Why, despite the low temperatures/high altitudes, does friction not prevent ice from forming on aircraft?
Friction does play a role, but not enough of a role to prevent icing in most cases. The exterior skin of jet airliners cruising at high altitude and speed can increase by as much as 60° F thanks to friction between the air and the aircraft. This can certainly help to keep ice off the airframe, but the moisture that produces icing is rare at high altitude, anyway. At lower altitudes, the aircraft is flying more slowly and the effect of friction is much smaller, and there’s more moisture, so icing can still occur despite the warming effect of friction. The Concorde heated up enormously, like all supersonic aircraft do when they exceed the speed of sound. But it also flew at nearly 60,000 feet, where there was practically no moisture to begin with. Needless to say, icing in cruise was not a problem for the Concorde. I don’t know how well it handled icing during climbs and descents.
