def net_radiation(rns, rnl):
    """
    Calculate the net radiation (Allen et al. 1998).

    Parameters
    ----------
    rns : float
        Incoming net shortwave radiation (MJ m-2 day-1).
    rnl : float
        Outgoing net longwave radiation (MJ m-2 day-1).

    Returns
    -------
    float
        Net radiation (MJ m-2 day-1).

    """
    return rns - rnl