We are always talking about air pollution, gases emitted by vehicles and industries, global warming and climate change. However, there are many people who do not know what is the atmosphere, what are its characteristics, its layers and the great importance it has for life on Earth.
In this article, we are going to explore in detail what is the atmosphere, its characteristics, the layers it is composed of and why it is essential for life on our planet.
What is the atmosphere?
The atmosphere is a gaseous layer that surrounds a planet or celestial body and is held in place by gravity. Depending on the planet, this layer can vary in density and size. On some planets, the atmosphere is composed primarily of light gases such as hydrogen and helium, while on others, such as Earth, it is composed of a variety of elements vital to life.
The Earth's atmosphere extends approximately to the 10.000 kilometers above the surface of the planet, although most of the gases that compose it are concentrated in the first 11 kilometers of altitude. This layer provides us with the gases essential for life and is responsible for regulating the Earth's temperature, protecting us from harmful solar radiation and allowing life to flourish on the planet.
The origin of the Earth's atmosphere dates back to the early stages of the planet's formation. In its early days, the Earth was surrounded by a dense layer of gases composed mainly of hydrogen and helium. However, as the planet cooled and life began to develop, the atmosphere changed due to processes such as photosynthesis, which added oxygen to the gas mix.
Main characteristics of the atmosphere
The atmosphere has several fundamental characteristics that make life on Earth possible. One of its most notable aspects is its gaseous composition. The Earth's atmosphere is composed of various gases, the most abundant being:
- Nitrogen (78,08%)
- Oxygen (20,94%)
- Argon (0,93%)
- Carbon dioxide (0,04%)
In addition, in smaller proportions, water vapor, neon, helium, methane, molecular nitrogen and other trace gases are also found. steam It is especially important for the water cycle and can occupy between 1% and 4% of the atmosphere, depending on location and weather conditions.
Another important characteristic of the atmosphere is that its composition and structure vary with altitude. In the first 100 kilometers we find the homosphere, where the gas mixture is homogeneous. Beyond this height, in the heterosphere, gases are stratified into layers according to their molecular weight, with hydrogen and helium present in the upper layers.
Layers of the atmosphere
The Earth's atmosphere is divided into several layers, each with unique characteristics that serve vital functions for life on Earth. These five main layers are:
- Troposphere: It is the layer closest to the Earth's surface and contains the largest amount of atmospheric gases. All meteorological phenomena and the conditions suitable for life as we know it develop here. Its height varies between 6 kilometres at the poles and 18 kilometres at the equatorial zone. Despite being the warmest, temperatures at its upper limit can reach -50 °C.
- Stratosphere: It extends from 18 to 50 kilometers above sea level. It is where the ozone layer, which absorbs most of the harmful ultraviolet radiation coming from the Sun, thus protecting living beings from these harmful rays. In the stratosphere, temperatures increase as you go up, reaching -3 °C due to the concentration of ozone.
- Mesosphere: This layer is located between 50 and 80 kilometres high and is the coldest part of the atmosphere, with temperatures that can drop to -80 °C. It is in this layer that most meteorites disintegrate when they come into contact with the Earth's atmosphere.
- Thermosphere: Also known as the ionosphere, it extends from 80 to 800 kilometres above sea level. Temperatures in this layer can fluctuate dramatically, reaching up to 1.500 °C during the day. The ionosphere is crucial for the transmission of radio and telecommunications signals, as it reflects electromagnetic waves.
- Exosphere: This is the outermost layer, extending from 800 to 10.000 kilometres. In this region, gases disperse into space and where light elements such as helium and hydrogen escape. It is the boundary between the atmosphere and outer space.
The ozone layer in the stratosphere
La ozone layer, located in the stratosphere, is crucial to protecting life on Earth. It forms a barrier that absorbs between the 97% and 99% of ultraviolet radiation high-energy radiation from the Sun. This radiation is highly dangerous for living organisms, as it can cause DNA damage and increase the risk of skin cancer, among other conditions.
Ozone (O3) is formed when oxygen molecules (O2) interact with ultraviolet radiation, generating an ozone molecule. This process of ozone formation and destruction is what allows solar radiation to be filtered, regulating the Earth's temperature and making it habitable. However, the ozone layer has been damaged due to the emission of chemicals such as chlorofluorocarbons (CFCs), which has led to the appearance of the well-known hole in the ozone layer, especially over Antarctica.
Importance of the atmosphere
The atmosphere plays a role fundamental in life on Earth. Among its most important functions are:
- Radiation protection: The layers of the atmosphere, especially the ozone layer, protect us from ultraviolet (UV) radiation from the Sun, preventing it from reaching the Earth's surface in its entirety.
- Temperature regulation: The atmosphere acts as a natural heating system, keeping Earth's temperature within a life-sustaining range through the natural greenhouse effect. Without the atmosphere, temperatures would rise and fall dramatically between day and night, making life on Earth impossible.
- Water cycle: Through evaporation, condensation and precipitation, the atmosphere maintains the water cycle, which is vital for plant and animal life.
- Protection against meteorites: The atmosphere also acts as a barrier to small meteorites, disintegrating them before they reach the Earth's surface.
In short, the atmosphere is a critical layer for life on Earth. Not only does it protect us from the dangers of space, it also regulates the climate, provides oxygen, and maintains the planet’s thermal balance. As concerns about climate change and pollution increase, it is crucial that we take steps to protect our atmosphere and ensure it continues to play its vital role in protecting life as we know it.