当我看到讨论大气中的二氧化碳时，我看到两种单位都被使用，取决于来源。例如，这个答案下的评论。< / p >

Since multi-atomic gases like N2, O2, H2O and CO2 are not ideal gases (even monatomic gases are not absolutely ideal) I would guess that for realistic atmospheric samples at different altitudes and times, the CO2 concentrations expressed in ppmV and μmol/mol would not be numerically identical. Further, due to the variations in concentrations of the other constituents they wouldn't even be strictly proportional.

Is there a handy, approximate conversion constant, or function, that is more accurate than unity? Is there a nearly-exact one?

我认为这就是它:

ppm(mol)=ppm(v) x(密度CO2/密度总atmos) x(分子量总atmos/分子量CO2)。

尝试一些数字运算，看看是否有意义

根据美国二氧化碳信息分析中心:

尽管在他们的数据表中他们使用术语“ppmv"，他们解释:

二氧化碳混合比报告为世界气象组织(WMO) X85摩尔分数刻度中干燥空气的每摩尔微摩尔(µmol/mol = ppmv)。这在二氧化碳和其他温室气体的WMO摩尔分数刻度和大气测量的不确定性:

缩写可以是ppm, ppb等，而广泛使用的缩写如ppmv (v代表体积)是错误的，应该放弃。在评审论文时，或者当我们是合著者时，我们应该说服第一作者放弃ppmv符号。体积与摩尔分数无关。< / p >

Supposing you know the mole fraction, if you literally wanted to calculate the parts per million by volume, first you need to define what that would mean. Are you interested in the ratio of the volume of CO2 separately isolated relative to the whole volume? Or are you interested in the volume of CO2 separately isolated, relative to the sum of all the gases separately isolated? For either of these methods, you would need to choose a temperature and pressure, such as the actual temperature and pressure of a sample, or standard temperature and pressure.

Then you need an equation of state at least for the CO2, that is more real than the ideal gas law, such as van der Waals.