Category Archives: atmospheric science

atmospheric science, fog, methane, Titan

The Fog Creeps in on Methane Feet

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On Titan, That Is

Artists concept of Titan surface beneath its foggy atmosphere. Courtesy NASA. Click to embiggenate.
Artist's concept of Titan surface beneath its foggy atmosphere. Courtesy NASA. Click to embiggenate.

Astronomer Mike Brown of CalTech (who tweets under the name PlutoKiller) has a fascinating discussion on his blog about fog banks hovering over Titan’s south pole. Titan, if you haven’t been following outer solar system news, is the largest moon of Saturn. It has this thick atmosphere hanging over a frigid surface which itself boasts pools of hydrocarbons in the form of liquid and ice. The hydrocarbons are in the form of ethane (on the surface) and now it appears that the methane forms fog banks in the atmosphere. Methane breaks down in the presence of sunlight to make ethane, so this whole thing seems to point to some sort of cycle between atmosphere and surface on Titan.

I say “seems” because, as Mike discusses, there’s a lot of atmospheric science work to be done to completely understand what’s happening on this shrouded world to make methane clouds form.  Want to know more and see a cool pic? Run over to Mike’s blog and read what he has to say. He also has a link to his science paper outlining the fogbank on Titan and a nice, insightful discussion on peer review of his paper — and he invites folks knowledgeable in the Titan atmosphere to review his paper before it goes to publication.  How cool is that!

atmosphere, atmospheric science

Cloud Watching

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Eyeing Noctilucent Clouds

Noctilucent clouds seen over Blair, Nebraska. Image by Mike Hollingshead, as seen on Spaceweather.com. Go on over there for more gorgeous images. Click to embiggen.
Noctilucent clouds seen over Blair, Nebraska. Image by Mike Hollingshead, as seen on Spaceweather.com. Go on over there for more gorgeous images. Click to embiggen.

Folks lucky enough to be outside the past night or two in parts of North America and Europe have been treated to fine displays of noctilucent clouds.  These are ghostly looking clouds that seem to glow in the sky long after the Sun has gone down. People in northerly latitudes see them quite often, but it has been rare to see them as far south as France, for example, and certainly very rarely over southern Nevada and other mid-latitude locales.

Noctilucent means “night-shining” and nobody’s quite sure exactly what causes these glowing apparitions. They first appeared about the time of the eruption of Krakatoa in the 1885, and they are likely related to the distribution of fine dust in the upper atmosphere. But, where that dust comes from (it’s tough to waft dust from volcanoes UP to where these clouds form) is still a topic of great discussion among atmospheric scientists. It’s possible that dust from space is involved in some way.  The clouds themselves are made of water ice crystals that have formed around tiny particles of dust. They seem to be occurring more frequently now, over wider ranges of latitude. It’s very possible that their spread is related to global warming — also a topic under a lot of discussion these days.

Want to know more about these clouds?  Go here and here to read about what some atmospheric scientists have to say about noctilucent clouds. And, by all means, go outside tonight (and maybe the next few nights) and keep an eye out for glowing, wispy clouds like the ones in the picture above.

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Thanks to everyone who has written to wish us well during our recent move back to Colorado.  We’ve made it in fine shape and are settling in nicely.  It’s good to be back online and sharing science with y’all!