Liquid nitrogen
From waht I have seen liquid nitrogen is pretty clear, when it is not ‘steaming’. Granted, I have only seen it in small quantities.
I wonder if Triton’s Liquid nitrogen ever spills out on the surface? Would it boil away into gas quickly? And how would it act if it ever rained down to the surface? Seeing the nitrogen geysers would be a fantastic sight.
I also wonder if Pluto ever has liquid nitrogen on or under its surface when it is at its closest to the Sun.