def latent_heat_lambda(air_temperature):
    """
    Function to calculate the latent heat of vapourisation,
    lambda, from air temperature. Source: J. Bringfelt. Test of a forest
    evapotranspiration model. Meteorology and Climatology Reports 52,
    SMHI, Norrkopping, Sweden, 1986.

    Input:
        - air_temperature: (array of) air temperature [Celsius]

    Output:
        - L: (array of) lambda [J kg-1 K-1]

    Examples:
        >>> latent_heat_lambda(25)
        >>> 2440883.8804624998
        >>> t=[10, 20, 30]
        >>> latent_heat_lambda(t)
        >>> array([ 2476387.3842125,  2452718.3817125,  2429049.3792125])

    Parameters
    ----------
    air_temperature

    Returns
    -------
    ndarray
    """
    return 4185.5 * (751.78 - 0.5655 * (air_temperature + 273.15))
