dew point

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dew point:

see dewdew,
thin film of water that has condensed on the surface of objects near the ground. Dew forms when radiational cooling of these objects during the nighttime hours also cools the shallow layer of overlying air in contact with them, causing the condensation of some water vapor.
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Dew Point


the temperature at which air becomes saturated by water vapor when cooled at a given moisture content and a constant pressure. The condensation of water vapor begins when the dew point is reached in the air or on objects in contact with the air.

The dew point is one of the major characteristics of humidity and can be calculated from the temperature and humidity of the air or determined directly with a condensation hygrometer. If the relative humidity is less than 100 percent, the dew point is always less than the actual air temperature. The dew point decreases with decreasing relative humidity.

At saturation, that is, at a relative humidity of 100 percent, the actual temperature coincides with the dew point. Thus, at a temperature of 15°C, the relative humidities of 100, 80, 60, and 40 percent correspond to the dew points of 15.0°, 11.6°, 7.3°, and 1.5°C, respectively.

dew point

[′dü ‚pȯint]
The temperature and pressure at which a gas begins to condense to a liquid.
The temperature at which air becomes saturated when cooled without addition of moisture or change of pressure; any further cooling causes condensation. Also known as dew-point temperature.

dew point

dew pointclick for a larger image
If the temperature is +30°C and there is 15 gm of water vapor per kg of dry air and the air is cooled to +20°C, saturation will occur. +20°C is the Dew point. Similarly, Dew point is +33°C if air with 5 gm of water vapor per kg is cooled till it becomes saturated.
The temperature to which a given parcel of air must be cooled at constant pressure and constant-water-vapor content for saturation to occur. It is the temperature at which the saturation vapor pressure of the parcel is equal to the actual vapor pressure of the contained water vapor. Any further cooling usually results in the formation of dew or frost. Also called the dew-point temperature. When this temperature is below 0°C, it is sometimes called the frost point.
References in periodicals archive ?
Our multivariable analysis of bronchiolitis hospital admissions revealed that patients were less likely to be admitted with an increasing dew point (higher moisture content).
Proceeding from the aforementioned, it was decided to determine the dew point temperature for CFB and PF boilers [8] and to research chemical composition of ash deposits forming in APH tubes.
With the dew point at least 2[degrees]F below dry bulb, the relative humidity will generally be about 90 percent.
Typically the dew point is lowered by 40-50 degrees so they never attain the -40[degrees]dew point air required for resin drying and during hot/humid conditions, they often have to be taken offline.
The traditional method of determining the hydrocarbon dew point online is to use a chilled-mirror device that reduces the temperature of a mirror in a measurement chamber filled with the natural gas until enough hydrocarbon mist condenses on the mirror to be detected.
From Figure 5, we can see the circulating air dew point (Td) increases about 3UF(1.
You can see that the dew point is a measure of the amount of water vapor in the air.
A dew point analyzer is also valuable in monitoring the effect of negative pressure on the case of the inductor.
Both external and internal dew point and thermal control probes are available.
Dew Point Sensor--Generally the dew point sensor needs to be replaced yearly.
In combination with advances in sensor technology and integration, the transmitters provide superb precision and state-of-the-art functionality; taking humidity, temperature, and dew point measurements to a new level of performance ([less than] 0.
Improvements to the Michel Instruments MDM300 dew point hygrometer enable it to measure the dew point of drying air down to -70 degC in less than 10 minutes.