Sublimation

The process by which substances are turned directly from a solid state into a gas is called sublimation.

On Pluto, ice turns directly into gas and this is called sublimation.

It uses dry ice pellets (capsules of frozen carbon dioxide), blown at supersonic speed onto the railhead through a small nozzle. Any leaf contamination on the line is frozen, becoming brittle. The pellets then change instantly from solid to gas without going through a liquid stage (a process known as sublimation).