Calculating Saturation Vapor Pressure?

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SUMMARY

This discussion focuses on calculating Saturation Vapor Pressure (SVP) for two specific conditions: Pw, the saturation vapor pressure at water temperature, and Pa, the saturation vapor pressure at air dew point. The user establishes that relative humidity can be calculated using the formula: relative humidity = (saturation vapor pressure at dew point) / (saturation vapor pressure at existing air temperature). The user confirms that Pws, the saturation pressure of water vapor in moist air, corresponds to Pa, while pw, the partial pressure of water vapor, relates to Pw. The reference link provided is from Engineering Toolbox, which contains relevant equations and diagrams.

PREREQUISITES
  • Understanding of Saturation Vapor Pressure (SVP) concepts
  • Knowledge of relative humidity calculations
  • Familiarity with dew point temperature
  • Basic grasp of vapor pressure terminology
NEXT STEPS
  • Research the Clausius-Clapeyron equation for calculating SVP
  • Explore the psychrometric chart for visualizing humidity and temperature relationships
  • Learn about the differences between Pw and Pa in meteorological contexts
  • Investigate tools for measuring dew point and relative humidity accurately
USEFUL FOR

Atmospheric scientists, meteorologists, and engineers involved in HVAC systems or environmental studies will benefit from this discussion, particularly those focusing on humidity and vapor pressure calculations.

CognitiveNet
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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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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.
 

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