# 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

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 ?
A continuous supply of cold unsaturated air from the east allowed the surface temperature to converge with the dewpoint temperature and drop below freezing as precipitation fell on the afternoon of 16 February.
The dry-bulb and dewpoint temperature data that served as input parameters for the calculations were obtained from the National Climatic Data Center (1997).
The dewpoint temperature is the temperature at which condensation occurs for air with a certain relative humidity.
The crossover temperature represents the minimum dewpoint temperature observed during the maximum heating of the day.
An altitude with an ambient air temperature of -4 degrees C and a dewpoint temperature of -5 degrees C has a great potential to contain clouds with supercooled liquid water.
Return and supply air dewpoint temperatures were obtained with a chilled mirror hygrometer.
The ability to monitor vital parameters is standard practice amongst many industries, for example food manufacturers are now able to check dewpoint temperatures of compressed air and take action to prevent spoiled batch runs, electronic component manufacturers are able to monitor nitrogen gas purities and take action to prevent high oxygen levels causing weak solder joints.
It provides measurement accuracy of [+ or -] 2[degrees]C for dewpoint temperatures ranging from -50[degrees]C to ambient.
The unit provides measurement accuracy of [+ or -] 2 C for dewpoint temperatures ranging from -50 C to ambient.
We did not detect a discernible influence on the conditions in the bounce house from their presence as temperature variations over time paralleled those outside the structure and dewpoint temperatures remained nearly constant.
However, dewpoint temperatures offshore, obtained from ship reports and compared with sea surface temperatures along the coast, provide a much better measure on the potential for dense coastal fog: dewpoints similar to or higher than the sea surface temperature favor fog.

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