What Is Dew Point?

In simple terms, the dew point is the temperature at which the air can no longer hold all of its water vapor so that some of that vapor condenses into liquid water, forming dew or frost.

More technically, it is a meteorological term that refers to the temperature to which air must be cooled to become saturated with water vapor, assuming constant moisture content and air pressure.

When the air temperature drops to the dew point temperature, relative humidity becomes 100%.

1, The dew point is the temperature where air is saturated with water vapor. Below this temperature, dew (or frost) forms.

2, At the dew point, the relative humidity is 100%.

3, Increasing humidity (amount of water vapor) or increasing pressure raises the temperature of the dew point.

4, Dew point figures into the heat index. When humidity is high, perspiration doesn’t evaporate, it feels sticky or muggy, and the risk of heat exhaustion and heat stroke increase.

Dew Point and Relative Humidity

The dew point closely relates to relative humidity, which is a measure of the amount of water vapor present in the air compared to the maximum amount the air can hold at that temperature.

As the air temperature approaches the dew point, the relative humidity increases. When the air temperature equals the dew point, the air is saturated, and the relative humidity is 100%.

Conversely, a high difference between the air temperature and the dew point indicates low relative humidity.