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Atmosphere: Volcanic Ash, Noctilucent Clouds, Sprites, Meteor Trains, Plumes...
 Volcanic Noctilucent  Sprites Meteors Plumes Releases Zodiacal Other


[Wiki Atmosphere]

Airmen study the atmosphere and learn about the weather as part of their basic training. However there are a few things of interest that are simply not discussed because they are irrelevant to aviation or extremely rare. Airmen and passengers do, however, sometimes get the opportunity to witness some of these events which will be described below.

Afterglow from Sarychev at LAX. (Wiki)
Further reading:
[Wiki Eruption Column]
[Wiki Volcanic Ash]
[Wiki Stratospheric Aerosols]
[Wiki Volcanic Gasses]
[Wiki Particulate Matter]
[Wiki Aerosols]
[Wiki Sunset]
Russia's Sarychev Peak  (NASA), (Wiki)
Active volcanoes in the solar system? Yes, Jupiter's moon "Io"  (NASA), (Wiki)
Suspended ash from Russia's Sarychev Peak 2009 over Canada (Wik-ash)
Volcanic ash can be visibly detected for weeks after an eruption far away from the volcano that produced it. The area immediately around the volcano and its dense ash plume (Wiki) will quickly be restricted for obvious reasons and most of the ash will fall nearby. Much of the visible plume consists of water vapor, like cloud, which will quickly dissipate. However smaller particles may be suspended for thousands of miles, and others in the upper atmosphere will simply float around the world for many weeks! Essentially there are two main types of suspended volcanic material that will stay visible, fine "Tephra" Ash (small rock or glass particles) and Sulfur Dioxide SO2 gas which forms Sulfate Aerosols. The ash can be visible for many days looking similar to a thinning smog and stay suspended for weeks contributing to beautiful sunsets. They vary in size and fall quicker with weight, proportionate to size. The Sulfate Aerosols can also be visible and look similar to high thin Cirrus Clouds for many days, but their affects in the Stratosphere can persist for several years causing cooling of the Earth's climate. Both spread and dissipate rather gradually traveling as clouds in the wind, like a giant swarm.

Big eruptions are in the magnitude of one every couple of years. Astronauts filmed a spectacular eruption on 12 June 2009 from the International Space Station of Russia's Sarychev Peak (6MB QuickTime) (NASA) (Wiki) (map). This eruption punched well through the Tropopause into the Stratosphere where the particles traveled all around the world. Above is an image of its giant ash cloud from an airliner over central Canada. Notice the higher bluish SO2 cloud behind and above it. The SO2 created a high altitude Cirrus looking cloud that spread around the world and could easily be seen by jet traffic in the Atlantic Ocean and Europe as textured thin cloud with defined details many days later until it slowly dissipated. Eventually the lower ash also spread out and formed a marked haze layer at the tropopause everywhere in the northern hemisphere that could be easily seen on the Earth's limb in twilight. Weeks later, sunsets and sunrises were still showing an obviously exaggerated afterglow due to this upper ash layer as in the photo to the left from Los Angeles, USA. The volcanoes near the Russian Kamchatka Peninsula and Alaska's Aleutian Islands are remarkably active and affect the North Pacific airways each year. Further away in the Philippians in 1991 Mt. Pinatubo (Wiki) had an even larger eruption which also caused beautiful sunsets in North America and Europe. Even more spectacular was the legendary 1883 eruption of Krakatau (Wiki) where global visual and climatic effects lasted several years. Noctilucent Clouds, discussed below, were also first documented after Krakatau's extreme eruption. You may wish to also read about "1816 -the Year with out a Summer" [wiki] caused by 1815's Mount Tambora [wiki] eruption .

Specialized scientific satellites (SO2 Map) (TOMS) can track associated Sulfur Dioxide clouds until they dissipate, but volcanic ash clouds are not as detectable. In addition, please note that aircraft weather radar does NOT detect volcanic ash. Iceland's 2010 eruption of Mt. Eyjafjallajokull (Wiki), (NASA), that closed European airspace with unprecedented economic repercussions, showed us that the technology is still being developed. It must be noted that, until further defined, any amount of ash is considered detrimental to aircraft and must be avoided. The trick of course, is to better define what constitutes as "ash" for aviation purposes. [CAA Info], [UK MetOffice ash Charts], [UK MetOffice aviation], [maps]

There are many active volcanoes around the world with continuous local ash and gas releases. Most smoldering volcanoes leave a thin local haze (Wiki) which stays at relatively low altitudes and dissipate quickly. Perhaps you have seen volcanic aerosols before and not realized it? For example, one volcano in  Japan (Mt Asama), (map) often fills the sky over Tokyo (130km SE) with a slight haze that most aviators falsely assume is pollution. Note that the vast majority of volcanic eruptions are simply low-level local events.

Volcano Krakatau 1883 (Wiki) (Sarychev 2009) Volcanic Stratospheric sulfur aerosols at 55,000 feet mid-Atlantic Ocean (Wik-=SO2)

NLC from ISS 2003 (Don Pettit NASA)

2014 Noctilucent Cloud Season SOON now, starting late May.

Link: [2013 Sightings]

Further reading:
[] Recommended
[Project PoSSUM .org]
[SpaceWeather daily map] -lower left
[NASA 2012 info]
[Wiki Noctilucent Clouds NLC]
[Polar Mesospheric Clouds PMC]
[Shuttle Plume adds to NLC]
[Wiki L-1011/Pegasus/AIM]
[Wiki Nacreous Clouds + PSC]
[Wiki Atmospheric Chemistry]
[NLC Observers Homepage]
[NLC -Submit your observation]
[Wiki Cloud Iridescence]
Noctilucent Clouds from an airliner.
Southern Noctilucent Clouds (EO)
There is a 2014 campaign to observe NLC from space using the XCOR Lynx [Lynx] [wiki] space plane called Project Possum [PoSSUM].
Unrelated, but perhaps interesting. On Saturn's moon Enceladus there are giant geysers of water vapor shooting up over 100 km. How would that look from the ground? (Wiki) (NASA) (Update)
Noctilucent Clouds from an airliner, looking north.
Noctilucent Clouds "NLC" (Wiki) are extremely high altitude wispy clouds that are so thin and difficult to see that you must observe them in twilight, practically at night with the sun shining only upon them because of their great altitude. Maximized with the sun about 11 below the horizon they can appear quite bright when they are there, however they are not always present. They come and go from night to night or even hour to hour. There is also a season from late May until mid August, for the Northern Hemisphere. From the aircraft you can see more clearly that they are often in giant clumps, separated by nothing. They are really  simply southward extensions from a giant pole cloud region where they are known as Polar Mesospheric Clouds PMC (Wiki). They are about 250,000 to 280,000 feet high and so are visible from many miles away. Winds and atmospheric oscillations at that altitude may make the clouds move as fast as your aircraft. Regardless, with a bright display overhead, you will feel humbled by your own relatively low altitude. Enjoy. (more below)
What makes a Noctilucent Cloud appear? You need 4 things. 1) enough moisture, 2) a cool enough temperature, 3) condensation nuclei, and 4) be in the right place at the right time to see them. Points one and two are related because the high altitude mesosphere temperature doesn't have to be as cool if the moisture is higher.  Apparently they were first documented after the exceptional eruption of Krakatau in 1883 that would have put some moisture into the extreme heights of the stratosphere and beyond into the mesosphere. NASA has also detected that some Space Shuttle exhaust also contributes to moisture at this level. Chemists, of course, have figured out that Earth's natural CH4 Methane Gas (Wiki) converts to H2O water by natural cosmic radiation (CH4-NASA) in the Mesosphere which leads a constant natural source of moisture for NLC. Of interest to pilots, to be discussed in the future, will be the rumored top secret US Aurora (Wiki) hypersonic spy plane, which could have methane powered engines. The coolest temperature of the entire planet Earth also happens to be at this high level of about 280,000 feet which is the top of the Mesosphere. Here temperatures can drop to about -100 C when the atmosphere is expanded by lower-level warming temperatures of summer. Incidentally, yes, that does mean that there is also a theoretical additional cooling from the moon due to tidal forces on the atmosphere.

All pilots know the basics of precipitation, super-cooled water droplets, and condensation nuclei (CCN) from pollutants and natural aerosols. But in turns out the primary source of condensation nuclei up at this height are thought to be some of the 100 tons of cosmic dust and micrometeorites that the Earth collects every day. NLC research is on going.

Lastly, it turns out that it is rather tricky to actually see Noctilucent Clouds. The season is only from late May until mid August. You need clear skies which are often obscured by low maritime cloud in the Arctic. You must be far enough north, usually well above 50, which rules out most of the world's population. NLC are only exceptionally visible from America or London. Northern Canadians, Scots, Scandinavians, Russians and Alaskans share an advantage. If you are too far north, you can't see them because it doesn't get dark. The sun needs to be well below the horizon which happens to be very late at night when most of us are asleep. If everything is working for you, then you still have to be in the right place at the right time with a display occurring. Aircrew have the advantage if you can get a twilight route on a great circle track between Europe and N. America in season.

Did you know that some Orbital Science [OS] pilots flying an ex-Air Canada Lockheed L-1011 airliner launched the AIM [AIM] satellite to study Noctilucent Clouds? They used the airborne Pegasus-XL rocket to put the AIM satellite in high polar orbit to learn more about NLC's water, temp, and dust. That same aircraft also put up a Canadian satellite [ACE] that studies atmospheric ozone, related to the Nacreous Clouds below.

Modern digital cameras can make NLC photography pretty easy. Hold the camera still and click in Automatic for starters. Other things to try include: turn your flash off, support camera still, manually focus to infinity, turn night mode on, activate noise reduction, compensate exposure +/- 1 or 2 as required, or use manual settings.

Other interesting high altitude clouds are Nacreous Clouds, also known as Polar Stratospheric Clouds (PSC), which are 50,000 to 80,000 feet high. They are a rare stratospheric cloud which is known as the "Mother of Pearl" cloud because of the iridescent multi-color look that it has. They are most common at winter in the southern Antarctic over Antarctica where temperatures are coolest and only a handful of researchers can witness them. However, they can rarely appear in the high northern Arctic in winter often associated with a stratospheric wave which creates a further dip in temperature allowing them to form. Temperatures must be below -78 C. Opposite to NLC, these PSC clouds are a winter phenomena that increase with the lack of sunlight in the arctic and cooling during winter. Very quickly, as the sun first emerges with Spring, a chemical reaction related to the evaporation of these clouds causes ozone depletion and creates the infamous Ozone Holes (Ozone Hole) that allow ultra violet radiation (UV) to the surface. Global warming at Earth's surface causes atmospheric expansion and cooling at high altitudes which should cause more PSCs in the future.

 In the tropics, a completely unrelated but similar looking (and smaller) "mother of pearl" cloud may sometimes be witnessed when a giant thunderstorm manages to punch into the stratosphere. Occasionally, iridescent Pileus Cap Cloud (more) may be seen.

Further reading:
[Wiki Sprites]
[Wiki TLE]
[Wiki Lightning].
[Wiki Plasma]
[Wiki Aeronomy]
[Geo Inst. U of Alaska Fairbanks]
[NASA Sprite Observing]
[Report Form]
[Yukka Ridge FMA Colorado]
[Euro Sprite Blog]
[Stanford University VLF]
[Photos: Lightning Wizard]
[ How to]
[ Sprites]
[Euro Sprite Blog]
Oscar van der Velde 2009
NMTech/NASA 1997 University of Alaska, Fairbanks
All aircrew have been close to Lightning (Wiki) and witnessed this amazing low-level light show, but few have ever seen a vertical "lightning" phenomena above a thundering cumulonimbus cloud. These Transient Luminous Events TLE (Wiki) last for only a split second and may raise up to 100 kilometers (60m miles) into the sky touching space. They are so rare that even NASA only first acknowledged their existence starting 1989. Since then there has been a lot of study but there are many things still unknown. We are not just talking about about Upward Superbolts, but rather an entire family of phenomena often generally referred to as Sprites. They all have enchanting names that include Red Sprites, Carrot Sprites, Blue Jets, Giant Blue Jets, Blue Starters, ElvesTrolls, Gnomes, and Pixies. Keep your eyes open and you will see one... eventually.

Astronauts have successfully filmed them using special high-speed low-light video cameras. There are also a few permanent research stations. The Yukka Ridge Field Station [YRFS] in Colorado, USA overlooks the great plains and often gets amazing results. Occasionally amateurs are now getting good video of them as well due to the affordability of high-end electronics and specialist software. Although they seem to be associated with particularly energetic thunderstorms that produce "Spider Lightning" and "Positive" lightning, there is otherwise no way of predicting them and their appearance seems a bit random.

There was a false rumor, started due to a defective photo, that a Sprite contributed to the failed reentry of the Space Shuttle Columbia in 2003 with another proven documented fault. However, no Sprite/Aircraft encounter has ever been witnessed and so avoidance should be strongly considered. It is considered very likely that an unmanned high altitude NASA balloon was downed by a blue jet in 1989.

Despite being very rare, Sprites and Blue Jets can be seen from aircraft, given the correct conditions, as I have personally witnessed several myself. Aircrew can assist researchers with observations by noticing the location and time for later analysis. Researchers will cross reference with archived weather satellite images to try to learn more [Report Form].

The concept of "Dark Lightning" may be of further interest [NASA-YouTube].


Meteor Trains
Further reading:
[Wiki Meteoroid]
[Wiki Meteorite]
[Wiki Earth Grazing Fireball]
[NASA Arctic Asteroid], [More]
[Yukon Meteor 2000], [Wiki]
[Utah Skies Asteroid 2009]
[NASA airborne Leonid Trains]
More: see our [Meteors] page.
Ewald Lemke, Yukon 2000 [of Atlin Realty]
Leonids Meteor Train 1998 [JAS]
Meteor Train 2012 []
Don Brown, 18 Nov 2009 [Utah Skies]
Long lasting Meteor "Smoke" Trains are pretty rare events for someone to witness, despite the Earth getting about 100 tons of space debris each day. I am sure you will get mesmerized if you ever see one and become hooked on Astronomy! Where was it from? Where did it go? What secrets of the universe were locked inside, and perhaps still drifting in the Stratosphere as dust? Did life come from meteors? Did some water come from space? Mysteries.

A great photograph (lower left) of a meteor train was taken 17 Nov 1998 by Ghazalah Al-Abed over Jordon [Jordanian Astronomical Society] about 20 minutes before sunrise.

A bright meteor, thought to be a small asteroid, was seen overhead the Canadian Yukon on 18 Jan 2000. It illuminated the sky like daylight and left a train that lasted 10 to 15 minutes [Story]. Ewald Lemke photographed the animated sequence at left in morning twilight. Later, NASA sent its research modeled U2 aircraft  high in the Stratosphere to collect some of its dust particles [NASA] and the search was on for pieces that may have hit the ground [Wiki].

Below is a spectacular image of a meteor train following a bright fireball on 19 Nov 2006 over Ireland. Conor McDonald of the Northern Ireland Astronomical Society [EAAS] and colleagues witnessed a -10 Fireball whose bright train lasted for 7 minutes while he took photographs. If you compare dates of these photos, you will notice many of these trains are reliably caused by Leonids Meteors. NASA studied this shower a few years ago during its peak using airborne observatories, flown by your NASA colleagues [Airborne Trains].

Above is another shot of a meteor train, oddly resembling a rocket plume. It was taken by Mr. Don Brown of Park City, Utah Dawn 18 Nov 2009, Rocky Mountains, USA. A bright meteor fireball over Utah left a remnant "train" in the upper atmosphere that was observed with first light, hours later, during dawn Wednesday 18th November 2009. Did you see a cloud resembling a rocket plume high above you before sunrise? It would have been visible for quite a distance from Utah or Colorado. [more], [more2] Utah, USA. Please contact me if there are any airborne images of this event.

Conor McDonald, Northern Ireland. 19 Nov 2006 [N. Ireland Amateur Astronomy Society]

Further reading:
[Wiki Plume]
[NASA Shuttle SRB rockets]
[Wiki Saturn V plume]
[Wiki Rockets]
[Shuttle Plume adds to NLC]
[Airborne YouTube STS117]  
[Airborne YouTube STS133]
More: see our [Space] page.
[Wiki Rocket Plume]
NASA STS-2. 12 Nov 1981 [NASA]
STS-120. 23 Oct 2007
NASA Ozone red from space [layer] [NASA]
NASA / Kim Shiflett STS-117. 8 June 2007 [NASA]

Big rockets like the old Saturn V or Space Shuttle can burn 15 tons of fuel in a second on takeoff. That is enough fuel to keep a Boeing 747 jumbo jet up in the air for 1 1/2 hours, so obviously there is going to be some kind of plume (Wiki) left behind. In 6 second, its the same amount of fuel for a jumbo to go from Los Angeles to London! The fascination with plumes is that it allows you to briefly comprehend the height and distance of the rocket that you would otherwise have no reference to judge. For just few minutes things that are truly far away seem incredibly close, before our perspective returns to its domestic normality. It gives us a chance to perceive that space is very far away, yet incredibly close at the same time.

For the foreseeable future, plumes are a required part of getting into space. The only way to get a payload up there is to exert a huge amount of energy which requires rocket engines. Solid fuel rockets, such as those attached to the Shuttle, are even more efficient. Its ironic that although the Space Shuttle has done enormous work researching the Ozone layer [Ozone], it has also contributed to its demise [Rockets]. Its plume has provided aerosols that have assisted Stratospheric Cloud "Nacreous Cloud" creation and ozone depletion. Further, its exhaust has also added moisture to help form the much higher Mesospheric Clouds "Noctilucent Clouds" [Shuttle NLC], [Noctilucent].

STS-120. 23 Oct 2007
YouTube video of Space Shuttle STS-133 from commercial airliner. Passenger Neil Monday (24 Feb 2011)

Further reading:
[Wiki Twilight Phenomena]
[Wiki Plume]
Controlled Gas release from STS-39. (CIV)
Dennis Mammana, California, USA  ( Jan Petter Jorgensen, Norway. 2009
When a rocket's exhaust is in space it no longer behaves like a simple earth bound plume. The gases are free to expand in all directions to a great size which looks very unique. The spectacular sight may be called a Twilight Phenomena [Wiki] as it can really only be seen in twilight when the sky darkens. Other releases may include scheduled waste dumps [toilet], or planned gas releases such as the [CIV] for experimentation.

These releases are very high and can be seen from hundreds of miles away. If you live near an active space launch facility then you will eventually see one. As an example, observers as far away as Phoenix can sometimes witness a display over Vandenberg near Los Angeles. There are some useful Vandenberg plots [Space Archive] which can assist in observing these plumes. Michael J O'Leary managed to get a very good animated sequence [Extremely-cool-gif] of a Minotaur release in 2005.

In 2009 there was a totally bizarre sight over Russia's White Sea that was witnessed by people nearby in northern Norway. A ground shot taken by Mr. Jan Petter Jorgensen, in the early dawn of Wednesday 9 Dec 2009 shows a distant illuminated missile plume, followed by bluish fuel venting, and an unusually giant luminous spiral from a destroyed satellite. Please contact me if you saw this phenomena from the air. [more1], [more2], [more3], [more4], [more5]


Zodiacal Light
Further reading:
[Wiki Zodiacal Light]
[Wiki Zodiacal Dust]
[Wiki Gegenschein]
[Wiki Cosmic Dust]
[Wiki Interplanetary Dust]
[Wiki Exozodiacal Dust]
[Wiki Accretion Disc]
[Wiki Circumstellar Disk]
[Wiki Protoplanetary Disk]class="ul2"
The Zodiacal Light is caused by dust particles in the planetary plane of the solar system. The further away you go away from the sun, the easier it is to see. These dust discs have been observed around other stars and are known as an Exozodiacal Disc [link] as in the examples above of Beta Pictoris PRC06-25 [more], a distant star in the southern hemisphere. It is possible that a zodiacal cloud may indicates a higher probable presence of planets [link]. Interestingly, all solar systems are thought to originate initially from a Protoplanetary Secretion Disc [link], as in the example below of PRC95-45c far away in the Orion Nebula. Interestingly, the Herschel infrared Space Telescope has also discovered water in far away Protoplanetary Discs [JPL].
Protoplanetary Secretion Disc - in Orion Nebula
Zodiacal Light left, Milky Way right. It is very obvious when conditions are right.
The Zodiacal Light [link] is not an atmospheric affect at all. Like the Milky Way, it has nothing to do with Earth what so ever. However, unlike the Milky Way, it is much closer and locally in our own Solar System. We are falsely categorizing it as an atmospheric effect because you may think it is when you notice it for the first time.

The Zodiacal Light is caused by scattered sun light on many countless small particles out in space that are in our solar system like mini dust planets. The dust originated from little bits of asteroids and comets that continually collide and evolve their orbits. They are mostly in the same plane as the planets and are concentrated greater nearer the sun mostly within the orbit of Venus. Individually, they have no significance, but together they can faintly reflect the sun like a faint hazy fog. This real glow is called the Zodiacal Light and it is always there. Unfortunately you cannot always see it because varying geometry sometimes has it low enough on the horizon to get confused with dawn or dusk. A normal murky smoggy sky may also rob you of the contrast to see it. However if you have a clear clean sky with favorable geometry the Zodiacal Light can appear incredibly bright. Given the right conditions, your view will be so obvious that you will not understand why you have never seen it before! Theoretically it can extend all the way up in the sky surrounding the zodiac and even have another reflective peak in the anti-sun position called the Gegenschein [link].

The Zodiacal Light is also known as the False Dawn because it is very similar to the first appearance of dawn, but without the follow-up of brightening immediately afterwards. In the tropics it can extend vertically upward but at higher latitudes it is always slanted with the zodiac. This makes it easy to identify from dawn because one edge will be slanted and the other may be vertical or over hanged, unlike a real evenly spread symmetrical dawn. In the northern hemisphere the Zodiacal Light is best observed in evening twilight in the Spring, or morning twilight in the Autumn.

Some Micrometeoroids [link] are actually particles from the Zodiacal Light. Pilots flying NASA's U2 aircraft [link] [U2] have actually collected Micrometeorites from the upper atmosphere for further study of their Presolar Grains [link] and collected at the Johnson Space Center, Texas. This dust is packed with information and modern analysis can figure out what kind of dust has been obtained. Alternatively, we actually have some particles returned from a comet in space using NASA's "Stardust" probe [more]. The Herschel Infrared Space Telescope has found that supernova are a major source of dust JPL.

Further reading:
[Wiki St Elmo's Fire]
[Wiki Ball Lightning]
[Wiki Ice Crystal  Halos]
[Atmospheric Optics Ice Halos]
[Atmospheric Optics Ice Crystals]
Green Flash, see our [Sun] page.
Airborne 22 Halo, Sundogs, and Pillar
Typical St Elmo's Fire. (Wiki)
Of the many other things that can be seen from an aircraft, St. Elmo's Fire [link] is probably the most dramatic to see for the first time. Originally reported rarely by sailors, it is also visible on aircraft windscreens when flying near electrically charged precipitation. It appears as dim static mini-lightning and flickers quickly, often only lasting a split second. The aircraft has been designed to coupe with static electric charge.

Although I have never seen a photo, I have heard first hand from several aircrew who have seen Ball Lightning [link]. If anyone ever gets an image, please send it into me.

Other fascinating sights are Halos [Wiki], [Atmospheric Optics]. These eye-catching perfectly-round circles and their associated bits are caused by ice crystals [Atmospheric Optics]. The standard 6 sided shape of a slowly falling gravity-aligned ice crystal is responsible for most of these sightings, but rarer affects are possible. From the ground, these ice crystals are often many miles away at heights over 30,000 feet. However, from the aircraft they could be just in the air around your immediate vicinity and a small climb of less then 200 feet may get you completely clear of the affect. The most common observations include the 22 Halo, followed by the left and right Sundogs [Wiki], and vertical ice Pillars [Wiki].

Something different?  : Plasma finger and St. Elmos Fire from the cockpit
   Looking through the cockpit window at St. Elmo's Fire towards a rare plasma finger (?) from the abyss. (Wiki)
Sand / Dust / and Smoke:
Further reading:
[Wiki Aerosols]
[Wiki Dust]
[NASA/GSFC Aerosol Maps]
[GSFC Sahara Desert Dust]
[GSFC Gobi Desert Dust]
[USGS Dust and Coral]
[NASA Dust and Hurricanes]
To be expanded in the future, but a quick mention. Dust from the Sahara Desert [link] does make it to the Caribbean and rarely to the USA. In fact, Gobi Desert dust [link] has made it across the Pacific Ocean to the USA as well. Forest Fire Smoke and Smog also spreads around the world.

This page with the NASA/GSFC team will allow you to see the current world's aerosols and backdated images [maps].

  Watch this interesting link to Caribbean Coral: [USGS]  
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