Atmospheric Science is the investigation of the earth's gaseous envelope. Experiments performed at Arecibo measure upper atmosphere composition, temperature and densities in order to understand the controlling physical processes. The Arecibo Radio Telescope can measure the growth and decay of disturbances in the changing layers of charged particles which populate the region known as the ionosphere ( altitudes above 30 miles ). The "big dish" is also used to study plasma physics processes in the electrically charged regions of the earth's atmosphere. where radio waves are influenced most.