Relative Humidity to Absolute Humidity Calculator

Absolute Humidity Equation:

\[ AH = \frac{RH}{100} \times \frac{P_{sat} \times M}{R \times T} \]

Absolute Humidity (AH):

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1. What is Absolute Humidity?

Absolute humidity (AH) is the actual amount of water vapor in the air, measured in grams of water per cubic meter of air (g/m³). Unlike relative humidity, it doesn't depend on temperature, making it a more precise measurement of moisture content.

2. How Does the Calculator Work?

The calculator uses the absolute humidity equation:

\[ AH = \frac{RH}{100} \times \frac{P_{sat} \times M}{R \times T} \]

Where:

\( AH \) — Absolute humidity (kg/m³)
\( RH \) — Relative humidity (%)
\( P_{sat} \) — Saturation vapor pressure (Pa)
\( M \) — Molar mass of water (0.018 kg/mol)
\( R \) — Universal gas constant (8.314 J/mol·K)
\( T \) — Temperature (K)

Explanation: The equation converts relative humidity to absolute humidity by accounting for temperature-dependent saturation vapor pressure and fundamental physical constants.

3. Importance of Absolute Humidity

Details: Absolute humidity is crucial for meteorological studies, HVAC system design, industrial processes, and understanding human comfort levels. It directly affects evaporation rates and heat transfer.

4. Using the Calculator

Tips: Enter relative humidity (0-100%) and temperature in °C. The calculator will output absolute humidity in g/m³. Temperature must be above -273.15°C (absolute zero).

5. Frequently Asked Questions (FAQ)

Q1: What's the difference between absolute and relative humidity?
A: Absolute humidity measures actual water vapor content, while relative humidity measures how saturated the air is relative to its maximum capacity at that temperature.

Q2: Why is absolute humidity typically measured in g/m³?
A: Grams per cubic meter provides intuitive understanding of water content, though the SI unit is kg/m³ (1 kg/m³ = 1000 g/m³).

Q3: How does temperature affect absolute humidity?
A: Absolute humidity can remain constant as temperature changes, unlike relative humidity which varies significantly with temperature.

Q4: What are typical absolute humidity values?
A: Comfortable indoor range is 6-12 g/m³. Below 5 g/m³ feels dry, above 15 g/m³ feels muggy. Maximum possible depends on temperature.

Q5: When is absolute humidity more useful than relative humidity?
A: For scientific applications, material drying processes, and when comparing moisture content across different temperatures.