What does Dense atmosphere feel like?
- Thread starter DElrick
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GypsyComet
SOC-14 1K
Breathing "changes gear", and those with more than a touch of claustrophobia may feel acutely uncomfortable unless they are also swimmers.
The actual pressure difference can run quite a range, so anything from the sensation of being in an enclosed steam room up to a swimming sensation even when dry and walking.
Oxygen poisoning can occur even if the actual atmospheric fraction is normal, as the higher pressure alters the osmotic rates of oxygen flow across the membranes in the lungs. At "normally dense" pressures this won't be too bad, at least for someone born at "standard" pressures. It might get dicey for a human born in a thin atmosphere, or alien races adapted to Thin or Very Thin.
The actual pressure difference can run quite a range, so anything from the sensation of being in an enclosed steam room up to a swimming sensation even when dry and walking.
Oxygen poisoning can occur even if the actual atmospheric fraction is normal, as the higher pressure alters the osmotic rates of oxygen flow across the membranes in the lungs. At "normally dense" pressures this won't be too bad, at least for someone born at "standard" pressures. It might get dicey for a human born in a thin atmosphere, or alien races adapted to Thin or Very Thin.
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far-trader
SOC-14 10K
The way it seems to be meant to read is a higher pressure atmosphere but of the same standard mix. How dense is dense is the question I guess.
Some issues might be:
Breathing (minor to severe problems). I think you might have to work harder to move really dense atmo through your lungs. You might even need an assist apparatus, the opposite of the compressor mask, one that (somehow) reduces the pressure.
Pressure itself (minor to severe problems). Mostly when transitioning back to normal pressure. Like the bends (decompression sickness) perhaps in severe cases. Could include nitrogen narcosis and oxygen toxicity. But this one only be if the atmosphere were really dense and the person were breathing it unaided for a while and then too quickly went back to normal pressure. Or it might just be aches and pains from the pressure. Temporary sinus problems, vision distortion, and such from the pressure on the body if the pressure is much greater and the exposure sudden.
Internal combustion engines (and other fuel burners) from offworld (especially if designed for standard pressure) will need to be retuned at least or they won't run well. Poor range and more maintenance at least, simply not working in some cases.
Water boils at a higher temperature
If it's a normal gas mix (which is I think the intent of the rules, but it's really not clear) then you don't have to worry about extra fire hazards but if your take on it is a higher concentration of oxygen then that is a serious issue, along with others.
Some issues might be:
Breathing (minor to severe problems). I think you might have to work harder to move really dense atmo through your lungs. You might even need an assist apparatus, the opposite of the compressor mask, one that (somehow) reduces the pressure.
Pressure itself (minor to severe problems). Mostly when transitioning back to normal pressure. Like the bends (decompression sickness) perhaps in severe cases. Could include nitrogen narcosis and oxygen toxicity. But this one only be if the atmosphere were really dense and the person were breathing it unaided for a while and then too quickly went back to normal pressure. Or it might just be aches and pains from the pressure. Temporary sinus problems, vision distortion, and such from the pressure on the body if the pressure is much greater and the exposure sudden.
Internal combustion engines (and other fuel burners) from offworld (especially if designed for standard pressure) will need to be retuned at least or they won't run well. Poor range and more maintenance at least, simply not working in some cases.
Water boils at a higher temperature
If it's a normal gas mix (which is I think the intent of the rules, but it's really not clear) then you don't have to worry about extra fire hazards but if your take on it is a higher concentration of oxygen then that is a serious issue, along with others.
flammable. lots of chemical problems (for humans) with higher oxygen concentrations or pressures.
other factors are worth considering. projectile weapons may have shorter ranges, explosives may have smaller effects radii, winds will be slower, fast winds will be extremely destructive, flying animals can be heavier, flying fish may truly fly, less solar radiation on the ground, sound may carry farther.
far-trader
SOC-14 10K
Hmm, yes, sound. Interesting stuff there too flykiller.
Speed of sound will be slower I think (perhaps not significantly for hearing but it could affect ranging systems that use sound if not adjusted).
Voices and other sounds will be different (higher pitch).
Not just flying animals, but winged vehicles can be built different too. More lifting bodies or stub wings. All dependant on local gravity of course, and in most cases the two will balance.
All these are only going to be noticeable in extremely dense atmo though I think. Most of the time the PCs won't be affected.
One thing that might be useful and prominent in even mildly denser atmosphere is weather. It's likely to be a lot wetter, and maybe stormier, as precipitation/condensation will happen easier (I think).
Speed of sound will be slower I think (perhaps not significantly for hearing but it could affect ranging systems that use sound if not adjusted).
Voices and other sounds will be different (higher pitch).
Not just flying animals, but winged vehicles can be built different too. More lifting bodies or stub wings. All dependant on local gravity of course, and in most cases the two will balance.
All these are only going to be noticeable in extremely dense atmo though I think. Most of the time the PCs won't be affected.
One thing that might be useful and prominent in even mildly denser atmosphere is weather. It's likely to be a lot wetter, and maybe stormier, as precipitation/condensation will happen easier (I think).
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GypsyComet
SOC-14 1K
At the world-wide level, temperatures and climate will tend to be a bit more homogenous and probably slightly warmer, unless odd atmospheric chemistry negates the tendency to absorb and keep more solar radiation. Storms will likely be larger and slower, but no less destructive. Atmospheric water content will depend on hydrographic percentage and continental positioning, as always, but I suspect precipitation will come more easily, so coastal regions will be the only fertile areas unless the adjacent ocean is large enough to push water-bearing storms well inland. As such, large continents will be deserts ringed by green (or whatever).
Thanks for these answers guys. Definitely some good material here.
They are going to Jenghe (C799663-9). About 150 years ago, the orbit of Jenghe’s moon decayed to the point where it hit the planet. The resulting damage caused widespread earthquakes and flooding. The climate is still recovering, with large amounts of dust still in the atmosphere (which is the taint).
Jenghe's sun is M0V, which means the habitable zone is orbit 0. From Scouts, I worked out the gravity as 0.87 and the average temperature as around 23 degrees C.
I figured there'd be a large gravitational pull from the proximity to the sun, so the tides would be impressive. I hadn't thought about the storms.
I've figured that there are loads of islands of various sizes, with not much in the way of large landmasses left, so there would be nothing to break the wind up allowing it to be more volatile (sort of like the roaring forties in the Southern oceans on earth).
I'm not a scientist though, so some of this may be ignorant hand-waving. Any thoughts gratefully received.
They are going to Jenghe (C799663-9). About 150 years ago, the orbit of Jenghe’s moon decayed to the point where it hit the planet. The resulting damage caused widespread earthquakes and flooding. The climate is still recovering, with large amounts of dust still in the atmosphere (which is the taint).
Jenghe's sun is M0V, which means the habitable zone is orbit 0. From Scouts, I worked out the gravity as 0.87 and the average temperature as around 23 degrees C.
I figured there'd be a large gravitational pull from the proximity to the sun, so the tides would be impressive. I hadn't thought about the storms.
I've figured that there are loads of islands of various sizes, with not much in the way of large landmasses left, so there would be nothing to break the wind up allowing it to be more volatile (sort of like the roaring forties in the Southern oceans on earth).
I'm not a scientist though, so some of this may be ignorant hand-waving. Any thoughts gratefully received.
far-trader
SOC-14 10K
Just a late thought, along the lines of atmo composition, I think any atmo significantly different from the standard gas mix is likely intended to be under the Exotic or Corrosive values, like your higher than standard oxygen idea. Just for what it's worth. The UWP definitions are kinda vague on the whole issue.
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far-trader
SOC-14 10K
Ditto me on the IANAS 
but...
How big a moon? Anything that could be properly called a moon actually impacting the world is gonna be "buh-bye" world. Nothing remotely habitable left for a loooooong (eons) time. We're talking crust cracking, globe spanning super volcanoes, earthquakes off the scale, oceans evaporating, air so thick with dust, ash, sulfur, etc. that you could literally cut it with a knife, if said knife didn't melt in the heat or succumb to the extreme acid rain first It's a doomsday scenario, quite literally hell on earth.
At the very least, if you need some huge (but survivable) catastrophe, scale it down to the moon being upset in it's orbit by a close encounter with some other body (huge rogue dark star or mini black hole). The moon is still there, just much closer, resulting in higher tides, more earthquakes, increased vulcanism from the added internal heating and crust stress, melting icecaps raising sea levels from the increase in greenhouse gasses, and so on. Something like that would be more believable I think.
but...How big a moon? Anything that could be properly called a moon actually impacting the world is gonna be "buh-bye" world. Nothing remotely habitable left for a loooooong (eons) time. We're talking crust cracking, globe spanning super volcanoes, earthquakes off the scale, oceans evaporating, air so thick with dust, ash, sulfur, etc. that you could literally cut it with a knife, if said knife didn't melt in the heat or succumb to the extreme acid rain first
It's a doomsday scenario, quite literally hell on earth.At the very least, if you need some huge (but survivable) catastrophe, scale it down to the moon being upset in it's orbit by a close encounter with some other body (huge rogue dark star or mini black hole). The moon is still there, just much closer, resulting in higher tides, more earthquakes, increased vulcanism from the added internal heating and crust stress, melting icecaps raising sea levels from the increase in greenhouse gasses, and so on. Something like that would be more believable I think.
Don't know. I lifted that from library data (Behind the Claw I think) and I'm just trying to work with it.
Maybe the moon didn't hit the planet, but spun off into the sun after causing the tides and stuff. Or maybe it broke up before it hit, which would explain the dust/taint but without the more extreme results.
Or maybe I should just change the library data...
Thanks for the comments though.
hirch duckfinder
SOC-13
--*LURK*--
(I am playing in this game....at least there seems to be some chance we will actually arrive at Jenghe ;-))
(I am playing in this game....at least there seems to be some chance we will actually arrive at Jenghe ;-))
far-trader
SOC-14 10K
No problem, they're free
Breaking up wouldn't change the end result much though.
You mention dropping it into the sun, so I'm guessing you need to get rid of the moon because it's not there is some data? Anyway, if it broke free of the planet's gravity it'd probably have enough to go extrasolar. It's unlikely it'd head straight into the sun. And having a moon that was once part of the system wandering around out there might be an adventure hook in itself. Of course it wouldn't be moving fast, and everyone would know exactly where it was but still, say somebody left something precious in that moon lab when they scrambled to evacuate...
...oh, blast, security has been breached, I detect an active scan of these communications from an outside source. Suggest initiate a kill trace immediate.
:file_23:
Breaking up wouldn't change the end result much though.
You mention dropping it into the sun, so I'm guessing you need to get rid of the moon because it's not there is some data? Anyway, if it broke free of the planet's gravity it'd probably have enough to go extrasolar. It's unlikely it'd head straight into the sun. And having a moon that was once part of the system wandering around out there might be an adventure hook in itself. Of course it wouldn't be moving fast, and everyone would know exactly where it was but still, say somebody left something precious in that moon lab when they scrambled to evacuate...
...oh, blast, security has been breached, I detect an active scan of these communications from an outside source. Suggest initiate a kill trace immediate.
:file_23:
Easy way to find out: talk to your local dive shop about it, and see if they have a bell and a deep pool, and will let you try it.. The canonical "dense" is defined in TNE, somewhere, as, IIRC, up to 2Atm. ANything more, IIRC becomes exotic.
You can also, in some states, simply buy time in a hyperbaric chamber. (Some require a dive license or prescription, I've read). Again, your local dive shop may be able to arrange something for you.
I wouldn't count on it being free.
You can also, in some states, simply buy time in a hyperbaric chamber. (Some require a dive license or prescription, I've read). Again, your local dive shop may be able to arrange something for you.
I wouldn't count on it being free.
BlackBat242
SOC-14 1K
As far as my understanding of gaseous & planetary physics goes (which isn't very far), while there are a number of things that can cause a thin, very thin, or less atmosphere to form, or a normally-dense atmosphere to be partially removed, from a 1-G world, isn't the only way to get a more dense atmpsphere by having a gravity of more than 1?
Even if the planetary formation process creates more gas than Earth's did, unless there is something to hold more gas in closer to the ground, then gas pressure, rotational inertia vectors partially cancelling gravitational effects, etc. will simply extend the atmosphere further out... resulting in the loss of the excess gas?
Anyone have access to a planetary physics book... or a planetary physicist?
Even if the planetary formation process creates more gas than Earth's did, unless there is something to hold more gas in closer to the ground, then gas pressure, rotational inertia vectors partially cancelling gravitational effects, etc. will simply extend the atmosphere further out... resulting in the loss of the excess gas?
Anyone have access to a planetary physics book... or a planetary physicist?
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far-trader
SOC-14 10K
After thinking, google had some insight, cheaper than paying for a treatment
Hyperbaric chambers, as used for deep dive decompression seem to go up to nearly 6 atmospheres. There's no real problem adapting to this pressure (ear popping, just chew gum or swallow), as mentioned before the big problem is rapid decompression, as in going from a very dense atmo to a standard atmo, you get the usual decompression problems.
Therapeutic ones are not that high, not even 2 atmospheres and there's no decompression worries at all.
The high pressure ones do change your voice to a higher pitch, like helium will do.
Hyperbaric chambers, as used for deep dive decompression seem to go up to nearly 6 atmospheres. There's no real problem adapting to this pressure (ear popping, just chew gum or swallow), as mentioned before the big problem is rapid decompression, as in going from a very dense atmo to a standard atmo, you get the usual decompression problems.
Therapeutic ones are not that high, not even 2 atmospheres and there's no decompression worries at all.
The high pressure ones do change your voice to a higher pitch, like helium will do.
Blackthorne:
Atmospheric pressure is a function of depth and density.
If you have a denser gas mix, you get more weight in the column, and thus higher pressure.
If you have a taller atmosphere, you get more weight in the column, and hus higher pressure.
Now, atmospheric height is a function of outgassing, gravity, solar wind, and magnetic protection from the solar wind. I don't pretend to know the formulae, but it's well established for these factors.
Atmospheric density is also a function of outgassing, life processes, inorganic chemistry.
Local surface pressure varies in a given location by several percent just by weather...
Atmospheric pressure is a function of depth and density.
If you have a denser gas mix, you get more weight in the column, and thus higher pressure.
If you have a taller atmosphere, you get more weight in the column, and hus higher pressure.
Now, atmospheric height is a function of outgassing, gravity, solar wind, and magnetic protection from the solar wind. I don't pretend to know the formulae, but it's well established for these factors.
Atmospheric density is also a function of outgassing, life processes, inorganic chemistry.
Local surface pressure varies in a given location by several percent just by weather...
--*LURK*--
(I am playing in this game....at least there seems to be some chance we will actually arrive at Jenghe ;-))
Of course you'll arrive at Jenghe. You may regret being there of course...
Getting rid of the moon is easy. Just handwave and it wasn't there to begin with. I just don't want to invalidate the library data without at least trying to fit to it.
Mind you, that's an interesting idea about an unattached moon. I'll have to make a note on that for another day...
Cheers
David
Ever go through a swamp when the outside temp is 40*C+ like in Brazil or the Okefenokee in Florida/Georgia in August when breathing feels like ingesting water rather than air. A feeling of pea soup being stuck permanently to all parts of your body with each step feeling laboured. That would be a close feeling for a low dense atmosphere.
Fritz_Brown
Super Moderator
Well, Dan, you may just have to chew gum while you're "at depth", but if you stay too long, you will have problems. And, the longer you stay, the slower you have to take "coming up".
