Atmosphere Composition

Earth’s Atmosphere: Structure and Functions

Introduction to Atmosphere:

Earth’s atmosphere is a dynamic and complex mixture of gases, forming a thick gaseous envelope essential for the survival of life. Governed by gravity, this atmospheric layer is a key component in shaping Earth’s climate, weather patterns, and overall environmental conditions.

Layers and Characteristics of the Atmosphere:

Earth’s atmosphere is divided into layers, each distinguished by specific properties such as temperature, pressure, and gaseous composition. These layers, from the troposphere to the exosphere, exhibit varying density and play an important role in regulating Earth’s thermal balance. The greenhouse effect, which results from the selective permeability of the atmosphere to solar radiation, maintains an average surface temperature of 15°C.

Composition Dynamics of the Atmosphere:

Atmospheric composition is not stable; It develops with altitude. Carbon dioxide and water vapor, for example, are prevalent up to an altitude of about 90 km, while oxygen reduces to near-zero levels at about 120 km.

The air that forms the atmosphere is a complex mixture of gases. The dominant gases include nitrogen (78%) and oxygen (21%), with the remaining 1% including argon, carbon dioxide, ozone, water vapor, and myriad other gases.

Intensive Exploration of Atmospheric Gases:

Nitrogen (N₂) is the most abundant gas in the atmosphere, vital to the survival of plant life. This essential element undergoes a transformation process, facilitated by soil bacteria, making it accessible to plants. Nitrogen’s role extends to maintaining the nitrogen cycle, a biochemical process important for plants’ chlorophyll production.

• Oxygen:
Oxygen (O₂), the second most abundant gas, serves as a lifeline for humans and animals through respiration. Additionally, green plants contribute to oxygen levels during photosynthesis, creating a delicate balance. The oxygen cycle, which is intricately linked with the lithosphere, biosphere and atmosphere, ensures the existence of various life forms.

• Carbon Dioxide:
Carbon dioxide (CO₂), making up just 0.036% of the atmosphere, has the greatest impact. It is indispensable for photosynthesis in plants but also contributes significantly to the greenhouse effect. Global initiatives such as the Kyoto Protocol and the Paris Climate Conference attempt to regulate and reduce the effects of elevated carbon dioxide levels.

• Ozone:
Ozone (O₃), found in the stratosphere, acts as a shield against harmful ultraviolet radiation from the Sun. Human activities, particularly the release of chlorofluorocarbons (CFCs), have led to the formation of the ozone hole, leading to international agreements such as the Montreal Protocol and Kigali Agreement for ozone layer protection.

• Inert Gases:
Argon, which constitutes about 0.93% of the atmosphere, is the most important inert gas. While neon, helium, krypton, and xenon exist, they do not have any significant effect on Earth’s weather processes.

• Water Vapour:
Water vapor, a volatile gas, fluctuates in quantity depending on geographic and climatic conditions. It plays an important role in the greenhouse effect, a major contributor to Earth’s atmospheric warming. Beyond its climate impact, water vapor aids in a variety of meteorological phenomena, from dew and fog to cloud formation and precipitation.

• Aerosol:
Aerosols, microscopic suspended particles in the atmosphere, originate from a variety of sources such as sea salt, soil, pollutants and even meteorites. These particles serve as nuclei for water vapor condensation, forming clouds. Aerosols also play a role in the scattering of light, contributing to atmospheric optical phenomena.

Understanding the complex structure and functions of Earth’s atmosphere is not only a scientific pursuit but a necessity to address contemporary environmental challenges and ensure the sustainability of our planet. The delicate balance of gases and atmospheric dynamics underlines the interconnectedness of Earth’s ecosystems and the delicate balance that must be preserved for the well-being of our global environment.


Earth’s atmosphere is an important mixture of gases, which forms a protective layer important for life.
Ruled by gravity, it influences climate, weather, and environmental conditions.

Layers and Characteristics:
Divided into layers with different properties (temperature, pressure).
From the troposphere to the exosphere, each layer controls Earth’s thermal balance.
The greenhouse effect maintains an average surface temperature of 15°C.

Dynamics of Composition:
Atmospheric composition changes with altitude.
Nitrogen and water vapor extend up to 90 km; Oxygen becomes almost zero at 120 km.
Major gases: Nitrogen (78%), oxygen (21%), argon, carbon dioxide, ozone, water vapor, and others.

Exploring Atmospheric Gases:

The most abundant gas important for plant life.
Soil bacteria facilitate transformation for plant access.
Maintains the nitrogen cycle important for chlorophyll production in plants.

second most abundant; Necessary for human and animal respiration.
The oxygen cycle linked to the lithosphere, biosphere and atmosphere ensures diverse life forms.

Carbon Dioxide:
0.036% in the atmosphere; Important for photosynthesis but contributes to the greenhouse effect.
Global initiatives such as the Kyoto Protocol and the Paris Climate Conference aim to regulate elevated levels.

Found in the stratosphere, protects against harmful UV radiation.
The ozone hole was caused by human activities such as CFC releases; International agreements such as the Montreal Protocol address this.

Inert Gases:
Argon (0.93% of the atmosphere) is the most important inert gas.
Neon, helium, krypton, and xenon have no significant effect on Earth’s climate.

Water Vapour:
There are fluctuations depending on geography and climate.
Major contributor to the greenhouse effect; Affects meteorological events.

Fine particles in the atmosphere from various sources.
Act as nuclei for water vapor condensation, cloud formation, and contribute to atmospheric optical phenomena.