Dew Point (or Dew-point Temperature) - 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 constant).
Dew point (dew-point temperature) The temperature to which a given parcel of air must be cooled at constant pressure and constant water-vapor content in order for saturation to occur.
Dew
Source: Excerpt from The Book " Weather "
Distribution: Worldwide, most common in coastal and tropical areas.
**Dew Point**
"N O T E" All weather articles written by the author, weather records for Bath, Pa. USA, graphs, graphics, pictures, are copyrighted and are owned by the author.
The dew point or dewpoint of a given parcel of air is the temperature to which the parcel must be cooled, at constant barometric pressure, for the water vapor component to condense into water, called dew.
Dew points indicate the amount moisture in the air. The higher the dew points, the higher the moisture content of the air at a given temperature.
dew cell"A type of hygrometer used to determine the dewpoint. The equilibrium vapor pressure at the surface of a saturated salt solution is less than that for a similar surface of pure water at the same temperature.
dew - Water condensed onto grass and other objects near the ground, the temperatures of which have fallen below the dewpoint of the surface air due to radiational cooling during the night, but are still above freezing; ...
dew-point hygrometer
An instrument used for determining the dewpoint; ...
Dew-point temperature
This is a measure of the moisture content of the air and is the temperature to which air must be cooled in order for dew to form.
Dew - water condensed upon the surfaces of objects near the ground when temperatures of the surface air have fallen below the dew point due to cooling during the night but are still above freezing ...
dew: condensed moisture (water vapor), appearing as small drops on a cool surface; usually occurs after or during a very warm day.
dew point: the certain temperature at which dew begins to form and water vapor chages to liquid form.
Dew Point Temperature-The temperature to which the air must be cooled for water vapor to reach saturation, i.e. cloud formation.
Dew-point
The temperature to which air must be cooled (at constant pressure and constant water vapour content) for saturation to occur.
Frost point
When the dew-point falls below freezing it is called the frost point.
DEW: Moisture that has condensed on objects near the ground, whose temperatures have fallen below the dewpoint temperature.
DEWPOINT: The temperature to which the air must be cooled for water vapor to condense.
DEW Condensation in the form of small water drops that forms on grass and other small objects near the ground when the temperature has fallen to the dew point, generally during the nighttime hours.
dew: when liquid water from the atmosphere condenses on plants and objects near the ground.
dewpoint: the temperature that air must reach before condensation can occur. The air is saturated at this point.
Dew Point- the temperature to which a certain amount of air must be cooled in order for saturation to occur (a cloud or fog to form); the drier the air the lower the dew point and the more air is needed to be cooled for a cloud or fog to form.
Dew Point - The point at which the air at a certain temperature contains all the moisture possible without precipitation occurring. When the dew point is 65oF, one begins to feel the humidity.
Dew Point or Dew Point Temperature: The temperature to which a parcel of air must be cooled at constant water vapour content (and constant pressure) for saturation to occur.
Dew Point - As the surface of the earth cools at night, warm moist air near the ground is chilled and water vapour in the air condenses into droplets on the grass and other objects.
Dew Point (Dew-Point Temperature) A measure of atmospheric moisture. The temperature to which air must be cooled, at constant pressure and moisture content, in order for saturation to occur.
Dew-Point
(Dewpoint Temperature) Temperature to which a volume of air must be cooled at constant pressure and constant moisture in order to reach saturation; any further cooling causes condensation.
Dew - A form of condensation consisting of small water drops on grass or other objects near the ground that forms when the surface temperature drops below the dew point. Usually associated with radiation cooling on clear, calm nights.
Dew Water droplets formed by condensation of water vapor on a relatively cold surface.
Dew- Moisture from water vapor in the air that has condensed on objects near the ground, whose temperatures have fallen below the dewpoint temperature.
Dew - Water that forms on objects close to the ground when its temperature falls below the dew point of the surface air.
Dew Point - The temperature of which air must be cooled for it to be saturated.
Frozen Dew
When liquid dew changes into tiny beads of ice. This occurs when dew forms and temperatures later drop below freezing.
FRST ...
DEW: Moisture that condenses on objects near the ground.
DEWPOINT: The temperature to which the air must be cooled for water vapor to condense. The larger the spread of temperature and dewpoint, the drier the air.
Dew: Water droplets condensed over the grass or any other surface next to the soil.
Doldrums: The equatorial belt of calms or light winds, variable in direction, between the two systems of trade winds.
Dew point- The temperature at which condensation begins.
Droughts- Long periods of low precipitation.
dew point- temperature at which air at constant pressure must cool to become saturated with water vapor, followed by condensation.
down draft- a rapidly descending column of cooling air that causes heavy rains and violent wind gusts.
Dew Point - The temperature at which water starts to condense out of a particular air mass. The dew point temperature changes only when the moisture content of the air changes. The higher the dew point, the greater the moisture content is in the air.
Dew- Water that condenses onto grass and other objects near the ground.
Dew Point- The temperature to which a certain volume of air must be cooled to bring the relative humidity to 100 percent.
Dew PointDPDOn a buoy report, dominant wave period (seconds) is the period with the maximum wave energy.
Td 850 is the dew point temperature at 850 mb,
TT is the total-totals index,
f 850 is the 850-mb wind speed (in knots),
f 500 is the 500-mb wind speed (in knots), and ...
Frost Point: Dew point below freezing.
Fractus: Ragged, detached cloud fragments; same as scud.
Friction Head: The decrease in total head caused by friction.
Black iceThin, new ice that forms on fresh water or dew covered surfaces; it is common on roadways during the fall and early winter and appears "black" because of its transparency.
Radiation FogA fog that forms when outgoing longwave radiation cools the near-surface air below its dew point temperature.
Total-Totals IndexA stability index and severe weather forecast tool, equal to the temperature at 850 mb plus the dew point at 850 mb, minus twice the temperature at 500 mb.
ADVECTION FOG Fog that develops when warm moist air aloft moves over a colder surface, cooling that air to below its dew point. An example is Arctic Sea Smoke, a form of sea fog.
See absolute humidity, dew point, mixing ratio, relative humidity, specific humidity. Humidity coefficient A measure, proposed by Angstrom, of the precipitation effectiveness of a region. Humidity element The transducer of any hygrometer, i.
Frost develops under conditions similar to dew, except the temperatures of the Earth's surface and earthbound objects falls below 32°F. As with the term "freeze," this condition is primarily significant during the growing season.
In general, the differences in temperature, dew point, and winds measured at the 850 mb and 500 mb levels of the atmosphere are considered in this index. Values of 250 or greater indicate a potential for severe weather.
16 What is the dew point?
2A.17 What's the difference between Humidity and Relative Humidity?
2A.18 Does the dew point temperature have to be above a certain value for a thunderstorm?
2A.19 Why does the weather sometimes get 'stuck in a rut'?
2A.
The 850 dew point provides information on the moisture content of the lower atmosphere. The vertical extent of the moist layer is represented by the difference of the 700 mb temperature and 700 mb dew point.
For condensation to occur at the dew point water vapor needs a surface to condense on. In the atmosphere water vapor starts to condense on microscopic particles suspended in the air: dust, soot, volcanic ash, salt spray, etc.
Black frost occurs when the dew point is too low for frost to form. That is the temperature is below zero but there is not enough moisture in the air to produce a visible frost.
RADIATION FOG Fog that is created when radiational cooling at the earth's surface lowers the temperature of the air near the ground to or below its dew point.
Advection fog Occurs when warm, moist air moves over a cold surface and the air cools to below its dew point.
As this is usually measured in a fixed rain gauge, small amounts of dew, frost, rime, etc., may be included in the total.
ADVECTION FOG
Fog that develops when warm moist air moves over a colder surface, cooling that air to below its dew point.
 See also: Temperature, Air, Surface, Weather, Cloud
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