1. What is the Pressure of Water Vapor Formula?

The formula calculates the actual pressure of water vapor in air based on relative humidity and the saturation vapor pressure at a given temperature. It provides a fundamental relationship in atmospheric science and humidity calculations.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( p_v \) — Pressure of Water Vapor (Pascal)
• \( \Phi \) — Relative Humidity (unitless, between 0 and 1)
• \( p_s \) — Partial Pressure of Water Vapour in Saturated Air (Pascal)

Explanation: The formula directly relates the actual vapor pressure to the maximum possible vapor pressure at saturation, scaled by the relative humidity percentage.

3. Importance of Water Vapor Pressure Calculation

Details: Accurate water vapor pressure calculation is crucial for meteorological forecasting, HVAC system design, industrial processes, and understanding atmospheric conditions and comfort levels.

4. Using the Calculator

Tips: Enter relative humidity as a decimal value between 0 and 1, and the saturation vapor pressure in Pascal. Both values must be valid (relative humidity 0-1, saturation pressure > 0).

5. Frequently Asked Questions (FAQ)

Q1: What is relative humidity?
A: Relative humidity is the ratio of the partial pressure of water vapor to the equilibrium vapor pressure of water at the same temperature, expressed as a percentage.

Q2: How is saturation vapor pressure determined?
A: Saturation vapor pressure depends on temperature and can be calculated using various empirical formulas like the August-Roche-Magnus approximation.

Q3: What are typical values for water vapor pressure?
A: Water vapor pressure typically ranges from 0 to about 4000 Pascal at room temperature, depending on humidity levels.

Q4: Why is water vapor pressure important in weather forecasting?
A: Water vapor pressure helps determine dew point, relative humidity, and is crucial for predicting precipitation, fog formation, and other weather phenomena.

Q5: How does water vapor pressure affect human comfort?
A: Higher water vapor pressure (higher humidity) can make temperatures feel warmer and reduce the body's ability to cool through evaporation, affecting perceived comfort levels.