Can the Concept of Humidity Be Applied to Non-H20 Molecules?

[Simfish]

So we define humidity as..
"Relative humidity is defined as the amount of water vapor in a sample of air compared to the maximum amount of water vapor the air can hold at any specific temperature in a form of 0 to 100%"

But these definitions of humidity are overly specific to Earth's atmosphere. Is there a more general formulation of the concept that could apply to other molecules? I know that it's related to the statistical distribution of speeds in a group of molecules (and the respective vapor pressure of such molecules if they are found as a liquid under specified temperatures). So if there was enough mercury liquid, could we have a humidity value for mercury? (would saturation values be determined experimentally since theoretical results for all molecules can't always be precise at 2008's lvl of understanding?). And then could we also have dew point values for other molecules like mercury? (or say, methane on Titan's atmosphere, or some other molecule on that of Venus?)

 

[Mapes]

You can divide the partial pressure of any element or molecule by its saturation vapor pressure to determine its effective relative humidity.

You could calculate the "humidity" of mercury even without any liquid present.

 

[quicknote]

Thank you for your interesting question. You are correct in stating that the current definition of humidity is specific to Earth's atmosphere and is based on the properties of water vapor. However, the concept of humidity can be applied to other molecules and their vapor pressure in a similar way.

In general, humidity can be defined as the amount of a specific molecule in a gaseous state compared to the maximum amount that can be present at a specific temperature and pressure. This can be expressed as a percentage or as a partial pressure. So, in the case of mercury, if there is enough liquid mercury present, we could theoretically measure its humidity, which would be the amount of mercury vapor compared to the maximum amount that can exist at a given temperature and pressure.

In terms of dew point, this is a measure of the temperature at which a gas will start to condense into a liquid. This concept can also be applied to other molecules and their vapor pressure. For example, on Titan's atmosphere, methane can exist in a gaseous state but also has a dew point temperature at which it will start to condense into a liquid.

However, it is important to note that these values would need to be determined experimentally as theoretical calculations may not always be accurate due to the complexity of molecular interactions. As our understanding of different molecules and their properties continues to evolve, we may be able to more accurately predict humidity and dew point values for a wider range of substances.

In conclusion, while the current definition of humidity is specific to water vapor in Earth's atmosphere, the concept can be applied to other molecules and their vapor pressure. Further research and experimentation will help us better understand and measure humidity and dew point values for various substances in different environments.