See the following article:
A-Train Earth Monitoring Mission Will Feature Five Satellites
at the link
http://www.space.com/spacenews/archive04/missionarch_051704.html
A line from the article: "Using a laser radar, or lidar, Calipso will study the interaction of small particles, or aerosols, in the atmosphere with clouds in an attempt to determine their effect on the Earth’s climate."
Plus four other sats doing neat things in atmosphere monitoring.
