def aerodynamical_resistance_soil(u_i_soil):
    """
    Computes the aerodynamical resistance of the soil

    .. math ::
        r_{a,s}=\\frac{1}{\\left(0.0025T_{dif}^{\\frac{1}{3}}+0.012u_{i,s}\\right)}

    Parameters
    ----------
    u_i_soil : float
        instantaneous wind speed just above soil surface
        :math:`u_{i,s}`
        [m s-1]

    Returns
    -------
    ras : float
        aerodynamical resistance
        :math:`r_{a,s}`
        [sm-1]

    """
    Tdif = 10.0
    return 1.0 / (0.0025 * Tdif ** (1.0 / 3.0) + 0.012 * u_i_soil)
