reply to post by Thorazine
Thorazine: responding to your concerns about 15 minutes of persistence - using the study from 1972 that you put up and that you initially put up in
another thread and which was not favorable to your side then anymore than it is favorable to your side now.
Observation seems to be something that you leave under your pillow when you rise in the morning. For others, it is crucial and for some, it is
survival, enabling persons to get through the day unharmed. In WWII, as previously stated, we learned that contrails can persist for, perhaps, 15
minutes. The 'perhaps' is because with the hundreds of contrails mixed with smoke and flak and natural cirrus and clouds and weather, it was,
understandably, difficult to time an individual contrail. The 15 minutes is a recollection from one WWII veteran.
Take a look at the quote as you put it up from the introductory paragraph of the study you presented:
"It is often observed that contrails spread considerably...Under favorable conditions, a lateral spread of kilometers is observed...If sufficient air
traffic exists, an entire overcast of contrail cirrus may develop and persist for hours with rapid growth in the ice budget of individual
Now take a look at the entire quote, the first 3 or 4 sentences of the study (and please note what 'an entire overcast of contrail cirrus' means):
Measurements of the Growth of the Ice Budget in a
It is often observed that contrails spread considerably beyond the initial width defined by the outward extension of the wing-tip vortices. Under
favorable conditions, a lateral spread of kilometers is observed with presumably comparable vertical spreading. If sufficient air carrier traffic
exists, an entire overcast of contrail cirrus may develop and persist for hours with rapid growth in the ice budget of individual contrails.
So, clearly, this introduction is not talking about an individual contrail but rather a situation similar to WWII where another veteran was quoted as
saying that an artificially created cloud layer persisted for several hours over Berlin.
Let's paint a picutre: air traffic over a region (i.e. London) is very heavy and creates what is known as a cloud corridor. Weather exists, on more
days than not, and this condition, combined with a northern latitude, serves contrail formation. Let's paint another picture: air traffic over a
region (i.e. Las Vegas) is heavy and creates what is known as a cloud corridor but there is no weather and no front and temperatures, even at
altitude, are non-conducive and, combined with a lack of humidity, should, in a persistent contrail by the book world, produce no contrails. So
that's our picture. Back to your study - looking at what these researchers have to say about air traffic:
There has been increasing concern over the amount of cirrus triggered through contrail formation. These results would not, however, suggest that
increased air carrier traffic could increase the water vapor at subtropopause levels, a theme that is currently fashionable. On the contrary, the
development of large numbers of precipitation size ice crystals in contrails results in precipitation and an ultimate exchange of water vapor to lower
levels. Given reasonable frequency of contrail growth occurrence, the net effect of air carrier traffic may likely, in fact, be to lower the water
abundance at the levels of most frequent air travel.
So if conditions are conducive to persistent contrails, they are also conducive to rain-out and fall-out and evaporate-out which equals: no visible
contrails. Makes sense - doesn't it? London, with its' weather, rains. Las Vegas, with it's lack of weather, doesn't. However, Houston, there's a
problem. How is that possible with no humidity and alot of heat? Carnicom asked and answered this question and came up with chemtrails. The X
factor. Moving on, fuel content, even in 1972, was a concern:
With any given fuel (or proportionality constant) there results a critical temperature for each altitude above which contrail formation is
impossible. In order that the contrail be visible a temperature as much as several degrees below the critical temperature is generally
So fuel content is important and could be manipulated to produce contrails where no contrail has gone before.
(Please see next post for continuation!)
edit on 4-9-2012 by luxordelphi because: make person plural
edit on 4-9-2012 by luxordelphi because: correct spelling
edit on 4-9-2012 by luxordelphi because: correct spelling of picture