Relative Humidity Calculator
Use this calculator to determine the relative humidity of the air based on its dry-bulb temperature and dew point temperature.
Result:
Understanding Relative Humidity
Relative humidity (RH) is a crucial meteorological term that describes the amount of water vapor present in the air relative to the maximum amount of water vapor the air can hold at a given temperature. It's expressed as a percentage. When the air is fully saturated with water vapor, the relative humidity is 100%.
Why is Relative Humidity Important?
- Human Comfort: High relative humidity can make hot temperatures feel even hotter because it inhibits the evaporation of sweat from the skin, which is our body's natural cooling mechanism. Low relative humidity can lead to dry skin, eyes, and respiratory passages.
- Weather Forecasting: RH plays a significant role in predicting precipitation, fog, and dew formation.
- Indoor Air Quality: Maintaining optimal indoor RH levels (typically between 30-60%) is important for health, preventing mold growth (too high), and avoiding static electricity or damage to wooden furniture (too low).
- Industrial Processes: Many manufacturing and storage processes require precise control of relative humidity to ensure product quality and prevent spoilage.
How is Relative Humidity Calculated?
Relative humidity can be determined using various methods, but a common approach involves the dry-bulb temperature and the dew point temperature. The dry-bulb temperature is simply the ambient air temperature measured by a standard thermometer. The dew point temperature is the temperature at which the air becomes saturated with water vapor, and condensation (dew) begins to form if the air is cooled further at constant pressure.
The calculator above uses a widely accepted approximation based on these two temperatures to estimate the relative humidity. The core principle is comparing the actual vapor pressure (derived from the dew point) to the saturation vapor pressure (derived from the dry-bulb temperature).
Using the Calculator
- Dry-Bulb Temperature: Enter the current air temperature in degrees Celsius.
- Dew Point Temperature: Enter the dew point temperature in degrees Celsius. This value will always be less than or equal to the dry-bulb temperature. If the dew point is equal to the dry-bulb temperature, the air is saturated, and RH is 100%.
- Calculate: Click the "Calculate Relative Humidity" button to see the result.
Interpreting the Results
The result will be a percentage indicating the relative humidity. For example, a reading of 50% RH means the air contains half the maximum amount of water vapor it could hold at that specific dry-bulb temperature. A higher percentage indicates more moisture in the air, while a lower percentage indicates drier air.