What is the composition of Earth's atmosphere?

The Earth's atmosphere is primarily composed of nitrogen (78%), oxygen (21%), and trace amounts of other gases.

The Earth's atmosphere is a layer of gases that surrounds the planet, held in place by gravity. It is composed of several gases in varying amounts. The most abundant gas is nitrogen, which makes up about 78% of the atmosphere by volume. Nitrogen is a colourless, odourless, and tasteless gas that is relatively inert and plays a crucial role in the nitrogen cycle.

The second most abundant gas is oxygen, accounting for about 21% of the atmosphere. Oxygen is essential for most forms of life on Earth, as it is used in the process of respiration and combustion.

The remaining 1% of the atmosphere is made up of trace gases. These include argon, carbon dioxide, neon, helium, and methane, among others. Argon, a noble gas, makes up about 0.93% of the atmosphere. Carbon dioxide, although present in small amounts (about 0.04%), plays a significant role in Earth's climate because it absorbs heat and contributes to the greenhouse effect.

In addition to these gases, the atmosphere also contains water vapour, which varies in concentration but typically makes up about 1-3% of the atmosphere. Water vapour is responsible for weather phenomena and is a major factor in climate and temperature regulation.

The atmosphere also contains tiny solid particles, such as dust, pollen, and pollutants. These particles can influence weather and climate, and some can be harmful to human health.

In summary, while nitrogen and oxygen make up the majority of the Earth's atmosphere, a variety of other gases and particles are also present and play important roles in supporting life and shaping our climate.