def A99_eq22(T, a):
    """A99 equation 22."""
    Tref = 298.15
    return a[0] + a[1] * (T - Tref) * 0.01 + a[2] * (T - Tref
        ) ** 2 * 1e-05 + a[3] * 100.0 / (T - 225) + a[4] * 1000.0 / T + a[5
        ] * 1000000.0 / (T - 225) ** 3
