APOD: Sprite Lightning in HD (2019 Oct 08)

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APOD: Sprite Lightning in HD (2019 Oct 08)

Post by APOD Robot » Tue Oct 08, 2019 4:06 am

Image Sprite Lightning in HD

Explanation: This phenomenon occurs in the sky over our heads, not the sea. It is a type of lightning known as red sprite, and rarely has it ever been photographed in this detail. Even though sprites have been recorded for over 30 years, their root cause remains unknown. Some thunderstorms have them, but most don't. These mysterious bursts of light in the upper atmosphere momentarily resemble gigantic jellyfish. A few years ago high speed videos were taken detailing how red sprites actually develop. The featured image was captured last month in high definition from Italy. One unusual feature of sprites is that they are relatively cold -- they operate more like long fluorescent light tubes than hot compact light bulbs. In general, red sprites take only a fraction of a second to occur and are best seen when powerful thunderstorms are visible from the side.

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Ann
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Re: APOD: Sprite Lightning in HD (2019 Oct 08)

Post by Ann » Tue Oct 08, 2019 4:09 am

Interesting. The upper and lower structures of these phenomena are quite different.

Why are these things red?

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Re: APOD: Sprite Lightning in HD (2019 Oct 08)

Post by orin stepanek » Tue Oct 08, 2019 10:52 am

Weird looking stuff! Al most looks like some type of uprooted plant! :shock:
SpritesHD_Vetter_1000.jpg
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Re: APOD: Sprite Lightning in HD (2019 Oct 08)

Post by TheZuke! » Tue Oct 08, 2019 1:25 pm

Ann wrote:
Tue Oct 08, 2019 4:09 am
Interesting. The upper and lower structures of these phenomena are quite different.

Ann
I wonder if that is a boundary layer effect.

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Re: APOD: Sprite Lightning in HD (2019 Oct 08)

Post by BDanielMayfield » Tue Oct 08, 2019 2:06 pm

Ann wrote:
Tue Oct 08, 2019 4:09 am
Interesting. The upper and lower structures of these phenomena are quite different.

Why are these things red?

Ann
Red on top but purple on the bottom. It's interesting that, as the high speed video shows, these electrical discharges flow downward on the bottom but upward on top.
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Re: APOD: Sprite Lightning in HD (2019 Oct 08)

Post by BDanielMayfield » Tue Oct 08, 2019 2:16 pm

TheZuke! wrote:
Tue Oct 08, 2019 1:25 pm
Ann wrote:
Tue Oct 08, 2019 4:09 am
Interesting. The upper and lower structures of these phenomena are quite different.

Ann
I wonder if that is a boundary layer effect.
When these rare phenomena occur, are they always at about the same altitude?
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Re: APOD: Sprite Lightning in HD (2019 Oct 08)

Post by TheOtherBruce » Tue Oct 08, 2019 2:26 pm

Ann wrote:
Tue Oct 08, 2019 4:09 am
Interesting. The upper and lower structures of these phenomena are quite different.

Why are these things red?
Maybe there's a connection to red aurora filaments being due to atomic oxygen. If so, it's probably saying something relevant about the energy levels involved.
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Re: APOD: Sprite Lightning in HD (2019 Oct 08)

Post by neufer » Tue Oct 08, 2019 3:15 pm

Click to play embedded YouTube video.
TheOtherBruce wrote:
Tue Oct 08, 2019 2:26 pm
Ann wrote:
Tue Oct 08, 2019 4:09 am

Interesting. The upper and lower structures of these phenomena are quite different.

Why are these things red?
Maybe there's a connection to red aurora filaments being due to atomic oxygen.
Oxygen is primarily green...nitrogen is primarily red.
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Re: APOD: Sprite Lightning in HD (2019 Oct 08)

Post by TheOtherBruce » Tue Oct 08, 2019 3:31 pm

neufer wrote:
Tue Oct 08, 2019 3:15 pm
TheOtherBruce wrote:
Tue Oct 08, 2019 2:26 pm
Maybe there's a connection to red aurora filaments being due to atomic oxygen.
Oxygen is primarily green...nitrogen is primarily red.
Whoops, looks like I misunderstood the Wikipedia section on auroral colours.
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Re: APOD: Sprite Lightning in HD (2019 Oct 08)

Post by neufer » Tue Oct 08, 2019 3:33 pm

Click to play embedded YouTube video.
BDanielMayfield wrote:
Tue Oct 08, 2019 2:06 pm

It's interesting that, as the high speed video shows, these electrical discharges flow downward on the bottom but upward on top.
It all looks mostly downward to me(... with a pinch in the middle :?: )
https://en.wikipedia.org/wiki/Pinch_(plasma_physics) wrote:
<<A pinch is the compression of an electrically conducting filament by magnetic forces. The conductor is usually a plasma, but could also be a solid or liquid metal. Pinches were the first type of device used for controlled nuclear fusion. Pinches occur naturally in electrical discharges such as lightning bolts [and sprites :?: ], the aurora, current sheets, and solar flares.>>
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The ionosphere

Post by neufer » Tue Oct 08, 2019 3:58 pm

https://en.wikipedia.org/wiki/Ionosphere wrote:


<<The ionosphere is the ionized part of Earth's upper atmosphere, from about 60 km to 1,000 km altitude, a region that includes the thermosphere and parts of the mesosphere and exosphere. The ionosphere is ionized by solar radiation. It plays an important role in atmospheric electricity and forms the inner edge of the magnetosphere. It has practical importance because, among other functions, it influences radio propagation to distant places on the Earth. The region below the ionosphere is called neutral atmosphere, or neutrosphere.

The E layer is the middle layer, 90 km to 150 km above the surface of the Earth. Ionization is due to soft X-ray (1–10 nm) and far ultraviolet (UV) solar radiation ionization of molecular oxygen (O2). After sunset an increase in the height of the E layer maximum increases the range to which radio waves can travel by reflection from the layer.

The D layer is the innermost layer, 60 km to 90 km above the surface of the Earth. Ionization here is due to Lyman series-alpha hydrogen radiation at a wavelength of 121.6 nm ionizing nitric oxide (NO). In addition, high solar activity can generate hard X-rays (wavelength < 1 nm) that ionize N2 and O2. Recombination rates are high in the D layer, so there are many more neutral air molecules than ions.

As early as 1839, the German mathematician and physicist Carl Friedrich Gauss postulated that an electrically conducting region of the atmosphere could account for observed variations of Earth's magnetic field. Sixty years later, Guglielmo Marconi received the first trans-Atlantic radio signal on December 12, 1901, in St. John's, Newfoundland (now in Canada) using a 500 ft kite-supported antenna for reception. The transmitting station in Poldhu, Cornwall, used a spark-gap transmitter to produce a signal with a frequency of approximately 500 kHz and a power of 100 times more than any radio signal previously produced. The message received was three dits, the Morse code for the letter S. To reach Newfoundland the signal would have to bounce off the ionosphere twice. Dr. Jack Belrose has contested this, however, based on theoretical and experimental work. However, Marconi did achieve transatlantic wireless communications in Glace Bay, Nova Scotia, one year later.

In 1902, Oliver Heaviside proposed the existence of the Kennelly–Heaviside layer of the ionosphere which bears his name. Heaviside's proposal included means by which radio signals are transmitted around the Earth's curvature. Heaviside's proposal, coupled with Planck's law of black-body radiation, may have hampered the growth of radio astronomy for the detection of electromagnetic waves from celestial bodies until 1932 (and the development of high-frequency radio transceivers).>>
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Re: APOD: Sprite Lightning in HD (2019 Oct 08)

Post by pferkul » Tue Oct 08, 2019 4:12 pm

B/W, inverted, and flipped, looks very much like a winter scene in the woods.
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