a wonder of the nature

8/8/2019 A Wonder of the Nature

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DEFINITION:discharge of electricity between a cloud and the ground or within a cloud, accompanied by a

bright flash.



HOW IS IT FORMED??y Main cause-separation of charges

y These charges when create strong enough field cause an

electric discharge.y These discharges are triggered by cosmic rays which ionize

atoms which release electrons.

y Electrons are accelerated by electric fields, ionizing air

molecules( making the air conductive) thus, starting a lightning

strike.

y Lightning is also formed due to volcanic eruptions which

produce sufficient amount of dust to create static charge.



WHY IS IT A WONDER??y THE CORE REASON IS STILL UNKNOWN.

y SCINTISTS ARE STILL WORKING TO SOLVE THE

MYSTERYHOW IS THE CHARGE FORMED?y THEY HAVE PROPOSED A LOT OF THEORIES

y NO THEORY IS COMPLETELY SATISFACTORY



THEORIES

y Electrostatic induction hypothesis

y Polarizing mechanism hypothesisy Leader formation and return stroke

y Discharge

y Gurevichs runway breakdown theory

y Gamma rays and runway breakdown theory

polarization theory is the most accepted one



Charge

separation

polarization

theory

The mechanism by which chargeseparation happensis still the subject of research. :[18]

Falling droplets of ice and rain becomeelectrically polarizedas they fall throughthe Earth's naturalelectric field;Colliding iceparticles becomecharged by electrostaticinduction



Types of discharges



Types of strikes1 Cloud to ground 2 Ground to cloud

Most destructive Generally hits on high altitude

regions Cloud to ground lightning

occurs when electrical chargetravels between negatively charged cloud base andpositively charged ground

Known as upward lightning

Rarer than the previous one



3 Cloud to cloud

Intra cloud Inter cloud

y Most common

y In a single cloudy Both charges within the same

cloud

y Visible for miles

y More uncommon

y Between two cloudsy Opposite chages located in

different clouds



Lightning does not strike twice at

same place??!!y Peoples belief

y Completely untrue

y There was an incident whereTHE EMPIRE STATE BUILDING

WAS HIT 15 TIMES IN 15 MINUTES



Interesting factsy A lightning bolt has enough energy to lift a large ocean

liner to an amazing SIX feet into air

y The most powerful lightning strikeever recorded in United Statesstruck the cathedral of learningof the University of Pittsburgh on

July 31, 1947. The bolt dischargedapproximately three hundred forty

five thousand amps. This wasenough current to light six hundredthousand 60W light bulbs for the duration of the flash

which is only thirty five millionth of a second.



Some notable strikes..y In Bresia,Italy,1769;lightning struck on a

church igniting 100 tons of gun powder,killing around300 people, one sixth of thecity

y in 1902 a lightning struck and damaged thetop of Eiffel tower causing reconstruction

y There were many instances of lightningstriking fuel tanks towers etc., causingfatalities and huge loss in property.

y One among every 3000 persons in U.S.A getstruck by a lightning once in life time.



In science field, we still have to know theactual reason behind this wonderfulmechanism

In development field, we need to find better ways to protect ourselves from this and may be try to use the energy of lightening .

thank you!

a wonder of the nature

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