Atmospheric Electricity

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Dalibard’s Experiment

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The Earth’s Electric Field

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The “Carnegie” Curve: measurements of the Earth’s Electric Field

Thunderstorm Frequency

Charging Mechanisms

• Induction– Result is a

polarized hydrometeor

• Ion particle charging

• Particle-particle charging

E+++

++

--- -

-

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Charging by induction

Initially neutral

Introduce a charge, creating an electric field

+-----

+

++

+ + E

Charging by inductionContact charging

- +

E

Selective Ion Capture

- - - - --

--

--

+ + + ++

++

+ ++

- +

E

Gravity plays a role in differential charge separation

Negative charge transfer to larger particles, which then fall to lower levels in the cloud.

The Earth’s Electric Field

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Storm Electrification

• Is NOT well understood• There is more than one

parameter– Buoyancy– Hydrometeor type– Conductivity

• Even within the same storm

• Role of charge separation

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Corona or Point Discharge

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• The presence of some sort of conductive point• Disruption of the

Electric Field• Electron Avalanche

(non-ohmic)

Corona (point discharge)

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Lightning Types

Frequency of occurrence

The Electrification of thunderstorms is related to thermodynamics

Different slopes for different storms

Why the slopes may differ

Flash rate is greatest when storm intensity is greatest

Cloud Physics and electrification

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Hail and ground strokes

Field Mill

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