Further Humidity equations

Partial Vapour Pressure Equations

• Magnus Formula, where p_w is the saturation vapour pressure for water measured in Pa, and T is the temperature measured in °C.
• Sonntag Formula, where p_w is measured in Pa and T in K.
• The Arden Buck equation, where p_w is measured in hPa (hundreds of Pa) and T in °C.
• The Geoff-Gratch equation, where p_w is measured in hPa and T in K. T_st is the boiling point of water at 1atm (ie 273.16K) and p_st is the partial pressure of steam in hPa at 1atm (ie 1013.246hPa.)

Water Vapour Enhancement Factor

• For higher pressures (up to 2MPa)