So what exactly is humidity you might ask? It’s a rather simple question, but it’s a good one and also one that plays quite an important role in our lives as well as the balance of the ecosystem around us and our planet. Because even small changes and/or fluctuations in the level of moisture in our atmosphere can have noticeable effects on us, and with that being said let’s just dive straight into things.
Basics of Humidity
To answer the above question we first posed humidity is simply the amount of water vapor present in the air, and obviously the next question would be just what exactly is water vapor? Another easy answer, it’s just the gaseous state of water. Our next sub-topic is going to be addressing the issue of what all this conceptual knowledge translates to in the physical world. You can get a best whole house humidifier if you are planning to keep your home humid.
Now this is the part where it just slightly begins to get more complex. See, the level (or measure) of humidity in the atmosphere indicates the likelihood of rain, dew, and/or fog. If you do some further thinking you’ll also come to the conclusion that the higher the humidity level in the air the less ‘useful’ and effective the act of sweating is in cooling your body and regulating your body temperature, and there is a very good reason for that…which is that higher humidity means that the air surrounding your body has less ‘free molecules’ (a very impromptu term I just made up by the way) to absorb additional water into it. Remember that sweat is largely water and in order for it to work completely it must be able to not only leave the body but it must also leave the surface of the body and get carried away by the air. This can’t happen as easily when the atmosphere is practically soaked with water anyway. And that folks…is how high humidity can really be detrimental to your current situation.
The Different Types of Humidity
If you’re thinking that humidity is just a single term or definition of a natural process then you are sadly mistaken. There’s actually 3 different ‘types’ of humidity, and each one serves their own distinct purpose. We’ll need to break them down to get a better understanding.
The first ‘kind’ of humidity is going to be called “Absolute Humidity”, and this is the kind of humidity that is the total mass of all water vapor in any given volume of air. Just think of this as the simplest one where all you’re doing is measuring how much moisture is around you…period! Also, you should know that Absolute Humidity does not account for temperature.
The second type of humidity that there is, is going to be called the “Relative Humidity”, and this one is going to be a little more complicated to describe and therefore a little bit more difficult to understand. But bear with me, I’ll explain everything and then it’ll make sense.
So the precise definition of Relative Humidity is that it is the ratio of the partial pressure of water vapor in the atmosphere to the equilibrium of vapor pressure of water over a flat surface of pure water at any given temperature. Yes, yes I know…it’s confusing and uses some rather ‘technical’ terminology that the average layperson may not be familiar with. Which is why i’m going to break it all down for you right now.
For the first part of this definition, you will notice that there is a specific term that it references…”partial pressure” that is. In order to properly grasp the overall definition of Relative Humidity we have to first figure out what that word means. Partial Pressure that is, and the answer to that is that Partial Pressure is the hypothetical pressure of that gas if it alone occupied the entire volume of its original mixture at the same temperature. In plain English, what this means is that if you take all the of the gases out of the atmosphere (or container) except for one and you left the volume of your container the same as well as leaving the temperature alone as well then that resulting number is what is your Partial Pressure.
Alright, now we have to move on to the second term that may confuse some people. The second term is, of course, the “equilibrium vapor pressure”. Which is defined as the amount of pressure exerted by a vapor in thermodynamic equilibrium with its condensed phases (which are fancy-sounding ways of describing said vapor’s liquid and solid solid state so matter) at any given temperature in a closed system. Now I know that this term basically just made things even more annoyingly difficult to understand than before. It introduced yet another term that we don’t know, but we’re not going to cover the definition of the term “thermodynamic equilibrium” (which is the term I was just referring to now) because it’s not necessary to understand the original equilibrium vapor pressure and because if we go down this route we could end up in an infinitely-regressing cycle wherein we keep looking for definitions of this word and that. So let me just explain, in a nutshell, what equilibrium vapor pressure is…it’s really just a measure of a liquid’s evaporation rate. Simple enough right? Of course it is.
Now it’s time to tie the two definitions back to each other and explain what the concept of Relative Humidity means. So basically, Relative Humidity is where you take that whole ‘pressure of an individual gase alone’ and then compare it to the rate at which a liquid/solid can get absorbed into the atmosphere. Easy enough to get right? Now once you do all the math for this whole ‘Relative Humidity’ stuff you will get a final answer in the form of a percentage.
Finally, we have the last ‘measure’ of humidity on the last…the Specific Humidity of our air, and the definition is simply that it is the ratio fo the mass of water vaport to the total mass of the moist air parcel. Another way of thinking about it is that Specific Humidity is the ratio of the mass of water vapor in the air to the mass or dry air, and the effects in real life is that there is a direct correlation/relationship between the temperature of the atmosphere and the amount of water vapor needed to reach full saturation of humidity in said atmosphere. The more a temperature goes up, the more moisture you will need to fully saturate the atmosphere, and vice versa.
OK, so now ;you have a very simple and basic understanding of humidity. That way, in case you ever needed to impress someone…like say at a social gathering or a date; you can cite this article and its knowledge as something you found interesting…or at least useful.