earthkit.meteo.thermo.array.vapour_pressure_from_mixing_ratio
=============================================================

.. py:function:: earthkit.meteo.thermo.array.vapour_pressure_from_mixing_ratio(w, p)

   Compute the vapour pressure from mixing ratio.

   :param w: Mixing ratio (kg/kg)
   :type w: :class:`number` or :class:`array-like`
   :param p: Pressure (Pa)
   :type p: :class:`number` or :class:`array-like`

   :returns: Vapour pressure (Pa)
   :rtype: :class:`number` or :class:`array-like`

   The computation is based on the following formula:

   .. math::

       e = \frac{p\;w}{\epsilon + w}

   with :math:`\epsilon =  R_{d}/R_{v}` (see :data:`earthkit.meteo.constants.epsilon`).