1. What is Partial Vapor Pressure?

Partial vapor pressure (e) is the pressure exerted by water vapor in the air. It represents the contribution of water vapor to the total atmospheric pressure and is calculated from relative humidity and saturation vapor pressure.

2. How Does the Calculator Work?

The calculator uses the partial vapor pressure equation:

Where:

• \( e \) — Partial vapor pressure (hPa)
• \( RH \) — Relative humidity (%)
• \( e_s \) — Saturation vapor pressure (hPa)

Explanation: The equation calculates the actual vapor pressure in the air based on the relative humidity and the maximum vapor pressure the air could hold at that temperature.

3. Importance of Partial Vapor Pressure Calculation

Details: Partial vapor pressure is essential in meteorology, HVAC systems, and industrial processes where humidity control is critical. It helps determine dew point, relative humidity, and is used in various environmental and comfort calculations.

4. Using the Calculator

Tips: Enter relative humidity as a percentage (0-100%) and saturation vapor pressure in hPa. Saturation vapor pressure varies with temperature and can be calculated using various formulas like the August-Roche-Magnus approximation.

5. Frequently Asked Questions (FAQ)

Q1: What's the difference between partial vapor pressure and saturation vapor pressure?
A: Saturation vapor pressure is the maximum pressure water vapor can exert at a given temperature, while partial vapor pressure is the actual pressure exerted by water vapor in the air.

Q2: How does temperature affect vapor pressure?
A: Saturation vapor pressure increases exponentially with temperature, meaning warmer air can hold significantly more water vapor than cooler air.

Q3: What units are used for vapor pressure?
A: Vapor pressure is typically measured in hectopascals (hPa) or millibars (mb) in meteorology, which are equivalent (1 hPa = 1 mb).

Q4: How is partial vapor pressure related to dew point?
A: Dew point is the temperature at which air becomes saturated (RH=100%) and condensation begins, which occurs when the partial vapor pressure equals the saturation vapor pressure.

Q5: Why is partial vapor pressure important in weather forecasting?
A: It's crucial for predicting fog, dew, frost formation, and understanding atmospheric moisture content which influences precipitation and cloud formation.