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]
(chemistry)
The temperature and pressure at which a gas begins to condense to a liquid.
(meteorology)
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

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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 ?
Thus the water dew point for gasoline exhaust gas at 53 [degrees]C can be derived.
The CDT dryers can be equipped with an optional by-pass to meet the demands of seasonal variations of dew point requirements above zero in summer and below zero in winter.
Figure 5, (Page 30) from weatherspark.com (a subscription service of weather data based on NOAATs data, McAllen Miller International Airport) documents dew-point history for 2014 plotted against dew point. The 75[degrees]F, 65[degrees]F, 55[degrees]F and 45[degrees]F (24[degrees]F, 18[degrees]F, 13[degrees]C and 7[degrees]C) scale lines were added for clarity.
The dew point is the temperature ([degrees]F) to which air must be cooled to produce dew (assuming a constant barometric pressure).
A flue gas stream typically has a dew point of 120 to 136[degrees]F (49 to 58[degrees]C).
Humidity (dew point) is, along with temperature, one of the key thermal environment indices; it is typically measured at 25 degree Celsius, 50% RH.
To comply, the gas is superheated to a minimum of 50[degrees]F above the highest dew point of the gas at the pressure regulators located ahead of the burner section.
The PF boiler test data obtained previously showed that the dew point of oil shale flue gas fluctuates between 75 and 80[degrees]C and does not depend on boiler thermal load or boiler design [3].
Wednesday, the temperature and dew point in Eugene were both 50 degrees, resulting in a relative humidity of 100 percent - and fog, Taylor said.
A primary air mixture of outdoor and return air conditioned to a 50[degrees]F (10[degrees]C) dew point is delivered at 55[degrees]F (13[degrees]C) to spaces maintained at 75[degrees]F (24[degrees]C) with design relative humidity levels of 50%.
The test apparatus was built around a Bureau of Mines chilled mirror dew point tester, which is accepted by the industry for use in assessing gas quality and dew points.
Without a groundcover, crawlspace dew points can be much higher than outside air.