returns the psychrometric properties of moist air for the specified parameters.


returns the specified property for the given parameters.

Details and Options

  • spec should be an association with keys corresponding to the following parameters:
  • "DewPointTemperature"dew point temperature
    "DryBulbTemperature"dry bulb temperature
    "HumidityRatio"humidity ratio
    "Pressure"air pressure
    "RelativeHumidity"relative humidity
    "WetBulbTemperature"wet bulb temperature
  • "DryBulbTemperature" is necessary, as is the inclusion of one of the other temperature or humidity measures. "Pressure" is optional.
  • In the case of inclusion of multiple humidity measures, values will be used in the following order of precedence: "DewPointTemperature", "RelativeHumidity", "HumidityRatio", "DewPointTemperature".
  • A list of a single parameter can be supplied to calculate a range of values at once.
  • Unless specified, "Pressure" is assumed to have the value of Quantity[101325,"Pascals"].
  • PsychrometricPropertyData["Properties"] can be used to obtain a list of psychrometric properties.
  • Available properties include:
  • "CompressibilityFactor"compressibility factor
    "DewPointTemperature"dew point temperature
    "DryBulbTemperature"dry bulb temperature
    "HumidityRatio"humidity ratio
    "MolarEnthalpy"molar enthalpy
    "MolarEntropy"molar entropy
    "MolarIsobaricHeatCapacity"isobaric molar heat capacity
    "MolarIsochoricHeatCapacity"isochoric molar heat capacity
    "MolarMass"average molar mass
    "MoleFractionDryAir"mole fraction that is dry air
    "MoleFractionWater"mole fraction that is water vapor
    "PrandtlNumber"ratio of momentum diffusivity to thermal diffusivity
    "Pressure"air pressure
    "PsychrometricConstant"psychrometric constant
    "RelativeHumidity"relative humidity
    "SaturationDegree"degree of saturation
    "SoundSpeed"speed of sound
    "SpecificEnthalpy"specific enthalpy
    "SpecificEntropy"specific entropy
    "SpecificIsobaricHeatCapacity"isobaric specific heat
    "SpecificIsochoricHeatCapacity"isochoric specific heat
    "SpecificVolume"specific volume
    "ThermalConductivity"thermal conductivity
    "ThermalDiffusivity"thermal diffusivity
    "WetBulbTemperature"wet bulb temperature
  • Properties are returned using Quantity where appropriate.
  • Entropy and enthalpy properties are calibrated to be approximately zero for dry air at standard atmospheric pressure and 0 degrees Celsius.
  • PsychrometricPropertyData takes the option UnitSystem, which has the settings "Imperial" and "Metric". By default it uses the value of $UnitSystem.
  • PsychrometricPropertyData is based on a wide range of sources, with enhancement at Wolfram Research by both human and algorithmic processing.


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Basic Examples  (1)

Determine the relative humidity from other psychrometric parameters:

Calculate the dew point temperature:

Include pressure in calculations for the humidity ratio:

Scope  (3)

Obtain a list of properties:

Calculate all psychrometric properties for a set of parameters:

Calculate density for a list of temperatures:

Options  (2)

UnitSystem  (2)

By default, results are in "Metric" or Celsius units:

Set UnitSystem to "Imperial" to specify Fahrenheit:

UnitConvert can also be used to adjust the units:

Applications  (3)

Find the base height of cloud formation based on relative humidity and temperature:

Explore how humidity and temperature affect the speed of sound:

Investigate how the mole fraction of water changes with increasing air pressure:

Properties & Relations  (1)

Take current weather measurements and calculate relative humidity:

Compare to current relative humidity measurements:

Possible Issues  (2)

Dry bulb temperature should equal or exceed the wet bulb point temperatures:

Dry bulb temperature should equal or exceed the dew point temperatures:

A dry bulb temperature is needed for calculations:

Neat Examples  (2)

Create psychrometric charts for dry bulb temperature versus humidity ratio:

Calculate the density of water vapor in a cloud at 1 kilometer:

Examine the water vapor density in a cloud from 1 km to 12 km up:

Calculate the total mass of water vapor within a square meter column of cloud:

Wolfram Research (2017), PsychrometricPropertyData, Wolfram Language function,


Wolfram Research (2017), PsychrometricPropertyData, Wolfram Language function,


@misc{reference.wolfram_2020_psychrometricpropertydata, author="Wolfram Research", title="{PsychrometricPropertyData}", year="2017", howpublished="\url{}", note=[Accessed: 05-March-2021 ]}


@online{reference.wolfram_2020_psychrometricpropertydata, organization={Wolfram Research}, title={PsychrometricPropertyData}, year={2017}, url={}, note=[Accessed: 05-March-2021 ]}


Wolfram Language. 2017. "PsychrometricPropertyData." Wolfram Language & System Documentation Center. Wolfram Research.


Wolfram Language. (2017). PsychrometricPropertyData. Wolfram Language & System Documentation Center. Retrieved from