what does "Dewpoint mean"?

Question

In regards to weather

- like, why would that be of interest to a pilot - ?

Answer 1

The air holds water.
The warmer the air, the more water it can hold.
The cooler the air, the less water it can hold.

At any given time the air is holding an amount of water, and if that air is cooled, then it becomes relatively fuller with water.
At a certain temperature, it will become 100% full, or saturated, and if cooled further then the water condenses out of the air forming mist, fog or dew.
That temperature is the dew point. It will vary depending on how much water is in a given sample of air.

Answer 2

Dewpoint is the temperature (in degrees) to which air must be cooled in order to be saturated with water vapor already in the air. Moisture in the air creates more hazards during flight than any other weather phenomenon, which is why weather reports for pilots usually include the dew point as well as the temperature. When the two are compared, the difference reveals to the pilot how close the air is to being 100% saturated. This difference is called the 'temperature-dew point spread'. For instance, on a clear night when the dewpoint is colder than 32° F and the temperature-dew point spread is 50°F or less and decreasing, then this will indicate to the pilot that frost will form. And fog usually forms when the dew point and the temperature are within a few degrees of each other. (The air temperature being lowered to the dew point, or the dew point being increased to the air temperature causes fog formation). For more info, plus diagrams, use the link below.

Answer 3

I liked the answer from uknative but one more practical point for a pilot is that air density can affect the performance of an airplane. For instance a cold morning where the air is say 40 degF the plane will need less speed to take off than when it is 100 deg. Same with dewpoint, the more dense the air the more lift for the plane.

Answer 4

Water vapour in the air is constantly condensing into water droplets and the water droplets are constantly evaporating. The rate of evaporation depends on the temperature and most of the time it is higher than the rate of condensation and the air is dry.

As the temperature gets lower, the rate of evaporation decreases and the rate of condensation increases. The temperature at which the rate of condensation equals the rate of evaporation is called the dewpoint. At this temperature the air is said to be saturated and there is 100% relative humidity.

If the temperature falls further, the rate of condensation exceeds the rate of evaportion and the condensed water droplets appear as fog, cloud or dew.

Answer 5

Dew point is defined as the temperature at which air would become saturated if it were cooled sufficiently, a further lowering of this temperature being responsible for spontaneous condensation.
In other words,the dew point of air is the temperature for which the saturated vapour pressure is identical with the actual pressure of the vapour in the air.
It may be noted that water vapour also contributes to the total pressure of the air.

Answer 6

For the humidity of the air (that is being talked about), it is the temperature at which the air can not support higher humidity.

If the temperature rises, no problem, but if the temperature falls, then some of the water must come our of the air, either by condensation, or precipitation.

Answer 7

The temperature at which water vapor condenses into water.

Answer 8

time of morning when dew forms from condinsation in the air
elevation of the hight that dew reaches
dewpoint dataway and git your @ss outa the rain.

Answer 9

Point at which dew forms

Answer 10

where the rain hits the ground.