This story about noctilucent clouds on NASA’s Science website made me think about a few things.
What I wonder is this: could noctilucent clouds be a proxy for cosmic ray interactions? While there are a lot of high energy galactic cosmic rays (GCR’s), there are GCR”s that are coming in at low energies as well. The lower the energy, the higher in the atmosphere would be their primary target area. The lower the energy, the more the earth’s magnetic field is deflecting them, redirecting then towards the magnetic poles like the protons of the solar wind (which have much lower energies).
Noctilucent clouds are not yet well understood, and given the size of the NLC ice crystals, cosmic ray interaction could be a possible trigger for their formation. As many of you know, cosmic rays leave tiny nucleation tracks, in the atmosphere. much like they do when entering a cloud chamber in a nuclear physics lab. I built one once as high school student and watched cosmic rays and other background radiation zip through.
Tracking particles and cosmic rays in a cloud chamber
As occurs in a supercooled cloud chamber (dry ice is involved) it would seem to me that cosmic ray interaction with very rarefied supercooled water vapor could be occurring in the 60-90 km altitude range. While the mechasism of a cloud chamber relies on supersaturation to leave a visbile trail, an interaction that forms a small ice crystal in the nanometer range may not need supersaturation. And, given that NLC’s form mostly at high latitudes, as aurora borealis does, there may be an interactive component of some sorts with earth’s magnetic field.
I’m also thinking NLC’s may very well be the equivalent of “dark matter in the universe” for our atmospheric interface with space and incoming solar radiation. As mentioned in the article “There is a substantial population of invisible noctilucent clouds, a population of much smaller ice crystals (< 30 nm) that don’t scatter much sunlight.” They may be small, but may have an albedo effect of some sort that is undiscovered. This is all just conjecture on my part, but I thought it would make for interesting discussion. If nothing else, NLC’s illustrate that we still don’t know how all aspects of the atmosphere work, and the portion that is closest to space is the one that is the most difficult to measure. I welcome discussion. – Anthony
UPDATE: Here is an excellent powerpoint presentation on NLC’s:
http://gwest.gats-inc.com/nlc_epo/epo_nlc_lesson.ppt
h/t to Fernando Mafili from comments
Strange Clouds at the Edge of Space
August 25, 2008: When in space, keep an eye on the window. You never know what you might see.
Last month, astronauts on board the International Space Station (ISS) witnessed a beautiful display of noctilucent or “night-shining” clouds. The station was located about 340 km over western Mongolia on July 22nd when the crew snapped this picture:
Above: Noctilucent clouds photographed by the crew of the ISS: more.
Atmospheric scientist Gary Thomas of the University of Colorado has seen thousands of noctilucent cloud (NLC) photos, and he ranks this one among the best. “It’s lovely,” he says. “And it shows just how high these clouds really are–at the very edge of space.”
He estimates the electric-blue band was 83 km above Earth’s surface, higher than 99.999% of our planet’s atmosphere. The sky at that altitude is space-black. It is the realm of meteors, high-energy auroras and decaying satellites.
What are clouds doing up there? “That’s what we’re trying to find out,” says Thomas.
People first noticed NLCs at the end of the 19th century after the 1883 eruption of Krakatoa. The Indonesian supervolcano hurled plumes of ash more than 50 km high in Earth’s atmosphere. This produced spectacular sunsets and, for a while, turned twilight sky watching into a worldwide pastime. One evening in July 1885, Robert Leslie of Southampton, England, saw wispy blue filaments in the darkening sky. He published his observations in the journal Nature and is now credited with the discovery of noctilucent clouds.
Scientists of the 19th century figured the clouds were some curious manifestation of volcanic ash. Yet long after Krakatoa’s ash settled, NLCs remained.
“It’s a puzzle,” says Thomas. “Noctilucent clouds have not only persisted, but also spread.” In the beginning, the clouds were confined to latitudes above 50o; you had to go to places like Scandinavia, Siberia and Scotland to see them. In recent years, however, they have been sighted from mid-latitudes such as Washington, Oregon, Turkey and Iran
Above: Noctilucent clouds over Mt. Sabalan, a 15,784 ft extinct volcano in northwestern Iran. Photo credit: Siamak Sabet. [more]
“This year’s apparition over Iran (pictured above) was splendid,” says Thomas. The Persian clouds appeared on July 19th, just a few days before the ISS display, and were photographed from latitude 38o N. “That’s pretty far south,” he says.
The genesis and spread of these clouds is an ongoing mystery. Could they be signs of climate change? “The first sightings do coincide with the Industrial Revolution,” notes Thomas. “But the connection is controversial.”
NASA is investigating. The AIM satellite, launched in April 2007, is now in polar orbit where it can monitor the size, shape and icy make-up of NLCs. The mission is still in its early stages, but already some things have been learned. Thomas, an AIM co-Investigator, offers these highlights:
1. Noctilucent clouds appear throughout the polar summer, are widespread, and are highly variable on hourly to daily time scales. A movie made from daily AIM snapshots shows the 2007 NLC season unfolding over the north pole: watch it.
Right: A daily snapshot of noctilucent cloud activity over the North Pole in 2007. Click on the image to set the scene in motion. Credit: AIM/Goddard Space Flight Center Scientific Visualization Studio.
2. There is a substantial population of invisible noctilucent clouds. Thomas explains: “NLCs are made of tiny ice crystals 40 to 100 nanometers wide—just the right size to scatter blue wavelengths of sunlight. This was known before AIM. The spacecraft has detected another population of much smaller ice crystals (< 30 nm) that don’t scatter much sunlight.” Clouds made of these smaller crystals are stealthy and hard to see, but a key part of the overall picture.
3. Some of the shapes in noctilucent clouds, resolved for the first time by AIM’s cameras, resemble shapes in tropospheric clouds near Earth’s surface. AIM science team members have described the similarities as “startling.” The dynamics of weather at the edge of space may not be as unEarthly as previously supposed.
These findings are new and important, but they don’t yet unravel the central mysteries:
- Why did NLCs first appear in the 19th century?
- Why are they spreading?
- What is ice doing in a rarefied layer of Earth’s upper atmosphere that is one hundred million times dryer than air from the Sahara desert?
AIM has just received a 3-year extension (from 2009 to 2012) to continue its studies. “We believe that more time in orbit and more data are going to help us answer these questions,” says Thomas.
Meanwhile, it’s a beautiful mystery. Just ask anyone at the edge of space.
h/t to Jack Simmons for the NASA story link.
I think that would read better as “…as high UP and as low a pressure…”.
Must be time for bed.
Just some ideas:
1. The cloud’s source of water vapor are icy meteors (often from old comet orbits intersected by the earth) burning up.
2. Jet aircraft. If they fly in the stratosphere, perhaps some wator vapor can find its way up that high, tho that seems a stretch.
3. Volcanic eruptions into the stratosphere, but there’s been little of that since Pinatubo.
4. Cosmic rays. I think their flux is greater near the magnetic poles.
5. Maybe Arctic “warming”, but it seems a stretch for that to put water vapor at such an extremely high altitude.
Forgot another:
6. Rocket launches. Yes, most occur in low latitudes, but there are some polar orbit launches. There may be enough solar radiation in low latitudes to prevent or quickly re-evaporate the condensation/freezing of trace water vapor there.
Thanks for the pic Carsten – the trees in the foreground give me a much better idea of the amount of sky covered by the clouds.
Midnight you say – I haven’t been so far north since a trip I undertook to Canada’s northern extremities during the mid 1970s.
I fondly remember laying on the ice at midnight looking up at the aurora and marveling at its delicate beauty.
Embarrassingly I also remember staggering back to my tent after a couple of ‘anti freeze beverages’ and cursing the poor light which caused me to stumble and lose my way ;-P
Such is youth…
“Could they be signs of climate change? “The first sightings do coincide with the Industrial Revolution,” notes Thomas. “But the connection is controversial.””
They JUST can’t help themselves, can they?
I would bet the the connection would be less “controversial” (more “consensus”) if there were a way to scare people with this.
This phenomenon is also known as PMCs – Polar Mesospheric Clouds. They are formed – 50 MILES – above the surface. Hard to scare anyone with that.
Just as a reminder, here is the Master List of everything that has been reported to be caused by “global warming,” including acne
http://www.numberwatch.co.uk/warmlist.htm
Pam is wooed by beauty
and by the smell
of fresh baked bread.
From the death of pseudo-science
she’ll be safely led.
Yes Peter, I only found out Sir Fred was a real scientist many years after my SF binge of the 60s. I too haven’t bothered much with the recent crop. But then you could argue that there’s been some creative Science Fiction generated with an AGW theme in the last decade or two 🙂
Its interesting being old enough to have experienced the “climate change” of the last PDO shift in the late 70s and to see the cycles. Oceans Rule!!
(I’m almost embarassed to admit I worked for the down under BOM for a number of years 🙂
Thank you!
Anthony, as a layman, I hope this post opens a dialogue between the solar
and earth scientists pursuing separate [MHO] research on the sun’s and earth’s
respective magnetic cycles.
I would really enyoy seeing a graph of the respective min / max of solar
activity compared with earth magnetic field variation over time.
Regards,
Robert Doyle
Given the size of the particles, UV light is mostly reflected by these clouds while IR radiation passes through, and visible light is attenuated?
I know that when I worked in the Arctic and in the high mountains, high cirrus clouds made sunny days very cold ones as well. Noctilucent clouds would do the same thing.
As Steve E (22:13:30) : post suggests it would seem more NLCs might be related to the Sun.
Where I live it is often cloudy in the morning but when the Sun gets high in the sky the clouds “burn off”. And the inverse, when there is less Sun there are more clouds, would seem to be a given. Since the Sun’s intensirty is waning as we move into a new solar cycle we might expect to see more NLCs & PMCs.
Sorry, can’t help myself:
From the stark black of space
through wrenching shades of blue
and onto the ground
through sad shades of brown.
Back in the late 60s we trained for high level navigation by flying out to 18 or 20 W from the UK. The first trip I saw a nacreous cloud, big, fat, blobby, very white. It was fairly well above us — we were at forty fivish thousand feet. The next night in the same area was a noctilucent cloud, really high. I have wondered if the two sighting were connected.
quote But then you could argue that there’s been some creative Science Fiction generated with an AGW theme in the last decade or two 🙂 unquote
I ought to be grateful to AGW in a way — I wrote a short story about global cooling and sold it to Analog. A writer may gain respect from any of the big three, but only Analog brings self-respect… Thank you, Dr Hansen.
JF
Anthony;
Your intuition is great.
Now we have.
1 – clouds (real)
2 – Nuclei (true)
3 – Correlated with solar activity
4 – Possibly correlated with the terrestrial magnetic field.
5 – The isotopic analysis will provide the source of water.
The numbers of LOTTO, please
This Austin is a live one.
We have been touching on this issue of ‘are we naturally heading toward an ice age that is being warded off by global warming’ for quite a while on this blog. I have posted a link to a Scientific American article published in 2005 titled HOW DID HUMANS FIRST ALTER GLOBAL CLIMATE?
This article offers an alternate explanation to Fred Hoyle’s meteor on demand theory, although I wouldn’t count that out as a possibility; for the last 400K years or so.
I keep coming back to this article because it provides an effective explanation for both warming and cooling. Here are two links to the author William Ruddiman and the article I refer to.
http://en.wikipedia.org/wiki/William_Ruddiman
http://www.sciam.com/article.cfm?id=how-did-humans-first-alte
I don’t think I can reproduce the article here as Scientific American still wants payment for it but it is more than worth the read. I offer this excerpt from his conclusions which I believe is ok to reproduce (up to you Anthony).
Implications for the Future
The conclusion that humans prevented a cooling and arguably stopped the initial stage of a glacial cycle bears directly on a long-running dispute over what global climate has in store for us in the near future. Part of the reason that policymakers had trouble embracing the initial predictions of global warming in the 1980s was that a number of scientists had spent the previous decade telling everyone almost exactly the opposite—that an ice age was on its way. Based on the new confirmation that orbital variations control the growth and decay of ice sheets, some scientists studying these longer-scale changes had reasonably concluded that the next ice age might be only a few hundred or at most a few thousand years away.
In subsequent years, however, investigators found that greenhouse gas concentrations were rising rapidly and that the earth’s climate was warming, at least in part because of the gas increases. This evidence convinced most scientists that the relatively near-term future (the next century or two) would be dominated by global warming rather than by global cooling. This revised prediction, based on an improved understanding of the climate system, led some policymakers to discount all forecasts—whether of global warming or an impending ice age—as untrustworthy.
My findings add a new wrinkle to each scenario. If anything, such forecasts of an “impending” ice age were actually understated: new ice sheets should have begun to grow several millennia ago. The ice failed to grow because human-induced global warming actually began far earlier than previously thought—well before the industrial era.
In these kinds of hotly contested topics that touch on public policy, scientific results are often used for opposing ends. Global-warming skeptics could cite my work as evidence that human-generated greenhouse gases played a beneficial role for several thousand years by keeping the earth’s climate more hospitable than it would otherwise have been. Others might counter that if so few humans with relatively primitive technologies were able to alter the course of climate so significantly, then we have reason to be concerned about the current rise of greenhouse gases to unparalleled concentrations at unprecedented rates.
The rapid warming of the past century is probably destined to persist for at least 200 years, until the economically accessible fossil fuels become scarce. Once that happens, the earth’s climate should begin to cool gradually as the deep ocean slowly absorbs the pulse of excess CO2 from human activities. Whether global climate will cool enough to produce the long-overdue glaciations or remain warm enough to avoid that fate is impossible to predict.
That was a good powerpoint presentation, until it blamed manmade CO2 for it…
“Others might counter that if so few humans with relatively primitive technologies were able to alter the course of climate so significantly, then we have reason to be concerned about the current rise of greenhouse gases to unparalleled concentrations at unprecedented rates. ” Trevor Pugh
Hmmm. Could it be that mankind is somehow special? Could it be that you know Who keeps our climate stable? Or did our campfires produce enough CO2 to ward off global cooling? I doubt the latter.
Its all connected.
Life is so interesting now. Dang that Chinese curse.
“Thus, it appears, NLCs are another indication of climate change”
Well, so? Waves are an indication of ocean surface change. Earthquakes are an indication of land surface change.
I just somehow think that those last few slides were thrown in to get the further funding. Pity; spoiled an otherwise informative presentation.
PeterW,
Those renamed, newly-moustachioed, NASA types will be railing against the Hydrogen economy as it generates water vapour, and demanding the use of Carbon. Hehehe 🙂
BTW I saw a TV ad recently for a Toyota, I think, hydrogen powered car. Environmentally friendly as it produces only H2O, not CO2.
Hmm, I thought, water vapour is the worst greenhouse gas, isn’t it.
The Powerpoint presentation is quite interesting. Slide 11, NLC Occurrence Versus Time, is quite well correlated with sunspot numbers. When sunspots are high the NLC count is low and vice versa.
Slightly off topic:
At sunset two nights ago, here in New Hampshire, I noted that, very subtle in a deep blue and cloudless twilight sky, were faint wave-clouds of the dimmest grey. At the time I wondered if ash from the Alaskan eruption in early August was passing over.
Here’s the problem! We’ve got the spirits of luck dragons flying high in the atmosphere!
What beautiful clouds! They have the same unearthly quality as the auroras. Really feel the cosmic energies tapping on our windowpane there.
However – is anyone considering the combined effect of lower solar magnetic flux plus steadily-falling geomagnetic field? More clouds? We’ve hardly seen the Sun all August in the UK.
Another mechanism: neutral: for water in the mesopause.
http://www.atm.helsinki.fi/~tpnousia/nlcgal/nlcinfo.html
ENSO conditions: it may influence the concentration of OH in mesopause?
http://www.terrapub.co.jp/journals/EPS/pdf/5204/52040261.pdf
Here is a nice video on noctilucent clouds on the AIM project page at LASP.
http://lasp.colorado.edu/aim/aim_highlights.htm
enjoy!