APOD: Sakurajima Volcano with Lightning (2018 May 13)

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APOD: Sakurajima Volcano with Lightning (2018 May 13)

Post by APOD Robot » Sun May 13, 2018 4:08 am

Image Sakurajima Volcano with Lightning

Explanation: Why does a volcanic eruption sometimes create lightning? Pictured above, the Sakurajima volcano in southern Japan was caught erupting in 2013 January. Magma bubbles so hot they glowed shot away as liquid rock burst through the Earth's surface from below. The featured image is particularly notable, however, for the lightning bolts caught near the volcano's summit. Why lightning occurs even in common thunderstorms remains a topic of research, and the cause of volcanic lightning is even less clear. Surely, lightning bolts help quench areas of opposite but separated electric charges. Volcanic lightning episodes may be facilitated by charge-inducing collisions in volcanic dust. Lightning is usually occurring somewhere on Earth, typically over 40 times each second.

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Re: APOD: Sakurajima Volcano with Lightning (2018 May 13)

Post by Boomer12k » Sun May 13, 2018 9:12 am

An awesome display of Nature...

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heehaw

Re: APOD: Sakurajima Volcano with Lightning (2018 May 13)

Post by heehaw » Sun May 13, 2018 9:24 am

Why isn't there (or is there?) interstellar lightning?

DomeLord

Re: APOD: Sakurajima Volcano with Lightning (2018 May 13)

Post by DomeLord » Sun May 13, 2018 9:37 am

The potential difference between the inside & outside of the earth's crust is different. Charge resides on the outside of a sphere. The sphere's integrity is locally broken in a volcanic eruption enabling lightning discharges from the troposphere via very hot & ion rich lava & vog all the way down to real earth potential.

Electrical events are everywhere in the universe. Astronomers should be aware of that.

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Re: APOD: Sakurajima Volcano with Lightning (2018 May 13)

Post by orin stepanek » Sun May 13, 2018 11:19 am

I made a desktop wallpaper out of this APOD! Just a little cropping along the top! :D I put a different wallpaper each day!
I remember the volcano in Iceland also had lightning! 8-)
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Re: APOD: Sakurajima Volcano with Lightning (2018 May 13)

Post by Sa Ji Tario » Sun May 13, 2018 12:57 pm

You're right, look at this link
https://apod.nasa.gov/apod/ap100419.html

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Re: APOD: Sakurajima Volcano with Lightning (2018 May 13)

Post by Chris Peterson » Sun May 13, 2018 1:09 pm

heehaw wrote:
Sun May 13, 2018 9:24 am
Why isn't there (or is there?) interstellar lightning?
To have lightning you need a large difference in electric potential and a medium to heat up when charge travels between the regions of different potential. You have neither between stars.
Chris

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Chris Peterson
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Re: APOD: Sakurajima Volcano with Lightning (2018 May 13)

Post by Chris Peterson » Sun May 13, 2018 1:11 pm

DomeLord wrote:
Sun May 13, 2018 9:37 am
The potential difference between the inside & outside of the earth's crust is different. Charge resides on the outside of a sphere. The sphere's integrity is locally broken in a volcanic eruption enabling lightning discharges from the troposphere via very hot & ion rich lava & vog all the way down to real earth potential.
This lightning has nothing to do with potential between the inside and outside of the Earth. It's created substantially the same way all lightning is created- by charge separation mechanisms inside clouds. In this case, it's a dust cloud rather than a water cloud.
Chris

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Tszabeau

Re: APOD: Sakurajima Volcano with Lightning (2018 May 13)

Post by Tszabeau » Sun May 13, 2018 1:42 pm

Chris Peterson wrote:
Sun May 13, 2018 1:11 pm
DomeLord wrote:
Sun May 13, 2018 9:37 am
The potential difference between the inside & outside of the earth's crust is different. Charge resides on the outside of a sphere. The sphere's integrity is locally broken in a volcanic eruption enabling lightning discharges from the troposphere via very hot & ion rich lava & vog all the way down to real earth potential.
This lightning has nothing to do with potential between the inside and outside of the Earth. It's created substantially the same way all lightning is created- by charge separation mechanisms inside clouds. In this case, it's a dust cloud rather than a water cloud.
What about within the coma of a comet or a volcanic eruption on an atmosphere-less (or near to) body such as the earth’s moon?

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Re: APOD: Sakurajima Volcano with Lightning (2018 May 13)

Post by Chris Peterson » Sun May 13, 2018 1:52 pm

Tszabeau wrote:
Sun May 13, 2018 1:42 pm
Chris Peterson wrote:
Sun May 13, 2018 1:11 pm
DomeLord wrote:
Sun May 13, 2018 9:37 am
The potential difference between the inside & outside of the earth's crust is different. Charge resides on the outside of a sphere. The sphere's integrity is locally broken in a volcanic eruption enabling lightning discharges from the troposphere via very hot & ion rich lava & vog all the way down to real earth potential.
This lightning has nothing to do with potential between the inside and outside of the Earth. It's created substantially the same way all lightning is created- by charge separation mechanisms inside clouds. In this case, it's a dust cloud rather than a water cloud.
What about within the coma of a comet or a volcanic eruption on an atmosphere-less (or near to) body such as the earth’s moon?
Even if you have a charge separation mechanism (not obvious what that would be in a comet's coma, although it's possible in any volcanic eruption that produces thick dust), you still need a medium dense enough to ionize and provide a discharge path. That's not going to be present around a comet or on an airless body.
Chris

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Odd_Man_In

Re: APOD: Sakurajima Volcano with Lightning (2018 May 13)

Post by Odd_Man_In » Sun May 13, 2018 5:53 pm

Why is volcanic lightning still a mystery in 2018 A.D.? Am I missing something here? The source / cause is pretty much the same as storm lightning - turbulent motion of a cloud of polar particles, namely water droplets, plus, in the case of a volcano, silicate dust particles just pulverized.

The most abundant gas in a volcanic eruption, somewhere in excess of 90% of the entire gas budget in most eruptions (there are a few rare exceptions), is water. That percentage exceeds 99% in basaltic eruptions, especially on ocean islands. In fact, the only reason any magma, especially a low viscosity one such as basalt, produces ANY cloud at all is due to the presence of water either in the magma or coming in contact with the magma in the substrate.

Volcanology lesson aside, volcanic clouds obviously are more (rock) dust laden than are atmospheric clouds, so the presence of micron to submicron dustparticles increases overall electrical charge density, meaning that lightning is more likely in a volcanic cloud than in an atmospheric one. Eruptions are fairly rare and someone witnessing or recording lightning is rare, and rare times rare equals rare-squared, but volcanic lightning isn't rare when the sample set is limited to volcanic eruptions, especially those that involve enough water to produce a cloud.

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Re: APOD: Sakurajima Volcano with Lightning (2018 May 13)

Post by Chris Peterson » Sun May 13, 2018 6:00 pm

Odd_Man_In wrote:
Sun May 13, 2018 5:53 pm
Why is volcanic lightning still a mystery in 2018 A.D.? Am I missing something here? The source / cause is pretty much the same as storm lightning - turbulent motion of a cloud of polar particles, namely water droplets, plus, in the case of a volcano, silicate dust particles just pulverized.
I would distinguish between either being a "mystery" (which isn't the case) and each having many elements which remain poorly understood (which is quite true).
Chris

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