def Lambda(zhub, IECedition):
    """
    Calculate the IEC length scale.

    Lambda = 0.7*min(Zhat,zhub)

    Where: Zhat = 30,60 for IECedition = 2,3, respectively.

    """
    if IECedition <= 2:
        return 0.7 * min(30, zhub)
    return 0.7 * min(60, zhub)