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Originally posted by iskander
HowardRoark, so what is the normal dissipation rate for a contrail?
Then all I have to say, is that the last time I was in Portland, every day I personally witnessed unmarked (I looked), white jets flying a crisscross pattern and leaving a tic tac toe like grid that hung in the air for hours, and dissipated in a haze which covered the entire city.
Other commercial airliners which flew to and from PDX, left normal contrails which dissipated in about 30 seconds. Altitudes of commercial and unmarked jets were the same.
The trails, what ever they might be, settled around 5PM
Originally posted by iskander
HowardRoark, so what is the normal dissipation rate for a contrail?
Here, play around, then come back and tell all of us;
itg1.meteor.wisc.edu...
Then all I have to say, is that the last time I was in Portland, every day I personally witnessed unmarked (I looked), white jets flying a crisscross pattern and leaving a tic tac toe like grid that hung in the air for hours, and dissipated in a haze which covered the entire city.
Other commercial airliners which flew to and from PDX, left normal contrails which dissipated in about 30 seconds. Altitudes of commercial and unmarked jets were the same.
Cute, but overly simplified. It deoesn't reeally address the issue of ice supersaturated regions that well, since it implies that ice crystals formed in a supersaturated environment will eventually sublimate, which is not the case.
How do you know what the altitudes were?
Did you check the flights out on flight explorer?
It is physically impossible for the human dept persecution to determine if an airplane is flying at 20,000 feet or 30,000 feet. Our eyes are not far enough apart.
Use of a telescope won't help either.
With air temps of -40 or so, and the air being really really thin, tell me why a contrail must disappear quickly if the water has frozen
Also, if it does last long, how does that mean chemical spraying and which chemicals does that mean?
A cirrus cloud is a type of cloud composed of ice crystals and characterized by thin, wisplike strands, often accompanied by tufts. Sometimes these wispy clouds are so extensive that they are virtually indistinguishable from one another, forming a veil or sheet called "cirrostratus".
Originally posted by iskander
So a few (i think I counted about 6) jet liners can produce a cirrus cover large enough to cover the entire city in completely clear skies?
Cover that hangs literally for hours?
I don't think so, bur even if they can, that by default would count as weather modification.
Originally posted by iskander
Cute, but overly simplified. It deoesn't reeally address the issue of ice supersaturated regions that well, since it implies that ice crystals formed in a supersaturated environment will eventually sublimate, which is not the case.
Well, since now we're on the same page, give me an example of meteorological conditions that will support sustained crystallization for over 5 hours.
Typical tropical cirrus systems last for 19-30 ± 16 h.
Originally posted by iskander
Personally, the only possibility I managed to come up with was hail/snow, with the natural descent rate, and it's still not cutting anywhere close to 5 hours. Not to mention thermodynamics.
A two-dimensional cirrus cloud model has been developed to investigate the interaction and feedback of radiation, ice microphysics, and turbulence-scale turbulence, and their influence on the evolution of cirrus clouds. The model is designed for the study of cloud-scale processes with a 100-m grid spacing. The authors have incorporated a numerical scheme for the prediction of ice crystal size distributions based on calculations of nucleation, diffusional growth, advection, gravitational sedimentation, and turbulent mixing. The radiative effect on the diffusional growth of an individual ice crystal is also taken into account in the model. The model includes an advanced interactive radiative transfer scheme that employs the δ-four-stream approximation for radiative transfer, the correlated k-distribution method for nongray gaseous absorption, and the scattering and absorption properties of hexagonal ice crystals. This radiation scheme is driven by ice water content and mean effective ice crystal size that represents the ice crystal size distribution. To study the effects of entrainment and mixing on the cloud, a second-order turbulence closure has been developed and incorporated into the model. Simulation results show that initial cloud formation occurs through ice nucleation associated with dynamic and thermodynamic forcings. Radiation becomes important for cloud evolution once a sufficient amount of ice water is generated. Radiative processes enhance both the growth of ice crystals at the cloud top by radiative cooling and the sublimation of ice crystals in the lower region by radiative heating. The simulated ice crystal size distributions depend strongly on the radiation fields. In addition, the radiation effect on individual ice crystals through diffusional growth is shown to be significant. Turbulence begins to play a substantial role in cloud evolution during the maintenance and dissipation period of the cirrus cloud life cycle. The inclusion of turbulence tends to generate more intermediate-to-large ice crystals, especially in the middle and lower parts of the cloud. Incorporation of the second-order closure scheme enhances instability below the initial cloud layer and brings more moisture to the region above the cloud, relative to the use of the traditional eddy mixing theory.
Originally posted by iskander
That is precisely why the contrails of commercial jets dissipated with in 30 seconds. That's what got my attention in the firsts place.
Cirrus clouds don't just form and die, but can regenerate, detailed images of ice crystals show
Originally posted by iskander
If you want I can describe the digital camera resolution method to you in detail, but I'm getting a drift that you'd know all about proportional ranging.
Originally posted by LoneGunMan
Howard thinks Ice supersturation regions explain the entire CT issue. Howard
I personally am not talking about persistant contrails, I have seen those since I was a
child. I am talking about line after line of chemtrails that spread out and cause a complete overcast.
Originally posted by LoneGunMan
I am talking about seeing an entire car lot covered in a spiderweb
looking material.
The life cycle of clouds is an active area of research these days. Are you familiar with any of that research?
What factors do YOU think might affect the rate of sublimation?
Please answer this, because I need to try to figure out where your understanding of the physics and thermodynamics involved breaks down.
Why can’t a contrail last for longer than 30 seconds?
Proportional ranging. Is that where you compare the apparent size of two objects to determine how far away they are?
So, according to that theory, the plane that appears to be smaller in this photo is farther away from the camera than the plane that appears to be bigger, is that right?