HOW LIGHTNING FORMS

8/7/2019 HOW LIGHTNING FORMS

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HOW LIGHTNING FORMS


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Lightning is anatmospheric dischargeof electricity

accompanied bythunder, which typicallyoccurs duringthunderstorms, andsometimes duringvolcanic eruptions ordust storms.


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In the atmospheric

electrical discharge, aleader of a bolt of

lightning can travel at

speeds of

36,000 km/h (22,000

mph), and can reach

temperatures

approaching 30,000 C(54,000 F).


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How Lightning Forms


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There are some processes of lightning formation.


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It all starts with clouds thatbecome electrically charged.

Clouds themselves are made ofevaporated water particles thatare beginning to condense again.That means that heavier waterparticles and even ice particles

remain on the lower areas of thecloud while newly evaporatedparticles rise to the top.

As these particles rise and pushthrough the cloud to get to thetop, they collide with denser

water molecules at the bottom.This causes electrons to getknocked off and accumulate atthe bottom of the cloud. Thenow-positive water particles riseto the top, creating an electricalcharge in the cloud.

Clouds are Charged


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Evaporation is the process by

which a liquid absorbs heat

and changes to a vapor.

Rates of evaporation of water

depend on things like the

temperature, humidity, andwind.


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Condensation is the

process whereby watervapor in the atmosphereis returned to its originalliquid state.

In the atmosphere,condensation mayappear as clouds, fog,mist, dew or frost,

depending upon thephysical conditions of theatmosphere.


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Air Ionization When the electric field becomes

very strong (on the order of tens ofthousands of volts per inch),conditions are ripe for the air tobegin breaking down.

Now, the bottom half of theelectric-charged cloud holds anegative charge, and the top of theearth holds a stronger positivecharge. The stage is set for lightningto occur, as there is now an electriccharge between the cloud and the

earth. The ionized air (also known as

plasma) is much more conductivethan the previous non-ionized air.


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Lightning

Forms In order to neutralize the charges on both ends, theair starts to break down and form a pathway

through which positive ions and electrons cantravel.

Positive ions will want to reach the cloud so that

the electrical charge there will be neutralized, and

electrons will do the same thing with the earth.

A pathway is first formed through the ionized airbetween the cloud and the Earth.


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Dust and objects that may be in the air will force

the air to break down quickly, so the pathway isnot always straight from the cloud to the Earth.

Once it is formed, electricity travels through it in

the form of lightning.


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Since the path is notstraight, lightning often has

many arcs and rarely travelsin a straight line. Once thelightning has neutralizedthe air, the cloud, and the

Earth, it will not strikeagain. Sometimes it takesmore than one strike indifferent places in order to

do this. That is called alightning storm.


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Multiple Strikes

When the first strikeoccurs, current flows in anattempt to neutralize thecharge separation. This

requires that the currentassociated with the energyin the other step leadersalso flows to the ground.

The electrons in the otherstep leaders, being free tomove, flow through theleader to the strike path.


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So when the strike

occurs, the other stepleaders are providing

current and exhibiting

the same heat flash

characteristics of the

actual strike path. After

the original stroke

occurs, it is usuallyfollowed by a series of

secondary strikes.


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Lightning Strikes

Are electrical discharges caused by lightning,typically during thunderstorms.

Lightning strikes injure humans in severaldifferent ways: Direct strike, which is usually fatal.

Contact injury, when the person was touchingan object that was struck

Side splash, when current jumped from anearby object to the victim

Ground strike, current passing from a strikethrough the ground into a nearby victim. Astrike can cause a difference of potential inthe ground (due to resistance to current in theEarth), amounting to several thousand volts

per foot. Blast injuries, either hearing damage or blunt

trauma by being thrown to the ground.

Lightning can also damage electricalequipments such as telephones, modems, andcomputers.


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Lightning SafetyYour chances of being struck by lightning are estimated to be 1 in 600,000 but those chances can be reduced by following safety

rules

OUTDOOR

Look for appropriate shelter

such as building or car.

Avoid taking shelter undertrees. Trees attract lightning.

INDOOR

Stay off the phone. If lightningstrikes the phone line, the

strike will travel to every phoneon the line (and potentially toyou if you are holding thephone).

Stay away from plumbing pipes(bath tub, shower). Lightning

has the ability to strike a houseor near a house and impart anelectrical charge to the metalpipes used for plumbing.


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CONCLUSION

Lightning is the action of rising and descending

air within a thunderstorm separates positive

and negative charges.

Most lightning occurs within the cloud or

between the cloud and ground.

Lightning strikes can damage human and

electrical devices.


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REFERENCES

http://en.wikipedia.org/wiki/Lightning

http://www.ehow.com/about_6129434_thun

der-_amp_-lightning-occur_.html http://www.ehow.com/how-

does_4564049_lightning-form.html

http://science.howstuffworks.com/nature/natural-disasters/lightning.htm

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HOW LIGHTNING FORMS