GetTWetBulbFromTDewPoint Function

  function GetTWetBulbFromTDewPoint(TDryBulb, TDewPoint, Pressure) result(TWetBulb)
    !+ Return wet-bulb temperature given dry-bulb temperature, dew-point temperature, and pressure.
    !+ References:
    !+ ASHRAE Handbook - Fundamentals (2017) ch. 1

    real, intent(in)  :: TDryBulb
      !+ Dry-bulb temperature in °F [IP] or °C [SI]
    real, intent(in)  :: TDewPoint
      !+ Dew-point temperature in °F [IP] or °C [SI]
    real, intent(in)  :: Pressure
      !+ Atmospheric pressure in Psi [IP] or Pa [SI]
    real              :: TWetBulb
      !+ Wet-bulb temperature in °F [IP] or °C [SI]
    real              :: HumRatio
      !+ Humidity ratio in lb_H₂O lb_Air⁻¹ [IP] or kg_H₂O kg_Air⁻¹ [SI]

    if (TDewPoint > TDryBulb) then
      error stop "Error: dew point temperature is above dry bulb temperature"
    end if

    HumRatio = GetHumRatioFromTDewPoint(TDewPoint, Pressure)
    TWetBulb = GetTWetBulbFromHumRatio(TDryBulb, HumRatio, Pressure)
  end function GetTWetBulbFromTDewPoint