Clear Ice
Clear ice forms by the freezing of large supercooled water droplets when they come into contact with the airframe. The large droplets do not freeze immediately, due to the large amount of latent heat that is released in the change from water to ice, and because the water tends to run back over the airframe after impact. This results in very little air being trapped in the process, and so clear ice is about 8× as dense as rime ice.