Composition and Structure of the Atmosphere, Layers, Diagram

Structure of the Atmosphere

We are all aware that the existence of life on earth makes it a special planet. One of the prerequisites for life on this planet is access to clean air. Multiple gases are mixed together to form the air, which surrounds the earth on all sides. The term “atmosphere” refers to the air that surrounds the world. There are numerous elements that make up our atmosphere. However, the atmosphere’s structure is made up of a variety of layers.

Various gases are mixed together to form the atmosphere. It has gases that are essential for life, like oxygen for people and animals and carbon dioxide for plants. It surrounds the entire earth and is held in place by the earth’s gravity. It aids in preventing life-threatening UV rays and maintains the ideal temperature required for life. Typically, the atmosphere reaches up to 1600 kilometres from the surface of the globe. However, 32 km from the earth’s surface is where 99 percent of the atmosphere’s entire mass is contained.

Read about: Climate of India

Composition of the Atmosphere

Different kinds of gases are mixed together to form the atmosphere. The two primary gases in the atmosphere are oxygen and nitrogen, which together make up 99 per cent of the atmosphere. The remainder of the atmosphere is made up of other gases, including argon, carbon dioxide, neon, helium, hydrogen, and others. At altitudes of 120 km, the proportion of the gases changes in the upper layers of the atmosphere, making oxygen almost insignificant.

Similar to water vapour, carbon dioxide is only present up to 90 kilometres from the earth’s surface. About 78% of the gases in the Earth’s atmosphere are nitrogen, 21% are oxygen, 0.9 % are argon, and 0.1 % are other gases. The remaining 0.1 per cent of gases includes trace amounts of neon, water vapour, methane, carbon dioxide, and methane. As you move through the layers of the atmosphere, the makeup of the air remains unchanged. The number of molecules changes.

Carbon Dioxide

Carbon dioxide is an extremely significant gas in meteorology. It is opaque to emitted tidal radiation but transparent to incoming sun radiation (insolation). It filters off some of the terrestrial radiation and reflects back some of it toward the surface of the planet. For the most part, carbon dioxide is to blame for the greenhouse effect. The volume of carbon dioxide has been increasing during the past few decades, primarily as a result of the burning of fossil fuels, even if the volume of other gases in the atmosphere has remained steady. The primary cause of global warming is this rising carbon dioxide concentration.

Ozone Gas

Another significant element of the atmosphere, ozone, is primarily found between 10 and 50 kilometres above the surface of the globe. It serves as a screen by absorbing the sun’s ultraviolet radiation and blocking its path to the earth’s surface. Only the ozone layer in the stratosphere contains the small amount of ozone gas that is present in the atmosphere.

Water Vapour

Water vapour is the name for the gaseous form of water that exists in the atmosphere. It is the origin of all precipitation types. As you ascend, less water vapour is produced. It also gets smaller as you move away from the poles and toward the equator (or low latitudes) (or towards the high latitudes). Up to 4% of it, which is found in warm and humid regions, may be present in the atmosphere at any given time. Evaporation and transpiration are the two ways that water vapour enters the atmosphere. While transpiration occurs from plants, trees, and other living things, evaporation occurs in oceans, seas, rivers, ponds, and lakes.

Water vapour retains the heat that the planet radiates by absorbing some of the incoming solar radiation (insolation) from the sun. As a result, it works as a blanket, keeping the ground from getting too hot or too cold. The stability and instability of the air are also influenced by water vapour.

Layered Structure of the Atmosphere

Depending upon temperature there are five layers in the Structure of the Atmosphere. These are:

• Troposphere
• Stratosphere
• Mesosphere
• Thermosphere
• Exosphere

Structure of the Atmosphere Diagram

Here is the pictorial diagram of the Structure of the Atmosphere:

Troposphere

It is regarded as the Earth’s atmosphere’s base and lowest layer. The troposphere rises from the earth’s surface to a height of 8 km (at the poles) to 18 km (equator). Hot convection currents that force the gases upward are the primary cause of the equator’s higher height. Within this layer, a variety of meteorological changes take place. Water vapour and mature particles are present in this stratum. Temperature drops by 1 degree Celsius for every 165 metres of atmosphere height as height rises. The term for this is normal lapse rate. Between the troposphere and the stratosphere is the tropopause, or transitional zone.

Stratosphere

Above the troposphere, it is the second layer of the atmosphere. It rises 50 kilometres above the surface of the earth. Due to its low water vapour content, this stratum is extremely dry. The fact that this layer is above stormy weather and contains strong, consistent horizontal winds gives it some advantages for flight. This layer contains the ozone layer. The ozone layer shields the world from dangerous radiation by absorbing UV rays. The mesosphere and Stratosphere are separated by the Stratopause. 

Mesosphere

Over the stratosphere is the Mesosphere. It is the layer of the atmosphere that is the coldest. Starting at 50 km above the surface of the Earth and rising to 80 km is the mesosphere. In this layer, the temperature decreases with height. It hits -100 degrees Celsius after 80 km. In this layer, meteors burn up. Mesopause, the boundary between the mesosphere and the thermosphere, is the highest limit. 

Thermosphere

Between 80 and 400 km above the Mesopause, this layer can be found. This layer reflects radio waves that are emitted from the earth. With this layer’s height growing, the temperature begins to rise once more. The temperature here starts increasing with height. This layer contains satellites and the aurora.

Ionosphere

The Ionosphere is the name for the lower thermosphere. Ions, which are electrically charged particles, make up the ionosphere. The layer of the Earth’s atmosphere that is ionised by cosmic and solar radiation is known as this layer. It is situated 80 to 400 kilometres above the Mesopause.

Exosphere

It is the atmosphere’s topmost layer. The Exosphere refers to the region where atoms and molecules can escape into space. It reaches 10,000 kilometres from the thermosphere’s apex. Gases are very sparse in this sphere due to the lack of gravitational force. Therefore, the density of air is very less here.

Structure of the Atmosphere UPSC Facts

• From lowest to highest, the major layers are the troposphere, stratosphere, mesosphere, thermosphere and exosphere.
• About 78% of the gases in the Earth’s atmosphere are nitrogen, 21% are oxygen, 0.9 % are argon, and 0.1 % are other gases.
• The remaining 0.1 per cent of gases includes trace amounts of neon, water vapour, methane, carbon dioxide, and methane.
• The thermosphere is the hottest layer.

Structure of the Atmosphere FAQs

Q) What is the atmosphere made of?

Ans. About 78% of the gases in the Earth’s atmosphere are nitrogen, 21% are oxygen, 0.9 % are argon, and 0.1 % are other gases. The remaining 0.1 per cent of gases includes trace amounts of neon, water vapour, methane, carbon dioxide, and methane.

Q) How does the composition and structure of the atmosphere insulate the earth?

Ans.   The atmosphere acts as a thick layer of insulation, shielding the planet. The Greenhouse Effect is what happens when heat from the Sun is absorbed and kept inside the atmosphere, keeping the Earth warm.

Q) What is the best definition of atmosphere?

Ans. the gaseous envelope of a celestial body (such as a planet): the whole mass of air surrounding the earth.

Q) What are the main 5 layers of the atmosphere?

Ans. From lowest to highest, the major layers are the troposphere, stratosphere, mesosphere, thermosphere and exosphere.

Q) Which layer is the hottest?

Ans. The Thermosphere.

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