Relative humidity from dry-bulb and dew-point temperatures using the Tetens saturation-pressure formula.
Formula
$$ RH = 100 \cdot \frac{P_\text{sat}(T_\text{dew})}{P_\text{sat}(T_\text{db})}, \quad P_\text{sat} = 0.6108 \cdot e^{17.27 T / (T + 237.3)} $$
Symbol legend
| Symbol | Meaning | Unit | Source |
|---|---|---|---|
| $T_\text{db}$ | Dry-bulb temperature | °C | sensor |
| $T_\text{dew}$ | Dew-point temperature | °C | sensor / chilled-mirror |
| $RH$ | Relative humidity | % | result |
Sources
- ASHRAE Handbook - Fundamentals Ch.1.
- Tetens (1930) - Saturation vapour pressure.