“…The effect of black carbon on the scattering and absorption of solar radiation by cloud droplets has been investigated for almost four decades (Danielson et al, 1969;Chylek et al, 1984Chylek et al, , 1996Chylek et al, , 2000Twohy et al, 1989;Macke, 2000;Liu et al, 2002). Soot, either as an external attachment or as an internal inclusion, changes the refractive index of ice particles (Chylek and Hallett, 1992;Macke et al, 1996;Kuhn et al, 1998;Yang et al, 2002), and influences the scattering properties of ice particles, thereby altering the radiative forcing of ice clouds.…”