In simple terms, the dew point (dew point temperature or dewpoint) is the temperature at which a given concentration of water vapor in air will form dew. More specifically it is a measure of atmospheric moisture. It is the temperature to which air must be cooled at constant pressure and water content to reach saturation. A higher dew point indicates more moisture in the air; a dew point greater than 20 °C (68 °F) is considered uncomfortable and greater than 22 °C (72 °F) is considered to be extremely humid. Frost point is the dew point when temperatures are below freezing.