8.28.4 How Does Frost Form?

• Ice is formed through deposition (Gas directly to Solid).
• Cold moist air will form into hoar frost when passing over a very cold surface i.e our aircraft skin.
• Happens on the ground in very cold conditions, or in air above the freezing level.

8.28.4  Explain the processes involved in the formation of hoar frost on an aircraft on the ground and in flight.