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Relative Humidity Formula:
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Relative Humidity (RH) is a measure of how much water vapor is in the air compared to the maximum amount the air could hold at that temperature. It's expressed as a percentage, with 100% meaning the air is fully saturated with water vapor.
The calculator uses the Relative Humidity formula:
Where:
Explanation: The formula compares the actual amount of water vapor in the air (e) to the maximum possible amount at that temperature (es) and converts it to a percentage.
Details: Relative humidity affects human comfort, health, building construction, industrial processes, and weather patterns. It's crucial for HVAC systems, agriculture, and many manufacturing processes.
Tips: Enter both vapor pressure values in kilopascals (kPa). Both values must be positive numbers, with actual vapor pressure (e) always less than or equal to saturation vapor pressure (es).
Q1: What's the difference between absolute and relative humidity?
A: Absolute humidity measures the actual water vapor content (g/m³), while relative humidity measures how close the air is to saturation (percentage).
Q2: What are typical comfortable RH levels?
A: For human comfort, 30-50% RH is generally recommended. Below 30% can feel dry, above 60% can feel muggy and promote mold growth.
Q3: How does temperature affect RH?
A: Warmer air can hold more water vapor. If temperature rises without adding moisture, RH decreases. If temperature drops, RH increases.
Q4: What instruments measure vapor pressure?
A: Hygrometers, psychrometers, and modern digital sensors can measure vapor pressure directly or indirectly.
Q5: Why is RH important in weather forecasting?
A: High RH near the surface can indicate potential for fog, while aloft it helps predict precipitation potential and storm development.