Sublimation

Sublimation

Sublimation is defined as "a phase transition process from a solid to a gas without ever entering an intermediate liquid phase."

At normal pressures on Earth, the process of transitioning from a solid to a gas requires the compound to  become a liquid. However, sublimation occurs at a certain phase during a substance's triple point, which is where the three different states (gas, liquid, solid) can coexist in their respective forms. In order for sublimation to occur, the temperature and pressure must be below this triple point.

One example of sublimation in the real world is freeze-dried goods, such as meats or other food items. This process occurs by freezing the food items directly, then lowering the surrounding pressure of the air so that the water in the food item, which is frozen, can sublimate from the solid phase to the gas phase. By doing so, the food is essentially "dehydrated" but can still be consumed for up to years at a time when packaged properly.

Probably the best known example of sublimation is the solid form of carbon dioxide, also known as "dry ice." Dry ice is used in the food industry by those looking to keep items cold, without the mess or hassle of having to clean up melted ice cubes.