EPOW - Ecology Picture of the Week

Tale of the Contrails

Contrails or condensation trails from jet airliners
Ohio, USA

Explanation:  This week's double photo illustrates something not many of us consider when we engage in air travel:  the potential influence of airplane engine emissions on our atmosphere and on climate change.  

What are these lines across the sky?  They are contrails or condensation trails, formed of water vapor that condenses high in the flight altitudes of aircraft.  Researchers are investigating how contrails disperse and can block sunlight or trap radiant heat energy from the Earth's surface, and thus could add to atmospheric warming.

Are these tiny lines really a concern?  Consider that, in the U.S. alone, at any one moment there are on average about five thousand aircraft aloft.   

In the three days following September 11, 2001, virtually all U.S. aircraft were grounded, giving scientists an unprecedented opportunity to study effects of contrails.  One study discovered that the range of temperatures between warm days and cool nights increased by about two degrees Fahrenheit, suggesting that the incessant layer of contrails serves to buffer daily temperature fluctuations.  That is, contrails can reflect sunlight back into space during the day but also trap heat at night ... and the net result might be increased surface warming, but it's not entirely clear.  

Some researchers argue that the effect of contrails on temperature is minor compared to possible effects from airplanes' CO₂ emissions.  

A note about this week's photos:
     I took these photos during a cross-country flight on a commercial airliner.  I was at first intrigued by the four contrail lines we were flying parallel to (the uppermost photo in this week's offering) and realized that they were likely produced by two twin-engine jets.  
    Soon we overtook one of the jets and I grew a little uneasy as our plane flew closer and closer to that jet's flight path.  All was well, however, but I realized that we were contributing to an incessant, massive number of contrails that scar the skies day and night.