def refractivity_lwc(ν, θ):
    """Density specific complex refractivity due to liquid water.

    ν       GHz     frequency at which refractivity is evaluated
    θ       -       reciprocal temperature

    Returned is liquid density specific refractivity in m³/kg. Multiply by
    liquid water density to obtain unitless refractivity.

    Liebe et al. (1993).
    """
    ρL = 1000. # Density of liquid water kg/m³
    ε0 = 77.66 + 103.3 * (θ-1)
    ε1 = 0.0671 * ε0
    ε2 = 3.52
    γ1 = 20.20 - 146 * (θ-1) + 316 * (θ-1)**2
    γ2 = 39.8 * γ1
    εw = ε0 - ν * ((ε0 - ε1)/(ν + 1j*γ1) + (ε1 - ε2)/(ν + 1j*γ2))
    # Density specific refractivity
    return 1.5 / ρL * (εw - 1)/(εw + 2)