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Thanks very much Russell.
Thanks very much Dave,
The Saturn lightning or SED's (Saturn Electrostatic Discharge) were detected by the Cassini RPWS (Radio and Plasma Wave Science) instrument. This instrument used three wip antennae to pick up radio data from the lightning discharge within Saturn's atmosphere. If you have a radio on and there is a lightning storm nearby every time there is a discharge of lightning you hear static on your radio, this is how the RPWS instrument worked.
Saturn has three distinct cloud layers to a depth of about 200km. An upper cloud layer of frozen ammonia crystals, a mid layer of ammonium hydro-sulfide crystals and a lower layer of water ice crystals. The water ice crystals have potential energy.
From time to time a poorly understood heat source deep within the planet drives material from the water ice crystal cloud layer into rapid vertical motion at approx 100m/s. The water ice crystals now in motion are rubbing against one another and have kinetic energy, they develop charge until finally they discharge causing an outburst of SED's which are then detected by the Cassini RPWS instrument so long as Cassini is on the same side of Saturn relative to the SED's.
This is happening still relatively deep within the atmosphere. The up welling column of material originating from the water ice crystal layer bursts though the upper cloud layer. This is quite different material from that of the upper cloud layer and I would image a white spot.
Whenever Cassini RPWS detected SED's Georg Fischer from Cassini RPWS would contact our group with the challenge to hunt down the optical counterpart to his RPWS radio source.
Of course the absolute highlight of all this was The Great Storm of 2010/2011. Cassini RPWS detected a massive amount of SED's early in December 2010, by the third week of January 2011 so much material had been dredged up that it completely encircled the planet at that latitude and it remained active for months.
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