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Q: Where do contrails form?
A: Contrails are human-induced clouds that usually form at very high altitudes (usually above 8 km - about 26,000 ft) where the air is extremely cold (less than -40ºC). Because of this, contrails form not when an airplane is taking off or landing, but while it is at cruise altitude. (Exceptions occur in places like Alaska and Canada, where very cold air is sometimes found near the ground.) Thus, people who live under major air traffic routes, not people who live near major airports, are those who will see the most contrails. (However, some major airports are also under major air traffic routes, which can lead to confusion.) You can use an Appleman chart to predict contrail formation for your area. Of course, a contrail cannot form if no airplane passes through.
asd-www.larc.nasa.gov...
Are there different types of contrails?
Contrails are all made of the same materials and are formed in the same way, but exist for different lengths of time. Because of the differences in contrail "life-spans", contrails can be divided into three groups: short-lived, persistent (non-spreading), and persistent spreading. See the Contrail Formation Guide for more information on how contrails form.
Short-lived contrails look like short white lines following along behind the plane, disappearing almost as fast as the airplane goes across the sky, perhaps lasting only a few minutes or less. The air that the airplane is passing through is somewhat moist, and there is only a small amount of water vapor available to form a contrail. The ice particles that do form quickly return again to a vapor state.
Persistent (non-spreading) contrails look like long white lines that remain visible after the airplane has disappeared. This shows that the air where the airplane is flying is quite humid, and there is a large amount of water vapor available to form a contrail. Persistent contrails can be further divided into two classes: those that spread and those that don't. Persistent contrails look like long, narrow white pencil-lines across the sky.
Persistent spreading contrails look like long, broad, fuzzy white lines. This is the type most likely to affect climate because they cover a larger area and last longer than short-lived or persistent contrails.
Contrail cousins are things that look like contrails but actually arise from a different physical process. For example, under the right conditions you will see vapor trails form from the wingtips of a jet on takeoff or landing. This phenomenon results from a decrease in pressure and temperature in the wingtip vortex. If conditions are right, liquid water drops form inside the vortex and make it visible. These evaporate very quickly after they form.
Can contrails move, or do they stay in the location where they were formed?
Because contrails are formed at high altitudes where the winds are usually very strong, they will move away from the area where they originated. Often, when we look up into the sky, we will see old persistent contrails that formed far away but moved overhead because of the wind.
How are contrails different from other clouds?
Contrails are "human-induced" clouds since they are formed by water vapor condensing and freezing on particles from airplane exhaust. Contrails are always made of ice particles, due to the very cold temperatures at high altitude. Other types of clouds can be formed by water vapor that condenses on particles which are present in the atmosphere due to many sources, such as from volcanoes or dust storms, not specifically from aircraft exhaust. Those clouds are sometimes made of water droplets, and sometimes ice crystals, depending on the temperature where they form.
Contrails only form at very high altitudes (usually above 8 km) where the air is extremely cold (less than -40 degrees C). Other clouds can form at a range of altitudes, from very close to the ground, such as fog, to very high off the ground, such as cirrus clouds.
When were contrails first observed?
Contrails were first noticed during high-altitude flights in the 1920's. However, interest in contrails really blossomed during WWII when bombers could be sighted from miles away. In fact, numerous WWII veteran accounts tell of problems to aviation due to massive contrail formations. Planes could not find their targets, and sometimes collided with each other. In 1953, a scientist named H. Appleman published a chart that can be used to determine when a jet airplane would or would not produce a contrail.
Chemtrails? Need help?
Contrail Chemtrail Research Thread
The Chemtrail Hoax
Are these proof of Chemtrails or Contrails?
Chemtrail believers - I challenge you to debunk contrail science
Contrails: Understanding why they aren’t chemtrails
The Chemtrail Myth
This is not a chemtrail! Atmospheric Phenomenon explained
Why the Chemtrail Conspiracy is Implausible & Meteorologically Inaccurate
The Astounding Effect Of Contrails On Climate
How To Forecast Using Clouds Part 1
Originally posted by GeminiSky
Now lets think about this for a second: What if the chem-trails are being used to inoculate the world population?
Suppose they have two chemicals that react violently with each other and would cause instant death if combined in the human body.
How in the world would you innoculate anything or disperse any chemicals with the water vapour made by the exhaust of aircraft engines?
Originally posted by hawkiye
Regular jet contrails do not linger in the air all day like chem trails. How come the jets at the airports don't leave these trails?
Originally posted by hawkiye
So why do some jets not leave trails and others do?
Originally posted by hawkiye
And why are so many of them criss crossing the skies almost every day.
Originally posted by hawkiye
I live near a major airport and never see them leave persistent trails like that.
Originally posted by hawkiye
Why don't they leave them when taking off then?
Originally posted by hawkiye
Is it because they can turn them off and on hmmm?
Originally posted by hawkiye
When you have the same jets checkerboarding the sky all day it is not radio vectoring of normal traffic.
Originally posted by hawkiye
Air pressure makes little difference the jets either leave the trails or they don't.
Originally posted by ACTS 2:38
These sites are claiming to modify the weather and give examples of how they want us to believe they do it.
So I would not make claim as to them not spraying stuff into the air.
Originally posted by hawkiye
Regular jet contrails do not linger in the air all day like chem trails.
How come the jets at the airports don't leave these trails?
How many times have you seen military jets not leaving any lingering trail?
So why do some jets not leave trails and others do?
Regular jet contrails do not linger in the air all day like chem trails. How come the jets at the airports don't leave these trails? How many times have you seen military jets not leaving any lingering trail?
So why do some jets not leave trails and others do? The only logical answer is they are on purpose. So what is thier purpose then? And why are so many of them criss crossing the skies almost every day. It is not just normal air traffic because they don't leave trails? It's not to fight global warming becuase we know that is a hoax. So what is it then?
Are there different types of contrails?
Contrails are all made of the same materials and are formed in the same way, but exist for different lengths of time. Because of the differences in contrail "life-spans", contrails can be divided into three groups: short-lived, persistent (non-spreading), and persistent spreading. See the Contrail Formation Guide for more information on how contrails form.
Short-lived contrails look like short white lines following along behind the plane, disappearing almost as fast as the airplane goes across the sky, perhaps lasting only a few minutes or less. The air that the airplane is passing through is somewhat moist, and there is only a small amount of water vapor available to form a contrail. The ice particles that do form quickly return again to a vapor state.
Persistent (non-spreading) contrails look like long white lines that remain visible after the airplane has disappeared. This shows that the air where the airplane is flying is quite humid, and there is a large amount of water vapor available to form a contrail. Persistent contrails can be further divided into two classes: those that spread and those that don't. Persistent contrails look like long, narrow white pencil-lines across the sky.
Two jets same height one leaving chemtrail the other contrail that disappears normally:
www.youtube.com...
Originally posted by hawkiye
Oh and by the way my breath when it freezes in cold weather doesn't linger all day in the air it disappears right away... Kind of like a jet contrail