The four main gases in the Earth's atmosphere are Nitrogen, Oxygen, Argon, and Carbon dioxide. These gases make up the vast majority of the atmospheric composition.
Composition of the Atmosphere
According to the National Oceanic and Atmospheric Administration (NOAA), the dry atmosphere is primarily composed of these four gases. While there are many other trace gases and aerosols, these four are present in the highest concentrations.
Here is a breakdown of their approximate content:
| Gas | Symbol | Content |
|---|---|---|
| Nitrogen | N₂ | 78.084% |
| Oxygen | O₂ | 20.946% |
| Argon | Ar | 0.934% |
| Carbon dioxide | CO₂ | 0.042% |
Key Atmospheric Gases Explained
- Nitrogen (N₂): This is the most abundant gas in the atmosphere, making up over three-quarters of the air we breathe. It is relatively inert and plays a crucial role in diluting oxygen to the appropriate concentration for respiration. It's also essential for life through the nitrogen cycle.
- Oxygen (O₂): The second most abundant gas, oxygen is vital for the respiration of most living organisms. It is also necessary for combustion. Plants produce oxygen through photosynthesis.
- Argon (Ar): Argon is a noble gas and is the third most abundant component of the atmosphere. It is inert, meaning it does not readily react with other substances.
- Carbon dioxide (CO₂): Although present in a much smaller concentration than nitrogen and oxygen, carbon dioxide is an extremely important greenhouse gas, playing a significant role in regulating the Earth's temperature. It is also essential for plant photosynthesis.
Together, these four gases constitute over 99.9% of the dry atmosphere's volume. The remaining fraction consists of trace gases like neon, helium, krypton, hydrogen, as well as variable components like water vapor.
