White lines in sky are not made by flying saucers

February 20, 2012
By Taheem Williamson
Your Capital Bureau

Every year from December to February, the skies above North Florida are criss-crossed by eerie white lines.

These lines tend to peak around Christmas and into the New Year, leading the curious to seek answers about the phenomena.

Is it a government conspiracy? Are they made by UFOs?

No – they are “contrails” and they have been at the center of an environmental controversy for decades.

Richard Gragg, associate professor of environmental science and policy at Florida A&M University, said he has noticed strange contrails in Tallahassee and other areas.

“These contrails are unusual and different from what I am used to seeing in that they are emitted from planes in a grid pattern over a large spatial area. I am not aware of who is responsible,” he said.

Conspiracy theorists believe contrails are actually chemical trails or “chemtrails,” purposely sprayed in the sky to alter the atmosphere. Others believe the chemtrails weaken human immune system.

Hundreds of websites fuel these theories, but most, if not all, lack credible evidence. The Air Force denies any attempt to alter the atmosphere in any way. They dismiss websites that propagate these theories as hoaxes.

According to the National Weather Service, a contrail is the condensation trail left behind by a passing jet plane. Contrails form when hot, humid air from jet exhaust mixes with air of low vapor pressure and low temperature.

The mixing happens directly behind the plane, due to turbulence created by the engine. If condensation occurs, then a contrail becomes visible. Since air temperatures at high atmospheric levels are usually around -40 degrees Fahrenheit, a small amount of liquid is needed for condensation.

The water comes as a byproduct of plane engines. The formation of a contrail is similar to the process that allows people to see their breath on a cold day.

Contrails seem to appear and disappear just as fast as they are noticed, leaving residents wondering where they come from and where they go. Residents worry the trails may be having adverse effects on the atmosphere.

“Maybe that’s why the weather’s been so inconsistent,” Said Jimitri Holmes, a second year biology student from Ft. Myers, Fla. Holmes said he recalls numerous contrails in Tallahassee’s sky this winter as well as last winter. “I don’t remember seeing that much when I went home for the break,” Holmes said.

Marshall Paggart, assistant director of Tallahassee Regional Airport, said about 21 flights go through the airport daily. He also said traffic increased during January this year..

“There was an increase in traffic for January, but that was because of an influx of legislators.”

Paggart believes contrails pose no threat to the environment.

The contrail controversy goes back thirty years to the 1980s when people began noticing persistent white lines around the country.

In the 1990s, NASA studied the impact of contrails on the atmosphere.

Researchers found that the ice and water vapor from contrails have a minor effect on global warming, because they imitate greenhouse gases. However, the results were not sufficient enough to rule contrails as an environmental hazard.