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Today:1. Finish Ionosphere Conductivity2. Relate Auroral Currents with Ionospheric currents

What is Conductivity?

• The scalar conductivity σ is defined as the ratio of the current density to the electric field strength σ = J/E. For a resistive medium this is just the Spitzer conductivity:

• To get the components look at • So, σ can have many components:

(Another way to derive scalar conductivity)

Conductivity when particles gyrate

σ becomes a matrix

Now lets relate the ionospheric currents, to the field aligned magnetosphericcurrents:To start: How does the Aurora Work?

Substormstarts here

DE aurora

The Auroral Currents

Today

• Review Aurora and substorm• Begin atmospheric electrodynamics

• Cosmic rays• Lightning and thunderstorms

Note, missed classes can be made up by writing a 1-2 page summary of the material presented on that day, based on the on-line pdf file for the missed lecture: see http://earthweb.ess.washington.edu/bobholz/ess471-503/lectures/

Current Conditions: SuperDarn radars

http://superdarn.jhuapl.edu/rt/map/index.html

Substorm starts

Southward E-field before substorm (and after)

After substorm starts, B-field determined by Hall Currents

Energetic Electron beam

Discovery paper (Mozer et al, 1978)

Parallel

Electric

fields

Great Red Aurora

Jupiter aurora

Cosmic Radiation

June 2006

Astronomy Picture of the Day 2006 August 14

Solar Flare can produce 1030 ergs

• But a single Galactic Cosmic Ray can be over 1020 eV allby itself

30

neutron monitors

Cosmic Rays are the prime source for ions in the atmosphere

+,- ions generated per second per cubic centimeter

Cosmic Ray energy fluxcomparisons