Atmosphere:The Domain of Earth

The Earth on which we live has a perfect and balanced functioning system, concealing countless miracles, facts, wonders and marvels. Many have been discovered by science, but undoubtedly, there are still many mysteries on this Earth waiting to be uncovered.

The Earth is divided into four domains: lithosphere, hydrosphere, atmosphere, and biosphere. Today, let’s learn about a crucial domain of Earth – the atmosphere.

What is Atmosphere?

The atmosphere is the domain of Earth that extends from the surface to space. It is also known as the “envelope of gases”, which refers covering the Earth with layers of gases like the envelope covers anything. Every living being, whether human, animal, bird, or plant, relies on the atmosphere, as it provides the oxygen which we inhale. The atmosphere is a mixture of gases, including nitrogen, oxygen, argon, carbon dioxide, and other trace gases. About 21% of the atmosphere consists of oxygen, crucial for the sustenance of living organisms.

The boundary between the atmosphere and outer space is not clearly defined. The atmosphere is responsible for the blue color of the sky. When sunlight interacts with the Earth’s atmosphere, the blue color is scattered. Without the atmosphere, darkness would prevail everywhere. The atmosphere plays a significant role in changing weather conditions due to factors such as humidity, clouds, and air pressure.

The atmosphere acts as a shield against harmful solar rays, including those that could lead to dangerous diseases like cancer. It consists of major layers: troposphere, stratosphere, mesosphere, thermosphere, and exosphere. Each layer has its unique characteristics and functions.

Lets discuss each layer separately;


The troposphere is the first and lowest layer of the atmosphere. “Tropo” means change, and “sphere” means region or layer, indicating that the troposphere is the layer where all weather changes occur. Starting from the Earth’s surface, it extends up to 12 km. This layer is where all living things, including plants, animals, birds, and humans, exist. Additionally, clouds, rainfall, snowfall, winds, dust particles, water vapor, water balloons, and airplanes are found in this layer.

Approximately 75% of the gases in the atmosphere exist in the troposphere. The average temperature in this layer ranges from 15°C to -56°C. The lowest part of the troposphere is warmer because it is closer to the Earth, while its highest part is colder.


The stratosphere is the second-lowest layer of the atmosphere. “Strato” means ‘layer,’ and it is referred to as a layered region because gases and air layers are spread within this layer of the atmosphere. It begins above the troposphere and is separated from it by the tropopause. Starting from the tropopause, the stratosphere extends up to 15 km.Kts temperature increases with it’s height.

Within the layers of the stratosphere, there is a specific layer known as the ozone layer. . The ozone layer is situated in the upper part of the stratosphere. Composed of ozone gas (O₃), it serves as a shield against harmful solar ultraviolet rays (UV rays) that can cause dangerous diseases like skin cancer. The ozone layer absorbs these rays and prevents them from reaching the Earth. It wouldn’t be incorrect to say that life is not possible without the stratosphere.


Meso” means middle, and “sphere” means region, making the mesosphere the middle layer of the atmosphere, situated between the stratosphere and thermosphere. Its height ranges from 50 km to 80 km.

In space, there are meteoroids, which are chunks and fragments of space rocks. When these meteoroids enter Earth’s atmosphere, their speed increases, and due to atmospheric friction, they burn in the mesosphere. This burning phenomenon is what we perceive on Earth’s surface as a shooting star. Therefore, scientists often conduct research on this layer.

Weather balloons ,used for weather forecasting, are released into the mesosphere. These balloons are filled with hydrogen or helium. As the altitude increases, the temperature decreases in the mesosphere, ranging from -2.5°C to -90°C, making it the coldest layer. The upper layer of the mesosphere is known as the mesopause, where the temperature can drop to -100°C to -130°C.


Thermo” means hot; the thermosphere is the fourth layer of the atmosphere with an extremely high temperature ranging from -92°C to 1200°C, although the density here is very low. This characteristic prevents satellites in the thermosphere from melting. Positioned between the mesosphere and exosphere, it extends from 80 km to 400 km.

The thermosphere is remarkably thin, making it impassable for sound waves. An intriguing fact about this layer is the occurrence of the Aurora Borealis, commonly seen in polar regions. When charged particles from the Sun interact with Earth’s magnetic field, it generates the mesmerizing Aurora Borealis.


Exo” means outer; the exosphere is the outermost layer of the atmosphere, separating space from the atmosphere. It extends from 600 km to 10,000 km above the Earth. The density here is extremely low, allowing gases like hydrogen and helium molecules to move freely. Gravity is significantly reduced, and the temperature is cold. This layer is the first to interact with solar radiations, protecting the other atmospheric layers from UV radiations.

Understanding the Earth’s domain, the atmosphere, and its layers reveals how crucial they are for us and for the Earth.


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