GetTWetBulbFromRelHum Function

  function GetTWetBulbFromRelHum(TDryBulb, RelHum, Pressure) result(TWetBulb)
    !+ Return wet-bulb temperature given dry-bulb temperature, relative humidity, 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)  ::  RelHum
      !+ Relative humidity in range [0, 1]
    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 (RelHum < 0.0 .or. RelHum > 1.0) then
      error stop "Error: relative humidity is outside range [0,1]"
    end if

    HumRatio = GetHumRatioFromRelHum(TDryBulb, RelHum, Pressure)
    TWetBulb = GetTWetBulbFromHumRatio(TDryBulb, HumRatio, Pressure)
  end function GetTWetBulbFromRelHum