“Look! Up In the sky! It’s a bird! It’s a plane! It’s Superman! Yes, it’s Superman, strange visitor from another planet who came to earth with powers and abilities far beyond those of mortal men. Superman, who can change the course of mighty rivers, bend steel in his bare hands, and who, disguised as Clark Kent, mild-mannered reporter for a great metropolitan newspaper, wages a never-ending battle for truth, justice and the American way.” (Voice-over from The Adventures of Superman, an American television series from 1952-1958)
Superman could fly fast and high, so why no contrails?
Contrails are short for condensation trails, those puffy white exhaust clouds that form behind aircraft at high altitudes. They are the sky’s equivalent of the wakes boats leave behind them in the water.
Contrails are made of nano-sized ice particles
Ice forms around the impurities (acids, oxides, and minerals) in the hot exhaust of jet aircraft in the cold air of the upper atmosphere. Because planes flying at those altitudes are traveling at high speeds, the clouds are long and thin, like their relatives, cirrus clouds. The lines are sharp and crisp immediately behind the engines and gradually dissipate due to evaporation and turbulence.
With tens of thousands of flights in the sky every day, why isn’t the sky full of contrails?
Every day, three million passengers fly in and out of U.S. airports. At peak operational times, there are more than 5,000 flights in the sky at once. You’d think contrails would be everywhere, but they’re not because commercial airliners rarely produce them.
Most of the contrails we see are made by B-52 bombers on training missions
The higher the altitude, the greater the chance of contrails
Commercial aircraft rarely fly as high as 40,000ft. B-52s fly at 50,000ft, where the air is colder. The BBC says contrail formation occurs when the temperature reaches -40 degrees Centigrade. The ice crystals form visible clouds just like the frozen breath you exhale on cold winter days.
B-52s have eight huge engines, four on each wing
The contrails merge on both sides of the plane so what we see as two vapor trails is actually exhaust vapor from eight jet engines. Most commercial aircraft have only two engines. The wider the contrails, the longer they last and the easier they are to see from the ground.
Commercial aircraft engines burn fuel more cleanly than military versions
Military jets operate under different rules than civilian aircraft. Military aircraft are allowed to be noisier and emit more pollution. The more black exhaust produced on the ground, the easier it is for contrails to form at altitude. Look at the exhaust from these B-52 bombers, what aircraft mechanics refer to as oil burners. That’s a lot of particulate matter, mostly unburned carbons.
Skywriting
Skywriting has nearly disappeared, mostly replaced by small airplanes towing banners above tourist areas and crowds. The “clouds” left by skywriters are not made of ice crystals, but a waxy oil commonly called liquid smoke. In 1922, the first skywriting over New York City included the words CALL VANDERBILT 7200. Ad men were flabbergasted when tens of thousands of people called the number. The New York Times called this airborne graffiti “celestial vandalism on the walls of heaven.” Skywriting.com says the average cost to skywrite a personal message is about $8,500.
Conspiracy theorists rail about chemtrails
They believe contrails are really toxic chemicals sprayed into the atmosphere by the government to cause us harm. The government’s nefarious goals for these chemtrails are said to be (choose one):
- Controlling our minds.
- Sterilizing the general population.
- Committing biological warfare.
Regardless of gender or political party, as many as one person in three thinks there is some truth to one or more of those claims
Those who study such things say there are more believers in the computer age now that people can so easily join like-minded folks online. Chemtrail groups on Facebook are said by some to have more than 100,000 members. Closed groups like this become echo chambers where the only things presented are those that confirm and reconfirm the group’s shared beliefs. Regular readers know this to be an example of what behavioral scientists call confirmation bias, closely related to stereotyping.
Bonus
Contrails are there every day, but we usually pay even less attention to them than we do to clouds. When is the last time you lay in the grass on a hillside and looked at the sky, cloudgazing? All of us did it as kids, but few of us do it now. When was the last time you and a friend looked for recognizable shapes in clouds and compared your perceptions? Like Rorschach’s inkblots, there are no right or wrong answers, just interesting ways in which certain shapes, light and shadows combine to stimulate our imaginations.
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