Relative humidity is ratio of vapor pressure
============================================

**Relative humidity** is the ratio of actual water vapor pressure :math:`p` to saturation vapor
pressure :math:`p_0` at a given temperature. **Saturation vapor** is vapor in dynamic
equilibrium with a liquid or solid of the same composition in a closed system. In such
a system, the number of evaporating molecules is equal to the number of condensing
molecules per unit time.

**Links:**

#. `Wikipedia <https://en.wikipedia.org/wiki/Humidity#Relative_humidity>`__.

.. py:currentmodule:: symplyphysics.laws.thermodynamics.relative_humidity_is_ratio_of_vapor_pressure

.. py:data:: relative_humidity

    :attr:`~symplyphysics.symbols.thermodynamics.relative_humidity` of air.

Symbol:
    :code:`phi`

Latex:
    :math:`\varphi`

Dimension:
    :code:`dimensionless`


.. py:data:: actual_vapor_pressure

    Partial :attr:`~symplyphysics.symbols.classical_mechanics.pressure` of water vapor in the medium, representing how much water vapor is
    actually in the air.

Symbol:
    :code:`p`

Latex:
    :math:`p`

Dimension:
    :code:`pressure`


.. py:data:: saturation_vapor_pressure

    Equilibrium :attr:`~symplyphysics.symbols.classical_mechanics.pressure` of water vapor above a flat surface of liquid water or solid ice,
    representing how much water vapor the air could potentially contain at a given temperature.

Symbol:
    :code:`p_s`

Latex:
    :math:`p_\text{s}`

Dimension:
    :code:`pressure`


.. py:data:: law

    :code:`phi = p / p_s`


    Latex:
        .. math::
            \varphi = \frac{p}{p_\text{s}}