posted 07-10-2001 04:25 PM            

temperature ground level 106 f

@ 30,000 feet

RH 20 to 50%

temperature -35 to -40

Contrails here in spots today.

A brief tutorial on RH....

Relative humidity is not an absolute measure of atmospheric water vapor content. It depends upon the temperature and shape of the surface. Other measures of atmospheric moisture are mixing ratio, specific humidity, and dew point. Mixing ratio is the mass of water vapor per unit mass of dry air. Specific humidity is the mass of water vapor per unit mass of moist air. Dew point is the temperature to which moist air must be cooled, with pressure and mixing ratio held constant, in order for this air parcel to become "saturated." To get a "feel" for the difference between relative humidity and dew point, say any-town USA reported a temperature of 97 F, a dew point of 84 F, but a relative humidity of 67%. The relative humidity doesn't sound terribly bad, does it? However, this is misleading. The temperature and dew point combined to give a heat index of 126 F!

Because relative humidity is relative to "saturation" above a flat surface, it is possible to have humidities exceeding 100%. However, because of the ubiquitous presence of condensation nuclei (e.g., dust, salt, etc.), relative humidities in the Earth's atmosphere typically do not exceed 100% at the surface or 102% within clouds.
Air in our atmosphere is a mixture of gases with very large distances between molecules. Therefore, air can accommodate a large quantity of water vapor. Water vapor is not dissolved in air and air does not "hold" water vapor. The presence of the air is not relevant to the vapor pressure and could be replaced by a vacuum.

Because cloud droplet and air temperatures are nearly the same, it appears that saturation vapor pressure depends upon air temperature. Strictly speaking, it depends on the cloud droplet temperature.

posted 07-10-2001 04:43 PM            

What is the formula for RH, again?

Seeker, also expand on what you mean by "shape of the surface".

posted 07-10-2001 05:12 PM            

When you have a curved surface such as a droplet, each water molecule has fewer nearest neighbors than it would have on a flat surface. In a cloud, these droplets can be as small as a ten-thousandth of a micrometer and contain only a few dozen water molecules.

Of course, these figures are somewhat misleading because the molecules in the liquid water are three-dimensional and are moving in three dimensions. Therefore, consider these figures as a sort of average and perhaps this will help give you an idea of the situation. This effect of curvature on surface tension was discovered by Lord Kelvin.

With fewer nearest neighbors, there is now less attractive force holding the water molecule to the surface.

posted 07-10-2001 07:22 PM            

Relative humidity =

amount of water vapor
in the air
amount of water
vapor the air can hold

I'll get more detailed with a 5 page essay when time permits....

[Edited 3 times, lastly by cydoniaquest on 07-10-2001]

posted 07-10-2001 07:37 PM            

Relative humidity = e/es X 100%

Relative humidity may also be expressed as

RH = W/Ws X 100% where W is the actual mixing ratio

posted 07-10-2001 07:42 PM            

In other words, you are talking about the temperature/dewpoint spread which is a measure of relative humidity.

[Edited 1 times, lastly by cydoniaquest on 07-10-2001]

posted 07-10-2001 09:06 PM            

amount of water vapor
in the air
amount of water
vapor the air can hold

Air does not hold water vapor. Water vapor is not dissolved in air. This can easily be demonstrated by a thought experiment.

Imagine a closed container containing a beaker of pure water and a beaker of ocean water. Place the two solutions side by side so that they are at the same atmospheric temperature and pressure. The air above these two solutions is at the same temperature and pressure.

If air "holds" water vapor, then the two solutions should have the same saturation vapor pressure. However, the saturation vapor pressure above the saline solution is less than that above the pure water. In the saline solution, the salt ions replace some of the water molecules so that fewer water molecules are available for evaporation .

Sooooo, the presence of the salt reduces the rate of evaporation from the saline solution compared to the solution of pure water. This then is the reason why the saturation vapor pressure above the saline solution is less than that above pure water.

If I may add were it not for salt the Earth would be Mars...

posted 07-10-2001 10:29 PM            

Air does in fact hold water vapor as water vapor acts as just another gas. In fact, below is the breakdown of atmospheric composition in percent (by volume) of the Earth's atmosphere near the surface.

Basically we can divide the gases of the atmosphere into two categories, permanent gases and variable gases. First I'll list the permanent gases that make up "air" then the variable gases. Note that water vapor is considered to be a variable gas:

PERMANENT GASES

Gas | Symbol | Percent(by volume)

Nitrogen/ N2/ 78.08
Oxygen/ O2/ 20.95
Argon/ Ar/ 0.93
Neon/ Ne/ 0.0018
Helium/ He/ 0.0005
Methane/ CH4/ 0.0001
Hydrogen/ H2/ 0.00005
Xenon/ Xe/ .000009

VARIABLE GASES

Gas | Symbol | Percent (by volume)

Water vapor/ H2O/ 0 to 4
Carbon Dioxide/ CO2/ 0.034
Ozone/ 03/ 0.000004
Carbon monoxide/ CO/ 0.00002
Sulfur dioxide/ S02/ 0.000001
Nitrogen dioxide/ NO2/ 0.000001
Particles (dust,soot,etc.)/ 0.00001

As I said.....a more detailed essay to follow.

[Edited 3 times, lastly by cydoniaquest on 07-10-2001]

posted 07-10-2001 10:53 PM            

LOL cy, just injecting a little humor into mix...

Hey wait a minute...I didn't see barium on that list !!!

but seriously air is not required to sustain gases, gases exist in space and that is a vaccuum...

Because air is mostly empty space, each gas acts individually as if it alone existed. Most gases are indefinitely soluble in other gases. In an equilibrium state, the amount of vapor above a liquid depends almost entirely on the temperature of the liquid.

It all comes down to temperature.

posted 07-10-2001 11:07 PM            

"but seriously air is not required to sustain gases, gases exist in space and that is a vaccuum..."

I'm not sure I understand what you're trying to say here. As I just broke them down, air is mixture of gases including water vapor. Air doesn't sustain gases....air is composed of gases.

I think somehow you're getting into a conversation about partial pressures of gases and specific gravity of fluids?

Relative humidity is an excellent subject for the discussion of contrail formation, that deserves some delving into in detail...Temperature and pressure altitude (air density) do play an important role in how much water vapor a certain parcel of air can hold... I plan to go into great detail into this subject.

But are we still talking about relative humidity?

Somewhere along the line you lost me here....

[Edited 1 times, lastly by cydoniaquest on 07-10-2001]

posted 07-11-2001 12:44 AM            

I'm not sure I understand what you're trying to say here.

well...you said...

amount of water vapor
in the air
amount of water
vapor the air can hold

I made a rather good case that air does not hold h20 vapor, very small ten-thousandth of a micrometer,gravity free...I think where you may have gotten lost, was how far I'd go to prove it...lol...

Relative humidity is an excellent subject for the discussion of contrail formation, that deserves some delving into in detail...

Boy howdy...and so is temperature to me the defining factor in contrail production, and the best way to prove that contrails are other than contrails...the way I see it most of the verified accused chemtrails were well within normal variables in temperatures...I must admit when I looked at ADDS today I was surprised how cold it was up there considering what time of year it is on our tilt, I mean trails could have been produced at 30k from a 800 mile square block in the central U.S.

But are we still talking about relative humidity?

How about a pic of some partial pressures of gases and specific gravity of fluids?...lol...

posted 07-11-2001 01:52 AM            

I grabbed that from a post of maverick's (i think) at deb's board....

How I described it here is correct...

I thought you fell off the earth...

you know buzz is not too far off the "body" does act as a antenna booster for rf frequency, try putting your remote control fob for your keyless entry to your chin and push the button...your range of operation will increase by 40 feet, but then again the haarp thing... there's 6 or 7 haarp's out there world wide...and pathogens have been in our air since the dawn of time...

blah blah blah

posted 07-11-2001 02:33 AM            

certainly the 2 new additions to this website add dimension that other boards and sites can't possibly offer....

credibility is performed daily, and our actions lend to it or detract from it...

btw, I think someone else posted the link and mav posted the picture...or I would have never seen it....cool pic...

T/S

posted 07-11-2001 05:37 AM            

You say:

I made a rather good case that air does not hold h20 vapor, very small ten-thousandth of a micrometer,gravity free...I think where you may have gotten lost, was how far I'd go to prove it...lol...

You made no case! What are you talking about???!!! This is gibberish. Air does hold water vapor. This point is not even arguable. I've said for the second or third time now that Water vapor is considered one of the variable gases of which air is composed.

posted 07-11-2001 06:39 AM            

In other words, it is the temperature at which air equals 100% relative humidity. Moisture becomes visible in the form of fog, clouds, etc when the temperature of air = its dewpoint. We can therefore get an indication of how high or low relative humidity of a certain parcel of air is by the temperature/dewpoint spread. A larger spread indicates drier air.

By converting the temperature of the ambient air and dewpoint temperature to saturation vapor pressure (es) and actual vapor pressure (e) respectively, we can calculate relative humidity by dividing the actual vapor pressure by saturation vapor pressure.

I will get into showing how saturation vapor pressure is determined later....but let's use an example problem:

What's the relative humidity of air with a temperature of 29 degrees C and a dew point of 18 degrees C?

Answer: At 29 degrees C the saturation vapor pressure is 41mb. At a dewpoint of 18 degrees C, the actual vapor pressure is 21 mb, therefore the relative humidity = 21/41 X 100 percent = 51 percent.

The terms of this equation that we have yet to define fully is "actual" and "saturation" vapor pressure and how actual and saturation vapor pressure is determined.

Actual vapor pressure indicates the air's total vapor content. Saturation vapor pressure describes how much water vapor the air could hold at any temperature.

Put another way, saturation vapor pressure is the maximum pressure that water vapor molecules would exert if the air were saturated with vapor at a given temperature.

You're right about temperature Seeker, in the sense that the saturation vapor pressure then, depends primarily on air temperature. As air temperature increases, more water vapor is required to saturate the air. The increased vapor exerts more pressure, so the saturation vapor pressure goes up. In cooler air, fewer vapor molecules are required to saturate air, and the saturation vapor pressure goes down. So as you can see, there is a direct mathematical relationship between temperature and saturation vapor pressure.

We can calculate relative humidity then if we know the temperature and dewpoint, then we convert these temperatures to their respective "actual" and "saturation" vapor pressures, and then divide actual vapor pressure by the saturation vapor pressure and multiply by 100%.

So far....my purpose has been to define the basic terms such as "actual vapor pressure" and "saturation vapor pressure" and "dew point".....and to show how these terms are used in the relative humidity equation.

Later I will show how saturation vapor pressure is determined, and what type of instrument is used to measure relative humidity.

[Edited 4 times, lastly by cydoniaquest on 07-11-2001]

posted 07-11-2001 07:49 AM            

These quickly dissipate, and do not resemble persistent, engine-generated contrails or spraying in the form of "chemtrails" as we've come to associate them......although they are a function of the relationship between aerial humidity and pressure.

Air at lower pressure holds less moisture and can become saturated at higher relative humidities when it quickly goes from higher pressure to low pressure as from the bottom surface of the wing to the lower pressure area on the upper surface, thereby producing visible condensation.

[Edited 1 times, lastly by cydoniaquest on 07-11-2001]

posted 07-11-2001 09:03 AM            

As a pilot, I usually referred to the winds and temps aloft charts which are taken with weather balloon radiosone equipment. Skew T was more "Kanuck's" bag than mine, but the technology does fascinate me and I see the potential for it to be very accurate (although not guaranteed at present).

I'll have to find that GOES site that Kanuck presented on the Carnicom board and link it here. I think there is a good explanation made there for how these satellites determine atmospheric temperature, pressure and humidity at various altitudes using infrared technology. Much more efficient than weather balloons by the way, and the readings can be taken more often during the course of the day!

Let me look into that....and I'll get back to you 3T3L1. This would also make a great topic over at Chemtrail and Company II!

I'll get into the subject of adiabatic lapse rates here as well (which is relevant to the subject of relative humidity). Basically adiabatic lapse rate referrs to the rate at wich air cools due to the process of expansion as you climb in altitude. You can roughly estimate cloud heights by knowing the dewpoint temperature and ambient air temperature at groundlevel...And by knowing the adaibatic lapse rate of temperature loss due to expansion per each thousand feet of altitude gained, you can determine cloud bases at the point where temperature and dewpoint merge. At that point where dewpoint = temperature, air becomes 100% saturated and we see visible moisture (ie. clouds).

[Edited 1 times, lastly by cydoniaquest on 07-11-2001]

posted 07-11-2001 09:16 AM            

Mr. Leebay is a "new member" and thus could be suspected as a pot-stirrer, BUT nonetheless he did show that at least a few of these people are neither credible nor sane as witnesses to anything above their heads. By the way, "philmont" is right on in his post at the end of the thread, in more ways than one.
http://pub8.ezboard.com/fchemtrailschemtrails.showMessage?topicID=5077.topic

On a final note, I am BANNED from Cliff's, and I have never (and never will) post under any name that is different from the one that I am using now. My "handles" are: Topgun0069, Maverick Goose, and just plain ol' Maverick. That's all of 'em.

Maverick

posted 07-11-2001 09:56 AM            

quote:

---

What's the relative humidity of air with a temperature of 29 degrees C and a dew point of 18 degrees C?

Answer: At 29 degrees C the saturation vapor pressure is 41mb. At a dewpoint of 18 degrees C, the actual vapor pressure is 21 mb, therefore the relative humidity = 21/41 X 100 percent = 51 percent.

---

posted 07-11-2001 10:13 AM            

Relative humidity rh is defined as the ratio between the actual partial vapor pressure p to the saturation vapor pressure above water p_ws, given here in millibars. (The saturation vapor pressure above ice is p_is.) At low temperature relative humidity is defined with respect to saturation pressure above water. But the stable state below 0.01°C is ice and therefore usually you only can get the vapor pressure values above ice as a maximum value. As a consequence under normal environmental conditions the maximum existing relative humidity at temperatures below 0.01°C is:

T < 0.01°C : rh_max = (p_is / p_ws)x(100) [%rh]

posted 07-11-2001 11:37 AM            

To be honest, I never considered RH values over water or ice, but rather, with respect to pressure and temperature. Regardless of whether air is over water or ice, the factors that determine saturation are temperature and pressure, and moisture content per given parcel of air.

For example let's say an airmass originates over an ocean then moves inland over frozen tundra. It aquired it's moisture content over liquid water at a given temperature. But as the airmass moves over the frozen tundra, let's say it cools to its dewpoint. Clouds now form over the cooler land. The only relevent factor here then is temperature. If temperature of the airmass cools to its dewpoint we will have condensation and precipitation as the air becomes 100% saturated or reaches 100% relative humidity.

Now if the dewpoint temperature is well below zero, then the visible moisture sublimates directly to an ice crystal state from a gas to a solid as the RH reaches a given percentage of saturation.

Is this what Mark means by the phrase "with respect to ice"?

Maybe I'm misunderstanding the terms "above water" and "Above ice" or "With respect to water" and "With respect to ice". Does this litterally mean airmass above a body of water....or does it mean above the temperature at which water remains in it's liquid state?

[Edited 5 times, lastly by cydoniaquest on 07-11-2001]