# 2-3.Ask for saturation water vapor pressure

The saturation water vapor amount is the representation of g in the mass of water vapor that can be present in the space of 1m3.
Absolute humidity volume, saturation water vapor density is also known as, aka.
Saturation water vapor amount varies depending on the temperature.

Tetens's formula E = 6.11 × 10 at / (b + t) (hPa) t is (℃)
The case of the water surface a = 9.5, b = 265.5 The case of the ice surface a = 7.5, b = 237.3,

In the case of water surface: E (t) = 6.11 × 10 ^ (7.5t / (t +237.3)

Swva:Saturation water vapor amount
Swvp:Saturation water vapor pressure

Let’s try to the simulation of the included water vapor content on various conditions as 10 g/m3.

#### ◎ In the case of the temperature is 30 ℃

Saturation water vapor amount at the time of 30 ℃ is 30.4g/m3
Ψ = 10/30.4 x100 ≒ 32.9%

It will be about 32.9%. It is dry.

#### ◎ In the case of the temperature is 20 ℃

Saturation water vapor amount at the time of 20 ℃ is 17.3g/m3
Ψ= 10/17.3 x100 ≒ 57.8%

It will be about 57.8%. It has become moist than 30 ℃, but it is still a margin.

#### ◎ In the case of the temperature is 10 ℃

Saturation water vapor amount at the time of 10 ℃ is 9.4g/m3
Ψ= 10/9.4 x100 ≒ 106.4%

In the general environment, the humidity is 100%.
6.4% will be water by condensation.

Humidity are different amount of water vapor it contains is the same, but the temperature is different.
As temperature rises, the humidity will drop.