the thought.
> She's had a couple of choking incidents so I'm sure it'll be worth it.
>
> On Tue, 24 Aug 2004 11:28:08 GMT, "Scout" <scout...@hotmail.com>
katysails
katysails
(you had to get a PhD to come up with that????)
"Nav" <iga...@dr.sailing.net> wrote in message
news:412bd16e$1...@news.auckland.ac.nz...
Horvath
<stre...@diarrhea.com> wrote this crap:
>
>6. What is your favorite colour?
Paisley.
Hor...@Horvath.net
Pathetic Earthlings! No one can save you now!
Parallax
Sorry 'bout the dissertation, ya jes happed to hit on some of my grad
school work. Ball lightning and even the propogation of lightning
like discharges are proof that you do not need billion dollar (or even
million dollar, or even 100,000$)facilities to do real science. My
grad school work had no funding cuz my prof retired so I wandered the
halls of the nucular bldg scrounging old vacuum chambers, pumps, and
ancient HV power supplies. Got wrote up by the safety folks so many
times for exposed wiring that I finally piled dead equipment in front
of my lab door to make it look abandoned, damn it was fun.
B'leve it or not, the propogation of sparks is not well understood in
many cases. For lightning, the E field is well below that required to
produce breakdowna head of the discharge. Theories include UV
(produced in the spark) causing ionization ahead of it, QM tunnelling
of electrons out of the streamer into the air ahead, etc. Making big
sparks was a lot of fun and discharges in various gasses was really
cool. I still have some Lichtenburg Figures in plexiglas (sort of
like a frozen spark in clear plexi)that are amazing fractal
structures, even when viewed under a microscope.
Lightning scares the crap outa me but it sure is cool.
Nav
Parallax wrote:
> I still have some Lichtenburg Figures in plexiglas (sort of
> like a frozen spark in clear plexi)that are amazing fractal
> structures, even when viewed under a microscope.
> Lightning scares the crap outa me but it sure is cool.
Must have been a crap lab...
:-P
Cheers
Scout
The most potential I've worked with is about 40KV - didn't have many fancy
toys but I set a lot of pencils on fire with it. I can tell you it hurts
getting bit by it.
Had a decent vacuum pump we used to boil cold water and refrigerate apple
slices.
Scout
"Parallax" <dbo...@mindspring.com> wrote in message
news:792abaf9.04082...@posting.google.com...
Scout
Did you hear the theory that claims Mars may have lost its liquid water when
it lost its magnetic field?
If I remember correctly, the theorists claimed the planet was left
unprotected against solar wind, which was free to 'scrub' the atmosphere,
which lowered atmos pressure, allowed the liquid water to boil off and also
be 'scrubbed' from the planet. Or something like that.
Scout
"katysails" <katy...@worldnet.att.net> wrote in message
news:jQQWc.511439$Gx4.2...@bgtnsc04-news.ops.worldnet.att.net...
katysails
katysails
<OoozeOne> wrote in message
news:7g1oi0h554aekuv71...@4ax.com...
>
> Ahhh from the mouths of babes..or is that a babe?
>
> Haven't seen a recent pic ;-)
>
> On Wed, 25 Aug 2004 00:08:46 GMT, "katysails"
Scout
high pressure gas tanks tied off with ropes. I tried to explain the whole
sailing mentality but they weren't hearing any of it. "Must be chained" they
said, and then entered my name in the big book of sin. A shameful day
indeed.
Scout
"Parallax" <dbo...@mindspring.com> wrote
[snip]
> I wandered the halls of the nucular bldg scrounging old vacuum chambers,
pumps, and
> ancient HV power supplies. Got wrote up by the safety folks so many
> times [snip]
Scout
btw - did you see the SciAm story on the solar wind sailing spaceship?
Scout
"katysails" <katy...@worldnet.att.net> wrote in message
news:9o_Wc.245488$OB3....@bgtnsc05-news.ops.worldnet.att.net...
katysails
them a long time ago but can't remember who...
"Scout" <scout...@hotmail.com> wrote in message
news:Ks_Wc.514417$Gx4.2...@bgtnsc04-news.ops.worldnet.att.net...
katysails
<OooozeOne> wrote in message
news:kkuoi0todh8khc84a...@4ax.com...
> On Wed, 25 Aug 2004 11:06:37 GMT, "katysails"
> <katy...@worldnet.att.net> scribbled thusly:
>
> >Of what?
> >
> ><OoozeOne> wrote in message
> >news:7g1oi0h554aekuv71...@4ax.com...
> >>
> >> Ahhh from the mouths of babes..or is that a babe?
> >>
> >> Haven't seen a recent pic ;-)
>
> Well ummm errrr <shrugs>