what is the dew point ?

Question

and what is better for a nice weather: a high dew point or a low?

Thank you in advance.

Answer 1

The temperature to which the air must cool in order to reach saturation. The dewpoint is always equal or less than the temperature, it can never be more.

Clouds form lower in the sky with higher dewpoints because they don't have to cool as much to start forming. Generally at the surface, if the dewpoint and the temperature are equal then fog forms.

Lower dewpoints help suppress cloud development. If rain showers do occur, if the dewpoint is low enough then the rain may evaporate before reaching the ground. If it feels "muggy" out, then the dewpoint is usually high.

So I'd say, in general, low dewpoints are more often associated with nice weather. However, low is a relative term. The dewpoint depends largely on the temperature.

Answer 2

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 water vapor to condense into water, called dew. When the dew point temperature falls below freezing it is called the frost point, as the water vapor no longer creates dew but instead creates frost or hoarfrost by deposition.
Dew Point
Temp. °F (°C)
Human Perception Relative Humidity
Air Temp 90°F

75°F(24°C)+ Extremely uncomfortable, oppressive 62%
70°F(21°C) - 74°F Very Humid, quite uncomfortable 52% - 60%
65°F(18°C) - 69°F Somewhat uncomfortable for most people
at upper limit
44% - 52%
60°F(16°C) - 64°F OK for most, but everyone perceives the humidity
at upper limit
37% - 46%
55°F(13°C) - 59°F Comfortable 31% - 41%
50°F(10°C) - 54°F Very comfortable 31% - 37%
49°F(10°C)
or lower
Feels like the western US
a bit dry to some
30%

The dew point is associated with relative humidity. A high relative humidity indicates that the dew point is closer to the current air temperature. If the relative humidity is 100%, the dew point is equal to the current temperature. Given a constant dew point, an increase in temperature will lead to a decrease in relative humidity. It is for this reason that equatorial climates can have low relative humidity, yet still feel humid.

At a given barometric pressure, independent of temperature, the dew point indicates the mole fraction of water vapor in the air, and therefore determines the specific humidity of the air.

The dew point is an important statistic for general aviation pilots, as it is used to calculate the likelihood of carburetor icing.

Answer 3

Suppose there is an air mass with a temperature of 30 degree celcius containing some moisture.If ,by some method, you are decreasing the temperature one by one.Suppose when you reach 25 degree celcius, you observe the condensation of the moisture into tiny water droplets.Then this temperature is called the dewpoint temperature.
If air temperature and the dewpoint temperature are the same(as in the above case) air is said to be saturated and the Relative Humidity will be 100 percent.
So, a dewpoint 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.
Further,as the water vapour is a gas which contributes its own pressure to the total pressure of the air, the dew point can be expressed in terms of vapour pressure also.
That is, 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.
Therefore,for a saturated air,the air is actually at its Dew point, otherwise(if not saturated), the dew point is always below the air temperature.

Answer 4

Dew Point

All air contains water vapour of varying quantities. The dew point indicates the amount of moisture in the air. The higher the dew point, the higher the moisture content of the air at a given temperature. Conversely, the dew point of humid air will be higher than the dew point of dry air.

Dew point temperature is defined as the temperature to which the air would have to cool (at constant pressure and constant water vapour content) in order to reach saturation. A state of saturation exists when the air is holding the maximum amount of water vapour possible at the existing temperature and pressure.

Condensation of water vapour begins when the temperature of air is lowered to its dew point and beyond. The dew point, like other measures of humidity, can be calculated from readings taken by a hygrometer.

Answer 5

The Dew point is the temperature that the humidity will condense into water droplets. The higher the dew point the better the weather.

Answer 6

its how much moisture is in the air...nice weather u have a low dew point