"Look at that!" I exclaimed.
My elder sister looked at where my finger was pointing at in the sky; a jet had just flown by leaving a white trail behind. We gazed into the sky, mesmerised by the white trail the jet left as it moved farther away from our sight. After a while though, the track fades and disappears into thin air.
It happened so many times and we wondered what that could be. More than a decade later I got to know that those white streaks planes or jets leave behind are artificial clouds.
They are not smoke from the engines,They're called contrails,which is a shortened version of the phrase "condensation trail".
What Are Contrails?
The condensation trail that is being left behind jet aircrafts/planes are called contrails. Contrails are formed when hot moist air from the exhaust of a jet mixes with air from the atmosphere, which at high altitude is of much lower vapor pressure and temperature than the exhaust gas. The water vapor contained in the jet exhaust condenses and may freeze (At heights of 26,000 feet or more, the air is extremely cold; sometimes more than -40° F!).
Formation of cloud by the process of mixing is synonymous to the cloud you get when you exhale hot breath on a cold day and sometimes see your breath. The mixing takes place as a result of turbulence generated by the engine exhaust.
How Do The Gases In a Contrail Mix?
The mixing of gases present in the contrail rotates with respect to the surrounding air.
These regions of rotating flow are called vortices.
Any sharp surface, like the tip of a plane/jet wing, can cause vortical flow as it moves, if it is large enough or the flow has sufficient speed. In most cases, these trailing vortices may communicate with one another.
What are Jet/ Plane Engine Exhaust Made Of?
Jet engine exhaust is made up of carbon dioxide, sulfur oxides, nitrogen, unburned fuel, soot and metal particles, inclusive of water vapor.
The soot creates condensation spots for the water vapor. Any particles in the atmosphere provides an additional spot
Factors Affecting Contrails
Contrails are dependent on a jet's altitude, the temperature and humidity of the atmosphere; they may vary in their thickness, extent and duration.
The nature and level of persistence of jet contrails can be used to predict the weather.
A contrail which is thin and short-lived is an indicator of low-humidity air at high altitude, a sign of fair weather also: whereas a thick, long-lasting contrail reflects humid air at high altitudes and can be an early indicator of a storm.
When the contrails are visible and strong, it is possible to see the white streaks become wavy with rings floating high in the sky, like smoke rings from a giant cigar.
How Long Do Contrails Last In The Sky?
If you pay attention to contrail formation and duration, you will observe that they can rapidly vanish or spread horizontally into an extensive thin cirrus layer. How long a contrail stays intact, is dependent on the humidity level and winds of the upper troposphere. If the atmosphere is close to saturation, the contrail may exist for some period of time. Meanwhile, if the atmosphere is dry then as the contrail mixes with the environment it vanishes. Contrails can fade away, and can also persist and spread. It depends on the air they are formed in.
Effects Of Contrails to the Atmosphere
In climate studies, contrails are looked at closely as increased jet aircraft traffic may lead to an increase in cloud cover. It has been calculated that in certain heavy air-traffic corridors, cloud cover has increased by as much as 20%. An increase in cloud quantity changes the region's radiation balance. For instance, solar energy getting to the surface may be minimal, thus resulting in surface cooling. Also they reduce the terrestrial energy losses of the planet, resulting in a warming.
Recent research has suggested that the ice clouds contained in contrails causes greenhouse effects and contribute to global warming as part of the insulating blanket of moisture and gases in the atmosphere. Jet exhaust also alters the chemistry of the upper troposphere and lower stratosphere.
All White Streaks are Not Contrails
If you have seen an air show, where messages that looks like clouds are created in the sky with the use of airplanes. Are these clouds also contrails? Not really.
Skywriters fly in special patterns to create written messages visible from the ground with the use small airplanes equipped with special smoke machines . The smoke machines usually contains pressurized containers filled with oil.
At the command of a pilot, the machines spray oil onto the plane's hot exhaust system, where it quickly burns and makes clouds of dense white smoke. Pilots have to learn how to make unique patterns and control smoke machine carefully to be able to create special messages in the sky.
The messages which ranges from advertisements to marriage proposals, can be practical, personal or just simply silly. Skywriting has been in existence for donkey years. There are reports of successful skywriters before World War I, possibly as early as 1915.
Presently, skywriters take advantage of available technologies like satellite navigation to program messages before flight, thereby increasing accuracy and efficiency.
Why Some Planes/Jets Make Long Trails and Others Don't?
The major reasons are Contrails are actually a type of cirrus cloud. When the air is wet and cold enough the trails can stay around for a long time, and sometimes spread out and If the jets are in different regions of air, it affects the contrail duration.
The less common reason, is that different jets have different engines. Some engines will leave a contrail in air where another engine will not.
Contrails Are Not Chemtrails
A contrail as earlier discussed takes place when a plane travels at a high altitude (about 26,000 ft. or more) and compresses the air into a water vapor or ice crystals through jet engines or the wing tips pushing through the air.
This trail disappears after few minutes or there about, due to evaporation, because it's water. This is normal.
The term "chemtrail" is a relatively new word, which appeared in the last ten years or earlier when chemtrails appeared. A chemtrail is not normal.
A chemtrail is very different from a contrail. At first glance a chemtrail might look a bit like a contrail, but instead of disappearing like a contrail does, a chemtrail spreads out and forms a hazy cloud bank.
These trails journeys over the whole sky and sometimes take hours to vanish and eventually spread out to a “spider web” type of milky haze that covers the entire sky. These are formed from minute reflective metallic particulates that eventually reaches the earth. . They are known to turn what was originally a clear blue sky into a grey haze.
What Are Chemtrails Made Of?
Chemtrails are said to be geo-engineered aerosols that are loaded with toxic chemicals, including but not limited to: barium, strontium 90, aluminum, cadmium, zinc, viruses and “chaff.”
Chaff looks synonymous with snow, but it’s actually Mylar fibers (like in fiberglass) coated with aluminum, desiccated blood cells, plastic, and paper.
Yes! Chemtrails Are Harmful
Harmful To Our Food and Water
Since aluminum has a natural liking for water, all forms of life attract these oxides. Thus causing contamination of organic fruits, vegetables, and livestock if they’re exposed to the atmosphere, because plants readily absorb aluminum salts from the soil into their vascular systems. Everything absorbs aluminum salts and it’s present in the air.
Processed foods contains aluminum salts and aluminum sulfate is added to water to make it clear. According to Dr. Christopher Exley, Professor of Bioinorganic Chemistry at Keele University in the UK, we are in the “Aluminum Age” and it’s everywhere, but so unhealthy
Harmful To Our Environment
The “toxic cloud shield” formed by aerosolizing the atmosphere, minimises rainfall, attracts heat, and maximises humidity, leading to a plague of pests, diseases, mildews, molds, fungi and most importantly the depletion of our precious ozone layer that protects us from dangerous Ultraviolet rays.
Harmful To Our Health
As aforementioned, aluminum laden “chaff” falling from the sky enters the lungs causing upper respiratory diseases, lung cancer, breast cancer, and is the entrance to vulnerable areas of the body including arterial walls, where it gets piled up like a plaque.
Also, aluminum toxicity creates a number of neurological disorders and brain cancer, while radium and zinc cadmium sulfide interactively causes bone cancer.
Conclusion
When next you see contrails in the clear blue sky, be sure to be awed not only by how beautiful it looks but by the various scientific processes that has taken place to make that happen. If you get to see Chemtrails, do well by running for cover; but then if Chemtrails don't kill us, something else will. ✍
References
Contrail science
The truth about cancer
My expats world
Wonderopolis