Buck equation estimate for saturation vapor pressure (kPa).
Vapor Pressure (P)
3.1685 kPa
P = 0.61121 × exp((18.678 − T/234.5) × (T/(257.14 + T)))
Calculated using the Buck Equation
The vapor pressure of water is the pressure at which water vapor is in thermodynamic equilibrium with its condensed state. At higher temperatures, the vapor pressure increases exponentially.
Enter temperature in °C; the calculator returns saturation vapor pressure in kPa using the Buck equation.
At 25°C, P ≈ 3.17 kPa (example).
Q: Units? A: kPa. Q: Accuracy? A: Buck equation is empirical and accurate for many meteorological ranges.
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