def net_radiation_soil(rn_24, sf_soil):
    """
    Computes the net radiation for the soil

    .. math ::
        Q^{*}_{soil} = s_f Q^{*}

    Parameters
    ----------
    rn_24 : float
        net radiation
        :math:`Q^{*}`
        [Wm-2]
    sf_soil : float
        soil fraction
        :math:`s_f`
        [-]

    Returns
    -------
    rn_24_soil : float
        net radiation for the soil
        :math:`Q^{*}_{soil}`
        [Wm-2]

    Examples
    --------
    >>> import ETLook.radiation as rad
    >>> rad.net_radiation_soil(rn_24=200, sf_soil=0.4)
    80.0
    """
    return rn_24 * sf_soil