SFRPG

The forum for Science Fiction Role Playing Game inspiration and information! So Say We All!
It is currently Mon Jul 23, 2018 3:30 pm

All times are UTC




Post new topic  Reply to topic  [ 8 posts ] 
Author Message
PostPosted: Tue Jul 21, 2015 1:54 pm 
Offline
User avatar

Joined: Mon Dec 02, 2013 1:43 pm
Posts: 309
Location: Queens, NY
In the 2300 worldgen section, there's a chart where you determine atm oxygen based on ocean coverage, then multiply by atm pressure to determine total oxygen pressure.

Can someone tell me if that's the equivalent of partial pressure? And do the listed human tolerances of 0.05/0.4 hold up?

Also interested in some suggestions about comfort zones. What's a good cutoff point to make a note that the air is technically safe to breathe but can be difficult for newcomers?


Top
   
PostPosted: Tue Jul 21, 2015 4:02 pm 
Offline
User avatar

Joined: Tue Jul 08, 2008 8:42 pm
Posts: 2699
Location: Texas, USA
I believe that was the intent.

_________________
My friends call me Richard. You can call me Sir.
www.XmasDragon.com


Top
   
PostPosted: Tue Jul 21, 2015 4:51 pm 
Offline
Administrator
User avatar

Joined: Thu Jul 03, 2008 1:22 am
Posts: 5314
This might be of use: viewtopic.php?f=30&t=1254

And yes, partial pressure of a gas is its percentage in the atmosphere * the pressure of the atmosphere.

_________________
SFRPG Owner/Admin
This post (or any other post I made here) may not be quoted or copied beyond the SF RPG boards without my explicit permission.
evildrganymede.net - visit the The Worldbuilding Hub
Check out my Youtube channel for all my streamed gaming videos!


Top
   
PostPosted: Tue Jul 21, 2015 5:14 pm 
Offline
User avatar

Joined: Mon Dec 02, 2013 1:43 pm
Posts: 309
Location: Queens, NY
That link is really interesting. Makes me think that:

a) the oxygen % tied to hydro on that chart should plateau a bit more at the top end, perhaps only 1% per 10% water.
b) the effect of density might need to be seriously muted, e.g. multiply O2 % by (1+atm/10), so a 1.5 atm world with 20% O2 would have a ppO of 0.23

Something along those lines... or perhaps:

c) if there's oxygen producing life, ppO is 16+1d6 %


Top
   
PostPosted: Tue Jul 21, 2015 5:33 pm 
Offline
Administrator
User avatar

Joined: Thu Jul 03, 2008 1:22 am
Posts: 5314
Partial pressure is what it is - it's a real, physical measurement, not a game rule - so you can't "mute it" :). Your example world would have an O2 partial pressure of 1.5*0.2 = 0.3.

What's interesting is that even slightly denser atmospheres would cause a lot of problems for human habitability (which isn't surprising, since we're evolved to live on Earth with its atmospheric parameters). e.g. The Oxygen pressure would pretty much have to cap out at 0.35 (no matter how high the atmospheric pressure was) or every lightning strike would cause a firestorm. And the Nitrogen pp would have to remain low enough for humans to tolerate without nitrogen narcosis.

_________________
SFRPG Owner/Admin
This post (or any other post I made here) may not be quoted or copied beyond the SF RPG boards without my explicit permission.
evildrganymede.net - visit the The Worldbuilding Hub
Check out my Youtube channel for all my streamed gaming videos!


Top
   
PostPosted: Tue Jul 21, 2015 6:37 pm 
Offline
User avatar

Joined: Mon Dec 02, 2013 1:43 pm
Posts: 309
Location: Queens, NY
EDG wrote:
Partial pressure is what it is - it's a real, physical measurement, not a game rule - so you can't "mute it" :). Your example world would have an O2 partial pressure of 1.5*0.2 = 0.3.


Oh, I understand that. I was trying to come up with an approach that would create a sort of bell curve for oxygen content, so that increased ocean coverage and increased atm density offered a diminishing return.

And now I'm thinking that the weird mistake in 2300 is associating ocean coverage with a percentage of oxygen, when it ought to be a volume of oxygen. Regardless of how much other gas is there to start with, a plant's gonna produce what a plant's gonna produce, right?

There should be a chart that multiplies ocean coverage by planet surface area to determine a quantity of oxygen, which you'd calculate as a percentage of the total atmosphere.

A world that's Earth sized, with 70% ocean coverage, produces the baseline, 0.2 bars or whatever is an easy number. Earth's atm is 1 bar, so ppO is 20%
A world that's 5,000 km in radius, with the same ocean coverage, produces 60% as much, or 0.12 bars. If this world's total atm is 0.8, your ppO is 15%

And so on.


Top
   
PostPosted: Tue Jul 21, 2015 9:53 pm 
Offline

Joined: Tue Nov 24, 2009 10:44 pm
Posts: 138
EDG wrote:
Partial pressure is what it is - it's a real, physical measurement, not a game rule - so you can't "mute it" :). Your example world would have an O2 partial pressure of 1.5*0.2 = 0.3.

What's interesting is that even slightly denser atmospheres would cause a lot of problems for human habitability (which isn't surprising, since we're evolved to live on Earth with its atmospheric parameters). e.g. The Oxygen pressure would pretty much have to cap out at 0.35 (no matter how high the atmospheric pressure was) or every lightning strike would cause a firestorm. And the Nitrogen pp would have to remain low enough for humans to tolerate without nitrogen narcosis.


Hmm, has anyone ever distinguished things like if O2 pressure is high enough to translate lightning strikes into firestorms would be bad for any but very unusual life forms while presumably different Nitrogen pp ranges (perhaps with some limits) would be tolerable by different lifeforms.

Frank


Top
   
PostPosted: Tue Jul 21, 2015 10:46 pm 
Offline

Joined: Thu Jul 12, 2012 10:11 pm
Posts: 316
Location: Near Frankfurt, Germany
ffilz wrote:
EDG wrote:
Partial pressure is what it is - it's a real, physical measurement, not a game rule - so you can't "mute it" :). Your example world would have an O2 partial pressure of 1.5*0.2 = 0.3.

What's interesting is that even slightly denser atmospheres would cause a lot of problems for human habitability (which isn't surprising, since we're evolved to live on Earth with its atmospheric parameters). e.g. The Oxygen pressure would pretty much have to cap out at 0.35 (no matter how high the atmospheric pressure was) or every lightning strike would cause a firestorm. And the Nitrogen pp would have to remain low enough for humans to tolerate without nitrogen narcosis.


Hmm, has anyone ever distinguished things like if O2 pressure is high enough to translate lightning strikes into firestorms would be bad for any but very unusual life forms while presumably different Nitrogen pp ranges (perhaps with some limits) would be tolerable by different lifeforms.

Frank


Plenty of plant species have adapted to periodic fires; no doubt we´d see a lot more of that on worlds with high O2 partial pressure. Plus, presumably, oceanic (and probably all other aquatic) life would be unaffected by wildfires.

_________________
Space isn't remote at all. It's only an hour's drive away if your car could go straight upwards. Sir Frederick Hoyle
Earth is the cradle of humanity, but one cannot live in a cradle forever. Konstantin Tsiolkovsky
Man has earned the right to hold this planet against all comers, by virtue of occasionally producing someone completely bat**** insane. xkcd #556
Just like people, stars can be very important without being terribly bright. Phil Plait, "Bad Astronomy"


Top
   
Display posts from previous:  Sort by  
Post new topic  Reply to topic  [ 8 posts ] 

All times are UTC


Who is online

Users browsing this forum: No registered users and 1 guest


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
cron
Powered by phpBB® Forum Software © phpBB Limited