When humidifying with steam at atmospheric pressure, the difference between the enthalpy of the steam introduced and the enthalpy of the steam in the air is relatively limited, for this reason, the transformation causes only a slight increase in the air temperature and even if improperly, the process is called isothermal humidification, in fact it often is approximately drawn on the psychometric chart along the constant temperature line that passes through the point representing the conditions of the air before humidification, moving upwards.