Calculating Saturation Vapor Pressure?

In summary: "pw" refers to the partial pressure of water vapor, which is equal to the saturation vapor pressure at the water temperature (1).
  • #1
CognitiveNet
53
1
I'm trying to find the equations or diagrams for two types of Saturation Vapor Pressures:

1) Pw = Saturation vapor pressure at water temperature
2) Pa = Saturation vapor pressure at air dew point

My solution:

Relative humidity = (saturation vapour pressure at dew point)/( saturation vapour pressure at the existing air temperature). Since I know what the relative humidity is, I can find the SVP at dew point if I can calculate the SVP at the existing air temperature.

From the following link;
http://www.engineeringtoolbox.com/water-vapor-saturation-pressure-air-d_689.html
Question 1: Is "Pws= the saturation pressure of water vapor in moist air" equivalent to 1) or 2) or is it equivalent to "saturation vapour pressure at the existing air temperature"?

Question 2: From the link, is pw = partial pressure water vapor equal to 1)?
 
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  • #2
CognitiveNet said:
I'm trying to find the equations or diagrams for two types of Saturation Vapor Pressures:

1) Pw = Saturation vapor pressure at water temperature
2) Pa = Saturation vapor pressure at air dew point

My solution:

Relative humidity = (saturation vapour pressure at dew point)/( saturation vapour pressure at the existing air temperature). Since I know what the relative humidity is, I can find the SVP at dew point if I can calculate the SVP at the existing air temperature.

From the following link;
http://www.engineeringtoolbox.com/water-vapor-saturation-pressure-air-d_689.html
Question 1: Is "Pws= the saturation pressure of water vapor in moist air" equivalent to 1) or 2) or is it equivalent to "saturation vapour pressure at the existing air temperature"?
It is (2).
Question 2: From the link, is pw = partial pressure water vapor equal to 1)?
1 what? What are the units.
 

FAQ: Calculating Saturation Vapor Pressure?

1. What is saturation vapor pressure?

Saturation vapor pressure is the maximum amount of water vapor that can be present in the air at a given temperature before the air becomes saturated. At this point, the air cannot hold any more water vapor and any additional water will condense into liquid form.

2. How is saturation vapor pressure calculated?

The most commonly used formula for calculating saturation vapor pressure is the Goff-Gratch equation, which takes into account temperature and pressure. However, there are also simplified formulas that only use temperature, such as the Magnus formula and the Bolton formula.

3. What units is saturation vapor pressure usually measured in?

Saturation vapor pressure is typically measured in units of pressure, such as millibars (mb) or kilopascals (kPa). In some cases, it may also be measured in units of energy per unit area, such as joules per square meter (J/m^2).

4. How does humidity affect saturation vapor pressure?

The higher the humidity, the closer the air is to the saturation point and the higher the saturation vapor pressure will be. Humidity is a measure of the amount of water vapor present in the air compared to the maximum amount that the air can hold at a given temperature.

5. What role does temperature play in calculating saturation vapor pressure?

Temperature has a significant effect on saturation vapor pressure, as it directly affects the amount of water vapor that the air can hold. As temperature increases, so does the saturation vapor pressure, meaning more water vapor can be present in the air before it becomes saturated.

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