When a solid goes directly from solid to gas, it's called sublimation.

Here are some examples of sublimation:

* Dry ice (solid carbon dioxide) sublimates at room temperature, forming a foggy gas.

* Mothballs are made of a substance that sublimates, slowly releasing vapors that repel moths.

* Frozen water can sublimate in cold, dry environments, leading to the formation of frost.

Sublimation is a physical change, meaning the chemical composition of the substance remains the same. It's the opposite of deposition, where a gas directly changes into a solid.