(Or dewpoint temperature.) The temperature to which a given air parcel must be cooled at constant pressure and constant water vapor content in order for saturation to occur. When this temperature is below 0°C, it is sometimes called the frost point. The dewpoint may alternatively be defined as the temperature at which the saturation vapor pressure of the parcel is equal to the actual vapor pressure of the contained water vapor. Isobaric heating or cooling of an air parcel does not alter the value of that parcel's dewpoint, as long as no vapor is added or removed. Therefore, the dewpoint is a conservative property of air with respect to such processes. However, the dewpoint is nonconservative with respect to vertical adiabatic motions of air in the atmosphere. The dewpoint of ascending moist air decreases at a rate only about one-fifth as great as the dry-adiabatic lapse rate. The dewpoint can be measured directly by several kinds of dewpoint hygrometers or it can be deduced indirectly from psychrometers or devices that measure the water vapor density or mixing ratio. See dewpoint formula.

The temperature at which the air, cooled at constant pressure, becomes saturated with water vapour.

A measure of atmospheric moisture. It is the temperature to which air must be cooled in order to reach saturation, assuming air pressure and moisture content are held constant.

The temperature at which gaseous water condenses into visible water vapor, fog or clouds

The temperature to which air must be cooled for water to condense (water vapor to liquid).

Temperature at which vapour (at 100 percent humidity) begins to condense and deposit as liquid.

A calculated temperature at which water vapour will condense.

The temperature at which water vapor in any sample of air begins to condense.

The temperature at which water vapor condenses when the air is cooled at a constant pressure and constant moisture content.

the temperature air would have to be cooled to in order for saturation to occur. The dewpoint temperature assumes there is no change in air pressure or moisture content of the air.

The temperature to which air must be cooled, at constant pressure and moisture content, in order for saturation to occur. The higher the dew point, the greater the amount of water vapor in that vicinity. Dewpoints in the 70's make people feel uncomfortable.

The saturation temperature at which condensation of water vapor to liquid water takes place. (source: ASHRAE F97)

The temperature at which water vapor in air will condense at a given state of humidity and pressure.

The temperature at which moisture begins to form on a slick surface indicating 100% saturation of the air with moisture. That is how the dew gets on the grass in the morning. The dry bulb air temperature drops to the web bulb temperature level.

The temperature to which the air must be cooled for water vapor to condense.

Temperature at which air is saturated with moisture, or in general the temperature at which a gas is saturated with respect to a considerable component.

The temperature at which the air is fully saturated with water vapour at the pressure prevailing.

The temperature at which the water in the atmosphere will condense as drops on a surface.

The temperature at which water vapor condenses into droplets. When the dewpoint is at or above the surface air temperature, relative humidity is 100% and dew or fog can form. When the dewpoint is below the surface air temperature, relative humidity will be less that 100%, and the base of any clouds will be at an elevation where the dewpoint and air temperatures are equal.

The temperature to which air must be cooled, at constant pressure and water vapor content, in order for saturation or condensation to occur; the temperature at which the saturation pressure is the same as the existing vapor pressure; also called saturation point.