1. What is Relative Humidity?

Relative Humidity (RH) is the ratio of the partial pressure of water vapor in the air to the equilibrium vapor pressure of water at a given temperature. It expresses the current amount of moisture in the air relative to the maximum amount the air can hold at that temperature.

2. How Does the Calculator Work?

The calculator uses the Relative Humidity formula:

Where:

• \( RH \) — Relative Humidity (%)
• \( P_v \) — Actual vapor pressure (Pa)
• \( P_{vs} \) — Saturation vapor pressure (Pa)

Explanation: The formula calculates the percentage of moisture in the air compared to the maximum amount the air can hold at the same temperature.

3. Importance of Humidity Calculation

Details: Accurate humidity measurement is crucial for weather forecasting, HVAC systems, industrial processes, agricultural applications, and maintaining comfortable indoor environments. It affects human comfort, material preservation, and various industrial operations.

4. Using the Calculator

Tips: Enter actual vapor pressure and saturation vapor pressure in Pascals (Pa). Both values must be positive, and actual vapor pressure cannot exceed saturation vapor pressure. For accurate results, ensure measurements are taken at the same temperature.

5. Frequently Asked Questions (FAQ)

Q1: What is the difference between relative humidity and absolute humidity?
A: Relative humidity is a percentage of moisture relative to maximum capacity at a given temperature, while absolute humidity is the actual mass of water vapor per volume of air.

Q2: What are typical relative humidity ranges?
A: Comfortable indoor RH is typically 30-50%. Below 30% can cause dryness, above 60% can promote mold growth and feel uncomfortable.

Q3: How does temperature affect relative humidity?
A: As temperature increases, air can hold more moisture, so relative humidity decreases if moisture content remains constant. Conversely, cooling air increases relative humidity.

Q4: What instruments measure vapor pressure?
A: Psychrometers, hygrometers, and modern electronic sensors can measure vapor pressure directly or calculate it from temperature and humidity measurements.

Q5: Why can't actual vapor pressure exceed saturation vapor pressure?
A: Saturation vapor pressure represents the maximum water vapor the air can hold at a given temperature. If exceeded, condensation occurs (dew, fog, or precipitation).