Explain what is meant by dew point and its relationship to relative humidity.?

Question

Thank you!!!!!!!!

Answer 1

The temperature at which the water vapor in the air starts to condense out and form dew or fog.

This is an important temperature because it is also the temperature at which rain forms.  Warm air can hold more water vapor than cold air.  When the warm air is saturated with water vapor then a slight cooling will cause rain.  This is why you usually have storms on the edge of a cool front.  The cold mass of air hits warmer water vapor rich air and causes it to cool and so drop its water vapor, usually as rain.

Clearly if you are a pilot then knowing the dew point at a specific altitude will tell you when water will form on your plane and if you go beyond that altitude or it gets colder when ice will form and that is hugely important to avoiding crashes.

Humidity is how much water vapor is in the air and relative humidity is how much water vapor relative to the air pressure (more air can hold more water).  So when you cool air with a high relative humidity you get a lot of rain, if you super cool it then you can get snow or hail.

Thunderclouds can form towering columns of clouds that reach high into the atmosphere.  They have fierce internal winds and can force air high up into the atmosphere.  When warm humid air is force high up into cold air hail can form.  This is why often hail is a preliminary event to a tornado, it takes a lot of wind to raise the air so fast that it can freeze and then fall fast enough to hit the ground before it thaws.  Such massive wind movement can form a funnel cloud and a tornado.  Regardless, if you see hail and it is not below freezing at ground level then a major thunder storm is over head and the possibility of a tornado exists.

Relativity Humidity plus the dew point will predict when it rains.  Satellites monitor cloud formation, the national weather service regularly releases balloons to monitor the air temperature and humidity at altitudes, and of course many weather stations record the same events on the ground.  When you put all this data together you can make more accurate weather predictions.

According to Wikipedia:  http://en.wikipedia.org/wiki/Dew_Point

“The dew point (sometimes spelled dewpoint) is the temperature to which a given parcel of air must be cooled, at constant barometric pressure, for water vapor to condense into water. The condensed water is called dew. The dew point is a saturation point.

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.

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.

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 and fog, and estimate the height of the cloud base.”

According to Wikipedia:  http://en.wikipedia.org/wiki/Relative_hu...

“The relative humidity of an air-water mixture is defined as the ratio of the partial pressure of water vapor in the mixture to the saturated vapor pressure of water at a given temperature. Relative humidity is expressed as a percentage.”

Answer 2

Dewpoint is the temperature at which an air parcel, if cooled, would become saturated, i.e have a relative humidity of 100%, assuming no change in water vapor content.  

Relative humidity is simply the amount of water vapor in an air parcel RELATIVE to how much water vapor that air parcel can hold.  As air becomes warmer, it can hold more water vapor, thus for a given amount of water vapor, the warmer the air, the lower the relative humidity.

Answer 3

Relative humidity will be maximum(100 percent) at the dew point temperature.