地球表面的氧扩散同样吗?- 江南体育网页版- - - - -地球科学堆江南电子竞技平台栈交换 最近30从www.hoelymoley.com 2023 - 04 - 13 - t05:46:50z //www.hoelymoley.com/feeds/question/9052 https://creativecommons.org/licenses/by-sa/4.0/rdf //www.hoelymoley.com/q/9052 8 地球表面的氧扩散同样吗? Marijn //www.hoelymoley.com/users/5372 2016 - 11 - 06 - t12:32:07z 2021 - 10 - 15 - t12:06:04z < p >我们知道氧气来自树木和植物(光合作用),因此在丛林中,有很多的树木你期望更多的氧气比在沙漠里没有树木的地方。行走在沙漠中是艰苦的,但也由于存在更少的氧气吗?< / p > < p >我知道空气平均约21%的氧气。扩散和大风可能意味着至少有足够的氧气生活在沙漠和极地。但氧气也许可以降低在这些地区,人类需要的最小百分比是什么生活? < / p > //www.hoelymoley.com/questions/9052/-/9054 # 9054 1 戈登斯坦格回答的是氧扩散同样在地球表面? 戈登斯坦格 //www.hoelymoley.com/users/4507 2016 - 11 - 07 - t00:24:57z 2016 - 11 - 07 - t14:49:48z < p >植物光合作用确实有重大影响大气中的氧气浓度,可能看到的情节< a href = " http://scrippso2.ucsd.edu/plots " rel = " nofollow noreferrer " > < / >大气氧的研究。< / p > < p >强劲的季节性变化在光合作用,特别是在北半球高纬度地区,导致每年约20 ppm的氧气波动(ppm)。叠加在这是增加二氧化碳的“稀释效应”,主要是由于化石燃料的燃烧,这样我们实际上是失去大约19氧分子每年每百万。这些影响远小于短期波动可用氧气由天气引起的。你是正确的在说平均氧浓度约为21%。比较最优呼吸范围,对于人类来说,19.5 - 23.5%的氧气。人们往往失去意识大约10%的氧气,和死于窒息在5%左右或更少。上面的数据是海平面。在高山上海拔可以12%的氧气,这就是为什么它是如此难以攀登喜玛拉雅山最高的山峰。< / p > < p >采取长远的角度来看,即使在海平面有大量大气中氧含量的变化在过去的5.5亿年里,变化在10%和35%之间。< / p > < p >别担心,人体生理学是能够处理多< em > < / em >正常波动和趋势在大气中的氧含量。 But here is something which you might want to worry about: Suppose international efforts to curb greenhouse gas emissions are negated by continued human population growth? A worst-case scenario can be contemplated in which the global mean temperature rise attains, or even exceeds, 4.5 degrees Celsius during some time next century. In this case, at least a billion people, mainly in the tropics, will be subjected to extreme seasonal heat-stress. At the same time the cumulative effects of oxygen dilution in the atmosphere might become sufficiently high to exacerbate that heat-stress. This is a scenario that does have the potential to kill people.

//www.hoelymoley.com/questions/9052/-/9055 # 9055 3 JeopardyTempest回答的是氧扩散同样在地球表面? JeopardyTempest //www.hoelymoley.com/users/6298 2016 - 11 - 07 - t03:11:59z 2016 - 11 - 07 - t03:11:59z < p >基于链接从一个< a href = " https://chemistry.stackexchange.com/questions/27546/how-chemically-homogeneous-is-air " > < / >类似问题在大气分布在< a href = " https://chemistry.stackexchange.com/ " >化学SE < / >,我看着纬度的差异使两图像使用msi模型化学< a href = " http://ccmc.gsfc.nasa.gov/modelweb/models/msis_vitmo.php " rel = " nofollow noreferrer " > < / >策划网站(使用Janauary 1、2016、100 W经度,0公里高度)< / p > < p > < a href = " https://i.stack.imgur.com/b7vLc.gif " rel = " nofollow noreferrer " > < img src = " https://i.stack.imgur.com/b7vLc.gif " alt = "空气浓度" > < / > < / p > < p >是我的理解,这表明有超过15%的氧气在某些纬度不如别人。但它仍然是大约相同的整体比例的空气。为什么:< / p > < p > < a href = " https://i.stack.imgur.com/5FSWi.gif " rel = " nofollow noreferrer " > < img src = " https://i.stack.imgur.com/5FSWi.gif " alt = "在这里输入图像描述" > < / > < / p > < p >基本上纬度的差异是由于温度。低温度意味着更大的空气密度意味着更多的空气(氧气)。看到PV = nRT \查理定律。< / p >

I played with latitudinal cross-sections to see if I could spot any geographic issues, but this image from 30 north (which crosses the dry\arid US desert southwest, the fairly green US southeast, the northern Sahara, dry areas of the Arabian desert, Iran, and Tibet, and then fairly green southeast China:

longitudinal cross section

Still no significant variability apart from temperature.

I couldn't find information on the grid spacing or on what the model accounts for (it could be possible that the model doesn't even take into account land coverage, though that would seem to very poor when modeling atmospheric chemistry!!). But if this model has fair validity, it suggests there generally is very little difference due to landcover over large-areas; wind mixing makes the air extremely homogeneous. But this doesn't speak entirely to how much very local differences may exist, such as in a parking lot versus a patch of trees. Still, the effects apparently are unlikely to be very significant.

Perhaps walking in the desert is tough primarily because of the dry air\dust\heat\elevation?
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