Humidity vs Dew Point...Explain It Please...

[CampbellCarl]

I quite often hear reports of temperature, humidity and dew point. I think that humidity is stated as a percentage of moisture in the air (making 100* feel like 120*) but I really have never understood dew point, it's relativity to comfort (or lack thereof) and/or what it really means.

Can somebody esplain please in REAL easy, understandable words and meanings? (Please remember that I'm a dumb 'ol river rat and construction dude)

Thanx!


ps, I was going to ask if I should mix a second Bloody Mary but it's too late to ask that question...

 

[milkmoney]

Carl or Karl. The only thing I know is the humidity that I live in , jus plain sucks. Dry heat is so much easier [emoji2]

 

[rivrrts429]

Dew point is the temperature at which moisture falls out of suspension.

I'm pretty sure that's it. I stayed at a Holiday Inn once.

 

[spectras only]

Here you go Carl.
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 often 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.

 

[CampbellCarl]

Dew point is the temperature at which moisture falls out of suspension.

I'm pretty sure that's it. I stayed at a Holiday Inn once.

That sounds like rain...moisture falling out of suspension (sky)...

 

[stephenkatsea]

Dew Point - Think of it as the air temp necessary for dew to form on surfaces. Right now Accu Weather says the temp in LHC is 103, humidity is 20%, and dew point 55. So, if the temp were to be 55, with the given humidity, dew would form on surfaces. Don't see much dew in LHC. It does happen though, in the winter and rarely even then.

 

[Oso Viejo]

Here you go Carl.
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 often 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.

Oh yeah, this'll help^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

You are talking to CC here, he's from Whittier.

Here's an online tool, fock the formula: http://www.dpcalc.org/

 

[CampbellCarl]

Oh yeah, this'll help^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

You are talking to CC here, he's from Whittier.

Here's an online tool, fock the formula: http://www.dpcalc.org/

Hey...Richard Nixon went to school in Whittier and he turned out...oh, nevermind...

 

[Carlson-jet]

I quite often hear reports of temperature, humidity and dew point. I think that humidity is stated as a percentage of moisture in the air (making 100* feel like 120*) but I really have never understood dew point, it's relativity to comfort (or lack thereof) and/or what it really means.

Can somebody esplain please in REAL easy, understandable words and meanings? (Please remember that I'm a dumb 'ol river rat and construction dude)

Thanx!


ps, I was going to ask if I should mix a second Bloody Mary but it's too late to ask that question...

When that glass of good scotch whiskey on the rocks forms droplets on the outside of the glass at 7:00 a.m the glass is BELOW the dew point. When the moisture starts to evaporate it's time to DEW another one because the glass surface is to warm DEW to it being almost empty. This might apply to a bloody mary as well.

 

[djunkie]

Humid.

 

[CampbellCarl]

When that glass of good scotch whiskey on the rocks forms droplets on the outside of the glass at 7:00 a.m the glass is BELOW the dew point. When the moisture starts to evaporate it's time to DEW another one because the glass surface is to warm DEW to it being almost empty. This might apply to a bloody mary as well.

Well now...this is perfectly understandable...to me anyways...so the goal is to always keep the glass below the dew point...noted!

 

[530RL]

Dew point is as exactly described, the temperature that the current air would have to be cooled to become saturated by the water vapor currently present in the air. When it reaches the saturation point, the water vapor will typically become visible by a cloud layer, or in some cases a source of precipitation as water vapor saturation increases.

It is basically used to; 1) figure out if your swamp cooler will be affective, 2) predict weather, fog and cloud formation for visibility if one is gonna go flying in times prior to radar based weather forecast systems and 3) determine if one needs carb heat to keep your engine from dying due to the formation of ice in the venturi.

Quite frankly, I am not sure why the weather man even says what the dew point is anymore other than they always did it in the past.

I can't think of one time in my life I needed to know the dew point. :headscratch:

 

[CampbellCarl]

Dew point is as exactly described, the temperature that the current air would have to be cooled to become saturated by the water vapor currently present in the air. When it reaches the saturation point, the water vapor will typically become visible by a cloud layer, or in some cases a source of precipitation as water vapor saturation increases.

It is basically used to; 1) figure out if your swamp cooler will be affective, 2) predict weather, fog and cloud formation for visibility if one is gonna go flying in times prior to radar based weather forecast systems and 3) determine if one needs carb heat to keep your engine from dying due to the formation of ice in the venturi.

Quite frankly, I am not sure why the weather man even says what the dew point is anymore other than they always did it in the past.

I can't think of one time in my life I needed to know the dew point. :headscratch:

See post #10 above...

 

[Bobby V]

Hey...Richard Nixon went to school in Whittier and he turned out...oh, nevermind...

He was a POET.

 

[Chili Palmer]

Humidity is how soon swampass kicks in and dewpoint is how soon your margarita glass develops condensation. That's all you need to know. [emoji41]

 

[Sleek-Jet]

Dew point is as exactly described, the temperature that the current air would have to be cooled to become saturated by the water vapor currently present in the air. When it reaches the saturation point, the water vapor will typically become visible by a cloud layer, or in some cases a source of precipitation as water vapor saturation increases.

It is basically used to; 1) figure out if your swamp cooler will be affective, 2) predict weather, fog and cloud formation for visibility if one is gonna go flying in times prior to radar based weather forecast systems and 3) determine if one needs carb heat to keep your engine from dying due to the formation of ice in the venturi.

Quite frankly, I am not sure why the weather man even says what the dew point is anymore other than they always did it in the past.

I can't think of one time in my life I needed to know the dew point. :headscratch:

Dew Point is still used in forcasts, as it is a good indicator of how much potential energy can be found in the atmosphere. Warm humid air can hold more energy than dry air.

If anyone wants to get all weather geek about it, do a search on skew-t log-p charts. It allows you to model lifting a parcel of air into the atmosphere and predicting what happens....

 

[530RL]

Dew Point is still used in forcasts, as it is a good indicator of how much potential energy can be found in the atmosphere. Warm humid air can hold more energy than dry air.

If anyone wants to get all weather geek about it, do a search on skew-t log-p charts. It allows you to model lifting a parcel of air into the atmosphere and predicting what happens....

DUAT and DUATS has forecasts and they free.

Plus at 500 feet, I can be on the ground in seconds and I don't need no stinking airport. :champagne:

 

[Sleek-Jet]

DUAT and DUATS has forecasts and they free.

Plus at 500 feet, I can be on the ground in seconds and I don't need no stinking airport. :champagne:

Not only are you 500 feet in the air, you are still in sight of where you took off....

 

[TBI]

Not only are you 500 feet in the air, you are still in sight of where you took off....

That's deep man

 

[Paul65k]

DUAT and DUATS has forecasts and they free.

Pretty sure they're only free to registered users and then only licensed and student pilots can register as these services are funded by the aviation trust fund.......but then again maybe they changed this in the past years.

 

[Sleek-Jet]

Pretty sure they're only free to registered users and then only licensed and student pilots can register as these services are funded by the aviation trust fund.......but then again maybe they changed this in the past years.

at least a current medical. Though you can get the same info right off of the NOAA site.

 

[ToMorrow44]

Dew point is as everyone else described. Keep in mind that humidity is expressed as relative humidity, not absolute humidity. Basically, hotter air can hold more moisture than cooler air. So 50% humidity at 100* is not the same amount of water as 50% humidity in 60* air.

My only use for dew point is by noting the temp/dew point spread. If those two numbers are close, theres a lot of moisture in the air and it could turn into fog as the day cools off. Also you can approximate the ceiling on an overcast day with the temp/dewpoint spread. Pilot shit...