CO2 vs. H20

CO2 crystals have largely different light scattering properties then cirrus ice crystals. CO2 crystals of the same size of a hollow hexagonal ice crystal lets much more light through. I beleive this is because the CO2 crystal does not have a hollowing which results in more back and side scattering. If a photon strikes the surface of an octahedral CO2 crystal it will reflect backwards or be deflected forward. If a photon enters the hollowing of a cirrus ice crystal it will scatter several times, even if it may have originally been deflected in a forward path, it will travel out the same way it came in, backwards.