1. What is Relative Humidity?

Relative Humidity (RH) is the ratio of the current absolute humidity to the highest possible absolute humidity at that air temperature, expressed as a percentage. It indicates how much water vapor is in the air compared to how much the air can hold at that temperature.

2. How Does the Calculator Work?

The calculator uses the Relative Humidity equation:

Where:

• \( RH \) — Relative Humidity (percentage)
• \( e \) — Actual vapor pressure (kPa)
• \( e_s \) — Saturation vapor pressure (kPa)

Explanation: The equation calculates what percentage the actual water vapor pressure is of the saturation vapor pressure at the same temperature.

3. Importance of Relative Humidity

Details: Relative humidity affects human comfort, health, building construction, and various industrial processes. It's crucial for weather forecasting, agriculture, and HVAC system design.

4. Using the Calculator

Tips: Enter both actual vapor pressure (e) and saturation vapor pressure (es) in kPa. Both values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What's the difference between absolute and relative humidity?
A: Absolute humidity measures the actual amount of water vapor in the air (g/m³), while relative humidity measures how close the air is to saturation (%).

Q2: What are typical comfortable RH levels?
A: For human comfort, 30-50% RH is generally recommended. Below 30% may feel too dry, above 60% may feel muggy.

Q3: How does temperature affect RH?
A: Warmer air can hold more moisture, so RH changes with temperature even if the actual moisture content stays the same.

Q4: Why does RH matter in buildings?
A: High RH can promote mold growth, while low RH can cause dry skin and respiratory irritation.

Q5: How is saturation vapor pressure determined?
A: It's calculated from temperature using the Clausius-Clapeyron equation or looked up in thermodynamic tables.