Why do scientists study contrails today?
  Contrails are studied for many reasons today. These man-made clouds impact the climate in many ways; they modify the energy balance between sunlight and infrared energy in the atmosphere, and they may affect the water vapor content and chemistry of the upper troposphere. As the volume of commercial air travel increases (see A video showing worldwide air traffic in a 24-hour period), these effects will become more important. Scientists today are trying to learn more about the longevity of persistent contrails and how much they may affect the climate in the future.
