The amount of the total water as vapor, solid or liquid at a certain air volume or amount of the vapor in the atmosphere is called humidity. However, amount of the vapor in the air is proportional with the air temperature. It increases when the temperature of the air increases and vice versa.
There is a maximum amount of humidity or humidity limit for a given air volume according to its temperature. This limit is called as “saturation point” of air. Air can not take or carry humidity upper of this limit. When the humidity level in that volume of air has arrived to the saturation point, condensation starts, as we see rain in nature.
Relative humidity (RH) is the ratio of the amount of vapor that a certain air volume at a certain temperature carries, to the maximum amount of the vapor that air volume at that temperature can carry. This ratio is expressed as percentage to understand easily. When this rate becomes %100, it means that the air has the maximum amount of water that it can carry, that is to say it has reached to the maximum amount of humidity. Relative humidity gives an opinion about humidity saturating state of air and amount of humidity to reach to the saturation point at the same time.
When relative humidity is evaluated, the temperature must also be taken into care. Because the amount of maximum humidity of a certain volume of air rises as the temperature of that air rises. For example; relative humidity of the air is approximately the same as 50% RH, for both 2 grams per 1 m3 air at 0 °C in Xplace and 12 -13 grams per 1 m3 air at 35 °C in Yplace
