Studying jet contrails can be more interesting than anyone ever thought.

Contrails, which are lines of vapor and pollutants from jet engines, can alter temperatures and allow for the tracing of aircraft activities.

On Friday, David Travis, associate professor of geography at the University of Wisconsin-Whitewater, presented some of his findings from jet contrail research in a speech titled, “Jet Contrails and Climate: Information Gained From the Grounding of U.S. Airplanes Following the Sept. 11, 2001, Terrorist Attacks.”

After the Sept. 11 attacks, the government grounded all commercial flights for three days. The high-low temperature range for those days was compared to the thirty-year average and to the three days before and after. The days without commercial flights saw an increased temperature range of just over one degree Celsius.

Over 12,000 airplanes fly over America each day. As more planes fly over other countries, their contrails may have a global temperature effect. Currently, the effect they have is more regional and concentrated, Travis said.

Contrails occur in the upper levels of the atmosphere and are most noticeable in otherwise clear skies, but they often form on edges of cirrus clouds.

They are denser than cirrus clouds, so they are better able to reflect incoming solar radiation and block outgoing long-wave night-time radiation.

Travis used satellite images and data from thousands of weather stations nationwide for his research, which was aided by funding from the National Science Foundation.

“[Travis] did a very good analysis of a tremendous amount of data,” said Jay Stravers, associate professor of geology.

The government has been paying more attention to satellite contrail images to track unusual airplane activity, but the government is not alone in its watching.

Travis showed a satellite image from Sept. 12, 2001, that had contrails made by Air Force One and flanking jets returning to Washington, D.C. The official story is that President Bush returned on the night of Sept. 11. Travis also showed an image from space that clearly showed the plume of smoke rising from New York City on Sept. 11.

Kevin Kraujalis, a station manager for contract weather operations at Midway Airport and senior meteorology major, attended Travis’s lecture.

“Contrails do affect the weather more than I thought,” he said. “More follow-up on this needs to be done.”

Travis is still looking at further implications of jet contrails on the atmosphere. The number of planes in the sky is expected to double or triple by the year 2050.