Timeline for answer to An atmosphere that gets denser with increasing altitude, to support these flying creatures by thegreatemu
Current License: CC BY-SA 4.0
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| when toggle format | what | by | license | comment | |
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| Sep 28, 2023 at 20:39 | comment | added | thegreatemu | @MichaelRichardson see Nuclear Hoagie's comment pointing to another question that specifically addresses Rama | |
| Sep 28, 2023 at 13:40 | comment | added | Michael Richardson | @IlmariKaronen I guess it would depend on the size of the station and the speed of its rotation as to whether the pressure at the center would drop to a near vacuum. A Banks Orbital or Ringworld are examples of minimal loss of atmosphere from an open "top", but for cylinders in the style of Mckendree or O'Neill or Rama, what would the air pressure be at their axis? | |
| Sep 27, 2023 at 20:07 | comment | added | Ilmari Karonen | (See also: physics.stackexchange.com/questions/285922/…) | |
| Sep 27, 2023 at 20:02 | comment | added | Ilmari Karonen | @MichaelRichardson: Yes there is: centrifugal force (or inertia, if you prefer to look at things from a non-rotating reference frame). Any air inside a rotating station is going to start rotating along with it due to friction with the station's inner surface. And that will push it away from the axis of rotation, just like e.g. spinning a bucket of water pushes the water out towards the sides. | |
| Sep 27, 2023 at 19:48 | comment | added | Michael Richardson | @IlmariKaronen Unless the mass of the edge of the station is large enough to have a significant gravitational pull (not the centrifugal force) there is no reason that air would be pulled away from the center to form a near vacuum there. | |
| Sep 27, 2023 at 17:37 | comment | added | Robert Rapplean | Kudos for creative problem solving! | |
| Sep 26, 2023 at 15:45 | comment | added | Chieron | @NuclearHoagie ah, good to know. I guess that the lack of "upper atmosphere" to provide pressure will lead to a much flatter density profile. | |
| Sep 26, 2023 at 13:54 | comment | added | Nuclear Hoagie | @Chieron I was concerned about that too, but this answer suggests you wouldn't get major density stratification even in a cylinder tens of km in diameter: space.stackexchange.com/questions/31465/… | |
| Sep 26, 2023 at 8:50 | comment | added | Ilmari Karonen | @Chieron: True, but the scaling is anything but linear. Qualitatively, the bigger the station is, the less air there will be in the middle. As long as the station is at most a few kilometers / miles across, it's basically just a big air-filled rotating balloon, whereas if it's many hundreds of km / miles, there should be near vacuum in the middle. In between, where the diameter is comparable to the atmospheric scale height, there will be some pressure drop, but the actual math and physics needed to determine how much gets rather complicated. | |
| Sep 26, 2023 at 8:10 | comment | added | Chieron | Note that closer to the center of rotation the lower "gravity" will also result in a lower atmospheric density. Your blimp-creatures might not have it easier to fly there after all. | |
| Sep 26, 2023 at 5:07 | vote | accept | NimRad | ||
| Sep 26, 2023 at 5:06 | comment | added | NimRad | The best part about this answer is, that these stations actually exist as well in my setting- I really like this | |
| Sep 25, 2023 at 23:20 | history | answered | thegreatemu | CC BY-SA 4.0 |