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Relative Humidity Formula:
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Relative humidity (RH) is the ratio of the partial pressure of water vapor to the equilibrium vapor pressure of water at a given temperature. It is expressed as a percentage and indicates how much moisture the air contains relative to the maximum it could hold at that temperature.
The calculator uses the relative humidity formula:
Where:
Explanation: The formula calculates what percentage the current vapor pressure is of the maximum possible vapor pressure at that temperature.
Details: Relative humidity is crucial in meteorology, HVAC systems, agriculture, and industrial processes. It affects human comfort, plant growth, and various manufacturing processes.
Tips: Enter both vapor pressure (e) and saturation vapor pressure (e_s) in hPa. Both values must be positive, and e cannot exceed e_s.
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 expresses this as a percentage of the maximum possible at that temperature.
Q2: What is considered a comfortable relative humidity level?
A: For human comfort, relative humidity between 30-50% is generally recommended. Levels above 60% can feel stuffy, while below 30% can cause dry skin and respiratory irritation.
Q3: How does temperature affect relative humidity?
A: Warmer air can hold more moisture, so if the absolute moisture content stays the same, relative humidity decreases as temperature increases and vice versa.
Q4: Why is relative humidity important in weather forecasting?
A: RH helps predict fog, dew, frost, and precipitation. High RH near 100% often indicates possible condensation or precipitation.
Q5: How is saturation vapor pressure determined?
A: Saturation vapor pressure depends primarily on temperature and can be calculated using various empirical formulas like the Magnus formula or Arden Buck equation.