Earth's Atmosphere Composition

By volume, dry air near Earth’s surface is about 78.08% nitrogen, 20.95% oxygen, and 0.93% argon. The remainder consists of trace gases, including carbon dioxide, neon, helium, methane, and hydrogen; water-vapor abundance varies with location and weather. The basic claim is correct, but argon is the largest “other gas,” and proportions vary with altitude and humidity.