def hadley(XYZ, t, a=0.2, b=4, dz=8, d=1):
    """
    The Hadley Attractor.
    x0 = (0.39,-1,0)
    """
    x, y, z = XYZ
    x_dt = -(y**2) - z**2 - a * x + a * dz
    y_dt = x * y - b * x * z - y + d
    z_dt = b * x * y + x * z - z
    return x_dt, y_dt, z_dt