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Re: Lightning video/photos

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avatar Lightning video/photos
June 06, 2009 12:08AM
Anyone here try to get videos or photos of lightning? Both are extremely hard to get, especially in a photo. I didn't try that last weekend, but I did manage to get a couple quick videos in the mountains south of Dayton, NV last weekend. Luckily the cell was far enough away to be safe (????) to do this.








avatar Re: Lightning video/photos
June 06, 2009 09:27AM
Nice Vids Vince
I doubt that cell phone use in a lightning storm is a risk factor, just don't understand the physics of how that could occur. Agree that it is controversial. Probably a hold over from land line phones.


NOAA has a gallery of lightning photos.




http://www.lightningsafety.noaa.gov/photos.htm



The cure for a fallacious argument is a better argument, not the suppression of ideas.
-- Carl Sagan
avatar Re: Lightning video/photos
June 06, 2009 09:51AM
Some day when I feel like doing it I plan to question NOAA regarding their description of "types" of lightening strikes. They make frequent reference to both negative and positive strikes which for those trained in electronics makes no sense whatsoever. All electrical current, regardless of its environment, is the flow of negatively charged particles called electrons from the outer rings of atoms. They are called valence electrons. Elements with high conductivity such as copper have an abundance of valence electrons that hop from one atom to another. Elements with low conductivity have only one valence electron or none at all. No matter what some folks have been taught, electrical current goes from NEG to POS.

A negative charge is the presence of excess electrons. A positive charge is simply the absence of electrons. Electrons flow from an area of excess (NEG) to an area of absence (POS). This is electrical current. The potential charge is referred to as Voltage while the speed of the current is referred to as Amperage.

I have never understood how any lightening could be decribed as a Positive strike but NOAA and other weather people do it all the time. Positive charge, being an absence of electrons, is essentially nothing. How can nothing go anywhere?
avatar Re: Lightning video/photos
June 06, 2009 12:53PM
It's just the direction of the curernt flow during the strike.
avatar Re: Lightning video/photos
June 06, 2009 10:04AM
Since the earth is ground (-) and the clouds are positively charged (+) doesn't it make sense that lightning strikes from the ground up? Ground is where the negative (excess electrons) are, right?
avatar Re: Lightning video/photos
June 06, 2009 10:10AM
http://www.lightningsafety.noaa.gov/science.htm



The cure for a fallacious argument is a better argument, not the suppression of ideas.
-- Carl Sagan
avatar Re: Lightning video/photos
June 06, 2009 10:17AM
Frank,

I'm well aware of this NOAA desription of POS lightening and it's totally garbage. There is only one type of electrical current. The laws of physics can not be altered with bad terminology.

Jim
avatar Re: Lightning video/photos
June 06, 2009 10:14AM
Vince,

That's my take but weather people do not agree. There are also cloud-to-cloud strikes but those again would still be NEG to POS areas within the clouds. The whole idea of trained scientists calling a lightening strike POS blows my mind but they do it all the time.

It may be possible that some of the confusion comes from the electronics industry itself. Somewhere along the way they started preaching that electrical current flows from POS to NEG. This is totally wrong but for electronic purposes the computational values work out in either direction. I don't know who it was but it's been proven in labs that current flows from NEG to POS, not the other way around.

Jim
avatar Re: Lightning video/photos
June 06, 2009 10:20AM
Quote
tomdisco
Vince,

That's my take but weather people do not agree. There are also cloud-to-cloud strikes but those again would still be NEG to POS areas within the clouds. The whole idea of trained scientists calling a lightening strike POS blows my mind but they do it all the time.

It may be possible that some of the confusion comes from the electronics industry itself. Somewhere along the way they started preaching that electrical current flows from POS to NEG. This is totally wrong but for electronic purposes the computational values work out in either direction. I don't know who it was but it's been proven in labs that current flows from NEG to POS, not the other way around.

Jim

Check out the book
Lightning injuries
By Christopher J. Andrews,
http://books.google.com/books?id=-BeZVUh0LQ0C

http://yosemitenews.info/forum/read.php?1,12015,12015#msg-12015

Search the book on google books for "positive lightning"

From the NOAA site:
Sounds like "positive lightning" travels farther than more typical "negative lightning" , Positve version more common in winter.



The cure for a fallacious argument is a better argument, not the suppression of ideas.
-- Carl Sagan
avatar Re: Lightning video/photos
June 06, 2009 10:31AM
Interesting section from Wikipedia. "stepped leader formation" from cloud to ground, bolt from ground to cloud. See picture below.

From Wikipedia lightning

Leader formation and the return stroke
As a thundercloud moves over the surface of the Earth, an electric charge equal to but opposite the charge of the base of the thundercloud is induced in the Earth below the cloud. The induced ground charge follows the movement of the cloud, remaining underneath it.
An initial bipolar discharge, or path of ionized air, starts from a negatively charged mixed water and ice region in the thundercloud. Discharge ionized channels are known as leaders. The negatively charged leaders, generally a "stepped leader", proceed downward in a number of quick jumps (steps). Each step is on the order of 50 to 100 ft (15 to 30 metres) long but may be up to 165 ft (50 m).[21] As it continues to descend, the stepped leader may branch into a number of paths. The progression of stepped leaders takes a comparatively long time (hundreds of milliseconds) to approach the ground. This initial phase involves a relatively small electric current (tens or hundreds of amperes), and the leader is almost invisible when compared with the subsequent lightning channel.
When a stepped leader approaches the ground, the presence of opposite charges on the ground enhances the strength of the electric field. The electric field is strongest on ground-connected objects whose tops are closest to the base of the thundercloud, such as trees and tall buildings. If the electric field is strong enough, a conductive discharge (called a positive streamer) can develop from these points. This was first theorized by Heinz Kasemir. As the field increases, the positive streamer may evolve into a hotter, higher current leader which eventually connects to the descending stepped leader from the cloud. It is also possible for many streamers to develop from many different objects simultaneously, with only one connecting with the leader and forming the main discharge path. Photographs have been taken on which non-connected streamers are clearly visible.[22] When the down and up leaders meet, the flow of electric current greatly increases.
Once a channel of ionized air is established between the cloud and ground this becomes a path of least resistance and allows for a much greater current to propagate from the Earth back up the leader into the cloud. This is the return stroke and it is the most luminous and noticeable part of the lightning discharge.

Discharge




(timelapse photos with later time to the right)



The cure for a fallacious argument is a better argument, not the suppression of ideas.
-- Carl Sagan
avatar Re: Lightning video/photos
June 06, 2009 10:45AM
The NOAA site is not easy to find stuff and I keep stumbling on interesting sites including these with nice graphics:

http://www.srh.weather.gov/jetstream/lightning/lightning.htm

http://www.srh.weather.gov/jetstream/lightning/positive.htm



The cure for a fallacious argument is a better argument, not the suppression of ideas.
-- Carl Sagan
avatar Re: Lightning video/photos
June 06, 2009 01:16PM
Frank,

I'm not buying any of it. Lightning can not be the movement of positively charged particles. The only positively charged particles that exist in nature are positrons, which are bound with neutrons in the core of atoms. These particles remain inside the core of atoms and do not go anywhere except during a nuclear event where atoms are split. The entire theory that positively charged particles move about in the form of lightning is ridiculous. Ask a phycist to define a postively charged particle outside the nucleus of an atom. The lead terminal on a battery marked + simply means there is an abscence of free electrons at that terminal. Yet, we often treat that terminal as the "hot" terminal. The only thing it's got the hots for is some free electrons sitting on the other terminal.

Lightning is electrical current. All electrical current is the movement of negatively charged particles called electrons from an area of excess to an area of absence. Once this current is discharged this imbalance will be eliminated and sometimes even reversed (swapping polarity). A subsequent discharge in the opposite direction thus occurs but it's still NEG to POS.

Jim
avatar Re: Lightning video/photos
June 06, 2009 01:40PM
I just dunno!
It has been almost 40 years since I took a physics course. I figure that some on these meteorologists are sharper and have more recent training than I. Last I heard electricity wasn't even "movement" but a change in the "probability" of an electron being in one place or another. Even 40 yrs ago they were not talking of electons behaving like little planets orbiting around the nucleus or flowing from one place to another like water. But, I like I've said before, I am just a simple guy. Perhaps the positive and negative is merely a convention to describe some other physics event for us country folks!



The cure for a fallacious argument is a better argument, not the suppression of ideas.
-- Carl Sagan
avatar Re: Lightning video/photos
June 06, 2009 01:41PM
Quote
tomdisco
The only positively charged particles that exist in nature are positrons,

What about atoms that have lost an electron?
avatar Re: Lightning video/photos
June 06, 2009 01:58PM
Quote
eeek
Quote
tomdisco
The only positively charged particles that exist in nature are positrons,

What about atoms that have lost an electron?

eeek,

Valid question but electrical current is not the flow of atoms, only electrons. Also, each atom only loses an electron temporaily while it gains one from the next atom. That's what electrical current is--electrons jumping from one atom to the next, and the next, etc. This subject has bugged me for so long that I've just sent a lengthy communication to the head of the Physics Department at North Carolina State University asking them to shed some lightning, er light, on the subject. It will likely be awhile before a reply is forthcoming.

Jim



Edited 2 time(s). Last edit at 06/06/2009 02:01PM by tomdisco.
avatar Re: Lightning video/photos
June 06, 2009 02:16PM
Quote
tomdisco
Valid question but electrical current is not the flow of atoms, only electrons.

No, it's the flow of charge. That charge does not have to be electrons.
avatar Re: Lightning video/photos
June 06, 2009 07:22PM
Quote
eeek
Quote
tomdisco
Valid question but electrical current is not the flow of atoms, only electrons.

No, it's the flow of charge. That charge does not have to be electrons.

In electricity, charge does not flow. Charge is described as merely "potential" for energy flow. You can have a gazillion volts of charge available but nothing happens until a path is provided for that flow, then electrons will move from NEG to POS. Electrical current is the flow of those electrons.

Jim
avatar Re: Lightning video/photos
June 06, 2009 08:17PM
Quote
tomdisco


In electricity, charge does not flow. Charge is described as merely "potential" for energy flow. You can have a gazillion volts of charge available but nothing happens until a path is provided for that flow, then electrons will move from NEG to POS. Electrical current is the flow of those electrons.

Jim

(Feel better??)
http://www.pbs.org/wgbh/nova/sciencenow/3214/02-ask.html

Q: You hear meteorologists talk a lot about positive and negative lightning strikes. What is the difference between the two, and do you stand a greater chance of being hit by one or the other?
David Young, Tahlequah, Oklahoma
A: Dear David,
A positive cloud-to-ground lightning stroke brings down positive charge from the cloud to the ground, and a negative lightning stroke brings down negative charge to the ground. As in most electrical circuits, negatively charged electrons are what actually move when electrical currents flow in lightning. This is true for both positive and negative strokes. Consequently, during a negative stroke electrons flow downward, and during a positive stroke electrons flow upward, leaving behind a net positive charge. If you think of a thunderstorm as a big battery with one terminal up in the cloud and the other on the ground, the direction that the current flows depends upon which side has the more positive charge. Some parts of thunderstorms are more positive than the ground and some parts are more negative.
On average worldwide, negative lightning flashes make up the vast majority, about 90 percent of all strikes. However, it is possible to be under a region of a thunderstorm where most of the flashes are positive. By the way, positive lightning strikes are believed to be the most dangerous, since they can produce very large currents, up to 300,000 amps!



The cure for a fallacious argument is a better argument, not the suppression of ideas.
-- Carl Sagan




Edited 1 time(s). Last edit at 06/07/2009 07:01AM by Frank Furter.
avatar Re: Lightning video/photos
June 06, 2009 09:44PM
Quote
tomdisco
In electricity, charge does not flow.

Really? That's not what they taught me in E&M.
avatar Re: Lightning video/photos
June 07, 2009 06:33AM
Quote
eeek
Quote
tomdisco
In electricity, charge does not flow.

Really? That's not what they taught me in E&M.

Unfortunately, you were taught wrong. Charge =voltage. Current flow = amperage. Power (voltage x amperage) = wattage.

The term "charge" in electronics is simply the potential for energy flow. Once it finds an avenue for release it is thereafter referred to as current. It can't be both. When we hear something has so many thousands of volts it is essentially meaningless by itself. The punch of that potential is a factor of how fast it can move in the form of current.

Jim
avatar Re: Lightning video/photos
June 06, 2009 02:20PM
avatar Re: Lightning video/photos
June 06, 2009 07:08PM
Quote
eeek
http://en.wikipedia.org/wiki/Lightning#Positive_lightning

Repeat after me everybody, "I DO NOT BELIEVE IN POSITIVE LIGHTNING!"

None of the sources anybody is quoting, including Wikipedia, are even attempting to describe what positive lightning is (at the particle level) because they can not. They are just parroting bad terminology uttered elsewhere. If somebody trained as a physicist can define a positively charged particle outside the nucleus of an atom, I'm all ears.

Jim
Re: Lightning video/photos
June 08, 2009 08:56AM
Quote
Vince
Since the earth is ground (-) and the clouds are positively charged (+) doesn't it make sense that lightning strikes from the ground up? Ground is where the negative (excess electrons) are, right?

Now I'm not an expert on lightning (although I have a meteorology degree), but let's try this...

I don't think this is always true - there can be both negative charges (excess electrons) and positive charges (Deficit of electrons) in either cloud or ground, or just in the cloud itself. I think the important difference is whether the lightning travels CTG or GTC - and since lightning travels not as a single spark but as a series of steps across atmospheric charges initiated by a leader, it may be possible for the "leader" to travel from a positive site to a negative site, even if the electron flow in individual steps is always from - to +. Imagine a series of potentials in the atmosphere defined by differentials in charge. The cloud is positive, for argument's sake, and the earth is negative - but in the atmosphere, the charges are all over the place. Now imagine that an atmospheric differential exists between point a and point b (a is +, b is -) - a discharge occurs from b to a, leaving b with a small deficit - which then prompts another point c to discharge to b, and so on. Thus, by this iterative process, one can have a "pos to neg" stroke that does not defy the law of physics.
avatar Re: Lightning video/photos
June 06, 2009 02:25PM
avatar Re: Lightning video/photos
June 06, 2009 03:22PM
Quote
eeek
http://en.wikipedia.org/wiki/Lightning#Positive_lightning

As a result of their greater power, 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.[38]

From the Wikipedia article reference 38 about first aircraft known to be hit by "positive lightning":



http://web.archive.org/web/20041009230137/http://www.dft.gov.uk/stellent/groups/dft_avsafety/documents/page/dft_avsafety_500699.hcsp

History of the flight
The glider was operating from a gliding site at Dunstable, Bedfordshire, and was being used for a one day training course. At the time of the accident the glider was undertaking the last intended flight of the day for one of two students on that course. In accordance with the policy of the gliding club, both the instructor and student were wearing parachutes and the instructor had briefed his student on the use of his parachute and how to abandon the glider should this be necessary. Thunderstorm activity had been forecast for the area and although a large area of bad weather could be seen to the north of the airfield from which the glider was operating, it was advancing only very slowly towards the local flying area. Heavy falls of rain and wet snow could be seen beneath the advancing cloud line.
The glider had been towed to 2,200 feet agl and for approximately one hour had been soaring at heights up to 4,000 feet in the area between Leighton Buzzard and Bletchley. For the last part of the flight, the glider returned towards the airfield and was flying along the front edge of this large area of cloud, approximately 500 feet above its base, where the air was rising at 2 to 3 kt. The pilot reported that he was in clear smooth air and close to the cloud. Shortly before the accident, other gliders in the area had been returning to the airfield in view of the approaching bad weather. At a local time of approximately 1709 hrs, after the glider had climbed back towards 3,000 feet, the instructor also decided to return to the airfield ahead of the approaching weather and therefore turned away from the cloud. A short time later when he estimated that his course had diverged from the cloud line by some 30°, and they were approximately 2,500 feet agl (some 300 feet above the cloudbase), at an estimated 800 yards from the cloud in clear air and flying at a speed of some 80 kt, the glider was struck by lightning and large sections of its airframe disintegrated.
From that moment, the instructor later stated that his memory was not particularly clear. He remembered hearing a 'very loud bang' and then 'feeling very draughty'; he also believed that he may have momentarily lost consciousness. On recovering, he felt dazed and remembered slowly becoming aware that 'something was seriously amiss' and that this was 'a real emergency requiring unpleasant and decisive action'. He was able to shout to his student in the front cockpit two or three times to undo his straps and abandon the glider but, owing to some impairment of his hearing, the student was unable to hear him clearly. The student had already decided to abandon the glider and, after he had departed, the instructor followed but was surprised when he realised that he had not had to jettison his cockpit canopy. It was estimated that both parachutes had successfully inflated by 1,800 feet agl.
The lightning strike was only witnessed by a few people in the area, but many more saw its immediate aftermath with large items of slowly falling debris, two inflated parachutes, the fuselage descending vertically at high speed and a ball of smoke and fine debris next to the cloud where the glider had been struck. All witnesses reported that the flash of lightning occurred simultaneously with an extremely 'loud crack' and many of these, including one police officer in the centre of the nearby town (Dunstable), expressed the view that it was probably the loudest sound they could remember hearing. It was also recollected by many witnesses that this had been the first lightning flash of a series of discharges which had then occurred in that area over a period of some 15 minutes.
Apart from the damage to the hearing of both occupants, 'sooting' to the upper part of the instructor's jacket, parachute pack and the hair on the back of his head, neither suffered any major injuries as a result of the lightning strike. The student pilot landed on the roof of a disused petrol station adjacent to a busy road in the village of Northall, but escaped major injury. The instructor descended into a nearby field and suffered a broken ankle upon landing. The rescue services were quickly on the scene and both occupants were taken to hospital; the student pilot was allowed to return home later that evening and the instructor was released four days later after surgery to his ankle.



The cure for a fallacious argument is a better argument, not the suppression of ideas.
-- Carl Sagan




Edited 2 time(s). Last edit at 06/06/2009 03:26PM by Frank Furter.
Re: Lightning video/photos
June 06, 2009 09:33PM
I've always understood it to mean the direction of flow of the lightning. If the source in the cloud is positive relative to the earth below, the strike will flow upward, which is positive lightning. More normal flow is from negatively charged areas of the cloud, to the earth.



Gary
Yosemite Photo Galleries: http://www.pbase.com/roberthouse/yo
avatar Re: Lightning video/photos
June 07, 2009 05:21AM
Quote
Sierrafan
I've always understood it to mean the direction of flow of the lightning. If the source in the cloud is positive relative to the earth below, the strike will flow upward, which is positive lightning. More normal flow is from negatively charged areas of the cloud, to the earth.

It is all terribly confusing.
In prior posts on this thread (see page one) and in most sources so far as I can tell it appears that typical "negative lightning" event builds an invisible "stepped leader" of charge from the cloud's negative underside to the ground. The lightning bolt that occurs as a visible discharge builds heat and light from the ground to the cloud (see prior photo series).
In the "positive lightning" circumstance, the events occur in reverse. I would imagine that since positive lightning seems to build from the tops of clouds farther away that things like surface area, distance and charge density (aspects of a capacitor) must create a more powerful event once the discharge occurs. In the case of positive lightning, the charge "stepped leader" must build from the ground to the cloud top and visible lightning event (bolt) would grow from the cloud to the ground.
If appears that as a cloud with negative underside is positioned over the ground the ground develops a positive charge area. This positive charge collection is balanced by negative surrounding charges. In a sense, it is a donut with the hole representing the positive charge under the cloud. Therefore the "positive lightning" would "reach out" beyond the cloud to that more distant area of negative charge (the donut ring outside the collection of positive charges under the cloud ) to complete the circuit. In a typical scenario, positive lightning would strike farther out from the cloud structure. Would also explain why positive lightning is more associated with resolving or passing thunderstorms.



The cure for a fallacious argument is a better argument, not the suppression of ideas.
-- Carl Sagan




Edited 2 time(s). Last edit at 06/07/2009 05:58AM by Frank Furter.
avatar Re: Lightning video/photos
June 06, 2009 11:28PM
I remember in physics class that even though electrons move from (-) to (+) the current is said to move from the opposite direction. The only reason I could figure why "they" say that is to make the math easier as far as negative numbers and such. I'm great with physics and math but terrible with electricity stuff, lost a computer and a VCR this week and when I turn the headlights on in my car the temperature gauge reads over 250 degrees...oh well
avatar Re: Lightning video/photos
June 07, 2009 01:30AM
Quote
Vince
I remember in physics class that even though electrons move from (-) to (+) the current is said to move from the opposite direction. The only reason I could figure why "they" say that is to make the math easier as far as negative numbers and such. I'm great with physics and math but terrible with electricity stuff, lost a computer and a VCR this week and when I turn the headlights on in my car the temperature gauge reads over 250 degrees...oh well

The reason "why" is because they came up with the signs before they learned about electrons.
avatar Re: Lightning video/photos
June 07, 2009 07:00AM
Quote
eeek
Quote
Vince
I remember in physics class that even though electrons move from (-) to (+) the current is said to move from the opposite direction. The only reason I could figure why "they" say that is to make the math easier as far as negative numbers and such. I'm great with physics and math but terrible with electricity stuff, lost a computer and a VCR this week and when I turn the headlights on in my car the temperature gauge reads over 250 degrees...oh well

The reason "why" is because they came up with the signs before they learned about electrons.

When I took basic electronics at the Heald School of Electronics in San Jose our first instructor was an elderly man from England who had actually worked on the Jordrell Bank radar station in WW2. He taught us that electrons move from (-) to (+) and that that constituted the direction of current. He further stated that this was proven early on by a lab experiment which I've forgotten the reference to. Our next instructor, a much younger man, introduced us to semi-conductors but tried to teach us that current went in the opposite direction (+) to (-). Needless to say, he had a lot of upset students who subsequently struggled with the concept of following electrical paths. Mathematically, for the purpose of electronics design or repair, is does not matter because the computations work in either direction. However, in terms of understanding what is really happening, it is damned confusing. We later discovered that he was a product of later day instruction method that is counter to the truth. Much of the industry still subscribes to this (+) to (-) direction of flow, apparently for no other reason than it seems easier to understand. In everything else we are taught that positive means something of substance while negative means an absence of substance. Unfortunately, the opposite is true in electronics.

I suspect this is partially at the root of the expression "positive lightning". As a couple of you pointed out, it's just a grammatical reference to suddenly reversed polarity in the cloud/ground interface. The laws of electrical current have not changed. NEG still flows to POS; it's just now in an opposite direction relative to the environment.

The same thing happens in household electrical current which is AC (alternating current). Every second the polarity reverses 60 times (60 cycle) and the current goes in the opposite direction with each alteration. It's still (-) to (+) current flow. In Europe and many other countries it's 50 times per second. The lightning people would have you believe it's NEG in one direction and POS in the other direction. Ain't so.

Jim
avatar Re: Lightning video/photos
June 07, 2009 07:20AM
If we want to make this really complicated we can get into anode-cathode, oxidation-reduction, charging-discharging, polarity, biochemical reactions and cathode tubes.

<http://www.av8n.com/physics/anode-cathode.htm#i-zener>;



The cure for a fallacious argument is a better argument, not the suppression of ideas.
-- Carl Sagan




Edited 1 time(s). Last edit at 06/07/2009 07:21AM by Frank Furter.
avatar Re: Lightning video/photos
June 07, 2009 07:39AM
Frank,

It quotes that current flows opposite the direction of the electrons because they are negatively charged and that this is "conventional" thinking going back to Ben Franklin. That does not make it true. Conventional thinking is still stuck on the idea of a positive charge having substance while a negative charge does not. This is maddening. Why do all these people dismiss basic atomic structure? It's crazy.

Jim
Re: Lightning video/photos
June 07, 2009 08:56AM
Quote
tomdisco
Frank,

It quotes that current flows opposite the direction of the electrons because they are negatively charged and that this is "conventional" thinking going back to Ben Franklin. That does not make it true. Conventional thinking is still stuck on the idea of a positive charge having substance while a negative charge does not. This is maddening. Why do all these people dismiss basic atomic structure? It's crazy.

Jim

It was probably a poor choice to use 'negative', 'minus' etc. when referring to electrons, but I think it was done before there was any understanding of it (and there are still numerous attempts at analogies to explain somethng so basic as the 'flow' of electrons).

Negative or minus traditionally refers to a deficiency of something, at least so my bank tells me. If I could convince the bank that cash flows from negative to positive, life would be good, but that goes contrary to most normal understanding. Which is probably why bankers usually hire people to work on their electrical systems 8^). So it's natural for people to think the positive contributes to the negative, instead of the opposite in current flow.

But as far as explanations of lightning, I never delved into it beyond noting that there was 'positive and negative', and it seems simple enough to assume that normal lightning would flow from negatively charged (relative to earth) cloud areas and positive lightning would have current flow from an earth that's negative relative to wherever it's going in the cloud.

I haven't looked at all the references, but the internet has generally become so full of inaccurate and downright wrong info that I don't believe anything I read there that doesn't seem to make sense; with so many blog sites and click-and-publish html programs, anybody can say anything and get it online.



Gary
Yosemite Photo Galleries: http://www.pbase.com/roberthouse/yo




Edited 1 time(s). Last edit at 06/07/2009 09:00AM by Sierrafan.
avatar Re: Lightning video/photos
June 08, 2009 08:47AM
To make my life easier, in the days when, I always looked at it as electron current flow went from negative to positive and SIGNAL flow from positive to negative. It was the solid state guys that messed everything up with their stupid holes.



Old Dude



Edited 1 time(s). Last edit at 06/08/2009 08:48AM by mrcondron.
avatar Re: Lightning video/photos
October 07, 2014 01:59PM
Quote
mrcondron
It was the solid state guys that messed everything up with their stupid holes.

And how do you feel about phonons?
Re: Lightning video/photos
June 08, 2009 08:34AM
A few lightning pictures, from Lubbock, Texas and Mt. Washburn, Yellowstone:

Lightning Photos on Panoramio

The link is good - sometimes you have refresh Panoramio a couple of times to get a page show up - it is horribly incompatible with Internet Explorer.

When I figure out how to post photos, I will. smiling bouncing smiley



Edited 1 time(s). Last edit at 06/08/2009 09:00AM by bpnjensen.
Re: Lightning video/photos
June 08, 2009 11:33AM
This is a commonly misunderstood area of electrical theory.

Positive charges exist as the absence of an electron. Some examples are alpha particles (positively charged helium atoms, missing one electron) and "holes" in semiconductors. Alpha particles occur in nature as a result of radioactive decay. In semiconductors, you can get current by the movement of electrons or the movement of holes.

In metal, we talk about conventional current and electron current. "Conventional current" flows from positive to negative. "Electron current" flows from negative to positive. The actual charge carrier is the electron, of course. This all works because we arbitrarily call the charge of the electron negative. The reason for this is that electric current and voltage were discovered before the electron was discovered. It was easier to live with the ugliness of having the electron negatively charged, than to change the definitions of current and voltage.

Oh yes, charge really does flow. Electrons (and holes) move in response to an electric field. The ease with which this happens is called "mobility". As an example, the movement of electrons in aluminum causes electromigration.
avatar Re: Lightning video/photos
December 04, 2012 05:26PM
Quote
Vince
Luckily the cell was far enough away to be safe (????) to do this.

The cell phone itself would do little or nothing to attract lightning, The person holding it could provide a much more tempting target. So could any trees, rocks, etc., nearby.

(TMI, maybe): The hazard from a nearby lightning strike is that the object that gets struck may not provide an efficient path to ground by itself so the charge may spread out on its way into the ground. If the ground (perhaps wet) that you're standing on gets electrified by a lightning strike and your feet are any distance apart, part of the discharge could go through you. As I understand it, that last part is why lightning-safety instructions (such as these, reposted by Frank Furter) advise "minimizing contact with the ground".

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

I'm afraid the discussion elsewhere in this thread about how a charge could possibly travel from positive to negative, misses the point. The ground isn't negative; it's the ground, and other objects are termed positive or negative in relation to it. The process that builds up the charges in a thundercloud moves electrons around, making parts of the cloud more positive and other parts more negative by millions or billions of volts. You can end up with a discharge (lightning stroke) between the negative and positive parts of the same cloud (or different clouds), between the negative part of the cloud and the ground, or between the positive part of the cloud and the ground. The last kind is what's called "positive" lightning. It's reportedly less common than "negative" lightning but also more dangerous, because the positive charges usually accumulate at the top of the cloud. That means they have a much longer "gap" to span and by the time they're ready to flash, pack a much bigger wallop.



Edited 1 time(s). Last edit at 12/04/2012 05:29PM by gophersnake.
avatar Re: Lightning video/photos
December 06, 2012 09:15AM
gophersnake,

While I appreciate your attempt to shed more light on the positive lightening arguement, it's still wrong. Yes, what they are calling positive lightening may indeed be the discharge between a positive charge in the clouds and the ground, which is the negative charge. The ground itself in this instance is not neutral; it's negative. The lightening discharge that takes place does not originate in the clouds. It originates on the ground because that's where the excess electrons exist. These excess electrons travel by way of the lightening discharge to the area of lesser amounts of electrons in the clouds which we call positive.

The weather people try to claim that positive lightening travels from the positive charge in the clouds to the negative charge on the ground. This is ridiculous because electrical current can not flow in that direction. There is absolutely nothing that would induce a lessor number of electrons to travel towards an area of more electrons. It defies physics. There is cloud to cloud lightening as well but it's still negative to positive. I think the very idea of naming lightening as positive or negative is misleading. Lightening is lightening and it only travels in one direction. Physically, it can be up, down, or sideways. Electronically, it's negative to positive.

Jim
avatar Re: Lightning video/photos
January 01, 2013 09:37AM
Quote
Vince
Anyone here try to get videos or photos of lightning? Both are extremely hard to get, especially in a photo. I didn't try that last weekend, but I did manage to get a couple quick videos in the mountains south of Dayton, NV last weekend. Luckily the cell was far enough away to be safe (????) to do this.

You can use a lightning trigger to capture photos of lightning:

http://www.lightningphotography.com/tips.html



Edited 1 time(s). Last edit at 01/01/2013 11:52AM by eeek.
avatar Re: Lightning video/photos
January 01, 2013 11:53AM
Quote
vdrummer
You can use a lightning trigger to capture photos of lightning:

http://www.lightningphotography.com/tips.html

http://www.ske-art.com/skestuff9/B008456ZSE
Re: Lightning video/photos
October 05, 2014 12:46AM
Long exposures help.



Whew...old thread.
Re: Lightning video/photos
October 06, 2014 01:39PM
Quote
redpakotasea
Whew...old thread.

Thanks for reviving it with such a stunning shot!
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