Air Pollution as Seen From the Skies
From Mt. Etna to China to the Sahara, these striking satellite images of air pollution are from both natural and man-made causes
- By Sarah Zielinski
- Smithsonian.com, April 20, 2010
Those tracks in the sky are a familiar sight, especially to people living near routes heavily trafficked by high-altitude airplanes. When planes fly at about 26,000 feet or higher, water vapor condenses and freezes around particles in the aircraft’s exhaust, forming linear clouds that can persist and grow. Increased cloud cover could have an effect on climate, though scientists are unsure whether the contrails exacerbate warming or help to cool the planet. More worrisome, though, is aviation's contribution to anthropogenic climate change: airplanes emit a host of greenhouse gases, including carbon dioxide and methane.