Jan, detecting the atmosphere and even strong biosignatures like chlorophyll is a theoretical possibility for Earth-like exoplanets. Unfortunately, the technology to do so is out of our reach for many years, probably decades.
'Exoplanets on Sight' is a workshop for K-12 students where they learn about planets around other stars (exoplanets) and how chemistry affect their colors. The activity of the workshop is to create and paint an original planets based on its composition or simply being artistic. Here are images of the planet created by 24 middle school students during the ISMuL-NASA STEM Summer Academy 2013 at the University of Puerto Rico at Arecibo.