.. DO NOT EDIT.
.. THIS FILE WAS AUTOMATICALLY GENERATED BY SPHINX-GALLERY.
.. TO MAKE CHANGES, EDIT THE SOURCE PYTHON FILE:
.. "api/gallery/atmosphere/plot_05_dalton_partial_pressures.py"
.. LINE NUMBERS ARE GIVEN BELOW.

.. only:: html

    .. note::
        :class: sphx-glr-download-link-note

        :ref:`Go to the end <sphx_glr_download_api_gallery_atmosphere_plot_05_dalton_partial_pressures.py>`
        to download the full example code or to run this example in your browser via JupyterLite.

.. rst-class:: sphx-glr-example-title

.. _sphx_glr_api_gallery_atmosphere_plot_05_dalton_partial_pressures.py:


Dalton's partial pressures (1802)
=================================

John Dalton found that each gas in a mixture exerts the pressure it would
exert alone, and that the total is the sum. Water vapour in air is then an
ideal gas with its own partial pressure ``e``. The mixing ratio is the ratio
of the two partial densities, ``epsilon e / (p - e)``, and the specific
humidity is the vapour fraction of the total mass.

.. GENERATED FROM PYTHON SOURCE LINES 11-34



.. image-sg:: /api/gallery/atmosphere/images/sphx_glr_plot_05_dalton_partial_pressures_001.png
   :alt: Moisture at 1013 hPa total pressure
   :srcset: /api/gallery/atmosphere/images/sphx_glr_plot_05_dalton_partial_pressures_001.png
   :class: sphx-glr-single-img





.. code-block:: Python


    import matplotlib.pyplot as plt
    import numpy as np

    from earthsciencekit.atmosphere import mixing_ratio, specific_humidity
    from earthsciencekit.constants import R_DRY_AIR, R_VAPOR

    pressure, temperature = 101325.0, 293.15
    vapor = np.linspace(0, 4000, 201)
    w = mixing_ratio(vapor, pressure)
    q = specific_humidity(w)
    vapor_density = vapor / (R_VAPOR * temperature)
    dry_density = (pressure - vapor) / (R_DRY_AIR * temperature)
    np.testing.assert_allclose(w, vapor_density / dry_density)
    np.testing.assert_allclose(q, vapor_density / (vapor_density + dry_density))

    fig, ax = plt.subplots()
    ax.plot(vapor / 100, w * 1000, label="mixing ratio (per kg dry air)")
    ax.plot(vapor / 100, q * 1000, ls="--", label="specific humidity (per kg moist air)")
    ax.set(xlabel="vapour partial pressure [hPa]", ylabel="water vapour [g/kg]", title=f"Moisture at {pressure / 100:.0f} hPa total pressure")
    ax.legend()

    plt.show()


.. rst-class:: sphx-glr-timing

   **Total running time of the script:** (0 minutes 0.087 seconds)


.. _sphx_glr_download_api_gallery_atmosphere_plot_05_dalton_partial_pressures.py:

.. only:: html

  .. container:: sphx-glr-footer sphx-glr-footer-example

    .. container:: lite-badge

      .. image:: images/jupyterlite_badge_logo.svg
        :target: ../../../lite/lab/index.html?path=api/gallery/atmosphere/plot_05_dalton_partial_pressures.ipynb
        :alt: Launch JupyterLite
        :width: 150 px

    .. container:: sphx-glr-download sphx-glr-download-jupyter

      :download:`Download Jupyter notebook: plot_05_dalton_partial_pressures.ipynb <plot_05_dalton_partial_pressures.ipynb>`

    .. container:: sphx-glr-download sphx-glr-download-python

      :download:`Download Python source code: plot_05_dalton_partial_pressures.py <plot_05_dalton_partial_pressures.py>`

    .. container:: sphx-glr-download sphx-glr-download-zip

      :download:`Download zipped: plot_05_dalton_partial_pressures.zip <plot_05_dalton_partial_pressures.zip>`


.. only:: html

 .. rst-class:: sphx-glr-signature

    `Gallery generated by Sphinx-Gallery <https://sphinx-gallery.github.io>`_