Simon Timm
Just out of curiosity, how meteorologists and physicists measure the voltage and temperature of lightning? How are they sure lightning's temperature can exceed 50,000 degree F., or that they can exceed 1 billion volts?
Dan Robinson
The voltage measurement is possible due to the known dialectric (breakdown) strength of air (which is roughly 3 million volts per meter) . Charge has to reach a voltage high enough to overcome that for distances on the order of miles.
The temperature can be estimated by the wavelengths of emitted light.
The temperature can be estimated by the wavelengths of emitted light.
Dave Marshall
If you do the math right out of the physics books, a 5 mile long lightning bolt would be on the order of 10s of billions of volts. The actual distance a given voltage can 'jump' through air is very dynamic. Humidity, air pressure, and air pollution (to include dust, smog, bugs, hail, rain, cloud condensation, etc) can all dramatically increase the distance 1 billion volts can travel. If you do the math, 3 million v/meter only nets you a range of about 350 meters with 1 billion volts. That's a bit less than a quarter mile, which is only a tiny fraction of the actual range of a lightning bolt.
Really the old standby 1.2mm per 1000 volts only stands up in a laboratory run by an obsessive compulsive neat freak
However, if you have a vague idea of what your environment would be like (I mean, a cloud is a cloud, right?) you can crunch the numbers and get a fair idea of what voltage would be required to make it the 300m-5,000m between cloud and ground.
Really the old standby 1.2mm per 1000 volts only stands up in a laboratory run by an obsessive compulsive neat freak
However, if you have a vague idea of what your environment would be like (I mean, a cloud is a cloud, right?) you can crunch the numbers and get a fair idea of what voltage would be required to make it the 300m-5,000m between cloud and ground.Kurt Wayne
EF0
- Joined
- Sep 28, 2005
- Messages
- 34
On a related note, what do calculations show is the average amperage in a lightning strike?
Rob Wadsworth
EF5
Along the same lines as Dave M stated, just imagine the voltage of a strike from the upper anvil to the ground.
The 'bolt from the blue' is an exceeding powerful bolt that carries many Joules of voltage/discharge. Moreso than most other bolts, due to the dielectrics between a 40,000 ft anvil height and ground.
But lightning -most often- uses rain to conduct to Earth as it takes the least resistive path. But from the upper anvil to an area that has no rain to speak of, that 'bolt from the blue' must be a real sight to see. Anyone witness this phenomena - while on the subject of lightning energy?
The 'bolt from the blue' is an exceeding powerful bolt that carries many Joules of voltage/discharge. Moreso than most other bolts, due to the dielectrics between a 40,000 ft anvil height and ground.
But lightning -most often- uses rain to conduct to Earth as it takes the least resistive path. But from the upper anvil to an area that has no rain to speak of, that 'bolt from the blue' must be a real sight to see. Anyone witness this phenomena - while on the subject of lightning energy?
Jeff Richardson
EF2
"Rob Wadsworth...
But lightning -most often- uses rain to conduct to Earth as it takes the least resistive path. But from the upper anvil to an area that has no rain to speak of, that 'bolt from the blue' must be a real sight to see. Anyone witness this phenomena - while on the subject of lightning energy?"
Yes Rob, I have and it caught me quite by surprise. On June 13, 1998, I was driving west through Cushing, OK headed toward a supercell that, at the moment, was over Kingfisher, OK. There was a nice mammatus field overhead and I turned my camcorder up to get some shots when ZAP...a CG came out of the anvil and struck the ground about a mile to my south.
Fortunately, I also caught the bolt on video. Of course the tornado I bagged near Guthrie was icing on the cake
, but that "bolt from the blue" was quite a sight.
But lightning -most often- uses rain to conduct to Earth as it takes the least resistive path. But from the upper anvil to an area that has no rain to speak of, that 'bolt from the blue' must be a real sight to see. Anyone witness this phenomena - while on the subject of lightning energy?"
Yes Rob, I have and it caught me quite by surprise. On June 13, 1998, I was driving west through Cushing, OK headed toward a supercell that, at the moment, was over Kingfisher, OK. There was a nice mammatus field overhead and I turned my camcorder up to get some shots when ZAP...a CG came out of the anvil and struck the ground about a mile to my south.
Fortunately, I also caught the bolt on video. Of course the tornado I bagged near Guthrie was icing on the cake, but that "bolt from the blue" was quite a sight.
Last edited by a moderator:
Danny Neal
EF5
I have seen it several times, but the most memorable one was in San Jose, Illinois, a couple years ago. There was a line of cells about 20-25 miles to the west in Havana, and I could see distant CG and CC, as i stopped at a stop sign in town the whole left side lit up with a thunderous explosion. The curiosity in me got the best of me so I turned around to see what had happened..... about a block to my south was a tree scalded/scalped of its bark with a fresh "streak" shooting down one side of it. Pretty eerie as there were kids out playing and riding bicycles.
cdcollura
EF5
Good day all,
Above: Would that be Nikola Tesla, by any chance?
I constructed a 1.5 MILLION volt Tesla coil a few years ago, and it can launch sparks 3-6 feet (nearly 2m) in length, depending on conditions. Link is here: http://www.sky-chaser.com/tesla.htm
By far my worst experience with a positive CG (Anvil to ground) was when I was a kid in New York. A severe thunderstorm was over Bayshore, and I was at my home in Islip (15 miles away).
You could hear the very-faint low-rumbles of thunder in the distance, but a low-layer of clouds prevented you seeing the severe cell, anvil, etc. Sky was just overcast but bright grey, with kids playing outside and an otherwise normal day.
All of a sudden, a blinding flash cracked the sky across the yard. It was like an explosion, so powerful, and it's streak "burned" an image into my eyes that lasted for almost an hour. My mom freaked, thinking it was "Russians" attacking us (it was 1983, during cold-war) - That's how loud it was.
A window was broken by it, presumably from the shock-wave, and you felt it more (in your chest) than you heard it! Car alarms could be heard afterwards, and the power was knocked out for at least 12 hours afterwards. I was young and did not look for any evidence of the strike afterwards.
In fact, such lightning is called "reverse" lightning (or more appropriately, "positive" lightning). The more common, and much less-powerful "negative" lightning affects the areas under the thunderstorm base, which is negatively charged. The mid-sections and upper portions of the cloud hold a positive charge.
The negatively charged t-storm base induces positive charges under it along the Earth's surface. But, since like-charges repel, negative charges are induced in a ring-like formation around the storm and AWAY from it along the ground. This is why a positive bolt from the anvil hits OUTSIDE the storm. It often goes out into the clear air, and strikes the ground often 15 miles, or more, from the core of the storm (where all the "normal" negative strikes are ocurring).
Above: A bolt from the blue (out into the clear air and striking the negative "ring" away from the storm core). Actually, the bolt travels first from the GROUND then UP, and the return-stroke back. Negative lightning strikes down, then up (return stroke). The forward stroke is too fast to see, it's the return stroke we see.
Above: This is POSITIVE lightning, branching UP from the spire of the Sears tower in Chicago. This was in WINTER, Jan 7, 2008 to be exact, and during winter thunderstorms, ice crystals and larger anvil structure promotes such positive lightning.
It is clear to say that such LARGER positive bolts - referred to as "superbolts" - can easily be a hundred MILES long in extreme cases, sometimes between cells in a line.
In a normal "negative" bolt, the currents involved are in the ball-park of about 20,000 AMPS with about 100 million volts of electromotive force. The amount of energy involved is roughly 2 TRILLION joules, and much of it is released over a 10-50 millisecond period.
Positive bolts are a different story, and can be 10 to 100 times the parameters of normal "negative" discharges ... So you're talking something like a BILLION volts or so at a current of a quarter-million AMPS! Even worse, the energy spike can last up to 500 milliseconds, or 1/2 second, heating the air into a plasma hot enough to produce x-rays.
Proportionally, such a violent discharge will not only knock out power and split a tree in a direct hit ... It will have some substantial and dangerous thermal effects, including a shock-wave that can crack walls and break windows. It can also simply vaporize metal, not just burn things!
Imagine this hitting powerlines and what it would do to a home appliance? A direct hit with a "superbolt" would most likely kill a human instantly, and cause deep and severe 3-rd degree electrical burns.
Above: Would that be Nikola Tesla, by any chance?
I constructed a 1.5 MILLION volt Tesla coil a few years ago, and it can launch sparks 3-6 feet (nearly 2m) in length, depending on conditions. Link is here: http://www.sky-chaser.com/tesla.htm
By far my worst experience with a positive CG (Anvil to ground) was when I was a kid in New York. A severe thunderstorm was over Bayshore, and I was at my home in Islip (15 miles away).
You could hear the very-faint low-rumbles of thunder in the distance, but a low-layer of clouds prevented you seeing the severe cell, anvil, etc. Sky was just overcast but bright grey, with kids playing outside and an otherwise normal day.
All of a sudden, a blinding flash cracked the sky across the yard. It was like an explosion, so powerful, and it's streak "burned" an image into my eyes that lasted for almost an hour. My mom freaked, thinking it was "Russians" attacking us (it was 1983, during cold-war) - That's how loud it was.
A window was broken by it, presumably from the shock-wave, and you felt it more (in your chest) than you heard it! Car alarms could be heard afterwards, and the power was knocked out for at least 12 hours afterwards. I was young and did not look for any evidence of the strike afterwards.
In fact, such lightning is called "reverse" lightning (or more appropriately, "positive" lightning). The more common, and much less-powerful "negative" lightning affects the areas under the thunderstorm base, which is negatively charged. The mid-sections and upper portions of the cloud hold a positive charge.
The negatively charged t-storm base induces positive charges under it along the Earth's surface. But, since like-charges repel, negative charges are induced in a ring-like formation around the storm and AWAY from it along the ground. This is why a positive bolt from the anvil hits OUTSIDE the storm. It often goes out into the clear air, and strikes the ground often 15 miles, or more, from the core of the storm (where all the "normal" negative strikes are ocurring).
Above: A bolt from the blue (out into the clear air and striking the negative "ring" away from the storm core). Actually, the bolt travels first from the GROUND then UP, and the return-stroke back. Negative lightning strikes down, then up (return stroke). The forward stroke is too fast to see, it's the return stroke we see.
Above: This is POSITIVE lightning, branching UP from the spire of the Sears tower in Chicago. This was in WINTER, Jan 7, 2008 to be exact, and during winter thunderstorms, ice crystals and larger anvil structure promotes such positive lightning.
It is clear to say that such LARGER positive bolts - referred to as "superbolts" - can easily be a hundred MILES long in extreme cases, sometimes between cells in a line.
In a normal "negative" bolt, the currents involved are in the ball-park of about 20,000 AMPS with about 100 million volts of electromotive force. The amount of energy involved is roughly 2 TRILLION joules, and much of it is released over a 10-50 millisecond period.
Positive bolts are a different story, and can be 10 to 100 times the parameters of normal "negative" discharges ... So you're talking something like a BILLION volts or so at a current of a quarter-million AMPS! Even worse, the energy spike can last up to 500 milliseconds, or 1/2 second, heating the air into a plasma hot enough to produce x-rays.
Proportionally, such a violent discharge will not only knock out power and split a tree in a direct hit ... It will have some substantial and dangerous thermal effects, including a shock-wave that can crack walls and break windows. It can also simply vaporize metal, not just burn things!
Imagine this hitting powerlines and what it would do to a home appliance? A direct hit with a "superbolt" would most likely kill a human instantly, and cause deep and severe 3-rd degree electrical burns.
MatthewCarman
I read a weather book that talked about a super bolt. A lightningbolt that is rare and alot stronger than a normal bolt. I am pretty sure it is the same as a "bolt from the blue".
I hope it is ok to paste this information I have. Here is a list of lightningbolt's from Wikipedia. I have not changed anything. I thought some people might find this interesting.
Types of lightning
Some lightning strikes exhibit particular characteristics; scientists and the general public have given names to these various types of lightning. The lightning that is most-commonly observed is streak lightning. This is nothing more than the return stroke, the visible part of the lightning stroke. The majority of strokes occur inside a cloud so we do not see most of the individual return strokes during a thunderstorm.
Cloud-to-ground lightning
This is the best known and second most common type of lightning. Of all the different types of lightning, it poses the greatest threat to life and property. Cloud-to-ground lightning is a lightning discharge between a cumulonimbus cloud and the ground. It is initiated by a leader stroke moving down from the cloud (see Leader formation above).
Bead lightning
Bead lightning is a type of cloud-to-ground lightning which appears to break up into a string of short, bright sections, which last longer than the usual discharge channel. It is relatively rare. Several theories have been proposed to explain it; one is that the observer sees portions of the lightning channel end on, and that these portions appear especially bright. Another is that, in bead lightning, the width of the lightning channel varies; as the lightning channel cools and fades, the wider sections cool more slowly and remain visible longer, appearing as a string of beads.[30][31]
Ribbon lightning
Ribbon lightning occurs in thunderstorms with high cross winds and multiple return strokes. The wind will blow each successive return stroke slightly to one side of the previous return stroke, causing a ribbon effect.
Staccato lightning
Staccato lightning is a cloud to ground lightning strike which is a short-duration stroke that appears as a single very bright flash and often has considerable branching.[32]
Fork lightning
Another name for cloud-to-ground lightning. Not in formal usage. Refers to its branching (forking) nature. Compare sheet lightning below.
Ground-to-cloud lightning
Ground-to-cloud lightning is a lightning discharge between the ground and a cumulonimbus cloud initiated by an upward-moving leader stroke. It is much rarer than cloud-to-ground lightning.
Cloud-to-cloud lightning
Lightning discharges may occur between areas of cloud without contacting the ground. When it occurs between two separate clouds it is known as inter-cloud lightning and when it occurs between areas of differing electric potential within a single cloud, it is known as intra-cloud lightning. Intra-cloud lightning is the most frequently occurring type.[14]
These are most common between the upper anvil portion and lower reaches of a given thunderstorm. This lightning can sometimes be observed at great distances at night as so-called "heat lightning". In such instances, the observer may see only a flash of light without hearing any thunder. The "heat" portion of the term is a folk association between locally experienced warmth and the distant lightning flashes.
Another terminology used for cloud-cloud or cloud-cloud-ground lightning is "Anvil Crawler", due to the habit of the charge typically originating from beneath or within the anvil and scrambling through the upper cloud layers of a thunderstorm, normally generating multiple branch strokes which are dramatic to witness. These are usually seen as a thunderstorm passes over the observer or begins to decay. The most vivid crawler behavior occurs in well developed thunderstorms that feature extensive rear anvil shearing.
Sheet lightning
Another name for cloud-to-cloud lightning. Not in formal usage. Refers to the diffuse brightening of the surface of a cloud, because the actual discharge path is hidden. Compare fork lightning above.
Heat lightning
Main article: Heat lightning
Sheet lightning that occurs too far away for the thunder to be heard.
Dry lightning
Main article: Dry lightning
Dry lightning is a term in the United States for lightning that occurs with no precipitation at the surface. This type of lightning is the most common natural cause of wildfires.
Rocket lightning
It is a form of cloud discharge, generally horizontal and at cloud base, with a luminous channel appearing to advance through the air with visually resolvable speed, often intermittently.[33]
Positive lightning
See also: High voltage#Lightning
Positive lightning, also known colloquially as "bolts from the blue", makes up less than 5% of all lightning.[34] It occurs when the leader forms at the positively charged cloud tops, with the consequence that a negatively charged streamer issues from the ground. The overall effect is a discharge of positive charges to the ground. Research carried out after the discovery of positive lightning in the 1970s showed that positive lightning bolts are typically six to ten times more powerful than negative bolts, last around ten times longer, and can strike tens of kilometres/miles from the clouds.[35] The voltage difference for positive lightning must be considerably higher, due to the tens of thousands of additional metres/feet the strike must travel. During a positive lightning strike, huge quantities of ELF and VLF radio waves are generated.[36]
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.[37]
One type of positive lightning is anvil-to-ground, since it emanates from the anvil top of a cumulonimbus cloud where the ice crystals are positively charged. The leader stroke of lightning issues forth in a nearly horizontal direction until it veers toward the ground. These usually occur kilometers/miles from (and often ahead of) the main storm and will sometimes strike without warning on a sunny day. An anvil-to-ground lightning bolt is a sign of an approaching storm, and if one occurs in a largely clear sky, it is known colloquially as a "Bolt from the blue."[38]
Positive lightning is also now believed to have been responsible for the 1963 in-flight explosion and subsequent crash of Pan Am Flight 214, a Boeing 707.[39] Due to the dangers of lightning, aircraft operating in U.S. airspace have been required to have lightning discharge wicks to reduce the damage by a lightning strike, but these measures may be insufficient for positive lightning.[40]
Positive lightning has also been shown to trigger the occurrence of upper atmosphere lightning. It tends to occur more frequently in winter storms, as with thundersnow, and at the end of a thunderstorm.[14]
An average bolt of positive lightning carries a current of up to 300 kA (kiloamperes) (about ten times as much current as a bolt of negative lightning), transfers a charge of up to 300 coulombs, has a potential difference up to 1 gigavolt (one billion volts), and lasts for hundreds of milliseconds, with a discharge energy of up to 300 GJ (gigajoules) (a billion joules).[citation needed]
Ball lightning
A photo purportedly depicting natural ball lightning, taken in 1987 by a student in Nagano, Japan.
Main article: Ball lightning
Ball lightning may be an atmospheric electrical phenomenon, the physical nature of which is still controversial. The term refers to reports of luminous, usually spherical objects which vary from pea-sized to several meters in diameter.[41] It is sometimes associated with thunderstorms, but unlike lightning flashes, which last only a fraction of a second, ball lightning reportedly lasts many seconds. Ball lightning has been described by eyewitnesses but rarely recorded by meteorologists.[42] Scientific data on natural ball lightning is scarce owing to its infrequency and unpredictability. The presumption of its existence is based on reported public sightings, and has therefore produced somewhat inconsistent findings.
Laboratory experiments have produced effects that are visually similar to reports of ball lightning, but it is presently unknown whether these are actually related to any naturally occurring phenomenon. Ball lightning apparently is created when lightning strikes silicon in soil, and has been created in a lab in this manner.[43] Given inconsistencies and the lack of reliable data, the true nature of ball lightning is still unknown.[44] Until recently, ball lightning was often regarded as a fantasy or a hoax.[45] Reports of the phenomenon were dismissed for lack of physical evidence, and were often regarded the same way as UFO sightings.[44]
Ball lightning has carved trenches in the peat swamps in Ireland.[citation needed] Because of its strange behaviour, ball lightning has been mistaken for alien spacecraft by many witnesses, which often spawns UFO reports. One theory that may account for this wider spectrum of observational evidence is the idea of combustion inside the low-velocity region of axisymmetric (spherical) vortex breakdown of a natural vortex (e.g., the 'Hill's spherical vortex').[46] Natural ball lightning appears infrequently and unpredictably, and is therefore rarely (if ever truly) photographed. However, several purported photos and videos exist. Perhaps the most famous story of ball lightning unfolded when 18th-century physicist Georg Wilhelm Richmann installed a lightning rod in his home and was struck in the head - and killed - by a "pale blue ball of fire."[47]
Upper-atmospheric lightning
Representation of upper-atmospheric lightning and electrical-discharge phenomena
Main article: Upper-atmospheric lightning
Reports by scientists of strange lightning phenomena above storms date back to at least 1886. However, it is only in recent years that fuller investigations have been made. This has sometimes been called megalightning.[48][49]
I hope it is ok to paste this information I have. Here is a list of lightningbolt's from Wikipedia. I have not changed anything. I thought some people might find this interesting.
Types of lightning
Some lightning strikes exhibit particular characteristics; scientists and the general public have given names to these various types of lightning. The lightning that is most-commonly observed is streak lightning. This is nothing more than the return stroke, the visible part of the lightning stroke. The majority of strokes occur inside a cloud so we do not see most of the individual return strokes during a thunderstorm.
Cloud-to-ground lightning
This is the best known and second most common type of lightning. Of all the different types of lightning, it poses the greatest threat to life and property. Cloud-to-ground lightning is a lightning discharge between a cumulonimbus cloud and the ground. It is initiated by a leader stroke moving down from the cloud (see Leader formation above).
Bead lightning
Bead lightning is a type of cloud-to-ground lightning which appears to break up into a string of short, bright sections, which last longer than the usual discharge channel. It is relatively rare. Several theories have been proposed to explain it; one is that the observer sees portions of the lightning channel end on, and that these portions appear especially bright. Another is that, in bead lightning, the width of the lightning channel varies; as the lightning channel cools and fades, the wider sections cool more slowly and remain visible longer, appearing as a string of beads.[30][31]
Ribbon lightning
Ribbon lightning occurs in thunderstorms with high cross winds and multiple return strokes. The wind will blow each successive return stroke slightly to one side of the previous return stroke, causing a ribbon effect.
Staccato lightning
Staccato lightning is a cloud to ground lightning strike which is a short-duration stroke that appears as a single very bright flash and often has considerable branching.[32]
Fork lightning
Another name for cloud-to-ground lightning. Not in formal usage. Refers to its branching (forking) nature. Compare sheet lightning below.
Ground-to-cloud lightning
Ground-to-cloud lightning is a lightning discharge between the ground and a cumulonimbus cloud initiated by an upward-moving leader stroke. It is much rarer than cloud-to-ground lightning.
Cloud-to-cloud lightning
Lightning discharges may occur between areas of cloud without contacting the ground. When it occurs between two separate clouds it is known as inter-cloud lightning and when it occurs between areas of differing electric potential within a single cloud, it is known as intra-cloud lightning. Intra-cloud lightning is the most frequently occurring type.[14]
These are most common between the upper anvil portion and lower reaches of a given thunderstorm. This lightning can sometimes be observed at great distances at night as so-called "heat lightning". In such instances, the observer may see only a flash of light without hearing any thunder. The "heat" portion of the term is a folk association between locally experienced warmth and the distant lightning flashes.
Another terminology used for cloud-cloud or cloud-cloud-ground lightning is "Anvil Crawler", due to the habit of the charge typically originating from beneath or within the anvil and scrambling through the upper cloud layers of a thunderstorm, normally generating multiple branch strokes which are dramatic to witness. These are usually seen as a thunderstorm passes over the observer or begins to decay. The most vivid crawler behavior occurs in well developed thunderstorms that feature extensive rear anvil shearing.
Sheet lightning
Another name for cloud-to-cloud lightning. Not in formal usage. Refers to the diffuse brightening of the surface of a cloud, because the actual discharge path is hidden. Compare fork lightning above.
Heat lightning
Main article: Heat lightning
Sheet lightning that occurs too far away for the thunder to be heard.
Dry lightning
Main article: Dry lightning
Dry lightning is a term in the United States for lightning that occurs with no precipitation at the surface. This type of lightning is the most common natural cause of wildfires.
Rocket lightning
It is a form of cloud discharge, generally horizontal and at cloud base, with a luminous channel appearing to advance through the air with visually resolvable speed, often intermittently.[33]
Positive lightning
See also: High voltage#Lightning
Positive lightning, also known colloquially as "bolts from the blue", makes up less than 5% of all lightning.[34] It occurs when the leader forms at the positively charged cloud tops, with the consequence that a negatively charged streamer issues from the ground. The overall effect is a discharge of positive charges to the ground. Research carried out after the discovery of positive lightning in the 1970s showed that positive lightning bolts are typically six to ten times more powerful than negative bolts, last around ten times longer, and can strike tens of kilometres/miles from the clouds.[35] The voltage difference for positive lightning must be considerably higher, due to the tens of thousands of additional metres/feet the strike must travel. During a positive lightning strike, huge quantities of ELF and VLF radio waves are generated.[36]
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.[37]
One type of positive lightning is anvil-to-ground, since it emanates from the anvil top of a cumulonimbus cloud where the ice crystals are positively charged. The leader stroke of lightning issues forth in a nearly horizontal direction until it veers toward the ground. These usually occur kilometers/miles from (and often ahead of) the main storm and will sometimes strike without warning on a sunny day. An anvil-to-ground lightning bolt is a sign of an approaching storm, and if one occurs in a largely clear sky, it is known colloquially as a "Bolt from the blue."[38]
Positive lightning is also now believed to have been responsible for the 1963 in-flight explosion and subsequent crash of Pan Am Flight 214, a Boeing 707.[39] Due to the dangers of lightning, aircraft operating in U.S. airspace have been required to have lightning discharge wicks to reduce the damage by a lightning strike, but these measures may be insufficient for positive lightning.[40]
Positive lightning has also been shown to trigger the occurrence of upper atmosphere lightning. It tends to occur more frequently in winter storms, as with thundersnow, and at the end of a thunderstorm.[14]
An average bolt of positive lightning carries a current of up to 300 kA (kiloamperes) (about ten times as much current as a bolt of negative lightning), transfers a charge of up to 300 coulombs, has a potential difference up to 1 gigavolt (one billion volts), and lasts for hundreds of milliseconds, with a discharge energy of up to 300 GJ (gigajoules) (a billion joules).[citation needed]
Ball lightning
A photo purportedly depicting natural ball lightning, taken in 1987 by a student in Nagano, Japan.
Main article: Ball lightning
Ball lightning may be an atmospheric electrical phenomenon, the physical nature of which is still controversial. The term refers to reports of luminous, usually spherical objects which vary from pea-sized to several meters in diameter.[41] It is sometimes associated with thunderstorms, but unlike lightning flashes, which last only a fraction of a second, ball lightning reportedly lasts many seconds. Ball lightning has been described by eyewitnesses but rarely recorded by meteorologists.[42] Scientific data on natural ball lightning is scarce owing to its infrequency and unpredictability. The presumption of its existence is based on reported public sightings, and has therefore produced somewhat inconsistent findings.
Laboratory experiments have produced effects that are visually similar to reports of ball lightning, but it is presently unknown whether these are actually related to any naturally occurring phenomenon. Ball lightning apparently is created when lightning strikes silicon in soil, and has been created in a lab in this manner.[43] Given inconsistencies and the lack of reliable data, the true nature of ball lightning is still unknown.[44] Until recently, ball lightning was often regarded as a fantasy or a hoax.[45] Reports of the phenomenon were dismissed for lack of physical evidence, and were often regarded the same way as UFO sightings.[44]
Ball lightning has carved trenches in the peat swamps in Ireland.[citation needed] Because of its strange behaviour, ball lightning has been mistaken for alien spacecraft by many witnesses, which often spawns UFO reports. One theory that may account for this wider spectrum of observational evidence is the idea of combustion inside the low-velocity region of axisymmetric (spherical) vortex breakdown of a natural vortex (e.g., the 'Hill's spherical vortex').[46] Natural ball lightning appears infrequently and unpredictably, and is therefore rarely (if ever truly) photographed. However, several purported photos and videos exist. Perhaps the most famous story of ball lightning unfolded when 18th-century physicist Georg Wilhelm Richmann installed a lightning rod in his home and was struck in the head - and killed - by a "pale blue ball of fire."[47]
Upper-atmospheric lightning
Representation of upper-atmospheric lightning and electrical-discharge phenomena
Main article: Upper-atmospheric lightning
Reports by scientists of strange lightning phenomena above storms date back to at least 1886. However, it is only in recent years that fuller investigations have been made. This has sometimes been called megalightning.[48][49]
MatthewCarman
Main article: Sprites (lightning)
Sprites are large scale electrical discharges which occur high above a thunderstorm cloud, or cumulonimbus, giving rise to a quite varied range of visual shapes. They are triggered by the discharges of positive lightning between the thundercloud and the ground.[36] The phenomena were named after the mischievous sprite (air spirit) Puck in Shakespeare's Midsummer Night's Dream. They normally are colored reddish-orange or greenish-blue, with hanging tendrils below, and arcing branches above, their location, and can be preceded by a reddish halo.[48] They often occur in clusters, lying 50 miles (80 km) to 90 miles (145 km) above the Earth's surface. Sprites were first photographed on July 6, 1989 by scientists from the University of Minnesota and have since been witnessed tens of thousands of times.[50] Sprites have erroneously been held responsible for otherwise unexplained accidents involving high altitude vehicular operations above thunderstorms.[51]
Blue jets
Blue jets differ from sprites in that they project from the top of the cumulonimbus above a thunderstorm, typically in a narrow cone, to the lowest levels of the ionosphere 25 miles (40 km) to 30 miles (48 km) above the earth.[citation needed] They are also brighter than sprites and, as implied by their name, are blue in colour. They were first recorded on October 21, 1989, on a video taken from the space shuttle as it passed over Australia, and subsequently extensively documented in 1994 during aircraft research flights by the University of Alaska.[52][49]
On September 14, 2001, scientists at the Arecibo Observatory photographed a huge jet double the height of those previously observed, reaching around 50 miles (80 km) into the atmosphere. The jet was located above a thunderstorm over the ocean, and lasted under a second. Lightning was initially observed traveling up at around 50,000 m/s in a similar way to a typical blue jet, but then divided in two and sped at 250,000 m/s to the ionosphere, where they spread out in a bright burst of light.[53] On July 22, 2002, five gigantic jets between 60 and 70 km (35 to 45 miles) in length were observed over the South China Sea from Taiwan, reported in Nature.[52] The jets lasted under a second, with shapes likened by the researchers to giant trees and carrots.[citation needed]
Elves
Elves often appear as dim, flattened, expanding glows around 250 miles (402 km) in diameter that last for, typically, just one millisecond.[54] They occur in the ionosphere 60 miles (97 km) above the ground over thunderstorms. Their color was a puzzle for some time, but is now believed to be a red hue. Elves were first recorded on another shuttle mission, this time recorded off French Guiana on October 7, 1990. Elves is a frivolous acronym for Emissions of Light and Very Low Frequency Perturbations from Electromagnetic Pulse Sources.[55] This refers to the process by which the light is generated; the excitation of nitrogen molecules due to electron collisions (the electrons possibly having been energized by the electromagnetic pulse caused by a discharge from the Ionosphere).[49]
Triggered lightning
Rocket-triggered
http://en.wikipedia.org/wiki/File:Rinjani_1994.jpgVolcanic material thrust high into the atmosphere can trigger lightning.
Lightning has been triggered directly by human activity in several instances. Lightning struck Apollo 12 soon after takeoff, and has struck soon after thermonuclear explosions.[56] It has also been triggered by launching lightning rockets carrying spools of wire into thunderstorms. The wire unwinds as the rocket ascends, providing a path for lightning. These bolts are typically very straight due to the path created by the wire.[57]
Flying aircraft can also trigger lightning.[58]
Volcanically triggered
Extremely large volcanic eruptions, which eject gases and material high into the atmosphere, can trigger lightning. This phenomenon was documented by Pliny The Elder during the AD79 eruption of Vesuvius, in which he perished.[59]
Laser-triggered
Since the 1970s,[60][61][62][63][64] researchers have attempted to trigger lightning strikes by means of infrared or ultraviolet lasers, which create a channel of ionized gas through which the lightning would be conducted to ground. Such triggered lightning is intended to protect rocket launching pads, electric power facilities, and other sensitive targets.[65][66][67][68][69]
In New Mexico, U.S., scientists tested a new terawatt laser which provoked lightning. Scientists fired ultra-fast pulses from an extremely powerful laser thus sending several terawatts into the clouds to call down electrical discharges in storm clouds over the region. The laser beams sent from the laser make channels of ionized molecules known as "filaments". Before the lightning strikes earth, the filaments lead electricity through the clouds, playing the role of lightning rods. Researchers generated filaments that lived too short a period to trigger a real lightning strike. Nevertheless, a boost in electrical activity within the clouds was registered. According to the French and German scientists, who ran the experiment, the fast pulses sent from the laser will be able to provoke lightning strikes on demand.[70] Statistical analysis showed that their laser pulses indeed enhanced the electrical activity in the thundercloud where it was aimed—in effect they generated small local discharges located at the position of the plasma channels.[71]
Extraterrestrial lightning
Lightning requires the electrical breakdown of a gas, so it cannot exist in a visual form in the vacuum of space. However, lightning has been observed within the atmospheres of other planets, such as Venus, Jupiter and Saturn. Lightning on Venus is still a controversial subject after decades of study. During the Soviet Venera and U.S. Pioneer missions of the 1970s and '80s, signals suggesting lightning may be present in the upper atmosphere were detected.[72] However, recently the Cassini-Huygens mission fly-by of Venus detected no signs of lightning at all. Despite this, it has been suggested that radio pulses recorded by the spacecraft Venus Express may originate from lightning on Venus.(S&T, Mar. 2008)
Stephen Levine
EF4
"Human Cells Have Electric Fields As Powerful as Lightning"
O.K, folks. Try this on. A friend sent me an article that states that scientists have discovered after utilizing voltage sensitive nanoparticles, that electric fields in cells are up to FIVE TIMES the intensity of a lightning bolt.
www.dailygalaxy.com/my_weblog/weblog/2009/01/human-cells-hav.html
O.K, folks. Try this on. A friend sent me an article that states that scientists have discovered after utilizing voltage sensitive nanoparticles, that electric fields in cells are up to FIVE TIMES the intensity of a lightning bolt.
www.dailygalaxy.com/my_weblog/weblog/2009/01/human-cells-hav.html
cdcollura
EF5
Good day all...
Above: Ouch! Lichtenberg Figures on lightning victim (flash-over).
Above: Ouch! Lichtenberg Figures on lightning victim (flash-over).
Robert Edmonds
EF5
Note: A neat theory suggest that cosmic ray showers (I think it's the showers) trigger lightning. This is because typical voltage potentials in clouds are not enough to create a break down. Thus, I heard one guy say the holy grail for lightning research would be to detect the shower that could be identified with triggering a lightning bolt.
Tyler_Costantini
EF2
Has anyone on the board seen Sprites / Jets? and does anyone have any pics?
Tyler.
Tyler.
