THE atmosphere it is a coating of gases that the planet Earth has and that is maintained by the attraction of gravity.
Atmospheric gases are important for sustaining life on Earth, as their functions are: to provide oxygen to breathing of living beings, maintain the proper temperature, protect from incident radiation and distribute water through the rain.
The atmosphere protects the planet by absorbing ultraviolet radiation through the ozone layer, burning meteors by friction and temperature preventing them from reaching the surface and regulating the amount of heat by the effect stove.
The main gases that make up the atmosphere are: nitrogen (N2), oxygen (O2), argon (Ar), carbon dioxide (CO2), water vapor (H2O), helium (He) and hydrogen (H).
Atmosphere layers
The Earth's atmosphere has different characteristics along its length, which allows it to be divided by its dynamics into five layers according to altitude.
The layers of the atmosphere, from the closest to the furthest from the Earth's surface, are: troposphere, stratosphere, mesosphere, thermosphere and exosphere.
THE troposphere It is the layer of the atmosphere closest to the earth's surface, its altitude varies from 8 km at the poles to 20 km at the equator. It is where we live and where meteorological phenomena occur. Because it is formed by the highest concentration of gases, the troposphere is the densest layer and holds 80% of the weight exerted by the atmosphere.
THE stratosphere is the layer located after the troposphere, concentrates 19% of atmospheric gases and extends up to 50 km in altitude. It houses the ozone layer, which protects the planet's beings from the ultraviolet rays coming from the Sun. Its composition is rich in ozone (O3) and low in oxygen (O2).
THE mesosphere comes after the stratosphere and is the coldest layer of the atmosphere, as its temperature can reach -100ºC. It is located at an altitude of 80 km above the ground and is a region that has not been studied much, as planes and atmospheric balloons only travel to the layer before it.
THE thermosphere it is located above the mesosphere and is the hottest layer of the atmosphere, as the temperature can reach the upper limit of 2000 ºC. Its upper limit is 450 km above the earth's surface, so it is the most extensive layer. The ionosphere is a region located in this layer, characterized by the concentration of charged particles, where the aurora borealis and aurora australis phenomena occur.
THE exosphere it is the outermost layer of the Earth's atmosphere and is more than 900 km from the planet's surface, so it predates outer space.
Learn more about atmosphere layers.
composition of the atmosphere
The composition of atmosphere terrestrial is variable along the layers that compose it. It is basically formed by gases, water vapor and dust, which are particles in suspension.
In dry air volume, approximately 99% is formed by nitrogen and oxygen and 1% by other gases. Some of the gases that make up the atmosphere and their percentages are:
- 78.08% nitrogen
- 20.95% oxygen
- 0.93% argon
- 0.035% carbon dioxide
- 0.0018% neon
As we have seen, nitrogen is the most abundant gas in the atmosphere. It is important mainly because it is present in cellular structures such as DNA, amino acids and proteins.
Although it is necessary for living beings, it is not possible to use it in the form that is available in the air and then the fixation biological activity of the element is carried out by bacteria and cyanobacteria to make nitrogen assimilable through the nitrogen cycle. nitrogen.
Oxygen is indispensable for the existence of living beings for vital processes such as cellular respiration and photosynthesis.
Learn more about air composition.
primitive atmosphere
The Earth's atmosphere at the beginning was quite different from what we know today. It is believed that its formation, 4 billion years ago, was influenced by a great warming of the planet followed by cooling, which caused the release of gases.
The planet presented a mixture of hydrogen, methane, ammonia and water vapor, characterizing a highly reducing environment.
Gradually, chemical reactions took place, made possible by solar radiation and electrical discharges, changed the atmospheric gases and allowed the existence of living beings.
These gases would have undergone chemical reactions, by the action of solar radiation and electrical discharges in photochemical processes, giving rise to the current atmosphere. For example, ammonia (NH3) and methane (CH4) may have reacted with each other and formed nitrogen (N2) and carbon dioxide (CO2).
Also read about origin of earth.
Atmosphere of the solar system planets
The layer of gases that surrounds the planets has a variable composition. Check below the main characteristics of the atmosphere of the other planets of the Solar System.
The planet Mercury It has a simple atmosphere, almost no gases and is quite rarefied. The main gases that compose it are: oxygen, hydrogen and helium.
The planet Venus it is the hottest planet in the solar system and its dense atmosphere contributes to the retention of heat at the surface because of the greenhouse effect. The main gases that compose it are: carbon dioxide and hydrogen.
The planet Mars It is called the red planet because it has a high amount of dust in its atmosphere. The main gases that compose it are: carbon dioxide, nitrogen and argon.
The planet Jupiter It is a gas giant, whose atmosphere is basically made up of hydrogen and helium. Because of the intense winds on the surface of the planet, it is common for storms to occur, visualized as a large red spot.
The planet Saturn has a thick atmosphere, rich in hydrogen and helium. It also has small amounts of ammonia, which gives the white and yellow spots seen on the planet.
The planet Uranus is composed of hydrogen, helium and methane. The bluish color on the planet is caused by the absorption of red light by methane.
The planet Neptune has a dense atmosphere formed by the gases hydrogen, helium and methane and as with Uranus, the bright blue color of the planet comes from the amounts of methane in the atmosphere.
Read more about atmosphere of the planets.
