The point at which air becomes saturated with water molecules due to cooling is called the dew point.

Here's why:

* Saturation: When air holds the maximum amount of water vapor it can at a given temperature, it's considered saturated.

* Cooling: As air cools, its ability to hold water vapor decreases.

* Dew point: The dew point is the temperature at which the air becomes saturated and any further cooling will cause water vapor to condense into liquid water (dew, fog, clouds).

So, the dew point tells us how much moisture is in the air. The closer the dew point is to the actual temperature, the higher the humidity.