def energy2evap(energy, _latent_heat):
    """
    Convert energy (e.g. radiation energy) in MJ m-2 time to the equivalent
    evaporation, assuming a grass reference crop.

    Energy is converted to equivalent evaporation using a conversion
    factor equal to the inverse of the latent heat of vapourisation
    (1 / _latent_heat).

    :param energy: Energy e.g. radiation or heat flux [MJ m-2 time].
    :param _latent_heat Calculated by latent_heat(temperature_mean)
    :return: Equivalent evaporation [mm time-1].
    :rtype: float
    """
    return (1 / _latent_heat) * energy