APOD: Veins of Heaven (2014 Jul 31)

[APOD Robot]

Veins of Heaven

Explanation: Transfusing sunlight through a a still dark sky, this exceptional display of noctilucent clouds was captured earlier this month above the island of Gotland, Sweden. From the edge of space, about 80 kilometers above Earth's surface, the icy clouds reflect sunlight even though the Sun itself is below the horizon as seen from the ground. Usually spotted at high latitudes in summer months the night shining clouds made a strong showing this July. Also known as polar mesospheric clouds they are understood to form as water vapor driven into the cold upper atmosphere condenses on the fine dust particles supplied by disintegrating meteors or volcanic ash. NASA's AIM mission provides daily projections of noctilucent clouds as seen from space.

<< Previous APOD

This Day in APOD

Next APOD >>

[/b]

[geckzilla]

Beautiful composition and I love the title metaphor.

[owlice]

^ what she said.

[Pedr Fawr]

That should be "mesospheric" not "mesopheric". You left out the second "s"

[neufer]

That should be "mesospheric" not "mesopheric".

I love the title metaphor.

Is Geck suddenly going sopheric on us?

SOPHERIC: of or relating to the professional Jewish scribes,
the Sopherim, or the literature associated with them.

[Boomer12k]

Number 1 spoke in his non-emotional voice. "At S.P.E.C.T.R.E. our tentacles reach out to surround the world in our crushing embrace".

But this picture is MUCH BETTER!!!!! Awesome shot.

:---[===] *

[zbvhs]

So, what? Are these clouds lit by sunlight or do they glow in the dark somehow? If the latter, what's the mechanism? Static discharge of some sort?

[Psnarf]

How does water get up there? I recall that after the Space Shuttle drops the external solid fuel rockets, liquid hydrogen and oxygen take over. That leaves a water vapor trail. Does that water vapor then disperse to become condensed by meteor dust? 80 Km is a bit of a stretch for even the most powerful lightning storms, which seem to get up as far as the tropopause, but not beyond the stratosphere.

I propose that every rocket or balloon that reaches above the stratosphere carry a small tank or balloon of ozone gas to be released at the ozone layer altitude. It takes 70-140 years for a chlorine molecule from chlorofluorocarbons to sink far enough to stop catching oxygen ions; we have yet to release the last chlorofluorocarbon molecule. An amendment might add water vapor to increase the coverage of noctilucent clouds for our viewing pleasure.

[Psnarf]

Noctilucent clouds are lit by sunlight scattered by ice crystals. That's why you can see them only a short time after the sun sets. In the land of perpetual sunlight, whenever the sun sinks below a particular degree below the horizon, voila!

To calculate the degrees below the horizon, draw a tangent to Earth from the Sun to 80km, then a tangent to the horizon? Then see where they intersect?

[bstanding]

Rather than Veins of Heaven, I'd have gone with "veils of the morning" from Yeats' "The Lake Isle of Innisfree" :

And I shall have some peace there, for peace comes dropping
slow,
Dropping from the veils of the morning to where the cricket
sings;
There midnight’s all a glimmer, and noon a purple glow,
And evening full of the linnet’s wings.

[orin stepanek]

Beautiful photo! I divided it in halves and got two wallpapers!

[Chris Peterson]

How does water get up there? I recall that after the Space Shuttle drops the external solid fuel rockets, liquid hydrogen and oxygen take over. That leaves a water vapor trail. Does that water vapor then disperse to become condensed by meteor dust?

All parts of the atmosphere contain all the gases found anywhere in it. The amount of mixing that occurs vertically is determined by various factors, and in the case of water, much is trapped at the tropopause, and much of what passes that is condensed out in the stratosphere. But some still makes it to the mesosphere. Most of this water originally evaporated off the oceans. It's unlikely that human activities like spaceflight are significantly impacting the upper atmospheric water mass.

[hlwelborn]

Such a lovely little planet we have.

[Ann]

That's a lovely picture, and noctilucent clouds are really very beautiful.

Ann

[neufer]

How does water get up there? I recall that after the Space Shuttle drops the external solid fuel rockets, liquid hydrogen and oxygen take over. That leaves a water vapor trail. Does that water vapor then disperse to become condensed by meteor dust?

All parts of the atmosphere contain all the gases found anywhere in it. The amount of mixing that occurs vertically is determined by various factors, and in the case of water, much is trapped at the tropopause, and much of what passes that is condensed out in the stratosphere. But some still makes it to the mesosphere. Most of this water originally evaporated off the oceans. It's unlikely that human activities like spaceflight are significantly impacting the upper atmospheric water mass.

<<Nioctilucent clouds are composed of tiny crystals of water ice up to 100 nm in diameter and exist at a height of about 76 to 85 km, higher than any other clouds in Earth's atmosphere. Clouds in the Earth's lower atmosphere form when water collects on particles, but mesospheric clouds may form directly from water vapour in addition to forming on dust particles. The sources of both the dust and the water vapour in the upper atmosphere are not known with certainty. The dust is believed to come from micrometeors, although particulates from volcanoes and dust from the troposphere are also possibilities. The moisture could be lifted through gaps in the tropopause, as well as forming from the reaction of methane with hydroxyl radicals in the stratosphere.

The exhaust from Space Shuttles, which was almost entirely water vapour after the detachment of the Solid Rocket Booster at a height of about 46 km, was found to generate minuscule individual clouds. About half of the vapour was released into the thermosphere, usually at altitudes of 103 to 114 km. The exhaust can be transported to the Arctic region in little over a day, although the exact mechanism of this very high-speed transport is unknown. As the water migrates northward, it falls from the thermosphere down into the colder mesosphere, which occupies the region of the atmosphere just below. Although this mechanism is the cause of individual noctilucent clouds, it is not thought to be a major contributor to the phenomenon as a whole.

As the mesosphere contains very little moisture the ice crystals can form only at temperatures below about −120 °C. This means that noctilucent clouds form predominantly during summer when, counterintuitively, the mesosphere is coldest, therefore they can't be observed (even if they are present) inside the Polar circles because the Sun is never low enough under the horizon at this season at these latitudes. Noctilucent clouds form mostly near the polar regions, because the mesosphere is coldest there.

Ultraviolet radiation from the Sun breaks water molecules apart, reducing the amount of water available to form noctilucent clouds. The radiation is known to vary cyclically with the solar cycle and satellites have been tracking the decrease in brightness of the clouds with the increase of ultraviolet radiation for the last two solar cycles. It has been found that changes in the clouds follow changes in the intensity of ultraviolet rays by about a year.>>

[rstevenson]

Noctilucent clouds are lit by sunlight scattered by ice crystals. That's why you can see them only a short time after the sun sets. In the land of perpetual sunlight, whenever the sun sinks below a particular degree below the horizon, voila!

To calculate the degrees below the horizon, draw a tangent to Earth from the Sun to 80km, then a tangent to the horizon? Then see where they intersect?

From this description, they'll just intersect at the Sun, the point of origin of the two tangents. So I'm guessing that's not what you meant. How about a little diagram?

Rob

[DavidLeodis]

Hoping to find the date and time that the image was taken I looked up the image's Exif data that was available through the image properties and then using an Exif viewer website. I was amused to find that the image create date was "June 19, 2016 9:24:39AM (timezone not specified)".

I wonder what the actual date/time was

[Case]

I wonder what the actual date/time was?

The photographer only specifies “Date: July 2014” on the TWAN page.
The exif data also shows two modifications by Photoshop at 2014:07:17 23:31:04+02:00 and 2014:07:17 23:37:07+02:00. These are based on a pc clock, thus more likely accurate than date and time from the camera.
There are some stars faintly visible (Ursa Major, Perseus), that should't be in those positions yet at the date and time for the modification, which leads me to believe the photo was taken on the previous day or earlier. If the photo was taken on the 16th, it would be around 01:30 am, roughly toward the north. If it was taken earlier, it would be about 4 minutes later per day.

[DavidLeodis]

I wonder what the actual date/time was?

The photographer only specifies “Date: July 2014” on the TWAN page.
The exif data also shows two modifications by Photoshop at 2014:07:17 23:31:04+02:00 and 2014:07:17 23:37:07+02:00. These are based on a pc clock, thus more likely accurate than date and time from the camera.
There are some stars faintly visible (Ursa Major, Perseus), that should't be in those positions yet at the date and time for the modification, which leads me to believe the photo was taken on the previous day or earlier. If the photo was taken on the 16th, it would be around 01:30 am, roughly toward the north. If it was taken earlier, it would be about 4 minutes later per day.

Thanks Case for your helpful reply.