The process of changing a substance from a liquid to a gas at a temperature below its boiling point is called evaporation.

Here's why:

* Boiling occurs when a liquid changes to a gas at its boiling point, where the vapor pressure of the liquid equals the surrounding atmospheric pressure.

* Evaporation is a slower process that happens at temperatures below the boiling point. It occurs when molecules at the surface of the liquid gain enough energy to break free from the liquid's surface and escape into the air.

Let me know if you'd like to learn more about evaporation!