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NASA Snaps Mysterious "Night-Shining" Clouds
coondoggie writes to tell us that NASA has captured some pretty impressive images of the Alluring noctilucent (or "night-shining") clouds. These clouds are made up of ice crystals and dust and are formed at high altitudes near the poles. "Very little is known about how these clouds form over the poles, why they are being seen more frequently and at lower latitudes than ever before, or why they have been growing brighter. AIM will observe two complete cloud seasons over both poles, documenting an entire life cycle of the shiny clouds for the first time. 'It is clear that these clouds are changing, a sign that a part of our atmosphere is changing and we do not understand how, why or what it means,' stated AIM principal investigator James Russell III of Hampton University, Hampton, Va. 'These observations suggest a connection with global change in the lower atmosphere and could represent an early warning that our Earth environment is being changed.'"
http://www.spaceweather.com/nlcs/gallery2007_page9.htm has a Noctilucent Cloud gallery. I haven't seen them yet myself, but it'll be interesting to see if AIM manages to find an explanation for them. It's an intriguing mystery!
Murphey's fighting Occam, and we're in the stands.
Don't mod down just because you don't get the reference. How anyone could possibly not get the Simpsons reference here, I have no idea. Hand in your damn geek cards.
- None can love freedom heartily, but good men; the rest love not freedom, but license. -- John Milton
One theory trying to explain these clouds is the X-ray activity of the sun. The sun is a highly variable star when it comes to X-rays. During its 11-year cycle, the X-ray flux emitted by the sun varies by a factor of 15, with ferocious bursts. We are at a solar minimum, so we see few sun spots and the X-ray activity is also lower on average.
I found an article that is short and readable explaining the link between solar cycles and X-rays: http://solar.physics.montana.edu/nuggets/2000/000407/000407.html. Note that the X-ray activity can vary hugely from the current solar minimum to, say, the 2000-2001 solar max.
The problem is that we don't have that much data on it yet. We need to accumulate several cycles worth of observations before we can answer these questions:
* When does the sun emit X-rays? Is it linked to sun spots?
* What do solar X-rays do to the upper atmosphere?
The X-rays are absorbed by the ionosphere (fortunately for life forms), and this energy transfer is not well known. During each solar minimum, less X-rays arrive in the upper atmosphere, which therefore should cool down. Is it the reason why we see these noctilucent clouds? If so, they should start disappearing in a couple of years, when sun spots return.
This is a very interesting keyhole on a yet unknown mechanism. I hope we'll see updates on the subject.
Fantasy: http://ferrisfantasy.blogspot.com/
I've seen these several times over the North Atlantic in the summer.
If you're not paying attention, your first impression is that they look like cirrus clouds viewed from the ground, only much more beautiful.
It's when you remember that you're already 30+ thousand feet up, and that these look like cirrus do when you're on the ground, that you realize how high they are. (That's plain English for 'mesosphere.')
Like satellites, you can see them when your sky is dark but they are catching sunlight due to their altitude.
Right up there with northern lights as a visual treat.
Never shake hands with a man you meet in a fertility clinic.
Skeptics like to cherry pick the year 1998, because it had an exceptionally strong El Nino which raised global temperatures that year; compare to it, the following years don't look as warm. But if you look at the overall trend, the pre-1998 trend has largely continued post-1998. It certainly has not turned negative.
The whole "declining in 2007 to a 1983 level" means that there was some month in 2007 which was the same temperature as some month in 1983. What is relevant, however, is that the temperature trend was positive from 1999-2007.
Even Anthony Watts, the surface temperature skeptic, has contradicted the Telegraph's claims; he said, "On the TLT graph [note: he means the TLS graph], for the years 1998 to present, there appears to be a slight downward trend in lower stratospheric temperature [note: we don't live in the stratosphere; note also that greenhouse warming predicts stratospheric cooling along with tropospheric warming], and this is what I believe Christopher Booker is referencing in his article in the Telegraph. Note that there have been other downward trends in the nearly 30 year measurement history, but the overall trend in the TLT, TMT, and TTS channels has been positive, so a short downward trend doesn't necessarily prove anything." not to mention the newly revised figures for US surface temperatures showing that the 1930s had four of the 10 warmest years of the past century, with the hottest year of all being not 1998, as was previously claimed, but 1934 1998 and 1934 were a statistical tie both before and after the revised figures; the revision is not significant in that regard. We always knew that U.S. temperatures in the 1930s were comparable to the 1990s. This has nothing to do with global warming, however; globally, temperatures in the 1990s were significantly higher than the 1930s. As another poster said, it's become PC to tack on "global warming" to proposals in hopes of getting funding. Oh come on. If you think that you can sneak a shoddy proposal past a grant committee by tacking on an irrelevant reference to global warming, you're incredibly naive.