What are you talking about? There's nothing there about problems caused by moving from the mountains to the sea shore.
Thin Atmosphere
- Thread starter Timerover51
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What are you talking about? There's nothing there about problems caused by moving from the mountains to the sea shore.
Perhaps we are discussing a different sort of problem. O2 sat is not a problem - go from high to low, you're actually at an advantage. However, going from a cool dry climate to a hot humid climate invokes a different set of problems. The Gran Chaco is athwart the Tropic of Capricorn, much of it between the Tropic and the equator. Someone accustomed to a montane climate would find the hot, humid air of the region very oppressive. Rather like being used to Colorado and then finding yourself in a Houston summer. Especially if we're talking about troops on the march, there'd be problems with heat exhaustion and, possibly, dehydration if they weren't making sure to drink enough to replace the water they were losing.
Under the exertion of march, either condition would present symptoms including more rapid breathing and a tendency to fatigue more easily, therefore superficially similar to the fatigue one encounters on moving from low to high altitude, though based on different biological circumstances.
Timerover51
SOC-14 5K
Too high a pressure of Oxygen can do a nasty job on the lungs, as they discovered in WW2 when using pure oxygen breathing sets.
Has anyone ever speculated on what type of vegetation you would have on a thin to very thin atmosphere world? I keep thinking something on the order of Tundra or edge of tree line.
Has anyone ever speculated on what type of vegetation you would have on a thin to very thin atmosphere world? I keep thinking something on the order of Tundra or edge of tree line.
Timerover51
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Pardon my thread necromancy on this, but I found this comment in the In-flight Feeding book. I am not sure if these experiments were ever followed up or confirmed, but it does make for some possible ideas.
Hadn't yet, so spitballing some ideas...
(All degrees in °C)
first off, a quick google to confirm my understanding that temperature seems to be the primary issue for trees: Alpine Treelines: Functional Ecology of the Global High Elevation Tree Limits. This document notes that the growing season is primarily based upon soil temps being above freezing... it looks like the annual mean temperature for the treeline is about 6.5°
Also, remembering that water's boiling point correlates to pressure; lower pressure, lower boiling point. 273.16 K at a pressure of 611.2 Pa is the triple point; below that pressure, you only have solid and gaseous states. Standard pressure is 100kPa. Thin is 25 to 75 kPa, and very thin is 10-25 kPa, so we have a liquid water state.
For Very Thin, I find at Engineering Toolbox, roughly 50° to 64° boil, and 0° freeze.
For Thin, about 64° to 92° boil, and a 0° freeze point.
You've got competing size demands:
- minimum surface area for thermo-regulation
- maximum surface area for external respiration
- maximum surface area for solar absorption
- minimum cross-section for wind
If we assume the annual mean temp of 6.5° at 10cm below grade treeline...
We should see some trees or tree-like plants.
A nasa paper notes that at 0.1 Atm (the lower bound for VThin) terran plants think they're in a drought, no matter how much water there is. So, VT is unlikely to support terran plants without modifications (nor Vland's native life, either. Probably not Zhdantl's, either.)
The Snowline on earth at the equator is about 5500m, so about 50 kPa. Firmly in the middle of the thin type. So we know that Terran plant life can thrive at 50 kPa if the temps are warm enough, even tho' 10 kPa makes them think they're dying.
So, we need plants that respond to daily freeze-thaw cycles, with mean root temps of about 6.5°, and not much above 30° to 45° (vs the 50° of central Australia, which I'm using to set my vertical plant maximum temperature as a ratio of the boiling point).
Which means we need plants that react. Which, itself, is an established fact. It's just not usually profound enough.
If in an area moderated by large bodies of water and/or large thermal mass of heatable stone, the average daily temperature variation can be quite mild. 3° or so.
In areas of dry sand desert, daily temps can range easily 50° at Standard Pressure (100 kPa).
Mars, at 6 kPa mean and up to 13 kPa transient in the depths of the Hellas (11.5 kPa mean) (Seasonal and weather dependent) is low enough to preclude life as we know it, since it's too close to the triple point.
I'm thinking Thin isn't going to be thin enough to matter all that much, except for the variability in temps.
Very Thin, well, my initial run with Grand Survey shows that a size 6 is either going to freeze a couple hours after dark or boil daily at the equator. Tidelocking may in fact be essential to having a stable plant zone in the 6° to 30° range. In which case, think "streamlined" - the winds should be pretty steady, and the tallest plants get more light and have a lower surface area ratio on the non-leaf areas... I think Saguaro Cactus and Palms... on the cold edge. On the hot edge, more updraft, less water, more vertical sun: barrel cacti, grassoids, and dry-mosses.
I'll need to think some more and punch in the formulae for figuring temps to make much sense of the numbers before I can say much more.
Interpolating from Grand Survey... to granulate the different pressures...
with the right inputs, one can get liquid water below 80% of boiling on a 24 hour day... in a band.
So, that means pretty normal looking plant types.
I'm not confident in that, due to having interpolated heavily, and being on pain meds at the moment while putting together the spreadsheet, and I'm not certain that DGP got their numbers right in the first place, but it's close enough for game purposes.
So, for thin atmospheres, versus very thin, I am reasonably certain that they should be able to support pretty familiar looking plants.
Outside the "growing season" zone, there can still be extremophiles, such as the antarctic algae. Especially since daily peaks will liquify some surface water.
Shorter days are better.
with the right inputs, one can get liquid water below 80% of boiling on a 24 hour day... in a band.
So, that means pretty normal looking plant types.
I'm not confident in that, due to having interpolated heavily, and being on pain meds at the moment while putting together the spreadsheet, and I'm not certain that DGP got their numbers right in the first place, but it's close enough for game purposes.
So, for thin atmospheres, versus very thin, I am reasonably certain that they should be able to support pretty familiar looking plants.
Outside the "growing season" zone, there can still be extremophiles, such as the antarctic algae. Especially since daily peaks will liquify some surface water.
Shorter days are better.
Timerover51
SOC-14 5K
Interesting comments, Aramis. I do not have the Digest Group publications, so I was thinking mainly in terms of what grows here on Earth as samples.
One problem that did appear in World War 2, with the US operating large numbers of unpressurized aircraft at high altitudes, read B-17 daylight raids on Europe, along with other high-altitude bombing attacks, is the effects of gas-producing foods and high altitude. The result was the substitution of other equivalent foods for those causing large quantities of intestinal gases.
The chief offenders were: Cabbage, fresh Brussel Sprouts, Cauliflower, Broccoli, canned Sauerkraut, and of course, the Army bean.
The chief substitutes for the vegetables were: Carrots (fresh or canned). canned spinach, canned tomatoes, canned peas, canned beets, canned corn, canned string beans, and lettuce. The two substitutes for the Army Bean were canned corned beef on a 1-to-1 basis and rice on a basis of 0.55-to-1 for the beans.
This does represent an interesting way to temporarily incapacitate your players or the opponents.
The data on foods it taken from the US Army Quartermaster history of subsistence in Europe in World War 2.
One problem that did appear in World War 2, with the US operating large numbers of unpressurized aircraft at high altitudes, read B-17 daylight raids on Europe, along with other high-altitude bombing attacks, is the effects of gas-producing foods and high altitude. The result was the substitution of other equivalent foods for those causing large quantities of intestinal gases.
The chief offenders were: Cabbage, fresh Brussel Sprouts, Cauliflower, Broccoli, canned Sauerkraut, and of course, the Army bean.
The chief substitutes for the vegetables were: Carrots (fresh or canned). canned spinach, canned tomatoes, canned peas, canned beets, canned corn, canned string beans, and lettuce. The two substitutes for the Army Bean were canned corned beef on a 1-to-1 basis and rice on a basis of 0.55-to-1 for the beans.
This does represent an interesting way to temporarily incapacitate your players or the opponents.
The data on foods it taken from the US Army Quartermaster history of subsistence in Europe in World War 2.
Timerover51
SOC-14 5K
This is an interesting World War Two Army Air Forces manual: Survival at Altitude for Heavy and Very Heavy Bomber Crews
It does have a comment regarding night vision.
Survival at Altitude for Heavy and Very Heavy Bomber Crews
www.gutenberg.org
It does have a comment regarding night vision.
GypsyComet
SOC-14 1K
A study published within the last few years suggests that grain adaption was key to settling the high Himalayas. As the barley adapted the people followed it up the mountains.
kilemall
SOC-14 5K
On atmo effects, I’m thinking the easiest mechanic is applying encumbrance until acclimation or environmental drugs/suit-air system is done.
Hmm interesting point comes to mind, most thin atmo planets are also lower grav. Is it reasonably possible they may offset, less oxygen but less stress and weight to move?
Hmm interesting point comes to mind, most thin atmo planets are also lower grav. Is it reasonably possible they may offset, less oxygen but less stress and weight to move?
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Condottiere
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We'll have to terraform Mars to find out.
Zero gee does not do a body good, in the medium term.
Zero gee does not do a body good, in the medium term.
Spinward Flow
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There may be less "weight" involved, but the body mass remains the same.
In lower gravity you move with a different gait (bunny hopping on the moon, rather than walking in 1G, for example) which may have some efficiencies of movement involved, but your own personal body mass will remain largely unchanged (aside from clothing/environmental protection suit factors). This means that even if you are operating in 0.5G, moving around does not consume 50% of the energy required to move around at 1G. The correlation between gravity and "work" (requiring oxygen and chemical energy/food to do things) does not fall off in a 1:1 relationship with reducing gravity.
If it did fall off at a 1:1 ratio, astronauts in zero G would consume no oxygen or food at all ... and clearly that is not the case.
Here is an article someone posted on my discord about the effects of gravity on physiology:
Frontiers | Editorial: The Effects of Altered Gravity on Physiology
www.frontiersin.org
The conclusion is interesting.
Spinward Flow
SOC-14 5K
Indeed ...
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