Persistent Contrails have existed for 70+ years

The science behind how and why contrails form, persistent, and spread out, have been documented and observed consistently throughout the history of aviation.  The effects of contrails has changed throughout recent years because of engine technology, as high bypass jet engines creates cooler exhaust which is more likely to condense before it mixes with the surrounding air. The size and efficiency of engines are more conducive to big and impressive looking contrails. Combine that with the incredible amount of air traffic in the skies today, and the right atmospheric conditions, it's no wonder why lots of persistent contrails form in the skies daily.

Chemtrail believers claim that persistent contrails are a new thing, they call them chemtrails and claim that contrails don't last a long time, and they certainly don't spread out and cause cirrus clouds and overcast skies. They also claim that these persistent contrails started in the late 1990s.


Ask yourself, Is there a  physical or visible difference between chemtrails and persistent contrails?


Three good videos to start out with follows: *Must Watch!*





Here is a video of someones Popular Science Magazine, May 1969

(below is a crop of the section, from page 76, and the transcript)




Page 76, (isolated)


















  





Transcript:  "The reflectivity of the earth is also altered by jet contrails, say Dr. Walter Orr Roberts, director of the National Center for Atmospheric Research.

Contrails, Dr. Roberts explains, do not simply spread out at the 30-40,000-foot altitudes where jets fly, but spawn cirrus clouds by seeding the upper atmosphere with ice crystals from the water vapor in jet exhaust. On a clear day, you can often see this happening near heavily traveled airways.

"It is almost certain that on many occasions - 30 to 40 days a year, say - the cause of cirrus cloud cover can take in a substantial part of a continent, perhaps half of the U.S., and has a substantial influence on our radiation budget"


A very good video showing real world examples of Contrail
formations as well how "Grid" patterns form.




*CLICK* on the Articles, Pictures, and Videos to expand 
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Aircraft Contrails Factsheet

KCRA 3 WeatherPlus meteorologist Dirk Verdoorn
discusses contrails formed by jets





Skip to 1:00 on the video below.
Scott explains why contrails linger, and their association 
with frontal systems, causing them to persist.




This video explains how impossible it would be for aircraft
to contain the incredible amout of chemicals needed for the
amount of spraying people claim is going on. And why spraying
at high altitude is counter productive.
 




Here is a 9 year old video, it shows the incredible amount 
of air traffic over the USA. As you can see the likely event 
that aircraft routes intersect and create these "grids"
on days where the atmospheric conditions are right, is
very much a guaranteed occurrence.




A HIGH ALTITUDE MAP SHOWING THE COMMON 
FLIGHT PATHS OVER THE USA

A HIGH ALTITUDE MAP SHOWING THE COMMON 
FLIGHT PATHS OVER EUROPE 

PERSISTENT CONTRAILS THROUGHOUT HISTORY 


Exploring The Sky By Day - Terence Dickinson 1988
States that "Contrails can last for hours"

Washington Post; reprinted in The Gazette, of Eastern Iowa 
Dec 26 1980

Kingsport Times, Tennessee, Feb 11 1954

 San Mateo Times, Jan 12 1950
 

Waterloo Courier, April 16 1950

A page from a 1972 book titled "Clouds of the world"
(This was used in the first video)

https://plus.google.com/photos/107393796095434664991/albums/5363662113705530081/5363662635512318290?banner=pwa&pid=5363662635512318290&oid=107393796095434664991


1969 book titled "Clouds and Weather"
(Showing persistent and spreading contrails)

1969 Spreading Contrails

Cloud Study A Pictorial Guide 1957
(This was used in the first video)

A Color Guide To Clouds 1963
(This was used in the first video)

Arcadia Tribune, April 29 1970

























Transcript "Aircraft contrails begin to streak the normally bright Arizona sky at dawn. Through the day, as air traffic peaks, these contrails gradually merge into and almost solid interlaced sheet of cirrus cloud – an artificial cirrus cloud that is frequently as much as 500 meters deep"


The News Frederick MD, March 7 1944

Transcript Top right - “Contrails frequently have a tendency to cause a complete overcast and cause rain. In Idaho I have seen contrails formed in a perfectly clear sky and four hours later a complete overcast resulted“

Bottom left - "Contrails are a headache to combat pilots and are very difficult to control
Apparently they result only when the atmosphere is at a certain temperature and humidity."


Spokane Daily Chronicle July 7 1955

Transcript "An extremely persistent contrail might stay in the sky all day"


 Contrails over the World Trade Center 1994















http://www.flickr.com/photos/thierry62/3429012926


Twin Towers June 17 1985

 http://www.flickr.com/photos/bobmendo/19989783/


Contrails over Arizona 1989

http://www.flickr.com/photos/jlovely/1510717498/


Contrails over Oregon 1990

http://www.flickr.com/photos/markdint/3470370301/lightbox/


1977

http://www.flickr.com/photos/30159472@N04/5715276757/


Grand Rapids, Michigan 1964
 

http://www.flickr.com/photos/13717226@N00/6819996357/


February 1988

http://www.flickr.com/photos/brugge62/83381681/


 Plattsburgh NY 1988

http://www.flickr.com/photos/evanrapp/319068324/


Lake Norman NC, January 1983

South Dakota 1972

http://www.flickr.com/photos/dboo/5135914115/


January 9 1970

http://www.flickr.com/photos/mofotolab/52144900/in/photostream/


Yellowstone July 1985

http://www.flickr.com/photos/saruchan/3700208972/


Lake Leman Switzerland 1978

Center Island Toronto August 23 1980

http://www.flickr.com/photos/mcwidi_2/3593191977/


Spreading Contrails, Paris September 1989

http://www.flickr.com/photos/grissongs02/2837711801/


Preston, Lancashire, UK 1981

Las Vegas 1989

http://www.flickr.com/photos/canadagood/3068353370/


Rat Patrol TV Show February 20 1967

https://www.youtube.com/watch?v=3URrYnZS_Tw


Colorado December 6 1989

 U.K August 1944

"Messegelände" (Exhibition ground) Frankfurt/Main 1987

Persistent Contrails  1958

http://www.airliners.net/photo/0094277/L/


WWII Contrails 1944

http://images.google.com/hosted/life/ff756c4c69c54510.html


Contrails in 1953 and 1950 Nucear Test Films

 






Bomber Contrails 1944

B-24 Liberator Planes 1943-45

Fighter Planes Contrails 1941




1980 News report on Contrails




Douglas DC 8-62 leaving contrails 1982

Air Force Promo 1950

Why Contrails have gaps?

Contrails are clouds made from water vapor that condenses then freezes behind a plane engine. Since the engines are on constantly, it seems a bit odd when you see contrails with gaps in them, or even contrails that stop and start. If the engine is pumping out a constant amount of water, then why is the trail not constant? This puzzle is sometimes seized on by people who think that persistent contrails are actually “chem trails”, or some kind of deliberate spraying operation. 

But it’s actually very simple. The amount of water in the exhaust is pretty constant, but the amount of moisture in the air is not. The humidity varies with altitude, and a layer of low humidity can be sandwiched between two layers of high humidity. As a plane climbs or descends through this layer, then the trail will only form in the areas of high humidity, and so look like it was “switched off” in the area of low humidity.
You can get the same effect with temperature. A warm layer of air can actually lay on top of a colder layer in what is called an “inversion” (you’ll hear this on the weather sometimes, referred to as an “inversion layer”). When a plane flies through this inversion layer, the trail can be “broken”.
It’s not just climbing or descending flights either. The boundaries between these layers is not flat, and gravity waves or rising convection currents of air can create large volume of air that differ in temperature and/or humidity from the neighboring air, and so can break (or make) the contrail when then plane flies through them. You can think of these regions as invisible clouds:








































Similar explanations of a “broken contrail”

NOAA:

Occasionally a jet plane, especially if ascending or descending, will pass through a much drier or more moist layer of atmosphere which may result in a broken pattern to the contrail, with it appearing in segments rather than in one continuous plume.

AirSpace Magazine

If the contrail stops, then starts up again, creating a broken line, chances are the airplane flew through a dry patch.

Doc Weather

What is happening here is that warm air rising from the ground carries vast amounts of water vapor upwards into the highest levels of the atmosphere. This water vapor exists as massive, plumes of warm, moist air ascending to very high levels. When a rising plume reaches the upper atmosphere it condenses into high ice clouds known as cirrus or feather clouds. In the case of the jet contrail (condensation trail) in the first image, the condensing cloud formed where the aircraft passed through a rising plume of moist warm air. The air on either side of the plume was not sufficiently moist to support the formation of an enduring cloud. As a result the contrail only remained visible in the warmth plume.

This uneven humidity does not always result in an instant on/off for the contrail, but can result instead in some regions of the contrail being more persistent than others. This can lead to a gap forming a minute or more afte the contrail originally formed:

 Here’s what it looks like from a pilot’s perspective. You can see that that clouds occur in layers, and they are very unevenly distributed. The pilot said:

“I was flying today above a layer of Cirro-cumulus and snapped a couple of photos of a contrail below me that may be useful in explaining the stop/start nature of some contrails.
The aircraft was actually flying inside the layer and generating quite a thick trail, which either stopped or thinned out where the cloud stopped or thinned out, and started up again where the cloud resumed normal thickness.
Once again, the contrail is not above the cloud layer, but actually inside it.”