The dew point is the temperature to which air must be cooled to become saturated with water vapor. It is assumed that air pressure and water content is constant. When cooled further, the airborne water vapor will condense to form liquid water.

What is the difference between dew point and humidity?

The dew point is the temperature the air needs to be cooled to (at constant pressure) in order to achieve a relative humidity (RH) of 100%. ... For example, a temperature of 30 and a dew point of 30 will give you a relative humidity of 100%, but a temperature of 80 and a dew point of 60 produces a relative humidity of 50%.

What happens when the dew point is low?

If the temperature of air is lower than the dew point, water vapor condenses and leaves the air in the form of water. At this point relative humidity is essentially 100%. The dew seen of leaves in the morning is the result of atmospheric temperature falling below the prevailing dew point.