Absolute Humidity
=================

.. seo::
    :description: Instructions for setting up absolute humidity calculation
    :image: water-drop.svg

The ``absolute_humidity`` platform allows you to calculate absolute humidity from air temperature and relative humidity.

See the links at the bottom of the page for details on absolute humidity and the different saturated vapor pressure equations.

.. code-block:: yaml

    # Example configuration entry
    sensor:
      - platform: absolute_humidity
        name: Absolute Humidity
        temperature: air_temperature
        humidity: relative_humidity

      # Use any temperature and relative humidity source, e.g. a BME280:
      - platform: ...
        temperature:
          name: Temperature
          id: air_temperature
        humidity:
          name: Relative Humidity
          id: relative_humidity

Configuration variables:
------------------------

- **name** (**Required**, string): The name for the absolute humidity sensor.
- **temperature** (**Required**, :ref:`config-id`): The sensor that is used to measure the current temperature, in °C.
- **humidity** (**Required**, :ref:`config-id`): The sensor that is used to measure the current relative humidity, in %.
- **equation** (*Optional*): The saturated vapor pressure equation to use (see below).
- All other options from :ref:`Sensor <config-sensor>`.

Saturated vapor pressure equations
----------------------------------

There are several different equations for calculating saturated vapor pressure.
``Wobus`` is used by default, as it is notionally the most accurate, but any of the following can be used:

- ``Buck``: `Arden Buck equation <https://en.wikipedia.org/wiki/Arden_Buck_equation>`__
- ``Tetens``: `Tetens equation <https://en.wikipedia.org/wiki/Tetens_equation>`__
- ``Wobus``: `Wobus equation <https://wahiduddin.net/calc/density_altitude.htm>`__

See Also
--------

- :ref:`sensor-filters`
- :apiref:`absolute_humidity/absolute_humidity.h`
- `NOAA Discussion on Humidity <https://www.weather.gov/lmk/humidity>`__
- `Absolute humidity on Wikipedia <https://en.wikipedia.org/wiki/Humidity#Absolute_humidity>`__
- `How to calculate absolute humidity <https://www.environmentalbiophysics.org/chalk-talk-how-to-calculate-absolute-humidity/>`__
- `How to convert relative humidity to absolute humidity <https://carnotcycle.wordpress.com/2012/08/04/how-to-convert-relative-humidity-to-absolute-humidity/>`__
- :ghedit:`Edit`
