## 1. Introduction

The enthalpy of the humid air is, at a given pressure, the energy
necessary to heat 1 kg of dry air from the reference temperature T_{0}
to the temperature T, to vaporize at T_{0} the quantity of
water in the humid air having an absolute humidity of ω, and to heat
up the water vapor from T_{0} to T.

## 2. Calculation

#### General form

**H' = Cp'.(T-T**_{0}) + ω.Λ_{0}

With :

H' = enthalpy of humid air (J/kg_dry_air)

Cp' = specific heat of humid air (J/K/kg_dry_air)

T = temperature of calculation (K)

T

_{0} = temperature of reference (K)

ω = A

bsolute humidity of air
(-)

Λ

_{0} = vaporization enthalpy at T

_{0} (J/kg)

#### In practice, at 273 K

**H' = (1005 + 1884*ω).(T-273) +
2.5023.10**^{6}.ω