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Old 18-December-2004, 11:04 AM
VanderL VanderL is offline
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Hi Tim,

Thanks for the reply

Quote:
Saturn emits 1.78 times as much thermal energy as it gets from the sun, so it has a strong internal energy source that drives vertical convection.
That would mean the internal heat source produces 0.78 of the Sun's input, which doesn't impress me as something that would lead to a million times stronger lightning.

Quote:
On Earth, all weather happens in the troposphere, which is at most 5 or 6 kilometers deep, so that's the limit on any vertical convection path length.
Don't forget to include the sprites, blue jets and stuff like that, those effects are seen much higher in the atmosphere.

Quote:
The length of the convective path is directly related to the ability to separate charge and generate much stronger lightning.
There's also a relation between buildup of charge and the ability of the atmosphere to discharge. At a certain level discharge occurs, irrespective of the potential to build to higher charges based on "convective path length", in other words there are limits to charge buildup.

Quote:
So it's easy to see why lightning should be more powerful on all of the giant planets than on Earth.
I guess we don't know enough of Saturn's atmospheric activity to conclude this, I'm not surprised it is more powerful (after all size matters), but the factor of a million is certainly "astonishing" for Mr Gurnett, and I'm not going to argue his assessment.


Cheers.