What do we call the process where a fluid changes into a gas?

The process where a fluid changes into a gas is known as evaporation. This phenomenon occurs when molecules in a liquid gain enough energy to overcome intermolecular forces and enter the gas phase, usually by absorbing heat from their surroundings. It commonly happens at the surface of the liquid, even at temperatures below the boiling point, and is a key component of the water cycle, where water from lakes, rivers, and oceans transforms into water vapor.

In contrast, condensation refers to the process where a gas turns back into a liquid, such as when water vapor forms droplets on a cool surface. Sublimation is the transition of a solid directly into a gas without passing through the liquid state, as seen with dry ice. Deposition is the process of gas turning directly into a solid, like frost forming on cold surfaces. Understanding these different phase changes is crucial in aviation weather, as they influence cloud formation, precipitation, and overall atmospheric conditions.