La atmosphere The atmosphere is the gaseous envelope that surrounds the Earth and is held to it by the force of gravity. This vital layer not only contains the gases essential for the survival of living beings, but also acts as a shield against harmful solar radiation and is essential in the water cycle. To learn more about the importance of the atmosphere on our planet, you can visit the Earth's atmosphere.
Since its formation approximately 4600 million years, the atmosphere has undergone a number of significant changes in its composition. Initially, the atmosphere was composed mostly of carbon dioxide (CO2), with little or no oxygen present. It was only through the photosynthetic activity of the first living organisms that oxygen began to accumulate, eventually creating an atmosphere similar to the one we know today. To learn more about the composition of the atmosphere, see This article on the composition of the atmosphere.
The atmosphere can be divided into horizontal layers defined by different variables, such as pressure, temperature, density, chemical composition y electric and magnetic molecular stateThese layers are not uniform across the planet, as their thickness and characteristics can vary considerably depending on geographic location and climatic conditions. A detailed analysis of the layers of the atmosphere can be found in This resource on the layers of the atmosphere.
Below is a detailed description of the main layers of the atmosphere, starting from the Earth's surface and moving out into outer space:
1. Homosphere
La homosphere It extends to an altitude of approximately 80 kmIn this first layer, the chemical composition of the gases is relatively uniform. Here, the ideal gas laws apply, and a continuous mixing of atmospheric components is observed, resulting in variations in density and pressure at different altitudes. The homosphere is where meteorological phenomena develop and most of the climate events we experience occur. Changes in the structure of the atmosphere, including the homosphere, are essential to understanding climate, so feel free to read more at This article on the variation of temperature with height.
2. Heterosphere
Above the homosphere is the Heterosphere, which begins at an altitude of 80 km and extends into space. In this region, the chemical composition begins to vary, as lighter gases, such as helium and hydrogen, tend to be located in the higher layers, while heavier gases, such as oxygen and nitrogen, are found closer to Earth. Here, pressure and temperature decrease considerably, and the gas mixture is less uniform. For information on the phenomena in this layer, we recommend visiting This article about the atmosphere.
The heterosphere is divided into several sublayers: the nitrogen layer (up to 200 km), the atomic oxygen layer (between 200 and 1.000 km), and the helium layer (between 1.000 and 3.500 km). Gas separation occurs due to diffusion, resulting in a decrease in density with increasing altitude.
3. Troposphere
La troposphere It is the layer closest to the Earth's surface, which varies in height between 9 and 18 km depending on the location: lower at the poles and higher at the equator. This blanket of air not only hosts most of the life on Earth, but also contains approximately 75% of the mass of the atmosphere. In this layer, the temperature decreases with altitude, averaging a decrease of approximately 0.65 °C per 100 m altitude. For additional information on how these layers work, we suggest reading This article about the layers of the Earth.
The troposphere is where meteorological phenomena such as rain, winds, and storms occur. At the top of the troposphere is the tropopause, which marks the boundary between the troposphere and the stratosphere, where the temperature remains relatively constant and convective activity is minimized. To learn more about the types of clouds that form in this layer, see This article about altocumulus.
4. Stratosphere
La stratosphere extends from the tropopause, which is located approximately 15 km on the surface, up to the stratopause 50 km high. In this layer, the temperature begins to increase with altitude, a phenomenon that is due to the presence of the ozone layerThis ozone layer is crucial, as it absorbs most of the sun's harmful ultraviolet radiation, thus protecting life on Earth. To learn more about the importance of this layer, visit This article about the ozone layer.
Ozone is concentrated between the 20 and 30 km altitude. The stratosphere is also where commercial airplanes fly to avoid the turbulent effects of the troposphere.
5. Mesosphere
Located between the 50 and 85 km of altitude, the mesosphere It is the coldest layer of the atmosphere, with temperatures that can drop to -85 ° C at their maximum altitude. This is where meteorites disintegrate due to the high atmospheric density. Shooting star phenomena also occur in this region. To learn more about how these phenomena occur, see This article explains the formation of cirrus clouds.
La mesopause is the term used to refer to the upper border of this layer.
6. Thermosphere
La thermosphere, which extends from 85 km to 600 km, experiences a significant increase in temperature, which can reach up to 1500 ° CIn this layer, gas ionization is prominent, leading to the formation of the auroras. As the gases are ionized, they become electrically charged particles that affect radio communications and other technological systems. To understand how temperature varies with altitude, visit .
The International Space Station orbits in this layer, functioning as an international research laboratory.
7. Exosphere
La exosphere It is the outermost layer of the atmosphere, extending from 600 km to 10.000 kmIn this layer, gases are extremely rare and in an atomic state, meaning they have a very low probability of colliding with each other. This layer contains low-orbit and geostationary satellites, and is also a region where the atmosphere begins to merge with outer space. Here, satellites move at high speeds, and the atmosphere is almost nonexistent.
The exosphere also hosts the Van Allen Belts, which are regions of intense radiation where charged particles are trapped by Earth's magnetic field. For more information on how the atmospheres of other planets compare to ours, we invite you to read This article about Jupiter's atmosphere.
Impact of Climate Change on the Structure of the Atmosphere
Recent research has shown that human activity is altering the structure of the atmosphere. For example, greenhouse gases have caused the troposphere to expand and the stratosphere to contract. This phenomenon may be responsible for changes in weather patterns and the frequency of extreme weather events. For a broader perspective on the effect of greenhouse gases, you can visit This article on the conversion of greenhouse gases into stones.
The tropopause, which separates the troposphere from the stratosphere, has risen significantly over the past few decades, suggesting that the layer of the atmosphere closest to life on Earth is thickening as global warming progresses. This thickening could lead to increased intensity of storms and other weather phenomena.
Furthermore, the thinning of the stratosphere has been correlated with changes in temperature distribution, demonstrating that climate change continues to affect the atmosphere in multiple ways, highlighting the urgent need to address greenhouse gas emissions.
The atmosphere, in its complex stratification, is not only an essential component for life on Earth, but also a vital indicator of the environmental changes we are experiencing. It is crucial that we continue to study and understand these changes to protect our planet and ensure a sustainable future.
