This may seem an obvious question but I am unable to understand what the technical term for the surrounding water of an environment is, specifically surrounding a person/animal within that environment.

Humidity: This seems like the most obvious answer but 100% humidity still refers to air and as far as I understand doesn't apply to environments like the bottom of the ocean or a pond.

Is there a single term that describes the water content surrounding a person or animal?


1 Answer 1


What is capped at 100% is the relative humidity, that describes the degree of water saturation of air. Relative humidity only consider the water that is dissolved in the air, not all the water that exists in a given volume of air.

You are interested in the mixing ratio between air and water, which is referred to as specific humidity. Specific humidity is the ratio of the mass of water to the total mass of the moist air parcel.

That water, usually refers only to the one dissolved in the air parcel. However, it can easily be extended to include water droplets and other bodies of water. But that approach will require that you define an arbitrary volume over to which compute the mixing ratio, because you won't be able to treat this as a continuum problem.

For instance you can compute the mean mixing ratio between air and water on a 10 meters sphere around your object of interest. Then, the more water there is within that volume, the higher will be your mixing ratio. For example, if a person is swimming 10 m deep, the mixing ratio would be almost 1. And if the same person is in the desert more than 10 m away from any water body, the mixing ration will be close to zero (not cero because all the water in the person's body and what is always in the air).

  • $\begingroup$ Thank you for the detailed and well explained answer $\endgroup$
    – Maxmansung
    Feb 16, 2019 at 3:13

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