Which gas makes up the majority of Earth's atmosphere?

The majority of Earth's atmosphere is composed of nitrogen, which constitutes about 78% of the atmosphere by volume. This inert gas plays a critical role in maintaining the stability of the atmosphere and contributes to various atmospheric processes without directly participating in most chemical reactions that occur in the environment. Understanding nitrogen's dominance is essential for studying atmospheric sciences, as it influences weather patterns, climate, and biological systems.

While oxygen is vital for life and accounts for about 21% of the atmosphere, it does not surpass nitrogen in terms of abundance. Carbon dioxide and argon also exist in trace amounts, with carbon dioxide making up around 0.04% and argon about 0.93%. The higher proportions of nitrogen compared to these gases are fundamental in a variety of geological and biological cycles, further emphasizing nitrogen's critical role in the Earth's atmosphere.