Relative Humidity Calculator
The Relative Humidity Calculator determines the relative humidity percentage from various input parameters including dry bulb temperature, wet bulb temperature, or dew point temperature. This calculator is essential for HVAC design, meteorology, agriculture, and industrial process control.
Understanding Relative Humidity
Relative humidity (RH) is the ratio of the current absolute humidity to the highest possible absolute humidity at a given temperature. It is expressed as a percentage and indicates how much moisture the air contains relative to its maximum capacity at that temperature.
Calculation Methods
Wet Bulb Method
This method uses dry bulb and wet bulb temperatures measured with a psychrometer:
- Dry Bulb Temperature: The actual air temperature measured by a regular thermometer
- Wet Bulb Temperature: The temperature measured by a thermometer with a wet wick around the bulb
Dew Point Method
This method uses the dew point temperature and dry bulb temperature:
- Dew Point Temperature: The temperature at which air becomes saturated and water vapor begins to condense
Applications
- HVAC Systems: Design and control of heating, ventilation, and air conditioning systems
- Agriculture: Crop management, greenhouse control, and storage conditions
- Manufacturing: Process control in textiles, pharmaceuticals, and food processing
- Weather Forecasting: Meteorological observations and predictions
- Building Science: Moisture control and condensation prevention
- Health and Comfort: Indoor air quality and human comfort assessment
Relative Humidity Ranges
- 0-30%: Very dry air - may cause discomfort, static electricity, and respiratory issues
- 30-50%: Comfortable range for most applications and human comfort
- 50-70%: Moderate humidity - acceptable for many applications
- 70-100%: High humidity - may promote mold growth and condensation problems
Factors Affecting Relative Humidity
- Temperature: As temperature increases, relative humidity decreases (if absolute humidity remains constant)
- Atmospheric Pressure: Higher pressure can hold more moisture
- Air Movement: Ventilation affects moisture distribution
- Moisture Sources: Evaporation, respiration, and industrial processes