3828118-lightning-discharge

8/7/2019 3828118-Lightning-Discharge

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Lightning DischargeThis Project is contributed by :

Abdallah Ali [email protected]

Ali Nasser Ammar

Rasheed Mohammed EL-Ghorabee

Yousef awidatMohammed alkhatib


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For contacts

[email protected]


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Lightning DischargeLightning Discharge


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Project OutlineProject OutlineIntroductionIntroductionMechanism Of LightningMechanism Of LightningTypes of strikes & Types Of LightningTypes of strikes & Types Of LightningEffects Of LightningEffects Of LightningLightning SafetyLightning SafetyConclusionConclusionReferencesReferences


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I ntroduction A lightning strike can heat the air in a A lightning strike can heat the air in a

fraction of a second. When air is heatedfraction of a second. When air is heatedthat quickly, it expands violently and thenthat quickly, it expands violently and thencontracts, like an explosion that happenscontracts, like an explosion that happensin thein the blink of an eyeblink of an eye ..[ [Steve Goodman, A Lightning Primer, www.nasa.gov] ]


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100 lightning strikes per second .8 million lightning strikes per day .30000 C elsius is the temperature per strikes .1000 million volt per strike.20000 ampere per strike .


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Me chanism of LightningMe chanism of Lightning

It is the movement of electrons down from aIt is the movement of electrons down from aregion of region of more negative charge to a region of more negative charge to a region of less negative charge.less negative charge.Lightning results from the buildup and

discharge of electrical energy betweenpositively and negatively charged areas.Rising and descending air within athunderstorm separates these positive and

negative charges.


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Lightning MechanismLightning MechanismFirst stageFirst stage

A negatively chargedA negatively chargedray of electrical lightray of electrical light

falls down from thefalls down from thecloud to the ground incloud to the ground ina very little timea very little time

(about ms(about ms ))


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Lightning MechanismLightning MechanismSecond stageSecond stage

This ray approachesThis ray approachesthe ground in whichthe ground in which

it meet with theit meet with thepositively chargedpositively chargedwave that is foundwave that is found

at the top of theat the top of thegroundground


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Lightning MechanismLightning MechanismThird stageThird stage

The positivelyThe positivelycharged ray strikescharged ray strikes

the negativelythe negativelycharged wave andcharged wave andthen an extremethen an extreme

spark of light isspark of light isproduced, towardsproduced, towards

the ground.the ground.


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Lightning MechanismLightning Mechanismfourth stage

Finally the returnedFinally the returnedray that we see isray that we see is

produced, and itproduced, and itcontains the energycontains the energyof lightning and itsof lightning and its

heat, this happensheat, this happensin (in (2525ms).ms).


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Lightning Animation


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Types of StrikesTypes of Strikes

11--Cl oud to ground.Cloud to ground.

22--G round to c loud.G round to c loud.

33--Cl oud to c loud.Cloud to c loud.


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C loud to ground :



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Ground to cloud:Ground to cloud: The same as above with theThe same as above with theexception that usually a tall, earthexception that usually a tall, earth- -bound objectbound objectinitiates the strike to the cloudinitiates the strike to the cloud



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C loud to cloudC loud to cloud :: Also the same mechanics as Also the same mechanics asdiscussed above except the strike travels fromdiscussed above except the strike travels fromone cloud to another one cloud to another



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lightning Eff e ct lightning Eff e ct


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lightning Eff e ct lightning Eff e ct


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lightning Effectlightning Effect


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Lightning B enefitsW hats good about lightning?It produces a lot of the nitrogen

compounds that are important for plantgrowth. It provided early man with his onlysource of fire. Its better than fireworks onthe Fourth of July and its free !


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Lightning DamageLightning Damage

There are four basic types of There are four basic types of

lightning damage:lightning damage:

11--physical damagephysical damage

22--electromagnetic effect damageelectromagnetic effect damage


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Physical damage

The Physical damage is caused bycurrent flow and heat.

The average lightning strike contains20,000 amps.This current flow can arc across any gaps

in its path. If that arc takes place within aflammable material, it can cause a fire or explosion


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The core temperature of a lightningchannel is approximately 50 ,000 degrees Fahrenheit , or about five timesthe surface temperature of the sun.

W hen the air surrounding the lightningchannel is heated this rapidly, itexpands in a shock wave. This shock

wave can damage a structure

Physical d amag e


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Physical damage


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The on-off-on-off action of a lightning strikecauses the electromagnetic field surrounding thestrike to expand and collapse with the series of flashes.

This electromagnetic field motion can induceelectrical currents in nearby conductors,including wires and electrical equipment .

The electromagnetic field

effect


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Lightning SafetyLightning Safety

3030/ /30 30 Lightning Safety Rule:Lightning Safety Rule:

-- G o indoors if, after seeing lightning , youG o indoors if, after seeing lightning , youcannot count tocannot count to 30 30 before hearing thunder.before hearing thunder.Stay indoors for Stay indoors for 3030 minutes after hearingminutes after hearingthe last clap of thunder.the last clap of thunder.


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Lightning SafetyLightning SafetyWhat is the safest place?What is the safest place?Most people think that the tree was the safe placeMost people think that the tree was the safe place

to be in storm , But really is the most dangerousto be in storm , But really is the most dangerousplace.place.Electricity seeks the path of least resistance, andElectricity seeks the path of least resistance, andthe moisture (sap and water) inside a tree is athe moisture (sap and water) inside a tree is a

much better conductor than air.much better conductor than air.The result: a tree provides a preferred path for The result: a tree provides a preferred path for

lightning to reach groundlightning to reach ground ..


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Lightning SafetyLightning Safety

Can the car safe us fromCan the car safe us from

Thunderstorm?Thunderstorm? A car is very safe from the storm . A car is very safe from the storm .

If you are inside a car when lightningIf you are inside a car when lightningstrikes , the metal frame will conduct thestrikes , the metal frame will conduct theelectricity into the ground ,just do notelectricity into the ground ,just do nottouch anything metal or radio.touch anything metal or radio.


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Safety


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Safety


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References

3828118-lightning-discharge

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