Plain English Meaning

A type of ice that builds up on an aircraft as a rough, white, crusty layer. It forms when tiny, very cold water droplets in cloud freeze almost instantly the moment they hit the airplane.

Full Definition

A rough, milky, opaque type of structural ice formed by the rapid freezing of small, supercooled water droplets on impact with an aircraft surface. The fast freezing traps air between the droplets, giving rime its brittle, granular appearance. It typically forms in stratiform clouds at colder temperatures (generally between -15°C and -20°C, though it can occur in a wider range).

Context Anchor

Seen in structural icing discussions, especially when comparing types of ice that can form on , , , and other exposed aircraft surfaces.