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General considerations[edit]

On Earth, the lightning frequency is approximately 40–50 times a second or nearly

14 !illion flashes per year [1] and the a"erage duration is 0# seconds made up from a

num!er of much shorter flashes $stro%es& of around '0 microseconds[#]

(any factors affect the frequency, distri!ution, strength and physical properties of a )typical)

lightning flash in a particular region of the *orld +hese factors include ground

ele"ation, latitude, pre"ailing *ind currents, relati"e humidity, proximity to *arm and cold

!odies of *ater, etc +o a certain degree, the ratio !et*een -, -- and -. lightning may

also "ary !y season in middle latitudes /ecause human !eings are terrestrial and most of

their possessions are on the Earth, *here lightning can damage or destroy them, -.

lightning is the most studied and !est understood of the three types, e"en though - and

-- are more common types of lightning ightnings relati"e unpredicta!ility limits a

complete explanation of ho* or *hy it occurs, e"en after hundreds of years of scientific

in"estigation

 2 typical cloud to ground lightning flash culminates in the formation of an electrically

conducting plasma channel through the air in excess of 5 %ilometres $'1 mi& tall, from *ithin

the cloud to the grounds surface +he actual discharge is the final stage of a "ery complex

process['] 2t its pea%, a typical thunderstorm produces three or more strikes to the Earth per 

minute[4]

 ightning primarily occurs *hen *arm air is mixed *ith colder air masses, resultingin atmospheric distur!ances necessary for polari3ing the atmosphere [citation needed ] o*e"er, it

can also occur during dust storms, forest fires, tornadoes, "olcanic eruptions, and e"en in

the cold of *inter , *here the lightning is %no*n asthundersno*[5][] urricanes typically

generate some lightning, mainly in the rain!ands as much as 10 %ilometres $66 mi& from

the center[7][8][6]

+he science of lightning is called fulminology , and the fear of lightning is called astrapho!ia

Frequency of lightning[edit]

Main article: Distribution of lightning 

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9orld map sho*ing frequency of lightning stri%es, in flashes per %m: per year $equal;area

pro<ection&, from com!ined 1665–#00' data from the Optical +ransient =etector and 1668–#00'

data from the ightning maging >ensor

ightning is not distri!uted e"enly around the planet, as sho*n in the map

 2!out 70? of lightning occurs o"er land in the tropics *here atmospheric con"ection is the

greatest +his occurs from !oth the mixture of *armer and colder air masses, as *ell as

differences in moisture concentrations, and it generally happens at the!oundaries !et*een

them +he flo* of *arm ocean currents past drier land masses, such as the .ulf >tream,

partially explains the ele"ated frequency of lightning in the >outheast @nited >tates

/ecause the influence of small or a!sent land masses in the "ast stretches of the *orlds

oceans limits the differences !et*een these "ariants in the atmosphere, lightning is nota!ly

less frequent there than o"er larger landforms +he Aorth and >outh Boles are limited in

their co"erage of thunderstorms and therefore result in areas *ith the least amount of

lightning

n general, cloud;to;ground $-.& lightning flashes account for only #5? of all total lightning

flashes *orld*ide >ince the !ase of a thunderstorm is usually negati"ely charged, this is

*here most -. lightning originates +his region is typically at the ele"ation

*here free3ing occurs *ithin the cloud Cree3ing, com!ined *ith collisions !et*een ice and

*ater, appears to !e a critical part of the initial charge de"elopment and separation process

=uring *ind;dri"en collisions, ice crystals tend to de"elop a positi"e charge, *hile a hea"ier,

slushy mixture of ice and *ater $called graupel& de"elops a negati"e charge @pdrafts *ithin

a storm cloud separate the lighter ice crystals from the hea"ier graupel, causing the top

region of the cloud to accumulate a positi"e space charge *hile the lo*er le"el accumulates

a negati"e space charge

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ightning in /elfort, Crance

/ecause the concentrated charge *ithin the cloud must exceed the insulating properties of

air, and this increases proportionally to the distance !et*een the cloud and the ground, the

proportion of -. stri%es $"ersus cloud;to;cloud $--& or in;cloud $-& discharges& !ecomes

greater *hen the cloud is closer to the ground n the tropics, *here the free3ing le"el is

generally higher in the atmosphere, only 10? of lightning flashes are -. 2t the latitude of

Aor*ay $around 0D Aorth latitude&, *here the free3ing ele"ation is lo*er, 50? of lightningis -.[10][11]

ightning is usually produced !y cumulonim!us clouds, *hich ha"e !ases that are typically

1–# %m $0;1#5 miles& a!o"e the ground and tops up to 15 %m $6' mi& in height

On Earth, the place *here lightning occurs most often is near the small "illage of ifu%a in

the mountains of the eastern =emocratic Fepu!lic of the -ongo,[1#] *here the ele"ation is

around 675 m $',#00 ft& On a"erage, this region recei"es 158 lightning stri%es per 1 square

%ilometer $0'6 sq mi& per year[1']Other lightning hotspots

include -atatum!o in Gene3uela, >ingapore,[14] +eresina in northern /ra3il,[15] and )ightning

 2lley) in -entral Clorida[1][17]

Establishing conditions necessary for lightning[edit]

Main article: thunderstorm

n order for an electrostatic discharge to occur, t*o preconditions are necessaryH $1& a

sufficiently high electric potential !et*een t*o regions of space must existI and $#& a high;

resistance medium must o!struct the free, unimpeded equali3ation of the opposite charges

t is *ell understood that during a thunderstorm there is charge separation and aggregation

in certain regions of the cloudI ho*e"er the exact processes !y *hich this occurs are not

fully understoodI[18]

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+he atmosphere pro"ides the electrical insulation, or !arrier, that pre"ents free equali3ation

!et*een charged regions of opposite polarity +his is o"ercome !y )lightning), a complex

process referred to as the lightning )flash)

Establishing the electric field in CG lightning[edit]

Gie* of lightning from an airplane flying a!o"e a system

 2s a thundercloud mo"es o"er the surface of the Earth, an equal electric charge, !ut ofopposite polarity, is induced on the Earths surface underneath the cloud +he induced

positi"e surface charge, *hen measured against a fixed point, *ill !e small as the

thundercloud approaches, increasing as the center of the storm arri"es and dropping as the

thundercloud passes +he referential "alue of the induced surface charge could !e roughly

represented as a !ell cur"e

+he oppositely charged regions create an electric field *ithin the air !et*een them +his

electric field "aries in relation to the strength of the surface charge on the !ase of the

thundercloud – the greater the accumulated charge, the higher the electrical field

Lightning flashes and strikes[edit]

+he !est studied and understood form of lightning is cloud to ground $-.& 2lthough more

common, intracloud $-& and cloud to cloud $--& flashes are "ery difficult to study gi"en

there are no )physical) points to monitor inside the clouds 2lso, gi"en the "ery lo*

pro!a!ility lightning *ill stri%e the same point repeatedly and consistently, scientific inquiry is

difficult at !est e"en in the areas of high -. frequency 2s such, %no*ing flash propagation

is similar amongst all forms of lightning, the !est means to descri!e the process is throughan examination of the most studied form, cloud to ground

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 2 lightning stri%e from cloud to ground in the -alifornia, (o<a"e =esert

 2n intracloud flash 2 lightning flash *ithin the cloud, illuminates the entire !lan%et

Downward leader formation for negative CG lightning[edit]

 2 do*n*ard leader tra"els to*ards earth, !ranching as it goes

ightning stri%e caused !y the connection of t*o leaders, positi"e sho*n in !lue and negati"e in red

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n a process not *ell understood, a channel of ioni3ed air, called a )leader), is initiated from

a charged region in the thundercloud eaders are electrically conducti"e channels of

partially ioni3ed gas that tra"el a*ay from a region of dense charge Aegati"e leaders

propagate a*ay from densely charged regions of negati"e charge, and positi"e leaders

propagate from positi"ely charged regions

+he positi"ely and negati"ely charged leaders proceed in opposite directions, positi"e

up*ards *ithin the cloud and negati"e to*ards the earth /oth ionic channels proceed, in

their respecti"e directions, in a num!er of successi"e spurts Each leader )pools) ions at the

leading tips, shooting out one or more ne* leaders, momentarily pooling again to

concentrate charged ions, then shooting out another leader

eaders often split, forming !ranches in a tree;li%e pattern [16] n addition, negati"e leaders

tra"el in a discontinuous fashion +he resulting <er%y mo"ement of these )stepped leader$s&)can !e readily o!ser"ed in slo*;motion "ideos of negati"e leaders as they head to*ard

ground prior to a negati"e -. lightning stri%e +he negati"e leaders continue to propagate

and split as they head do*n*ard, often speeding up as they get closer to the Earths

surface

 2!out 60? of ionic channel lengths !et*een )pools) are approximately 45 m $148 ft& in

length[#0] +he esta!lishment of the ionic channel ta%es a comparati"ely long amount of time

$hundreds of milliseconds& in comparison to resulting discharge *hich occurs *ithin a fe*

microseconds +he electric current needed to esta!lish the channel, measured in the tens

or hundreds of amperes, is d*arfed !y su!sequent currents during the actual discharge

nitiation of the out*ard leaders is not *ell understood +he electric field strength *ithin the

thundercloud is not typically large enough to initiate this process !y itself [#1] (any

hypotheses ha"e !een proposed One theory postulates that sho*ers of relati"istic

electrons are created !y cosmic rays and are then accelerated to higher "elocities "ia a

process called runa*ay !rea%do*n 2s these relati"istic electrons collide and ioni3e neutral

air molecules, they initiate leader formation 2nother theory in"o%es locally enhanced

electric fields !eing formed near elongated *ater droplets or ice crystals[##] Bercolation

theory, especially for the case of !iased percolation, [#'] [clarification needed ] descri!es random

connecti"ity phenomena, *hich produce an e"olution of connected structures similar to that

of lightning stri%es

Upward streamers[edit]

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9hen a stepped leader approaches the ground, the presence of opposite charges on the

ground enhances the strength of the electric field +he electric field is strongest on

grounded o!<ects *hose tops are closest to the !ase of the thundercloud, such as trees and

tall !uildings f the electric field is strong enough, a positi"ely charged ionic channel, called

a positi"e or up*ard streamer, can de"elop from these points +his *as first theori3ed !y

ein3 asemir [#4][#5]

 2s negati"ely charged leaders approach, increasing the locali3ed electric field strength,

grounded o!<ects already experiencing corona discharge exceed a threshold and form

up*ard streamers

Attachment[edit]

Once a do*n*ard leader connects to an a"aila!le up*ard leader, a process referred to as

attachment, a lo*;resistance path is formed and discharge may occur Bhotographs ha"e

!een ta%en on *hich unattached streamers are clearly "isi!le +he unattached do*n*ard

leaders are also "isi!le in !ranched lightning, none of *hich are connected to the earth,

although it may appear they are[#]

Discharge[edit]

Return stroke[edit]

igh;speed photography sho*ing different parts of a lightning flash during the discharge process as

seen in+oulouse, Crance

Once a conducti"e channel !ridges the air gap !et*een the negati"e charge excess in the

cloud and the positi"e surface charge excess !elo*, a massi"e electrical discharge follo*s

+his is the return stro%e and it is the most luminous and noticea!le part of the lightning

discharge

 2 large electron current flo*s along the plasma channel from the cloud to the ground,

neutralising the positi"e ground charge as electrons flo* a*ay from the stri%e point to the

surrounding area +his huge surge of current creates large radial "oltage differences along

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the surface of the ground -alled step potentials, they are responsi!le for more in<uries and

deaths than the stri%e itself[citation needed ] Electricity follo*s the path of least resistance 2 portion

of the return stro%e current *ill often preferentially flo* through one leg and out another,

electrocuting an unluc%y human or animal standing near the point *here the lightning

stri%es

+he electric current of the return stro%e a"erages '0 %iloamperes for a typical negati"e -.

flash, often referred to as )negati"e -.) lightning n some cases, a positi"e ground to cloud

$.-& lightning flash may originate from a positi"ely charged region on the ground !elo* a

storm +hese discharges normally originate from the tops of "ery tall structures, such as

communications antennas +he rate at *hich the return stro%e current tra"els has !een

found to !e around 1J108 mKs[#7]

+he massi"e flo* of electric current occurring during the return stro%e com!ined *ith therate at *hich it occurs $measured in microseconds& rapidly superheats the completed leader 

channel, forming a highly electrically conducti"e plasma channel +he core temperature of

the plasma during the return stro%e may exceed 50,000 , causing it to !rilliantly radiate

*ith a !lue;*hite color Once the electric current stops flo*ing, the channel cools and

dissipates o"er tens or hundreds of milliseconds, often disappearing as fragmented patches

of glo*ing gas +he nearly instantaneous heating during the return stro%e causes the air to

explosi"ely expand, producing a po*erful shoc% *a"e that is heard as thunder

Re-strike[edit]

igh;speed "ideos $examined frame;!y;frame& sho* that most negati"e -. lightning

flashes are made up of ' or 4 indi"idual stro%es, though there may !e as many as '0 [#8]

Each re;stri%e is separated !y a relati"ely large amount of time, typically 40 to 50

milliseconds, as other charged regions in the cloud are discharged in su!sequent stro%es

Fe;stri%es often cause a noticea!le )stro!e light) effect[#6]

Each successi"e stro%e is preceded !y intermediate dart leader stro%es that ha"e a faster

rise time !ut lo*er amplitude than the initial return stro%e Each su!sequent stro%e usuallyre;uses the discharge channel ta%en !y the pre"ious one, !ut the channel may !e offset

from its pre"ious position as *ind displaces the hot channel ['0]

Transient currents during the flash[edit]

+he electric current *ithin a typical negati"e -. lightning discharge rises "ery quic%ly to its

pea% "alue in 1–10 microseconds, then decays more slo*ly o"er 50–#00 microseconds

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+he transient nature of the current *ithin a lightning flash results in se"eral phenomena that

need to !e addressed in the effecti"e protection of ground;!ased structures Fapidly

changing currents tend to tra"el on the surface of a conductor +his is called s%in effect,

unli%e direct currents )flo*ing through) the entire conductor li%e *ater through a hose

ence, conductors used in the protection of facilities tend to !e multi;stranded small *ires

*o"en together, that increases the surface area in"ersely in proportion to cross;sectional

area

+he rapidly changing currents also create electromagnetic pulses $E(Bs& that radiate

out*ard from the ionic channel +his is a characteristic of all electrical spar%s +he radiated

pulses rapidly *ea%en as their distance from the origin increases o*e"er, if they pass

o"er conducti"e elements, for instance electrical *ires, communication lines or metallic

pipes, they may induce a current *hich tra"els out*ard to its termination +his is the )surge)

that, more often than not, results in the destruction of delicate electronics, electrical

appliances or electric motors =e"ices %no*n as surge protectors $>B=& or transient "oltage

surge suppressors $+G>>& attached in series *ith these conductors can detect the lightning

flashs transient [irregular] current, and through an alteration of its physical properties, route

the spi%e to an attached earthing ground, there!y protecting the equipment from damage

Types[edit]

+here are three primary types of lightning, defined !y *hat is at the )ends) of a flash

channel +hey are intracloud $-&, *hich occurs *ithin a single thundercloud unitI cloud to

cloud $--&, *hich starts and ends !et*een t*o different )functional) thundercloud unitsI and

cloud to ground $-.&, that primarily originates in the thundercloud and terminates on an

Earth surface, !ut may also occur in the re"erse direction, that is ground to cloud +here are

"ariations of each type, such as )positi"e) "ersus )negati"e) -. flashes, that ha"e different

physical characteristics common to each *hich can !e measured =ifferent common

names used to descri!e a particular lightning e"ent may !e attri!uted to the same or

different e"ents

Cloud to ground CG![edit]

-loud;to;ground is the !est %no*n and third most common type of lightning t is the !est

understood of all forms !ecause it allo*s for scientific study gi"en it terminates on a

physical o!<ect, namely the Earth, and lends itself to !eing measured !y instruments Of the

three primary types of lightning, it poses the greatest threat to life and property since it

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terminates or )stri%es) the Earth -loud;to;ground $-.& lightning is a lightning discharge

!et*een a thundercloud and the ground t is usually negati"e in polarity and is usually

initiated !y a stepped leader mo"ing do*n from the cloud

"ositive and negative lightning[edit]-. lightning can occur *ith !oth positi"e and negati"e polarity +he polarity is that of the

charge in the region that originated the lightning leaders 2n a"erage !olt

of negati"elightning carries an electric current of '0,000 amperes $'0 %2&, and transfers

15 coulom!s of electric charge and 500 mega<oules of energy arge !olts of lightning can

carry up to 1#0 %2 and '50 coulom!s['1]

 2n"il;to;ground (Bolt from the blue)lightning stri%e initiates from the clear s%y a!o"e the cloud, then

dri"es an an"il through the cloud directly to the ground

@nli%e the far more common )negati"e) lightning, positi"e lightning originates from the

positi"ely charged top of the clouds $generally an"il clouds& rather than the lo*er portion of

the storm eaders form in the an"il of the cumulonim!us and may tra"el hori3ontally for

se"eral miles !efore "eering to*ards the ground 2 positi"e lightning !olt can stri%e

any*here *ithin se"eral miles of the an"il of the thunderstorm, often in areas experiencing

clear or only slightly cloudy s%iesI they are also %no*n as )!olts from the !lue) for this

reason Bositi"e lightning typically ma%es up less than 5? of all lightning stri%es ['#]

/ecause of the much greater distance to ground, the positi"ely charged region can de"elop

considera!ly larger le"els of charge and "oltages than the negati"e charge regions in the

lo*er part of the cloud Bositi"e lightning !olts are considera!ly hotter and longer than

negati"e lightning +hey can de"elop six to ten times the amount of charge and "oltage of a

negati"e !olt and the discharge current may last ten times longer[''] 2 !olt of positi"e

lightning may carry an electric current of '00 %2 and the potential at the top of the cloud

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may exceed a !illion "olts L a!out 10 times that of negati"e lightning ['4] =uring a positi"e

lightning stri%e, huge quantities of extremely lo* frequency $EC& and "ery lo*

frequency $GC& radio *a"es are generated['5]

 2s a result of their greater po*er, as *ell as lac% of *arning, positi"e lightning stri%es areconsidera!ly more dangerous 2t the present time, aircraft are not designed to *ithstand

such stri%es, since their existence *as un%no*n at the time standards *ere set, and the

dangers unappreciated until the destruction of a glider  in 1666['] +he standard in force at

the time of the crash, 2d"isory -ircular 2- #0;5'2, *as replaced !y 2d"isory -ircular 2-

#0;5'/ in #00,['7] ho*e"er it is unclear *hether adequate protection against positi"e

lightning *as incorporated['8]['6]

 2ircraft operating in @> airspace ha"e !een required to !e equipped *ith static discharge

*ic%s 2lthough their primary function is to mitigate radio interference due to static !uildupthrough friction *ith the air, in the e"ent of a lightning stri%e, a plane is designed to conduct

the excess electricity through its s%in and structure to the *ic%s to !e safely discharged

!ac% into the atmosphere +hese measures, ho*e"er, may !e insufficient for positi"e

lightning[40]

Bositi"e lightning has also !een sho*n to trigger the occurrence of @pper;atmospheric

lightning !et*een the tops of clouds and the ionosphere Bositi"e lightning tends to occur

more frequently in *inter storms, as *ith thundersno*, and in the dissipation stage of

a thunderstorm[41]

Cloud to cloud CC! and #ntra-Cloud #C![edit]

/ranching of cloud to cloud lightning, Ae* =elhi, ndia

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(ultiple paths of cloud;to;cloud lightning, >*ifts -ree%, 2ustralia

-loud;to;cloud lightning, Gictoria, 2ustralia

-loud;to;cloud lightning seen in.resham, Oregon

ightning discharges may occur !et*een areas of cloud *ithout contacting the ground

9hen it occurs !et*een t*o separate clouds it is %no*n as inter-cloud lightning , and *hen

it occurs !et*een areas of differing electric potential *ithin a single cloud it is %no*n

as intra-cloud lightning  ntra;cloud lightning is the most frequently occurring type [41]

ntra;cloud lightning most commonly occurs !et*een the upper an"il portion and lo*er

reaches of a gi"en thunderstorm +his lightning can sometimes !e o!ser"ed at great

distances at night as so;called )heat lightning) n such instances, the o!ser"er may see

only a flash of light *ithout hearing any thunder +he )heat) portion of the term is a fol%

association !et*een locally experienced *armth and the distant lightning flashes

 2n"il -ra*ler o"er a%e 9right Batman south of Fed*ater, +exas on the !ac%side of a large area of

rain associated *ith a cold;front

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 2nother term used for cloud–cloud or cloud–cloud–ground lightning is )2n"il -ra*ler), due

to the ha!it of charge, typically originating !eneath or *ithin the an"il and scram!ling

through the upper cloud layers of a thunderstorm, often generating dramatic multiple !ranch

stro%es +hese are usually seen as a thunderstorm passes o"er the o!ser"er or !egins to

decay +he most "i"id cra*ler !eha"ior occurs in *ell de"eloped thunderstorms that feature

extensi"e rear an"il shearing

$bservational variations[edit]

• %all lightning may !e an atmospheric electrical phenomenon, the physical nature of 

*hich is still contro"ersial +he term refers to reports of luminous,

usually spherical o!<ects *hich "ary from pea;si3ed to se"eral meters in diameter[4#] t is

sometimes associated *ith thunderstorms, !ut unli%e lightning flashes, *hich last only a

fraction of a second, !all lightning reportedly lasts many seconds /all lightning has

!een descri!ed !y eye*itnesses !ut rarely recorded !y meteorologists[4'][44] >cientific

data on natural !all lightning is scarce o*ing to its infrequency and unpredicta!ility +he

presumption of its existence is !ased on reported pu!lic sightings, and has therefore

produced some*hat inconsistent findings

• %ead lightning is the decaying stage of a lightning channel in *hich

the luminosity of the channel !rea%s up into segments Aearly e"ery lightning discharge

*ill exhi!it beading  as the channel cools immediately after a return stro%e, sometimes

referred to as the lightnings !ead;out stage /ead lightning is more properly a stage of 

a normal lightning discharge rather than a type of lightning in itself /eading of a

lightning channel is usually a small;scale feature, and therefore is often only apparent

*hen the o!ser"erKcamera is close to the lightning [45]

• Dr& lightning is used in 2ustralia, -anada and the @nited >tates for lightning that

occurs *ith no precipitation at the surface +his type of lightning is the most common

natural cause of *ildfires[4] Byrocumulus clouds produce lightning for the same reason

that it is produced !y cumulonim!us clouds [citation needed ]

• 'orked lightning is cloud;to;ground lightning that exhi!its !ranching of its path

• (eat lightning is a lightning flash that appears to produce no

discerni!le thunder  !ecause it occurs too far a*ay for the thunder to !e heard +he

sound *a"es dissipate !efore they reach the o!ser"er[47]

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• Ribbon lightning occurs in thunderstorms *ith high cross *inds and multiple return

stro%es +he *ind *ill !lo* each successi"e return stro%e slightly to one side of the

pre"ious return stro%e, causing a ri!!on effect[citation needed ]

•

Rocket lightning is a form of cloud discharge, generally hori3ontal and at cloud!ase, *ith a luminous channel appearing to ad"ance through the air *ith "isually

resol"a!le speed, often intermittently[48]

• )heet lightning is cloud;to;cloud lightning that exhi!its a diffuse !rightening of the

surface of a cloud, caused !y the actual discharge path !eing hidden or too far a*ay

+he lightning itself cannot !e seen !y the spectator, so it appears as only a flash, or a

sheet of light +he lightning may !e too far a*ay to discern indi"idual flashes

•

)mooth Channel lightning are positi"e cloud to ground lightning stri%es *here thefor*ard stro%e originates from the ground up*ards to the cloud +he smooth channel is

in the lo*er section of the lightning channel !ut should !ranch higher up $not "isi!le as

the )!ranching) is inside the cloud& [citation needed ] arge supercells generate tremendous

areas of positi"ely charged cloud material $thic% an"il& and *ind shear pre"ents

excessi"e negati"e stro%es as *ith )normal) thunderstorms =o*ndrafts, such as the

for*ard flan% do*ndraft $CC=&, !ring the positi"ely charged cloud material closer to the

ground, *here such lightning occurs [citation needed ]

• )taccato lightning is a cloud;to;ground lightning $-.& stri%e *hich is a short;

duration stro%e that $often !ut not al*ays& appears as a single "ery !right flash and

often has considera!le !ranching[46] +hese are often found in the "isual "ault area near

the mesocycloneof rotating thunderstorms and coincides *ith intensification of

thunderstorm updrafts 2 similar cloud;to;cloud stri%e consisting of a !rief flash o"er a

small area, appearing li%e a !lip, also occurs in a similar area of rotating updrafts[50]

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+his -. *as of "ery short duration, exhi!ited highly !ranched channels and *as "ery !right

indicating that it *as staccato lightning near Ae* /oston, +exas

• )uperbolts are !olts of lightning around a hundred times !righter than normal On

Earth, one in a million lightning stri%es is a super!olt[51][5#]

• )&mpathetic lightning is the tendency of lightning to !e loosely coordinated across

long distances =ischarges can appear in clusters *hen "ie*ed from space

• Clear-air lightning descri!es lightning that occurs *ith no apparent cloud close

enough to ha"e produced it n the @> and -anadianFoc%ies, a thunderstorm can !e

in an ad<acent "alley and not o!ser"a!le from the "alley *here the lightning !olt stri%es,

either "isually or audi!ly European and 2sian mountainous areas experience similar

e"ents 2lso in areas such as sounds, large la%es or open plains, *hen the storm cell is

on the near hori3on $*ithin # %ilometres $1 mi&& there may !e some distant acti"ity, a

stri%e can occur and as the storm is so far a*ay, the stri%e is referred to as a bolt from

the blue[5']

Effects[edit]

*ightning strike[edit]

Main article: Lightning strike

O!<ects struc% !y lightning experience heat and magnetic forces of great magnitude +he

heat created !y lightning currents tra"eling through a tree may "apori3e its sap, causing a

steam explosion that !ursts the trun% 2s lightning tra"els through sandy soil, the soil

surrounding the plasma channel may melt, forming tu!ular structures called fulgurites E"en

though roughly 60 percent of people struc% !y lightning sur"i"e,[54] humans or animals struc%

!y lightning may suffer se"ere in<ury due to internal organ and ner"ous system damage

/uildings or tall structures hit !y lightning may !e damaged as the lightning see%s

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unintended paths to ground /y safely conducting a lightning stri%e to ground, a lightning

protection system can greatly reduce the pro!a!ility of se"ere property damage ightning

also oxidi3es nitrogen in the air into nitrates *hich are deposited !y rain and can fertili3e

plant gro*th[55][5]

Thunder [edit]

Main article: Thunder 

/ecause the electrostatic discharge of terrestrial lightning superheats the air to plasma

temperatures along the length of the discharge channel in a short duration, %inetic

theorydictates gaseous molecules undergo a rapid increase in pressure and thus expand

out*ard from the lightning creating a shoc% *a"e audi!le as thunder >ince the sound

*a"es propagate not from a single point source !ut along the length of the lightnings path,

the sound origins "arying distances from the o!ser"er can generate a rolling or rum!lingeffect Berception of the sonic characteristics is further complicated !y factors such as the

irregular and possi!ly !ranching geometry of the lightning channel, !y acoustic echoingfrom

terrain, and !y the typically multiple;stro%e characteristic of the lightning stri%e

ight tra"els at a!out '00,000,000 mKs, and sound tra"els through air at a!out '40 mKs 2n

o!ser"er can approximate the distance to the stri%e !y timing the inter"al !et*een the

"isi!le lightning and the audi!le thunder it generates 2 lightning flash preceding its thunder

!y one second *ould !e approximately '50 metres $0## mi& in distanceI a delay of three

seconds *ould indicate a distance of a!out one %ilometer $0# mi& $'J'40 m& 2 flashpreceding thunder !y fi"e seconds *ould indicate a distance of approximately one mile

$1 %m& $5J'40 m& -onsequently, a lightning stri%e o!ser"ed at a "ery close distance *ill

!e accompanied !y a sudden clap of thunder, *ith almost no percepti!le time lapse,

possi!ly accompanied !y the smell of o3one $O'&

(igh-energ& radiation[edit]

+he production of M;rays !y a !olt of lightning *as theoretically predicted as early as

16#5[57] !ut no e"idence *as found until #001K#00#,[58][56][0] *hen researchers at the Ae*

(exico nstitute of (ining and +echnology detected M;ray emissions from an induced

lightning stri%e along a grounded *ire trailed !ehind a roc%et shot into a storm cloud n the

same year @ni"ersity of Clorida and Clorida +ech researchers used an array of electric field

and M;ray detectors at a lightning research facility in Aorth Clorida to confirm that natural

lightning ma%es M;rays in large quantities during the propagation of stepped leaders +he

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cause of the M;ray emissions is still a matter for research, as the temperature of lightning is

too lo* to account for the M;rays o!ser"ed [1][#]

 2 num!er of o!ser"ations !y space;!ased telescopes ha"e re"ealed e"en higher

energy gamma ray emissions, the so;called terrestrial gamma;ray flashes $+.Cs& +heseo!ser"ations pose a challenge to current theories of lightning, especially *ith the recent

disco"ery of the clear signatures of antimatter  produced in lightning[']

 Volcanic[edit]

Golcanic material thrust high into the atmosphere can trigger lightning

Golcanic acti"ity produces lightning;friendly conditions in multiple *ays +he enormous

quantity of pul"eri3ed material and gases e<ected into the atmosphere *ith explosi"e po*er,

creates a dense plume of highly charged particles, *hich esta!lishes the perfect conditions

for lightning +he ash density and constant motion *ithin the "olcanic plume continually

produces electrostatic ioni3ation, resulting in "ery po*erful and "ery frequent flashes

attempting to neutrali3e itself =ue to the extensi"e solid material $ash& content, unli%e the

*ater rich charge generating 3ones of a normal thundercloud, it is often called a dirty

thunderstorm

• Bo*erful and frequent flashes ha"e !een *itnessed in the "olcanic plume as far

!ac% as the 76 2= eruption of Gesu"ius !y Bliny +he Nounger [4]

• i%e*ise, "apors and ash originating from "ents on the "olcanos flan%s may produce

more locali3ed and smaller flashes up*ards of #6 %m long

• >mall, short duration spar%s, recently documented near ne*ly extruded magma,

attest to the material !eing highly charged prior to e"en entering the atmosphere [5]

Extraterrestrial lightning[edit]

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ightning has !een o!ser"ed *ithin the atmospheres of other planets, such

as Genus, upiter  and >aturn 2lthough in the minority on Earth, super!olts appear to !e

common on upiter

ightning on Genus has !een a contro"ersial su!<ect after decades of study =uring the>o"iet Genera and @> Bioneer  missions of the 1670s and 1680s, signals suggesting

lightning may !e present in the upper atmosphere *ere detected [] 2lthough the -assini–

uygens mission fly;!y of Genus in 1666 detected no signs of lightning, the o!ser"ation

*indo* lasted mere hours Fadio pulses recorded !y the spacecraft Genus Express $*hich

!egan or!iting Genus in 2pril #00& ha"e !een confirmed as originating from lightning on

Genus

Human-related phenomena[edit]

• Airplane contrails ha"e also !een o!ser"ed to influence lightning to a small degree

+he *ater "apor;dense contrails of airplanes may pro"ide a lo*er resistance path*ay

through the atmosphere ha"ing some influence upon the esta!lishment of an ionic

path*ay for a lightning flash to follo*[7]

• Rocket e+haust plumes pro"ided a path*ay for lightning *hen it *as *itnessed

stri%ing the 2pollo 1# roc%et shortly after ta%eoff

• Thermonuclear e+plosions !y pro"iding extra material for electrical conduction and

a "ery tur!ulent locali3ed atmosphere, ha"e !een seen triggering lightning flashes *ithin

the mushroom cloud n addition, intense gamma radiation from large nuclear

explosions may de"elop intensely charged regions in the surrounding air

through -ompton scattering +he intensely charged space charge regions create

multiple clear;air lightning discharges shortly after the de"ice detonates [8]

cientific study [edit]

"roperties[edit]

+hunder is heard as a rolling, gradually dissipating rum!le !ecause the sound from different

portions of a long stro%e arri"es at slightly different times [6]

9hen the local electric field exceeds the dielectric strength of damp air $a!out ' million "olts

per meter&, electrical discharge results in a strike, often follo*ed !y commensurate

discharges !ranching from the same path $>ee image, right& (echanisms that cause the

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charges to !uild up to lightning are still a matter of scientific in"estigation[70][71] ightning may

!e caused !y the circulation of *arm moisture;filled air through electric fields[7#] ce or *ater

particles then accumulate charge as in a Gan de .raaff generator [7']

Fesearchers at the @ni"ersity of Clorida found that the final one;dimensional speeds of 10flashes o!ser"ed *ere !et*een 10J105 and 14J10 mKs, *ith an a"erage of 44J105 mKs[74]

Detection and monitoring[edit]

Fay counter in a museum

Main article: Lightning detection

+he earliest detector in"ented to *arn of the approach of a thunder storm *as the lightning

!ell /en<amin Cran%lin installed one such de"ice in his house [75] [7] +he detector *as !ased

on an electrostatic de"ice called the electric chimes in"ented !y 2ndre* .ordon in 174#

ightning discharges generate a *ide range of electromagnetic radiations, including radio;

frequency pulses +he times at *hich a pulse from a gi"en lightning discharge arri"es at

se"eral recei"ers can !e used to locate the source of the discharge +he @nited >tates

federal go"ernment has constructed a nation*ide grid of such lightning detectors, allo*ing

lightning discharges to !e trac%ed in real time throughout the continental @> [77][78]

+he Earth;ionosphere *a"eguide traps electromagnetic GC; and EC *a"es

Electromagnetic pulses transmitted !y lightning stri%es propagate *ithin that *a"eguide

+he *a"eguide is dispersi"e, *hich means that their group "elocity depends on frequency

+he difference of the group time delay of a lightning pulse at ad<acent frequencies is

proportional to the distance !et*een transmitter and recei"er +ogether *ith direction finding

methods, this allo*s to locate lightning stri%es up to distances of 10000 %m from their origin

(oreo"er, the eigenfrequencies of the Earth;ionospheric *a"eguide, the >chumann

resonances at a!out 75 3, are used to determine the glo!al thunderstorm acti"ity[76]

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n addition to ground;!ased lightning detection, se"eral instruments a!oard satellites ha"e

!een constructed to o!ser"e lightning distri!ution +hese include the Optical +ransient

=etector $O+=&, a!oard the Or!Gie*;1 satellite launched on 2pril ', 1665, and the

su!sequent ightning maging >ensor $>& a!oard +F(( launched on Ao"em!er #8,

1667[80][81][8#]

Artificiall& triggered[edit]

• Rocket-triggered lightning can !e )triggered) !y launching specially designed

roc%ets trailing spools of *ire into thunderstorms +he *ire un*inds as the roc%et

ascends, creating an ele"ated ground that can attract descending leaders f a leader

attaches, the *ire pro"ides a lo*;resistance path*ay for a lightning flash to occur +he

*ire is "apori3ed !y the return current flo*, creating a straight lightning plasma channel

in its place +his method allo*s for scientific research of lightning to occur under a more

controlled and predicta!le manner [8']

+he nternational -enter for ightning Fesearch and +esting $-F+& at -amp

/landing, Clorida typically uses roc%et triggered lightning in their research studies

• *aser-triggered

>ince the 1670s,[84][85][8][87][88][86] researchers ha"e attempted to trigger lightning stri%es

!y means of infrared or ultra"iolet lasers, *hich create a channel of ioni3ed gas

through *hich the lightning *ould !e conducted to ground >uch triggering of

lightning is intended to protect roc%et launching pads, electric po*er facilities, and

other sensiti"e targets[60][61][6#][6'][64]

n Ae* (exico, @>, scientists tested a ne* tera*att laser *hich pro"o%ed lightning

>cientists fired ultra;fast pulses from an extremely po*erful laser thus sending

se"eral tera*atts into the clouds to call do*n electrical discharges in storm clouds

o"er the region +he laser !eams sent from the laser ma%e channels of ioni3ed

molecules %no*n as )filaments) /efore the lightning stri%es earth, the filaments

lead electricity through the clouds, playing the role of lightning rods Fesearchers

generated filaments that li"ed a period too short to trigger a real lightning stri%e

Ae"ertheless, a !oost in electrical acti"ity *ithin the clouds *as registered

 2ccording to the Crench and .erman scientists *ho ran the experiment, the fast

pulses sent from the laser *ill !e a!le to pro"o%e lightning stri%es on demand

[65] >tatistical analysis sho*ed that their laser pulses indeed enhanced the electrical

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acti"ity in the thundercloud *here it *as aimedLin effect they generated small local

discharges located at the position of the plasma channels[6]

"h&sical manifestations[edit]

ightning;induced remanent magneti3ation $F(& mapped during a magnetic field gradient sur"ey

of an archaeological site located in 9yoming, @nited >tates

*ightning-induced magnetism[edit]

+he mo"ement of electrical charges produces a magnetic field $see electromagnetism& +he

intense currents of a lightning discharge create a fleeting !ut "ery strong magnetic field

9here the lightning current path passes through roc%, soil, or metal these materials can

!ecome permanently magneti3ed +his effect is %no*n as lightning;

induced remanent magnetism, or F( +hese currents follo* the least resisti"e path, often

hori3ontally near the surface[67][68] !ut sometimes "ertically, *here faults, ore !odies, or

ground *ater offers a less resisti"e path[66] One theory suggests that lodestones, natural

magnets encountered in ancient times, *ere created in this manner [100]

ightning;induced magnetic anomalies can !e mapped in the ground,[101][10#] and analysis of

magneti3ed materials can confirm lightning *as the source of the magneti3ation [10'] and

pro"ide an estimate of the pea% current of the lightning discharge [104]

)olar wind and cosmic ra&s[edit]

>ome high energy cosmic rays produced !y superno"as as *ell as solar particles from the

solar *ind, enter the atmosphere and electrify the air, creating path*ays for lightning !olts

[105]

!n culture[edit]

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Further information: Lightning in religion

ightning !y (i%alo<us onstantinas -iurlionis $1606&

n many cultures, lightning has !een "ie*ed as part of a deity or a deity in and of itself

+hese include the .ree% god Peus, the 23tec god +laloc, the (ayan .od , >la"ic

mythologys Berun, the /altic BQr%onsKBer%Rnas, +hor  in Aorse mythology, @%%o in Cinnishmythology, the indugod ndra, and the >hinto god Fai<in[10] n the traditional religion of the

 2frican /antu tri!es, lightning is a sign of the ire of the gods Gerses in the e*ish religion

and in slam also ascri!e supernatural importance to lightning n -hristianity, the >econd

-oming of esus is compared to lightning [(atthe* #4H#7][u%e 17H#4]

+he expression )ightning ne"er stri%es t*ice $in the same place&) is similar to )Opportunity

ne"er %noc%s t*ice) in the "ein of a )once in a lifetime) opportunity, i.e., something that is

generally considered impro!a!le ightning occurs frequently and more so in specific areas

>ince "arious factors alter the pro!a!ility of stri%es at any gi"en location, repeat lightningstri%es ha"e a "ery lo* pro!a!ility $!ut are not impossi!le&[107][108] >imilarly, )2 !olt from the

!lue) refers to something totally unexpected

>ome political parties use lightning flashes as a sym!ol of po*er, such as the Beoples

 2ction Barty in >ingapore, the /ritish @nion of Cascists during the 16'0s, and the Aational

>tates Fights Barty in the @nited >tates during the 1650s[106] +he >chut3staffel, 

theparamilitary *ing of the Aa3i Barty, used the >ig rune in their logo *hich sym!oli3es

lightning +he .erman *ord /lit3%rieg, *hich means )lightning *ar), *as a ma<or offensi"e

strategy of the .erman army during 9orld 9ar

n Crench and talian, the expression for )o"e at first sight) is cou de foudre and colo di

fulmine, respecti"ely, *hich literally translated means )lightning stri%e) >ome European

languages ha"e a separate *ord for lightning *hich stri%es the ground $as opposed to

lightning in general&I often it is a cognate of the English *ord )rays) +he name of Ae*

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Pealands most cele!rated thorough!red horse, Bhar ap, deri"es from the

shared Phuang and +hai *ord for lightning[110]

+he !olt of lightning in heraldry is called a thunder!olt and is sho*n as a 3ig3ag *ith non;

pointed ends +his sym!ol usually represents po*er and speed

+he lightning !olt is used to represent the instantaneous communication capa!ilities of

electrically po*ered telegraphs and radios t *as a commonly used motif in 2rt

=ecodesign, especially the 3ig;3ag 2rt =eco design of the late 16#0s[111] +he lightning !olt is

a common insignia for military communications units throughout the *orld 2 lightning !olt is

also the A2+O sym!ol for a signal asset