APOD: Clouds Near the Edge of Space (2012 Aug 22)

[APOD Robot]

Clouds Near the Edge of Space

Explanation: Noctilucent or night-shining clouds lie near the edge of space. From about 80 kilometers above Earth's surface, the icy clouds can still reflect sunlight even though the Sun itself is below the horizon as seen from the ground. Usually occurring at high latitudes in summer months, the diaphanous apparitions are also known as polar mesospheric clouds and may be connected to global change in the lower atmosphere. This serene view features a lovely display of noctilucent clouds over water recorded last month near the coastal town of Vaxholm, Sweden. The picture was taken near local midnight.

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[bystander]

APOD Collection: Noctilucent Clouds

[Guest]

"and may be connected to global change"

And maybe not.

[emc]

Beautiful color and well composed! I enjoyed today’s picture. The rocks brought Nessie to mind.

My favorite clouds are cumulus… they are fun to relax under, imagining whatever.

[orin stepanek]

Does the Earth lose air and moisture as the atmosphere nears the edge of space?

[Chris Peterson]

"and may be connected to global change"

And maybe not.

"May" means maybe, which leaves open the alternatives. However, the evidence of such a connection between global warming and noctilucent clouds is quite strong, as there is now a solid connection between global warming and reduced mesospheric temperatures. There's also an anthropogenic methane connection. Obviously, any atmospheric phenomena that show a change in character over the period of AGW (as do noctilucent clouds) will attract the attention of climatologists.

Curiously not mentioned in the caption is the recent report (just a few days ago) that meteor dust and smoke apparently provide the material that these clouds nucleate on... indeed, meteor dust may be critical to their formation.

[emc]

Does the Earth lose air and moisture as the atmosphere nears the edge of space?

The atmosphere gradually gets thinner at higher altitudes so I don’t expect there can be conduction into outer space although I have no proof that my suggestion is correct. The Karman line Wiki page provides some interesting data and quite a nice picture…

[Chris Peterson]

Does the Earth lose air and moisture as the atmosphere nears the edge of space? :?

There is no actual "edge of space". The atmosphere simply gets thinner and thinner. The force of gravity isn't much less in the near Earth space environment than it is on the ground, so atmospheric gases remain tightly bound to the planet. The Earth's magnetic field limits the impact of many high energy particles, which could eject some gas molecules, but that does happen very slowly (and certainly happened on planets like Mars without a strong magnetic field). On Earth, biological and geological processes readily replace whatever tiny losses to space occur.

[bystander]

Curiously not mentioned in the caption is the recent report (just a few days ago) that meteor dust and smoke apparently provide the material that these clouds nucleate on... indeed, meteor dust may be critical to their formation.

http://asterisk.apod.com/viewtopic.php? ... 95#p181195

[John W.]

Does the Earth lose air and moisture as the atmosphere nears the edge of space?
There is no actual "edge of space". The atmosphere simply gets thinner and thinner. The force of gravity isn't much less in the near Earth space environment than it is on the ground, so atmospheric gases remain tightly bound to the planet. The Earth's magnetic field limits the impact of many high energy particles, which could eject some gas molecules, but that does happen very slowly (and certainly happened on planets like Mars without a strong magnetic field). On Earth, biological and geological processes readily replace whatever tiny losses to space occur.

Thanks for some great posts Chris. I do understand your reference to the Biological & Geological replacements for the small loss of air & moisture to space. However, I don't see how the equation balances?

Have their been any studies you know of that have been able to somehow measure this loss?

Thanks again:)

John W.
Henrico, VA

[Chris Peterson]

Thanks for some great posts Chris. I do understand your reference to the Biological & Geological replacements for the small loss of air & moisture to space. However, I don't see how the equation balances?

Well, it doesn't balance perfectly. But the atmosphere is maintained in a sort of metastability by multiple feedback mechanisms, both positive and negative.

Have their been any studies you know of that have been able to somehow measure this loss?

I'd be surprised if there haven't been, but I don't have any references.

[ta152h0]

I remember, years ago, a statement was made that the equivalent of one bus sized ice material enters the Earths system every day, presumably turning to vapor instantly, as well as tons of " dirt ". I don't think the earth system has 1000 mph jet streams that can propel materials. to that altitude.

[nstahl]

ta1520h you do realize that ice and "dirt" mentioned is entering from above, as meteors? As far as our losing air and moisture, no doubt we do. I'm sure estimates have been made but they'd be only that. I believe I've read it increases with strong solar "weather".