Composition of the Atmosphere:
AtmosGraph.gif (6392 bytes)The bulk of the  Earth's atmosphere is made up of nitrogen (79 percent) and oxygen (20 percent). The remaining 1 percent of the gases are: argon (0.9 percent), carbon dioxide (0.03 percent), and trace amounts of ozone, methane, carbon monoxide, hydrogen helium, neon, krypton, xenon and, of course, water vapor.