def F_air_penndorf1957(*args):
    """
    Returns :math:`(6+3_p)/(6-7_p)`, the depolarisation term :math:`F(air)` or
    *King Factor* using *Penndorf (1957)* method.

    Parameters
    ----------
    \*args : \*
        Arguments.

    Returns
    -------
    numeric
        Air depolarisation.

    See Also
    --------
    F_air_young1981, F_air_bates1984, F_air_bodhaine1999

    Notes
    -----
    -   The argument *wavelength* is only provided for consistency with the
        other air depolarisation methods but is actually not used as this
        definition is essentially a constant in its current implementation.

    Examples
    --------
    >>> F_air_penndorf1957(0.555)
    1.0608
    """

    return 1.0608